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RIM 2004 Reference Manual. A decision tool for

1. t na na na na na RIM USER S MANUAL Variable Gacs Gas Gec S Gc ay GMs Gps RO R10 R20 RES RPS NA AAA DO RSS HI wW Data Name Cost of tickle wait 10 days seed Cost of User Defined Option A Cost of User Defined Option B Cost of windrowing burn windrow Cost of herbicide only for broadleaf weed control Cost of broadleaf weed control wheat Cost of windrowing total burn Density of seeding Crop not phytoxically damaged Equivalent annual profit 10 years Equivalent annual profit 20 years Equivalent opening balance for 10 years Equivalent opening balance for 20 years Expected plant establishment wheat Competition factor of pasture on ryegrass Ryegrass competition factor in wheat Final balance after 10 years Final balance after 20 years Ryegrass germination 1 10 days after break Ryegrass germination 11 20 days after break Additional germination before in crop spaying Germination after in crop spraying Additional germination before in crop sprays Additional germination before in crop spraying Gross margin for sheep Ryegrass germination prior to the first chance to seed Germinated ryegrass seedlings at the break of season Germinated ryegrass plants 10 days after season break Germinated ryegrass plants 20 days after season break Ryegrass plants in early s
2. RIM USER S MANUAL derived from the phytoxicity table in the Crops amp weeds sheet and transferred to this table in the Biological results sheet Yields In calculating the results displayed in the Economics results and Biological results sheets we assume that the yields and the various impacts on yields e g rotation weed competition remain constant over the whole 20 year time frame This also applies to the gross margin results displayed near the top of the Select strategy sheet This makes those results easy to relate to current circumstances However in reality agricultural yields in Australia have shown clear upward trends in recent decades and this seems likely to continue For this reason we assumed that yields increase over time The rate of increase is hard to predict but over the long term is a very significant factor In the standard RIM model the annual rate of yield increases is set to 1 0 percent for crops and 0 5 percent for sheep products The latter value relates to production per hectare not per sheep The Biological results sheet includes a number of possible adjustments to the standard weed free yield e a percentage yield penalty for late sowing depending on the seeding strategies selected in the Select strategy sheet and the relevant yield penalty as entered in the Crops amp weeds sheet e a percentage yield penalty for not swathing barley canola taken directly from the Crops amp weeds sheet e
3. We particularly thank the following people for their help Amir Abadi ereer raids Touchstone Consultancy and Department of Agriculture WA Rob Barrett Lennard WA Herbicide Resistance Initiative David Bowran Department of Agriculture WA Roger Cousens 45 University of Melbourne Att DIiggle oS Sees dees Department of Agriculture WA CLIMA Alister Draper WA Herbicide Resistance Initiative Mike EWS assess tet Department of Agriculture WA CLIMA David Ferris 20058 WAHRI Gurjeet Gill rensar ee Then Department of Agriculture WA now Univ of Adelaide John Holmes 005 Then Department of Agriculture WA Rick Llewellyn University of Western Australia John Matthews Waite Institute University of Adelaide David Morrison 6 Then Department of Agriculture WA Bil ROY eeii sty cote tas eta es Consultant Brian Trenbath CLIMA Department of Agriculture WA Various other scientists at the Department of Agriculture Western Australia Institutions that contributed to the development of RIM Grains Research and Development Corporation The University of Western Australia The Department of Agriculture Western Australia Chapter Introduction This chapter gives a brief introduction to RIM this manual and its intended users and insight to users to help them in making long term decisions about management of ryegrass the most important weed o
4. Davidson R M 1992 Research into resistant weeds by the Victorian Department of Agriculture National Herbicide Resistance Extension Workshop Charles Hawker Conference Centre Waite Institute Adelaide GRDC Gill G Holmes J and Kelly R 1994 Herbicide Resistance A Reference Manual Miscellaneous Publication 16 94 Department of Agriculture Western Australia Kingwell R S and Pannell D J eds 1987 MIDAS A Bioeconomic Model of a Dryland Farm System Padoc Wageningen 207 pp Maxwell B Roush M and Radosevich S 1990 Prevention and management of herbicide resistant weeds In Heap J W ed Proceedings of the ninth Australian weeds conference Adelaide South Australia August 6 10 pp260 267 Morrison D A Kingwell R S Pannell D J and Ewing M A 1986 A mathematical programming model of a crop livestock farm system Agricultural Systems 20 243 68 Nelson P and Delane R eds 1990 Producing Lupins in Western Australia Bulletin 4179 Department of Agriculture Western Australia Pannell D J 1990 A model of wheat yield response to application of diclofop methyl to control ryegrass Lolium rigidum Crop Protection 9 6 422 428 Pannell D J 1995 Optimal herbicide strategies for weed control under risk aversion Review of Agricultural Economics 17 337 350 Pannell D J 1995a Economic aspects of legume management and legume reseatch in dryland farming systems of southern A
5. ha and Cpp is the cost of direct drill cultivation ha The cost of clover inoculum C ha can be calculated by multiplying the clover inoculation price Pn kg of seed by the seeding rate SRp kg ha Cic Pry x SRp The cost of insecticide application to pasture Cp ha includes the cost of insecticide only Cjop ha and the cost of application C2 ha Crp C C The fertiliser cost for pasture Cpp ha is simply the rate of application Rppp t ha multiplied by the price of fertiliser Ppp t Crp Rprp X Ppr If sowing is delayed the cost of tickle or shallow cultivation for pasture Coup ha is simply added to Cup above Cour RM cy Cocu where RM is the cost of repairs and maintenance for shallow cultivation ha and Cpsy is cost of diesel ha Control costs sheet Herbicide costs The generic equation for the cost of herbicide ha C is Cy Rm X Py Cy where R is the rate at which the herbicide is applied L ha or kg ha Py is the price of the herbicide unit and C is the application cost This equation is applied to all of the herbicide practices included in the model these being e Glyphosate at sowing knockdown option 1 Ga e Spray Seed at sowing knockdown option 1 Gip e Glyphosate Spray Seed 2 knocks Cey e Trifluralin Cir e Simazine Ceu e Artizine pre emergence Cupp e Glean pre emergence Com 19 RIM USER S MANUAL e S
6. the procedure is outlined in this chapter The procedure to add a new treatment option in RIM is not difficult but does require care to ensure that all sheets in the workbook have been altered accordingly The following instructions describe the order that the steps should be followed to ensure that the formulae correspond to the correct labels and errors do not appeat When making such substantial changes as the following always keep a copy of the unedited version and work on a renamed copy Instructions in italics are specific to RIM version 99 and would be somewhat different in RIM 2002 1 Insert a row into the Select strategy sheet at the appropriate position It is important to make a note of where you place this row because when you insert rows into other sheets as instructed later they must all correspond Insert all required labels and formatting in accordance with the rest of the sheet You may find it easier to simply copy another row into that row to ensure that the formatting colours borders protection are correct Update the treatment number in column A and renumber the treatments below it to ensure that all numbers in this column are now in numerical order 2 Insert a new row into the appropriate position in the Control costs sheet Do not forget to update the numbers in column A You will need to enter new formulae in this row but before you can do so you may need to add new information in the Prices and rates sheet to
7. a saved strategy or save a strategy for later until you have adjusted the macro for that purpose If you do you may end up overwriting important equations Instead you must first go in and change the macros In the macro sheet find the macro RestoreStrategy and edit it Change the ranges to correspond with the appropriate ranges in the Select strategy sheet Scroll down to RestoreStrategyl and change the ranges so that they correspond to the appropriate ranges for Strategy 1 in the Strategies sheet Change the remaining RestoreStrategyN macros Using the search and replace command for text can speed this procedure up but you need to be very careful not to replace something you shouldn t especially in another part of the macro module Follow the same procedure for the SaveStrategy macros Remember to start with the long version first Before you return to the Select strategy sheet to test your edited macros you MUST go to the Strategies sheet usually hidden in RIM and select Edit Clear All 32 ADDING A NEW TREATMENT Only then should you return to the Select strategy sheet So that you do not lose formulae and formatting firstly go to Save a strategy for later and click on each button for the save strategies 7 fo 5 By completing this procedure you avoid the risk that you will restore a set of data that doesn t line up with the place it s supposed to go into To ensure the Print this page years 1 10 button in the Selec
8. costs are withdrawn from the bank account so reducing interest earned The final bank balance approach is the method used in RIM because realistic complexities that are often ignored in long term financial analyses can be mote easily incorporated Prices and rates sheet The parameters in this sheet are either based directly on data obtained from various sources or derived from calculations based on this data Derived data relies on the equations as described in the proceeding sections of this chapter Cost of fuel The cost of fuel assumed to be diesel Cp L is used in the model to calculate the cost of direct drill cultivation Cpp shallow cultivation Cp y seed catching Cpsd cycloning Cpo and harvesting Cpr Oil and grease costs 15 RIM USER S MANUAL are assumed to be negligible so are not included as individual costs The cost of fuel depends on the quantity of fuel used for each operation Qp L ha as well as the price of diesel Pp L The generic equation used to determine the cost of fuel ha is Cp Qp XPp Seed catching and cycloning operating costs Seed catching and cycloning operating costs are calculated in the model The operating costs for seed catching Coso ha are found by multiplying the quantity of fuel required Ops L ha by the price of fuel Pp L and adding in the repairs and maintenance of the machinery RM ha Cosc Qpsc X Pp RM sc By substituting the rel
9. derived from wheat Rp barley R lupins R and or canola R all parameters have the unit ha R Ry Rg R Re Receipts for each crop ha are calculated in a similar way Using wheat as an example receipts are found by multiplying the relevant yield Yp t ha by the net price which is the sale price Pp t minus the cost of transport from farm to receival point C t and the cost of rail freight Cpr t Ry Yy x Py Cr Cpr Hay gross receipts R ha include the return from wheat hay barley hay canola hay lupin hay and summer pasture hay Ry Pug Vay Vip Vic Vn ip where P is the price of hay assuming all hay sells for the same price t Ypy is wheat hay yield t ha Y is barley hay yield t ha Yc is canola hay yield t ha Y is lupin hay yield t ha and Y p is pasture hay yield t ha The equation for silage gross receipts R ha uses the same yield parameters as for hay but with the price of hay replaced by that of silage P3 t R P Vg Y Yuc Ag Ypp 22 ECONOMIC EQUATIONS Pasture livestock gross receipts R ha is found by multiplying the stocking rate Skare DSE ha by the gross margin for sheep GM DSE Rp Spare X GMs Grazing is differentiated into sustainable grazing high intensity grazing and grazing in conjunction with cutting hay The gross margin for sheep is used in the equation to reduce the complexity that cou
10. farm in a region of Western Australia but need adjusting for other farm types and for other regions Users can readily alter the parameter values to suit their particular situation 36 SCOPE OF RIM amp CONTACT DETAILS Contact details for information pertaining to RIM To purchase RIM for information about RIM and for technical information related to herbicide resistance and weed management contact The Western Australian Herbicide Resistance Initiative WAHRI WAHRI Faculty of Natural and Agricultural Sciences The University of Western Australia 35 Stirling Hwy Crawley WA 6009 Phone 08 9380 7870 Email wahri agric uwa edu au Web site http wahri agtic uwa edu au For technical information related to herbicide resistance and weed management advice on using RIM effectively and advice on running RIM workshops contact Vanessa Stewart Vanessa Stewart Dryland Research Institute Agriculture Western Australia Merredin WA 6415 Phone 08 9081 3111 Email vstewatt agric wa gov au To suggest improvements changes or to report bugs in the RIM software or for advice particularly related to the software contact David Pannell David Pannell C Agriculture Western Australia Albany WA 6330 Phone 08 9892 8495 Fax 08 9844 8659 Email David Pannell uwa edu au 37 RIM USER S MANUAL Bibliography Cousens R 1985 A simple model relating yield loss to weed density Annuls of Applied Biology 107 239 252
11. impacts and competitiveness of lupins can be adjusted to approximate another legume crop if desired e g field peas chick peas faba beans The treatment options available to another legume using PRINCIPAL ASSUMPTIONS this proxy approach is the same as that available for lupins It is not possible to represent both lupins and another legume crop in a single model run in this version of RIM It is assumed in RIM that subterranean clover is self regenerating with a cost for establishment included only if the interval between clover phases in the rotation is three years or greater Cadiz pasture exists in the model as a representative of a new class of phase pasture species that is re sown regularly in the first year of any pasture phase rather than regenerating naturally after a crop phase Tillage and machinery It is assumed that a minimum tillage crop establishment system one pass operation is used An autumn tickle is included as a control option and may be selected by the user Machinery costs are calculated on a per hectare basis and include purchase and repayment costs The costs are only included if a strategy that requires the machinery is selected The cost is then distributed across all 10 or 20 years of the analysis If special machinery is required for a treatment e g seed catching it is assumed that it is purchased new and repaid over a specified period by default 8 years If the User wishes to include the purchas
12. in terms of tillage harvest and pest control are displayed in Table 12 The production cost for lupins is transferred from the Crop input rates and per hectare costs table in the Prices amp rates sheet into this table if lupins are grown in the year in question Likewise for wheat barley and canola the equivalent cost is transferred from Table 14 to this table but with savings in nitrogen fertiliser deducted from the cost Production costs for pasture are transferred from the total inputs calculation Prices amp rates sheet and placed in the table according to pasture grown and number of years of consecutive growth for each year that it is grown Data from Table 12 is used in the Economic results sheet to calculate non weed control costs for grain and pasture 28 THE CALCS SHEET Table 13 details the cost of re sowing regenerating clover pasture if it is required If this cost is applicable it is included in the production costs for regenerating clover pasture in Table 12 as explained above Table 15 displays the returns for pasture for each year in which pasture is selected as an enterprise It takes into account the strategies for grazing the stocking rate as calculated in Table 9 above and the sheep gross margin as calculated in the Prices amp rates sheet The total pasture returns from this table are transferred directly into the pasture livestock gross receipts line in the Economic results sheet Machinery costs are collat
13. legume crop wheat barley or canola grown after a legume lupins clover or cadiz is expected to achieve a higher yield than if grown after a non legume crop or volunteer pasture e It is expected that canola or lupins grown after a break of only one year e after a single year of wheat barley or canola will realise a lower than average yield due to the increased risk of disease occurring The applicable yield penalty is specified in the Crops amp weeds sheet e The set of available weed control options differs depending on the selected crops and pastures This selection in turn has a bearing on the number of ryegrass seeds in the soil in autumn and the number of ryegrass plants setting seed in spring resulting in varying levels of weed competition on crops and hence varying crop yields In RIM it is assumed that the variety of canola is triazine tolerant TT canola However the user may assume a non TT canola by imposing an appropriate chemical regime and making any necessary adjustments to yield Similarly the parameters specified in the model for barley pertain to Unicorn barley Even so there is sufficient flexibility in RIM for the user to alter the parameters to represent a different variety Weed control treatments and yields must be carefully changed to reflect the alternative barley variety selected The model has been designed to represent a farming system based on soil types suited to lupins The price yield rotational
14. of Glean pre emergence ha Corw Cost of green manuring wheat ha 40 Variable Corr Casp Cu Cup CHG Cusrw Cic Cinw Clop Clow Cip Cw Cm Cup Cup Cuw Co Cou Cosc Coc CRF Csw Cs Cs4E Csc Cscp Csi Csp Cspc Csm Cy Cswp Cr Crr Data Name Cost of Gramoxone crop top Cost of Glyphosate Spray Seed 2 knocks Cost of herbicide Cost of hay baling Cost of Hoegrass Extra cost of high seeding rate wheat Total cost of inoculation of legume pasture or lupins Cost of insurance wheat Cost of insecticide only pasture Cost of insecticide only wheat Cost of insecticide including application pasture Cost of insecticide including application wheat Cost of mowing total Cost of contract mowing Machinery amp input costs pasture Machinery amp input costs wheat Fixed operating cost for pastures Other selective herbicide Operating costs for seed catching Operating costs for cycloning Cost of rail freight Cost of seed including dressing cleaning etc wheat Cost of Select Cost of Simazine post emergence Cost of seed catching Cost of seed catching total burn Cost of cutting silage Cost of Spray Seed at sowing knockdown option 1 Cost of sowing pasture clover Cost of Simazine Cost of swathing Cost of seed catch windrow machinery purchase Cost of transport farm to receival point Cost of Trifluralin 41 Units
15. options These values are presented in the Control sheet They were selected by reviewing trial results conducted in RIM USER S MANUAL Western Australia and elsewhere and have been checked against farmer experience It is possible to alter these values if the user wishes to assume a different level of weed control Control treatments included in the model have different implementation times and will affect weeds at different stages of their life cycle Weeds germinate at different times following the break of season and continue to germinate well into the growing season Time of germination also affects the competitiveness of weeds Late germinating weeds are less competitive and so produce fewer seeds per plant Enterprise options In this version of RIM there are seven enterprise options wheat barley canola lupins regenerating pasture assumed to be subterranean clover phase pasture assumed to be cadiz serradella and volunteer pasture Almost any sequence of these enterprises can be specified in the Select strategy sheet The exception is that production of lupins or canola for two or more consecutive years is not permitted due to the very high yield losses that would occur from disease For some purposes cadiz and sub clover pastures are treated as being equivalent for factors such as weed treatment effectiveness and weed treatment costs The sequence of crops and pastures may affect yields for the following reasons e A non
16. percentage 11 20 days after the break G is included in the formula along with R to calculate ryegrass seeds m remaining at 20 days after the season break R2 Rs Resi x I Gyy The ryegrass seeds m at the time for post emergence spraying Rppo is calculated using R and the additional germination percentage after day 20 and before in crop spraying Gxc Ropes Rs X 1 Gycs The effect of competition by the crop on ryegrass seed set Rsp seeds m is described by the following equation which has been adapted by Diggle from Maxwell Roush and Radosevich 1990 Provision is made in the model to only include the parameters in this equation that are relevant to the specific strategies that are selected for a scenario 10 BIOLOGICAL EQUATIONS Ww Rop Rays X x t xs a Wy cxD a Wy f Gres where Rys is the maximum ryegrass seed production seeds m year a is the ryegrass background competition factor used to calculate base level of intra species competition affecting ryegrass seed production W is the healthy equivalent ryegrass plants m in spring is the competition factor of crop on ryegrass D represents density of crop plants m7 and either refers to high density seeding or standard density depending on what is selected in the model f is the competition effect of pasture on ryegrass equal to the competition factor of wheat multiplied by an assumed wheat equivalent pasture density Gres is
17. rx U MTR The equivalent opening balance is the same as the net present value concept as used by economists If it was possible to earn a constant profit per hectare per year over 10 years the equivalent annual profit EAP ha is an annual amount that would result in the FB after allowing for interest and tax Baty ra h aR EO gt r IK 1 r 1 1 MTR We use the PMT function in Excel which uses the parameters EOB N number of years and 7 When no allowance is made for tax and interest the formula is used as follows EAP PMT r N EOB 25 RIM USER S MANUAL However in Rim where we do make allowances for tax and interest the formula used is EAP PMT r x 1 MTR N 08 i 1 MTR This is equivalent to the complex looking equation given above The value of EAP is transferred into the Select strategy sheet as the average annual profit ha yr years 1 10 The final balance after 20 years FB ha the equivalent opening balance for 20 years EOB ha and the equivalent annual profit EAP ha are calculated as for the 10 year time period 26 Chapter The Calcs Sheet This chapter provides a descriptive explanation of the workings within the Calcs sheet hidden in RIM convert parameters from some sheets into appropriate forms for use in other sheets It also deals with selected strategies ensuring that only relevant calculations for those strat
18. the ryegrass plants m in early spring as calculated previously and s is the sub lethal effect of selective herbicides resulting in lower seed production of surviving weeds Ryegrass seeds m present at spring time R depend on the germination after in crop sprays Rpgs the additional germination percentage before in crop sprays Gac and the natural mortality of dormant seeds during the season M at the time for post emergence spraying Rss Rogs x 1 Gycs x I M 5 Spring seed produced Rsp seeds m is calculated by multiplying the number of seeds produced per plant R derived above by the ryegrass plants m setting seed in September Ggsg see above Rsp Rser X Gass The ryegrass seeds m present just before harvest Rsgy is based on the parameters spring seed present Rsp and ryegrass seeds present at spring time Rss as explained above R pu Rsp X Rss The ryegrass seeds present after summer R55 seeds m can be calculated by Rsas Rss Rsp x Psy kQ M5 where Psy refers to the proportion of seeds surviving harvest as calculated in the Calcs sheet and Mss is the percent natural mortality of seeds over summer as in the Crops amp weeds sheet Crop phytoxicity Phytotoxic damage occurs when a herbicide has adverse direct effects on a crop This number feeds into the expected weed free yield equations The proportion of crop not phytoxically damaged by a specific herbicide Penp is 11
19. Ccu Cos Csw Cm Cua Csc Cscs Cwsg Cwre Cswe Ca Cus All of the parameters are defined in the Appendix and all are explained above in the section describing the Control costs sheet except for Cy the seedcatch windrow machinery purchase ha The repayment costs are defined in the description in the Prices amp rates sheet 1 Repayment costs of machinery and are included in the Economics results sheet if the age of the machine is still within the loan repayment period The total variable input cost TVC ha is found by summing the total non weed control costs and the total weed control costs 23 RIM USER S MANUAL TVC TCw TCw Net returns To calculate the net returns NR ha the total variable costs are subtracted from the total receipts The net return for each year is transferred into the Select strategy sheet as the gross margin NR TR TVC Results that allow for inflation interest and tax The inflation rate on sale prices in agriculture has historically been lower than the inflation rate on input purchase prices This is commonly referred to in Australia as the cost price squeeze and in North America is recognised as the cause of the farm problem It is the reason why farmers have had to improve their productivity levels in order to remain in business In RIM it is assumed that this trend will continue for the time being so the inflation rate set on crop and sheep product pric
20. HEET 25 Secs ssidecaschece quvediveatvncduaesceude coectccuevucsbesdgsvaceuesvesigedeodteet i uesteonane 15 COSt Of UE ssiessiecs ssscaddeisdelecsssseasthadevcanssisogsdecsdets nenaiesbizesscdsiesiacdvpsyeersaesabeadieaendenssasedtess 15 Seed catching and cycloning operating Costs essessssesessesessreersereeresrsrresrsreereseesrssereees 16 Repayment costs of machinery cccscecesceesceeesecesscecssecesccecseceeaeecssecseneecsaeceeeeeesaeceteeeenaeens 16 Machinery and input costs fOr CrOPS esssseseesseeeesensersereeresrsreerrsresrssrerresrsressrsreersseeresseseeee 16 Extra cost of high Seeding Tat ii niione o neia e E E AEE EEEE 18 Total input costs for volunteer sub clover and cadiz serradella pastures 1 0000008 18 CONTROL COSTS SHEET esses scsi cvvsusteeseves hirie E aroe reaa AEAEE Ea EES EEE an iria 19 Herbicide COSTS suisse enea EE O ENE es ORE E 19 Other COSTS menena a e a a A EHR A ea A eR E a 20 ECONOMIC RESULTS SHEET ienr r E E N RE A 22 ILEA EAE E E E E S E E E E 22 NPIL LAE E E E E E E A E E 23 MARAA A TE E EEE AAAS E A EEE 24 Results that allow for inflation interest and taX ssoseseseseeeeeeeeseeersreerserrerrerreressee 24 THE CALCS SHEET 10 0 0 sscssscsccesssscscsscescssssscssenessssncssessessessessnessssnessessessessossnesessneseesoess 27 ADDING A NEW TREATMENT csscccssscsscssssscscsnessssssscesssssssssssnesssssessessessessessnessessesees 30 PROCEDURE TO CREATE A VERSION FOR PUBLIC RELEASE
21. RIM 2004 Reference Manual A decision tool for integrated management of herbicide resistant annual ryegrass Johanna M Pluske David J Pannell and Anne L Bennett School of Agricultural amp Resource Economics The University of Western Australia 35 Stirling Hwy Crawley Western Australia 6009 Last updated 27 May July 2004 RIM USER S MANUAL Citation Pluske J M Pannell D J and Bennett A L 2004 RIM 2004 Reference Manual A Decision Tool for Integrated Management of Herbicide Resistant Annual Ryegrass School of Agricultural and Resource Economics University of Western Australia Crawley Australia This Reference Manual is 2004 Johanna M Pluske David J Pannell and Anne L Bennett Table of Contents CREDITS AND ACKNOWLEDGEMENTS scsscsssssssscssesssssensssessssesssssescessnessssnesseses IV INTRODUCTION scscsssssssssssssessessssessessssessessssessessssessessssessessssessessssessessssessesessessesesseseesees 1 THIS MANUAL ae e E nE E E e EaSI te eves ynests ensetessoseut tvaces ts E ie 2 PRINCIPAL ASSUMPTIONS sseseseseeeeseroesesesecceroroesesesoceesosoesesecocoesoroeseseccerososoeseseeoeeesorsesecesoe 3 INTRODUCTION nri iro err e ea re E T e EEEE a er re Raar ais 3 OUTLINE OF ASSUMPTIONS cs dropi seet arrene EE beds cvytasrs sntaceevensieds sunete dboustuscs S Aen 3 USM R EE E A T T 3 Region and climatic VATIATION 0 ccsceece eee eeceesceeecesecesecusecusecusecasecseeeseesseenaeenseesseene
22. a percentage yield boost if green manuring is included in the previous year from the Crops amp weeds sheet e a yield boost when a cereal crop is grown after pasture or lupins The expected weed free crop yield e g wheat Yypy t ha is dependant on the crop position in the rotation i e the number of years it is grown after pasture or lupins In Table 9 in the Calcs sheet all of the yields for each possible rotation scenario are calculated Depending on selections made in the Select strategy sheet the appropriate yield is used in calculations in the Biological results sheet together with adjustments for yield penalties ot boosts to determine final weed free crop yield For wheat YFprp t ha the equation is YF wrw Ywew x 1 P s x 14 YBeay x Dp where YP refers to the percentage yield penalty for late sowing YBey denotes the percentage yield boost from previous green manuting and Dp is the total proportion of crop not affected by phytotoxic damage Following the same reasoning as above the final expected weed free yield for barley YF prp t ha can be calculated The only change is that for barley there may be a yield penalty for not swathing YPyns 12 BIOLOGICAL EQUATIONS YF re Yyrg X I YPs x 1 YPys x 1 Boy x Dp As there may also be a yield penalty for not swathing canola the equation to calculate final expected weed free yield for canola YF t ha has the same structure as for barley YF
23. and codes then for use in other tables depending on how the enterprise is used in the rotation There are 98 different enterprise codes combining enterprises and rotations Information is used in other tables in the Calcs sheet and elsewhere in sheets where data input into specific cells depends on the enterprise and or rotation Table 9 records the weed free crop yield crop sale price weeds killed in pasture stocking rate stocking rate at high density stocking rate if hay is cut and nitrogen saving from legumes for each of the 98 enterprise codes in Table 8 This information is used in the Biological results sheet in calculating weed free yield and in other tables in the Calcs sheet The crop sale prices t for wheat barley and canola for each of the relevant years that each crop is produced are presented in Table 10 The table relies on data presented in Table 9 as described above that has been derived from grain sale prices shown in the Prices amp rates sheet This information is transferred into equations for grain gross receipts in the Economic results sheet The yield figures calculated for wheat barley canola and lupin hay in the Biological results sheet are allocated to the relevant years of production in Table 11 The production of pasture hays presented in the Pasture sheet is similarly allocated This information is used in equations to calculate hay and silage gross receipts in the Economic results sheet Production costs
24. are average annual profit ha yr for years 1 10 or years 1 20 and net return or gross margin for each year ryegrass seeds m in the soil in April and ryegrass setting seed per m in November In addition other biological and economic results are provided in the Biological results and Economic results sheets see Chapters 3 and 4 This manual Information presented in this manual extends upon the detail found in the RIM 99 User s Manual It is expected that readers of this manual are familiar with the RIM 99 computer model and User s Manual but wish to gain a deeper understanding of the equations that drive the model A web page providing the latest information and relevant reference papers about RIM is available at http www general uwa edu au u dpannell rim htm We present the overall assumptions of the model in Chapter 2 the biological equations in Chapter 3 and the economic equations in Chapter 4 Details of a hidden sheet called the Calcs sheet are outlined in Chapter 5 to enable the user to fully understanding how RIM is driven Chapter 6 outlines the scope of Rim and provides contact details for people able to provide extra information or assistance The key variables used in the equations are listed in the Appendix Chapter Principal Assumptions This chapter outlines the principal assumptions behind the RIM model Introduction Results derived from a model such as RIM are contingent upon the assumptions driving them an
25. ass plants m in eatly spring as previously discussed M is the maximum proportion of wheat yield lost at high weed densities The default value of M for all crops is 0 60 selected on the basis of statistical analyses of field trials There are a wide range of values in the literature Pannell 1990 analysed data from 14 field trials in Western Australia New South Wales and Victoria amounting to 339 data points He estimated M to be 0 5436 Using the same data but a simplified statistical model Pannell 1995 then estimated M as 0 7525 Using data from a single field trial in Western Australia Pannell and Gill 1994 estimated M to be as low as 0 29 using a relatively sophisticated statistical model but 0 64 using a simple model From this information it appears that 0 6 is a reasonable best bet value to use The same equation is applicable for all crops but with the relevant parameters to each crop selected from either the Biological results or Crops amp weeds sheets For wheat in competition with annual ryegrass the default values are as 13 RIM USER S MANUAL follows Pow 100 M 0 60 a 5 and Ray 0 33 This competition function is similar to the widely used hyperbola of Cousens 1985 but is more flexible in that it allows representation of different crop densities Yield after weeds haying etc for each of the crops can be calculated by multiplying the expected weed free crop yield by the proportion of weed fr
26. ass seeds 20 days after the break Ryegrass seeds present in the soil after summer Ryegrass seeds just before break of season Ryegrass seeds present just before harvest Effect of competition by crop on ryegrass seed set Ryegrass seeds at the first chance to seed Number of ryegrass seeds Ryegrass seed produced in spring Ryegrass seeds present at time for post emergent spraying Ryegrass seeds at spring time Running total receipts 44 Units L ha L ha ha seeds m seeds m ha ha seeds m ha Lot kg ha ha seeds m yr ha ha ha ha ha seeds m t ha t ha ha seeds m seeds m 2 seeds m seeds m seeds m seeds m 2 seeds m seeds kg seeds m seeds m seeds m ha Variable Rurw Rvs Data Name Rate of nitrogen urea fertiliser wheat Viable ryegrass seeds just before season break Wheat receipts Sublethal effect of selective herbicides on seed production of surviving weeds High seeding rate of wheat Pasture seeding rate Wheat seeding rate standard Stocking rate Expected life of machinery Tax costs Total non weed control costs Total weed control costs Total receipts Adjusted total receipts Total variable input costs Adjusted total variable input costs Weeds remaining after grazing Weed free yield after a long break with no legume wheat Healthy equivalent weeds in spring Weeds surviving post emergent treatments Weeds surviving pre emergenc
27. cccssssssseeee 34 SCOPE OF RIM AND CONTACT DETAILS seeseseseseeseroesesececoeroroesesecoeeesoroesesecoeeosoeseseseeoe 36 CONTACT DETAILS FOR INFORMATION PERTAINING TO RIM cceccesceseeseseeescsseseseseceeseens 37 BIBLIOGRAPHY sicssesssccastiscsssctseassssesctacssacecssasedsesassisastessacseossesseansssecsedeacdeustecheasespesasasausiecsese 38 APPENDIX KEY TO VARIABLES USED IN EQUATIONS cscsscsssssssscssesessesnseees 40 RIM USER S MANUAL Credits and Acknowledgements The developers Main but not sole contributions David Pannell Project initiation and supervision General design of the model UWA and the spreadsheet Model implementation in current spreadsheet version 4 Manuals Vanessa Stewart Design and construction of the original spreadsheet version 1 Then UWA now Department of Ongoing input to model design content assumptions and testing Agriculture WA Anne Bennett Development of user friendly spreadsheet Improved model Then UWA WAHRI structure and re built the spreadsheet version 3 Manuals Marta Monjardino Review of data and functional relationships Information WAHRI Department of collection Agriculture WA Carmel Schmidt Improvements to data biology and spreadsheet version 2 Department of Agriculture WA now a consultant Steve Powles Detailed input into current biological structure of the model WAHRI UWA
28. ch of wheat PD p barley PD canola PD and lupins PD is based on the same formula Using wheat as an example the PD plants m is determined using seeding rate SRy kg ha average kernel weight KW mg and expected plant establishment Ep _ SRy x10 a PD KW W According to J Holmes pers comm the standard plant density for wheat is between 100 and 200 plants m Barley is expected to be slightly higher than wheat P Carmody pers comm estimates the density for canola to be between 83 and 117 plants m while J Holmes pers comm expects lupins to be between 40 and 66 plants m Javis ef al 1991 expect 75 per cent of wheat seeds to establish successfully and the same could be expected for barley P Carmody pers comm estimates 50 per cent of canola seeds will become established while Nelson and Delane 1990 believe 85 per cent of lupin seeds will establish The last 8 variables in the crop variables table in the Crops amp weeds sheet are based on figures derived from those working in the relevant fields and should only be changed with expert advice Phytotoxicity The values for yield loss due to toxic effects of herbicides on crops have been supplied by David Bowran from the Department of Agriculture Western Australia The percentage estimates presented in the table in the Crops amp weeds sheet can be altered if necessary Biological results sheet Ryegrass plants per square meter G
29. coenzyme A carboxylase mustant in annual ryegrass Lolium rigidum selected by sethoxydim Planta 190 176 181 39 RIM USER S MANUAL Appendix Key to Variables used in Equations Variable Data Name Units a Ryegrass background competition factor constant A Total area on which machinery is used ha c Competition factor on ryegrass constant C4 Cost of herbicide or insecticide application ha Cpe Cost of Atrazine pre emergence ha CATE Cost of Atrazine post emergence ha Cp Cost of burning crop stubble or pasture residues ha Ccuw Cost of cutting hay wheat ha Cosw Cost of cutting silage wheat ha Ccu Extra cost of shallow cultivation ha Ccup Shallow cultivation cost pasture ha Ccuw Shallow cultivation cost wheat ha Cp Cost of diesel fuel ha Cpp Cost of diesel direct drill ha Cor Cost of diesel harvest ha Coc Cost of diesel cycloning ha Cocu Cost of diesel shallow cultivation ha Coie Cost of other Dim for lupins or canola ha Cosc Cost of diesel seed catching ha Crp Environmental cost of burning ha Cecu Environmental cost of cultivation ha Crw Cost of fertiliser superphosphate amp urea wheat ha Crp Cost of fertiliser pasture ha CFR Cost of fire risk from burning dumps or windrows ha Crs Cost of Fusilade ha Cok Cost of Glean post emergence ha Con Cost of Glyphosate at sowing knockdown option 1 ha Cour Cost of Glyphosate crop top ha Cope Cost
30. d should be interpreted accordingly The principal assumptions are detailed in this chapter with minor assumptions described in relevant sections of Chapters 3 4 and 5 Outline of assumptions Time Frame The User can generate annual results from RIM for either a 10 or 20 year time period Weed populations are measured at six different times during the year with seed populations being monitored at seven specified times Region and climatic variation RIM is not limited to a region Default values pertain to the Merredin region but the model can be adapted to any region with a similar farming system RIM does not represent year to year variation in weather potential weed free yield or herbicide performance Yields in the model vary from year to year due only to the sequence of crops and pastures selected and the level of weed competition Climatic conditions do not rule out any of the treatment options Herbicide applications and weed control It is possible to specify a maximum number of applications for each group of herbicides before weeds are assumed to be mainly resistant in either the Start here sheet or the Select strategy sheet If ryegrass is fully resistant to a herbicide group the limit for that group should be set to zero Weeds other than ryegrass are assumed to be adequately controlled through the use of herbicides RIM contains assumptions regarding the control effectiveness kill percentage of the different weed control
31. d that results This cost is not included in the Control costs sheet but it is included as a reduction in receipts in the Economics results sheet Cutting a weedy crop for hay can greatly reduce ryegrass seed set For good results hay should be cut before the weed has a chance to set seed Gill Holmes and Kelly 1994 The cost of producing hay from a wheat crop for example Ccm ha is calculated using a similar equation to that for green manuring based on the added costs ha of hay baling Cup and glyphosate crop topping Cern to clean up any surviving weeds Com Cup Corr 20 ECONOMIC EQUATIONS Converting a crop into silage reduces weed seed set to a greater degree than cutting it for hay because the crop pasture is cut earlier and therefore the weeds have less opportunity to set seed The cost of producing silage from for example a wheat crop Cesp ha is calculated in the same way as for hay except that it is based on the cost of cutting silage C ha Cosw Cs Corr The cost of swathing Ce ha is based on the cost of fuel and repairs and maintenance to the tractor and swather For simplicity the cost in the model is based on a contract price Mowing is used as a weed control option in pasture only and involves cutting all the plants above a certain height before they set seed and then crop topping with glyphosate In so doing the taller ryegrass plants are selected over the improved pasture specie
32. e of second hand machinery the purchase cost can be adjusted in the Prices amp rates sheet Biological Equations This chapter presents the biological equations entailed in the RIM model T he biological equations in RIM are predominately used to determine the number of ryegrass plants per square meter the quantity of ryegrass seeds per square meter and crop yields The key factors that drive the pattern of ryegrass population change over time include initial ryegrass seed density in the soil the timing of ryegrass seed germination relative to the crop natural mortality of weeds and seeds seed production per plant impacts of weed and crop densities on seed production per plant and the timing and effectiveness of treatments to reduce weeds or seeds For the purpose of this model the year is broken into seven periods First rains of the growing season which allow crop sowing seeding to 10 days later 11 to 20 days after seeding up to time of post emergence herbicide application if selected post emergence spraying to mid spring mid spring to harvest and harvest to opening rains of the next season Crop related variables used in the equations include standard weed free yields for crops after a break of at least three years without a legume yield boosts for cereals after legumes canola or a pasture yield effects on crops of green manuring and swathing yield effects from disease in short rotations seeding rates savings in nitro
33. e rows for the time period when it would be used Remember to copy across the entire row Don t forget that if a cell refers to a reference in the Select strategy sheet then you need to allow for the column gap between years 10 and 11 Update all macros as needed You may firstly have to unprotect the macros by going into the Microsoft visual basic editor and entering the password The CopyYeat macro activated by selecting the grey Copy year button in the Select strategy sheet copies all of the treatments you have selected for a year 31 RIM USER S MANUAL In the CopyYear macro update the following lines to reflect the appropriate ranges to copy Set r2 Range Cells Year ToCopy Cells 16 YearToCopy Set r3 Range Cells 18 YearToCopy Cells 27 YearToCopy Set r4 Range Cells 29 YearToCopy Cells 43 Year ToCopy It is the numbers in the Cells function that you need to update So if you inserted a row into Row 12 then the changes that you would make would be 16 to 17 18 to 19 27 to 28 29 to 30 and 43 to 44 You then need to make the same changes to the macro Paste year in these rows For Rw 9 to 16 For Rw 18 to 27 For Rw 29 to 43 In the same way update the macros for the grey Blank all button by changing the ClearSheet macro to correct the following ranges Range C9 W 16 Select Range C18 W27 Select Range C29 W43 Select Do NOT go to the Select strategy sheet and select to restore
34. e treatments Weeds surviving seeding at day 0 Weeds surviving seeding at day 10 Weeds surviving seeding at day 20 Weeds surviving spring treatments Yield boost from previous green manuring Final weed free barley yield Final weed free canola yield Final weed free lupin yield Final weed free wheat yield Barley hay silage yield Canola hay silage yield Lupin hay silage yield 45 Units t ha seeds m ha constant kg ha kg ha kg ha DSE ha years ha ha ha ha ha ha ha proportion t ha ants m72 ants m72 ants m ants m ants m2 P P P plants m P P P ants m t ha t ha t ha t ha t ha t ha t ha Variable RIM USER S MANUAL FB EC 7FL IFW Data Name Pasture hay silage yield Ryegrass hay silage yield Wheat hay silage yield Yield penalty if lupins are sown into burnt crop stubble Yield penalty when break is only one year Yield penalty for late sowing Yield penalty for not swathing Wheat yield after weeds haying etc Weed free barley yield Weed free canola yield Weed free lupin yield Weed free wheat yield 46 Units t ha t ha t ha t ha t ha t ha t ha t ha
35. ed in Table 16 If seed catching or windrowing are selected in the Select strategy sheet it is assumed that machinery will be required and will incur repayment costs as calculated in the Prices amp rates sheet This translates to the cost of machinery ha for each year that repayments ate required The cost for each year is transferred directly into the seed catch windrow machinery purchase row of the Economic results sheet Table 17 presents the inflation figures for each year based on the rates of price and yield increase in the Prices amp rates sheet These figures are used to inflate the annual gross receipts and costs in the results that allow for inflation interest and tax in the Economic results sheet Yield penalty for late sowing in Table 18 simply shows the penalty for late sowing depending on the crop and number of days 10 or 20 that sowing was delayed These figures are used to calculate the yield penalty for late sowing in the Biological results sheet Competition functions showing yields at standard and high crop densities for varying levels of weed density are calculated in Table 19 using data from the Crops amp weeds sheet and a series of weed density levels from 0 to 1 000 These figures are used to generate the Charts that show the effect of weed density on wheat barley lupin and canola yields at standard and high crop densities 29 Adding a New Treatment Should you wish to add a new treatment option
36. ee yield with weeds Using wheat as an example the yield after weeds haying etc Yy t ha is found by multiplying the aforementioned parameters YFpry and PY Yy YF yry x PYy Note the model adjusts yield to zero if the crop has been used for hay silage or green manure If a crop is converted into hay or silage the following equation is used to estimate yield of hay Yup t ha using wheat as an example Ypy YFypy x Hy where HI is the harvest index for wheat The harvest index figures were supplied by Wal Anderson Agriculture Western Australia and are recorded in the Crops amp weeds sheet The equation for the other crops is the same as for wheat but with the relevant parameters substituted The yield of hay or silage made from ryegrass Yur t ha is calculated using the following equation R Yur SiR ec hig Reg Hig Where Rss refers to the ryegrass seeds m present at springtime as defined above Rsgg is the number of ryegrass seeds per kilogram Crops amp weeds sheet Note the equation is multiplied by 10 to convert the answer from kg m to t ha Pasture hay or silage can be produced from regenerated subterranean clover cadiz serradella phase or volunteer pastures Depending on the strategies selected the appropriate hay yield is transferred from the Hay Silage production table in the Pasture sheet to the Biological results sheet 14 Chapter Economic Equations This chapter outlines the economic eq
37. eeeesaes 3 Herbicide applications and weed control scsscseessceseeseeseseceseeseeecueeeecuseeeceseeaeeseeaeeeenaes 3 Enterprise Oph ons vss hss tieaetrn sn cabana sacs a ceeds a eee he tases Seek e pegs Meenas te e a o eS 4 Tillage and machinery 0 cccccecccececeseceseesseesseessesseesneesceseceseceaecuaecaaecacecaeeeaeenseeeseesseeeseeeeenaes 5 BIOLOGICAL EQUATIONS ssseseseseceesosoesesesecoesoroesesecocoesosoesesecocoesoroesesecoeeeroroesesesoeeesorsesesesoe 6 WEED CONTROL OPTIONS 39035 tecssice cs svscestacesdus dh cetd onto onens EEA E ER EAEE 6 CROPS amp WEEDS SHEET 3 20 cs255 reeet ius ona reei EEE TE SEESE te subdue DEKET aE EOE E a aE TR Ainas 7 Crop Varig bles sscscsies tnn a a e a Seed Ales E amp PHY LOLOXICIEY aaa aa aa aa gan ceaseccandedasacers O AEA aiaa oR EnS amp BIOLOGICAL RESULTS SHEET psies veces swvcesev cc entsstsuvevees cosntsve sevens coeustosee sevens rece savevh E aes E AIEN ESTN 8 Rye grass plants Per square metet cescceessecesecesnceceseceenceceeceeaceceaeeecacecaeceeaeeceseeeeaeeceseeeeae amp Rye grass Seeds Per SQUATE MELE e ce eececcesceesceseceecnsecnsecneeeaseeseeeseeeeeeeeeesecusecaecnaeenaeens 10 Crop DUYILONICIEY oy sted ods sensi assiae Mees E ei astineea i ova ET T E OVEA E ET A TO Ta Il NAA A satus tics E T E A tauunereasatteenennnned 12 ECONOMIC EQUATIONS csccscssssssssscsscssssscssssessssnsscesssssescessnesssssessessessescessnessssnessesooss 15 PRICES AND RATES S
38. egies are completed and form part of the results The information in this sheet is presented in tables and will be described accordingly T he Calcs sheet is hidden in the RIM model as its major role is to The first table is used to determine if each weed control option order and use of crops in rotation seeding time and other producer practices selected by the user are logical and acceptable Information from this table is transferred into the Select strategy sheet to generate either OK or Error messages Each enterprise is allocated a number for use throughout the Calcs sheet Enterprises consist of wheat barley canola lupins volunteer pasture regenerated subterranean clover pasture and cadiz serradella phase pasture Table 2 indicates which weed control treatments have been selected by the user by displaying the enterprise number for that year in each selected treatment row Treatments that are not selected are blank Table 3 shows the proportion of weeds surviving each selected control practice and is dependant upon enterprise information from Table 2 and the percentage reduction in current ryegrass or seed numbers for each treatment as displayed in the Control sheet The details in this table are use in Table 5 as described below Costs of each selected control practice are shown in Table 4 based on enterprise information from Table 2 above and the cost of the relevant ryegrass control treatments from the Control costs sheet T
39. ehind a harvester to catch chaff that is released from the back of the machine stops some ryegrass seeds returning to the soil Once the cart is full the contents can either be dumped in a heap and burnt or removed from the paddock Stewart 1993 Seed catching costs Cso ha combined with burning the dumps can be calculated by Cse Cosc PMT sc Crp 21 RIM USER S MANUAL where Cosc is the seed catching operating costs ha PMT is the seed catcher repayment ha and Cpg is the cost of supervising the fire when burning dumps windrows ha When there is a total burn rather than just burning windrows or dumps degradation to the environment such as that caused by erosion may result and incur a cost RIM allows the user to specify this environmental cost of burning Css ha If the whole paddock is burnt and not only the dumps seed catching costs Css ha are calculated by substituting Cj for Crp The only cost associated with windrowing and burning the windrow Crp ha is the cost of managing the fire risk from burning Cpr ha As with seed catching if the whole paddock is burnt the cost of windrowing total burn Cz ha is Crs instead of Cpr The cost of user defined option B Cup is specified by the user Economic results sheet Receipts Crop gross receipts R ha are the returns before production costs have been deducted for all crops grown and are calculated by summing receipts
40. erminated ryegrass seedlings at the time of the break of season i e the first chance to seed Gro plants m are calculated by multiplying the number of viable ryegrass seeds per square meter just before the break of the season Rys by the ryegrass germination prior to the first chance to seed Gp Gro Rys X Gps The number of ryegrass plants per square meter that are present 10 days after the season break Gpo is calculated using the following formula BIOLOGICAL EQUATIONS Grio Gr SWS Rys xG where WS signifies the proportion of weeds surviving beyond day 0 plants m which depends on the treatments selected in the Select strategy sheet Rys refers to the number of ryegrass seeds m that remained viable in the soil beyond the first chance to seed and G is the percentage of those viable seeds that germinate 1 10 days after the break as specified in the Crops amp weeds sheet The number of germinated ryegrass plants m alive at 20 days after the season break Grz is found in much the same way as for those surviving 10 days after the break Gro Grio XWS gio Rio x Ga where WS s is the proportion of plants m surviving beyond day 10 found in the Calcs sheet R refers to the number of ryegrass seeds m that remained viable in the soil beyond 10 days after the break and G represents the percentage viable seeds that germinate 11 20 days after the season break The user can specify that seeding occur
41. es is lower than the assumed inflation rate on input costs Consistent with the approach used in relation to increasing production trends most of the results in RIM do not allow for inflation The ones that do are a the Average annual profit values near the top of the Select strategy shect b a table of receipts costs interest and tax labelled Results that allow for inflation interest and tax near the bottom of the Economic results sheet and c just below that table results for Final balance Equivalent opening balance and Equivalent annual profit The equivalent annual profit is the same as the Average annual profit in a In finance jargon it is an annuity The description below relates to b and c In the table referred to above in b crop gross receipts R ha are adjusted for an increase in potential crop yield Icy and inflation for crop sale prices cp while pasture gross receipts Rp are adjusted for an increase in sheep pasture productivity I and inflation for sheep product prices I pp The model bases figures for these parameters on the rates of price and yield increase table in the Rates amp prices sheet Therefore total adjusted gross receipts TR2 can be calculated by TR R R R xIgy Ip Rp x1 sp XI spp Total variable costs are adjusted TVC ha by allowing for inflation for input costs Lo TVG TVC x Tic Interest received I ha in Year 1 is zero From Year 2 on
42. evant figures for cycloning the same equation can be used to determine operating costs for this activity Cog Repayment costs of machinery The cost of using windrowing seed catching and cycloning machinery is interpreted in the model as a yearly repayment for purchasing that machinery The annual payment PMT ha is calculated using a constant interest rate A the purchase price of the machinery P a time period representing the expected life of the machine A years and the total area over which the machinery is used 4 ha PMT rn eas Note the model will calculate this cost for each of the machinery types for the life of the machine even if it is used only once in that time period Machinery and input costs for crops The machinery and input costs for a crop include machinery maintenance costs ha and the total cost of crop inputs ha The machinery and input costs for wheat Cuny ha ate calculated using the following equation C uw RM pp RM y Cpp Cpy Cy Cwcw Cry Csw C mw RMpp refers to repairs and maintenance costs to machinery used for direct drill cultivation ha and RM pertains to the same but for harvesting ha The cost of diesel for direct drill cultivation Cpp ha and for harvesting Cbn ha are also included in this equation The remaining parameters are described below 16 ECONOMIC EQUATIONS For wheat the cost of insecticide Cyy ha is derived from
43. f crops in southern Australia As the model is not an optimisation model the optimal strategies are determined for different scenarios through a series of runs RIM allows the user to simulate many different combinations of weed control treatments and observe their predicted impacts on ryegrass populations crop yields and economic outcomes The user evaluates the strategies and decides on the optimal management regime to implement Re is a decision support system that is designed to provide information Underlying RIM is a dynamic simulation model The model is deterministic and integrates economic biological and agronomic components For economic aspects the time step is annual For biological processes particularly weed population dynamics seven periods of the year are defined The model is implemented in a spreadsheet program Microsoft Excel using formulae and Visual Basic macros The model includes approximately 500 parameters biological agronomic and economic which are adjustable by users Specification of values for each of these parameters was a major task in the development of RIM Sources of data and information were numerous and diverse Economic parameters were obtained from an existing whole farm economic model Morrison et al 1986 Kingwell and Pannell 1987 Pannell 1996 and updated from Budget Guides published for farmers Parameters for control effectiveness of weed control options were estimated based on long term f
44. f herbicide groups before weeds are mainly resistant In the grey column Used only change the formula in the cell that is relevant to the new herbicide e g if the new herbicide was in Group A you would go to the corresponding cell in the Used column and include the Y reference for the herbicide in the formula To ensure that you have completed all of the changes required you may like to run RIM with a strategy that includes the new treatment and check that the output is logical 33 Chapter Procedure to Create a Version for Public Release The password on all aspects of RIM99h is syt a Things to check in the development version before converting it into a release version 1 Check that all auditing arrows are removed 2 Check that all cells with blue text are not locked but that all others are b To save 1 Read the completed development version into Excel 2 Save As the latest version of the model into a new file 3 Run the ProtectAll macro the workbook has to be unprotected for this 4 Check that the visual basic code is password protected To do this run the visual basic editor Alt F11 and select Tools Project properties the last item in the menu Protection tick the little box and enter the password into the two bottom boxes 5 Work through each visible sheet unprotect it and then protect it with the password Leave Select strategy protected but without a password for now 6 Pr
45. gen fertiliser following lupins and pasture impacts of delayed seeding on yield parameters of the competition functions phytotoxic effects of herbicides and some physical control measures on each crop RIM does not include detailed simulation of the population dynamics for each possible pasture species so the biological impacts of a pasture phase on ryegrass populations are represented in a relatively simple way For each type of pasture the impact on ryegrass seed density under standard and high intensity grazing conditions is specified by the user The standard reduction in weed seeds is greater in a second or third consecutive year of pasture because the non tyegrass components of the pasture stand are denser and more competitive at these stages Weed control options There are a total of 35 different weed control options included in the RIM model Table 1 They can be broken into four separate groups selective herbicides 11 Chapter BIOLOGICAL EQUATIONS non selective herbicides 5 non herbicide treatments 16 and user defined treatments 3 Table 1 The weed control options included in the RIM model where N pertains to non selective herbicide S to selective herbicide and B to biological treatment non chemical Treatment a O 1 Knockdown option 1 glyphosate Group M 2 Knockdown option 2 Spray Seed Group L 3 2 knocks glyphosate Spray Seed Gr M amp L 4 Trifluralin Group D 5 Simazine
46. his information is fed directly into the Expenses section in the Economic results sheet Table 5 details the proportion of weeds surviving all treatments tillage herbicide and or harvesting and is based on data from Tables 2 and 3 above The results are transferred into the Biological results sheet to calculate the ryegrass plants m in each of the time periods represented The proportion of seeds surviving harvest as calculated in this table is also used in calculating ryegrass seeds per m after summer Biological results sheet 27 RIM USER S MANUAL The proportion of weeds remaining after grazing is calculated in Table 6 and is contingent upon whether the enterprise was devoted to normal or high intensity grazing as selected in the Select strategy sheet Depending then on the type of pasture the proportion of weeds killed is selected from data in Table 9 as described below This data is derived directly from either the ryegrass mortality table or the ryegrass mortality high intensity grazing table in the Pastures sheet Estimates for healthy equivalent weeds per m for ryegrass germinating at different times are presented in Table 7 They are calculated using the figures derived in the Biological results sheet ryegrass plants per m2 relevant figures from Table 5 as outlined above and from ryegrass variables and competitive indices for ryegrass found in the Crops amp weeds sheet Table 8 records the enterprises selected
47. ield experiments designed to evaluate their effects Bill Roy pers comm and from other field trials conducted by the Western Australian Department of Agriculture WADA Parameters for weed competition functions were calibrated in cooperation with weed scientists from WADA to provide relationships consistent with field trial evidence RIM represents a single field The user can specify whether or not the ryegrass population in the field is resistant to each herbicide group or how many applications of herbicides from each group ate available before resistance will develop This implies a sudden loss of herbicide efficacy which approximates the reality of herbicide resistance development by annual ryegrass in southern Australia Tardif e al 1993 A wide variety of non herbicide weed treatment options is RIM USER S MANUAL included so that as herbicides are lost the best substitute treatments can be identified The enterprise options available for users to select are wheat barley canola lupins volunteer pasture subterranean clover pasture and cadiz phase pasture The user may select these in any agriculturally feasible sequence There are inter year impacts of one enterprise on another depending on the sequence selected For example a cereal crop grown after a legume crop or pasture benefits from a higher yield and a reduced requirement for nitrogen fertilizer Pannell 1995a 1998 The main outputs that can be obtained from RIM
48. imazine post emergence Crip e Artizine post emergence Cure e Glean post emergence Geak e Hoegrass Ge e Fusilade Crs e Select C e Other Dim for lupins or canola Conc e Other selective herbicide Cor e Glyphosate crop top Car e Gramoxone crop top Corr Other costs The cost of use high crop seeding rate is shown as the extra cost of high seed rate Casg in the case of wheat that is presented in the table Crop inputs rates and per hectare costs in the Prices amp rates sheet A nominal cost is shown in the Control costs sheet for Seed at first chance Since sowing must occur anyway the cost that would be attributable to weed control is very low or zero The cost of the option tickle wait 10 days seed Cy ha is worked out by adding the extra cost of shallow cultivation Coup in the case of wheat ha and the environmental cost of cultivation Cza ha both of which are presented in the Prices amp rates sheet Green manuring involves using shallow cultivation to plough the standing crop into the soil This is done before the weeds set seed and so although it involves a loss in revenue it is an effective method of weed control The cost of green manuring C py with wheat used as an example crop ha is specified simply as the cost of ploughing the standing crop Cpe ha Corw Cocu However green manuring has an additional cost shown only indirectly in RIM which is the loss of crop yiel
49. ld be associated with modeling a sheep enterprise While this gross margin includes a deduction for the production costs of sheep it excludes costs specific to pastures which are accounted for separately The total receipts TR ha is an aggregate of each of the enterprise receipts as described above TR R R R Rp Expenses In RIM the total non weed control cost Cy ha is the sum of production costs for wheat barely lupins and canola crops Non weed control costs consist of figures for total machinery and input costs taken from the Prices amp rates sheet The total pasture production cost depends on the pasture enterprise used volunteer cadiz phase or regenerated subterranean clover pasture and takes the relevant total input cost figures directly from the Prices amp rates sheet Total weed control cost TC ha comprises of non selective and selective herbicide costs as identified under herbicide costs above as well as non herbicide weed control costs and environmental costs If a particular herbicide treatment is not selected in the Select strategy sheet the cost for that treatment is zero Depending on the herbicide strategies selected in the Select strategy sheet the model allocates the appropriate herbicide costs from the Control costs sheet to the Economic results sheet TCw Cot Csr Case Crr Csm Carpet Cope Csae Cate Coar Cue Crs Cs Corc Con Corr Cort Cusr Crw Cor
50. m surviving post emergent treatments R is the ryegrass seeds m present at the time for post emergent spraying and G is the germination percentage of seeds remaining in the seed bank at that time Crops amp weeds sheet The number of ryegrass plants m when weeds are setting seed in September Gpss is transferred to the Select strategy sheet as ryegrass setting seed Nov per m It is calculated from Gp as calculated above ryegrass plants m surviving spring treatments WSs and weed proportion surviving grazing W as derived in the Calcs sheet Grss Gres XWS gp Wag Ryegrass seeds per square meter The figure derived for ryegrass seeds m just before the break of the season Rspp for year one is transferred to the Select strategy sheet as ryegrass seeds in soil April per m3 and is taken from the Crops and weeds sheet viable ryegrass seed in April seeds m for year 1 The ryegrass seeds m in the soil in April for each of the remaining years is equivalent to the previous year s ryegrass seeds m in the soil after summer Rs49 as described below The ryegrass seeds m7 at the first chance to seed Ryp take into account Regg as above and the germination percentage prior to first chance to seed Gp Rsrc Rspp x 1 Gps The ryegrass seeds m in the soil at 10 days after the break R also considers the germination percentage but at 1 10 days after the break G Rsio Rsre x I G The germination
51. ment on seed catcher Standard wheat density Price of superphosphate fertiliser Price of silage Proportion of seeds surviving harvest Price of nitrogen urea fertiliser Price of wheat standard not after a legume Actual crop density wheat 43 Units proportion proportion proportion proportion proportion mg proportion ha t ha t ha kg proportion L plants m plants m plants m plants m unit t kg of seed ha ha plants m t t t t t plants m RIM USER S MANUAL Variable RL Rm S RM CU RM DD RMu RMsc i Rp Rpgs Rprp Rerw Rs Rs 10 Rs2 0 Rsas Rszp Rspu Rser Rsre Rsxc a Rsp Rsp Rss Rr Data Name Quantity of diesel fuel used Quantity of diesel used shallow cultivation Long term interest rate Crop receipts Ryegrass seeds 10 days after the break Ryegrass seeds 20 days after the break Barley receipts Canola receipts Ryegrass seeds at first chance to seed Hay receipts Rate of herbicide applied Lupin receipts Maximum ryegrass seed production Machinery R amp M shallow cultivation Machinery R amp M direct drill Machinery R amp M harvest Machinery R amp M seed catch Pasture livestock receipts Ryegrass seeds at time for post emergence spraying Rate of superphosphate fertiliser pasture Rate of superphosphate fertiliser wheat Silage receipts Ryegrass seeds 10 days after the break Ryegr
52. otect the workbook with password 7 Select Title sheet cell A1 8 Save the file 34 Chapter The Procedure to Convert Standard RIM to Workshop RIM 1 Blank all in Select strategy and save it as the strategy to all 12 strategies 2 Hide the columns for years 11 to 20 3 Delete the button View years 11 20 4 Add these tables to Start here Wheat Barley Canola Peas Vol Legume Pasture pasture Kill rates Trifluralin Group D 90 90 90 90 Crop pasture top 75 80 80 Gramoxone Seed catch burn 60 60 60 60 dumps Burn crop 20 20 20 20 20 20 stubble pasture residue Standard seeding rate 50 60 5 100 kg ha High seeding rate 80 100 7 130 kg ha Yield penalty sowing 10 5 12 0 delayed 10 days Yield penalty sowing 20 10 30 5 delayed 20 days 5 Grey out those variables in the later sheets protect them and include notes that they are From Start here sheet 35 Chapter Scope of RIM and Contact Details This Chapter explains the capacity of RIM and gives contact details if you need further information about RIM or herbuade resistane problems associated with the management of herbicide resistant annual ryegrass Understanding the scope of RIM is important for interpreting the results derived from the model T he following is a series of explanations describing RIM s capacity to solve RIM will not automaticall
53. pre emergence Group C 6 Atrazine pre emergence Group C 7 Glean pre emergence Group B 8 Use high crop seeding rate 9 Seed at first chance default 0 Tickle wait 10 days seed 1 Tickle wait 20 days seed 12 Simazine post emergence Group C 13 Atrazine post emergence Group C 4 Glean post emergence Group B 5 Hoegrass Group A 16 Fusilade Group A 7 Select Group A 8 Other Dim for lupins or canola Group A 9 Other selective herbicide 20 Grazing selected automatically if pasture 21 High intensity grazing winter spring 22 Glyphosate top pasture Group M 23 Gramoxone top lupins pasture Group L 24 Green manure 25 Cut for hay then glyphosate Group M 26 Cut for silage then glyphosate Group M 27 Swathe 28 Mow pasture then glyphosate Group M 29 User defined option A Spring 30 Seed catch burn dumps 31 Seed catch total burn 32 Windrow burn windrow 33 Windrow total burn 34 Burn crop stubble or pasture residues 35 User defined option B at or after harvest J y o WDWD MOD KDW ZZDS DVV DDD PNYHNHNHNETZ Crops amp weeds sheet Unless otherwise stated specified data in this sheet has been collected by talking to experts in industry or derived from the MIDAS model Specific RIM USER S MANUAL references are recorded in the Crops amp weeds sheet and can be found by scrolling to the right of the sheet Crop variables The standard density plants m2 for ea
54. presented below I Cirww WFY yi q SRG Crr C where WFY 1 is the weed free yield after a break with no legume t ha Ingw is the rate of insurance hail and fire for wheat Piy is the price of wheat t Crr is the rail freight cost t and C is the transport cost from farm to receival point t The equations for calculating the machinery and input costs for barley canola and lupins are similar to those for wheat with the only difference being the 17 RIM USER S MANUAL substitution of the relevant parameters for each crop Note that the cost of lupin seed includes inoculation cost Co ha Cultivation can be used by farmers to stimulate weed germination and subsequently uproot and kill plants Until recently it was the predominant method of weed control Currently in Western Australia tillage referred to as early tickle or a shallow cultivation is used by many farmers This has the effect of burying weed seeds to a depth of one to two centimetres which enhances weed germination Roberts 1997 Seedlings that then germinate can be eliminated by the following cultivation The effectiveness of cultivation is largely dependent on rainfall Gill Holmes and Kelly 1994 to ensure adequate weed germination and hence weed control When seeding is delayed the extra cultivation cost Cev ha termed extra cost of tickle shallow cultivation in the model is calculated by Coy RM oy Cocy where for
55. pring Ryegrass seeds at time for post emergent spraying Ryegrass plants setting seed in September Wheat harvest index Interest received 42 Units ha ha ha ha ha ha ha plants m proportion ha ha ha ha constant constant ha ha DSE plants m plants m plants m plants m seeds m plants m constant ha Variable Tcp Tey Tic Inrw Tsp Tspp KWw MTR Ms Mss NR NSL NSp Pe Penp Pp PDs PDe PD PDw Pu Pray Pin Py PMT PMT sc Pow Ppp Ps Psu Pur Pw PYw Data Name Inflation for crop sale prices Potential crop yield increase Inflation for input costs Rate of insurance hail and fire wheat Increase in sheep pasture productivity Inflation for sheep product prices Average kernel weight wheat Maximum yield lost at high weed densities Marginal tax rate Natural mortality of dormant seeds during the season Natural mortality of seeds over summer Net returns Savings in nitrogen fertiliser from growing lupins Savings in nitrogen fertiliser from growing pastures Clover seed price Crop not phytoxically damaged by a specific herbicide Price of fuel diesel Plant density barley Plant density canola Plant density lupins Plant density wheat Price of herbicide Price of hay Price of clover inoculation Purchase price of machinery Yearly repayment on machinery Yearly repay
56. represent the costs Please note that volunteer pasture and legume pasture in the Control costs sheet are in opposite columns in the Prices and rates sheet So if you are copying formulae by copying and pasting then you must check that your formulae are correct 3 Insert a new row into the appropriate position in the Control sheet Put in values for weeds killed or seeds removed prevented Update the numbers in the first column 4 Insert a new row into the Compatibility sheet so that it corresponds to the other new rows that you have entered Enter either 1 for yes or 0 for no to 30 Chapter 10 11 12 ADDING A NEW TREATMENT indicate what treatments that can be used on what enterprises Update the formatting and the numbers in column A Maintaining consistency with the previous rows inserted elsewhere in the workbook insert a new row into Table 1 of the Calcs sheet Copy formulae into this row from the row above Be careful when copying the formula into years 11 and above because these formula refer to cells in the Select strategy sheet and there is a blank column in that sheet after year 10 To ensure that the formulae that check compatibility work you must have updated the treatment numbers in column A You may need to update the error checking that is done below Table 1 depending on the nature of your added treatment Insert a new row into the appropriate position in Table 2 of the Calcs sheet Selec
57. s and the smaller plants are removed by the herbicide The cost of mowing pasture Cw ha is calculated using a contracted mowing rate as specified in the Prices amp rates sheet Cup ha and the additional cost of a follow up application of crop topping with glyphosate Carr Cu Cup Cour The cost of the user defined option A Cua ha is specified by the user Due to the negative effect that burning has on the soil most farmers have removed the burning option from their program apart from selective targeted use However herbicide resistance has forced some farmers to rethink this option as part of an overall plan for managing resistance The results of burning are dependent on paddock use and the quality and distribution of fuel available for the fire When stubble is grazed the effectiveness of a burn is decreased because the animals hooves bury the seed into the soil shielding it from the heat Davidson 1992 Grazing the stubble also means there is less fuel available for an effective burn Trials run by the Department of Agriculture suggest up to 80 of the viable seed can be destroyed by fire Gill Holmes and Kelly 1994 In this model the cost of burning crop residues Ch ha is set at a level that is meant to represent the labour cost of supervising the fire to ensure that it does not spread out of control The number of ryegrass seeds reaching the soil can be reduced when the crop is harvested Towing a cart b
58. s on day 0 10 or 20 RIM simulates weed and seed numbers at each of these points in time regardless of when seeding is specified to occur In the model ryegrass seeds m at the time for post emergent spraying Gpps is found by Gaps Grao XWS s2 SWS pp Rip x Ges WS is the proportion of plants m surviving beyond day 20 WS represents the proportion of plants m surviving pre emergence treatments R is ryegrass seed m 20 days after the break and Ges is the additional percentage germination before in crop spraying that is percentage germination of seeds remaining in the seed bank beyond day 20 not the percentage of the original seed bank Crops amp weeds sheet Note that WSpr captures the combined effect of pre emergence treatments over all the time periods up to the time for post emergence spraying In reality pre emergence treatments would kill weeds in earlier time periods but in RIM they are not removed from the population until this point in the simulation This simplification has no impact on the results of the model apart from it displaying higher than realistic weed densities in the first three time periods It has no effect on yields or seed production The ryegrass plants m in early spring Grke ie the density of weeds surviving all treatments is found using the following equation Gres Grps X WSgr Res x Gis RIM USER S MANUAL where WSpr is derived in the Calcs sheet and represents the plants
59. shallow cultivation RM_ is the cost of repairs and maintenance of machinery ha Cp y is the cost of diesel ha Extra cost of high seeding rate In the model there is an option for increasing the seeding rate Using wheat as an example the extra cost incurred from selecting this option Cyyypy ha is calculated by 1 C SR pw SRy x xC paw Rw SRy Pza gt C where SR is the high seeding rate kg ha SRy is the standard seeding rate kg ha and Cy is the cost of wheat seed ha Total input costs for volunteer sub clover and cadiz serradella pastures In calculating the total input costs for pastures Cp ha the equations are similar to those used for wheat except for the inclusion of a basic fixed operating cost for pasture Co ha termed other cost in the model The remaining parameters are explained below Cun Co Cpe Cie Cp Crp The cost of sowing pasture is only applicable for the year the pasture is sown Volunteer pasture is never sown Cadiz pasture is sown if it is was not grown in the previous year Clover pasture is sown if it was not grown in any of the previous three years In the case of clover the cost of sowing Csr ha is calculated using the following equation 18 ECONOMIC EQUATIONS Cspc SRp x Po RM py Cop where SR is the pasture seeding rate kg ha Po is the price of clover seed kg RMpp is the cost of repairs and maintenance for direct drill
60. t strategy sheet prints the correct range adjust the print range in the macro Print10 That is change Range A1 L67 Select to the correct range Likewise change the range Range A1 W67 Select for the Print20 macro 13 Tf the additional treatment is a herbicide you will need to change the TestHerbUsage macro so that it s label turns grey when the specified number of herbicide shots are used up You may also need to adjust some of the named ranges referred to by that macro Note that in RIM version 2002 you would instead adjust the conditional formatting in the Select strategy sheet There is no conditional formatting in RIM 99 14 In the Crops and weeds sheet you will need to check if your new herbicide is represented in the Phytotoxicity section and if not you will have to insert a new row with the appropriate levels This being the case you would then have to go to the Biological results sheet and insert an appropriate row and formulae to correspond with your new herbicide 15 If the additional treatment is a herbicide you will need to link it into the checking herbicide shots on the Select strategy sheet Scroll right across to column Y Time used and then go down to the blank cell that corresponds to the new herbicide Copy the cell above down into this cell Check that this formula adds up the number of shots used for that herbicide Scroll back to the left of the sheet and go down to the table Number of uses o
61. t the row above or below and copy it into your new row Check to make sure that the copying allows for the space after column 10 in the Select strategy sheet Update the treatment numbers in column A Insert a new row into the correct space in Table 3 of the Calcs sheet Do not forget to update the numbers in column A including the ones below the row that you have just inserted Again select and copy the row above or below into your newly inserted row Then scroll across to the right of Tab 3 to the HLOOKUP table for control percentages and copy the formulae from the cells in the row above or below your inserted row and paste them in your new row Insert a new row into the corresponding row in Tabk 4 of the Calcs sheet Copy the formulae into the new row from the row above or below Remember to update the treatment number in column A Insert a new row into the Expenses section of the Economic results sheet The formulae that you copy into this row will reference cells from the Calcs sheet As the top of this section contains non weed control costs that are not included in reference tables in the Calcs sheet it is easy to copy cells incorrectly Therefore you should check that the formulae that appear in the new tow correspond to the correct cells in the Calcs sheet Update Table 5 Proportion of weeds surviving beyond different time periods in the Calcs sheet Include the survival percentage for the new treatment in each of the appropriat
62. the following equation Cw Crow 4 where Cop is the cost of insecticide only ha and C is the cost of application ha The cost of weed control Cyqy in a wheat crop ha can be estimated by adding the cost of herbicide for broadleaf control Cyco ha and the cost of application C ha Cwcw Cweo Ca The cost of fertiliser Cry ha for a wheat crop is described by Crw Be x Rprw Por x Ruew NS NS gt where Ppp is the price of phosphate fertiliser t Rppy is the rate t ha at which the phosphate fertiliser is applied Pyris the price of nitrogen fertiliser t Rupp is the rate at which nitrogen fertiliser is applied t ha NS is the savings t ha in nitrogen fertiliser in years following lupins and NS is the savings t ha in nitrogen fertiliser after growing pasture In the model the cost of seed is estimated but it could be derived using the following formula In the case of wheat the cost of seed Cy ha can be determined using the equation below where Py Cg Cr is the opportunity cost of holding back the seed from sale Ry 1000 Cow Py Cee C7 where Pp is the sale price of wheat t Cpr is the cost of rail freight t Cr is the transport cost farm to receival point t and SRy is the seeding rate for wheat kg ha In RIM the cost of insurance is calculated for each crop with the equation to determine insurance for a wheat crop Cmi ha
63. uations used in the RIM model economics of weed management by illustrating the potential for some long term benefits from short term economic sacrifices Whether a preventative strategy provides long term economic benefits depends on several factors including the cost of the strategy its impact on weeds prices of outputs and the initial weed seed density R highlights the importance of taking a long term view on the Taking a long term view of economics is difficult due to such complexities as interest rates tax and price and or yield trends Validly comparing costs and benefits that occur in different years and assessing the overall economics of a strategy for which the gross margin changes from year to year is a challenge Economists and financial analysts use a standard discounting approach to assess long term investments so that all costs and benefits are expressed in the equivalent of their present day value Robison and Barty 1996 The Net Present Value NPV for each strategy of interest can be determined by discounting and adding the costs and benefits of all strategies The preferred strategy has the highest NPV It is common practice to equate the discount rate to the bank interest rate In so doing the process is equivalent to identifying the strategy which would result in the highest bank balance at the end of the period given the assumption that all income is deposited in the bank account and accumulates interest and all
64. ustralia Agricultural Systems 49 217 236 Pannell D J 1996 Lessons from a decade of whole farm modelling in Western Australia Review of Agricultural Economics 18 373 83 Pannell D J 1997 Sensitivity analysis of normative economic models Theoretical framework and practical strategies Agricultural Economics 16 139 152 Pannell D J 1998 Economic assessment of the role and value of lupins in the farming system In J S Gladstones C Atkins and J Hamblin eds Lupins 38 as Crop Plant Biology Production and Utilization CAB International Wallingford pp 339 351 Pannell D J and Gill G S 1994 Mixtures of wild oats Avena fatua and ryegrass Lolium rigidum in wheat competition and optimal economic control Crop Protection 13 5 371 375 Roberts S P 1997 Managing herbicide resistant ryegrass The role and value of competitive wheat varieties and seed catching in integrated weed management Honours Thesis Faculty of Agriculture University of Western Australia Robison L J and Barry P J 1996 Present Value Models and Investment Analysis The Academic Page Northport Alabama Stewart V A M 1993 Economics of integrated strategies for managing herbicide resistant ryegrass under continuous cropping Unpublished Honours Thesis Faculty of Agriculture The University of Western Australia Tardif F J Holtum J A M Powles S B 1993 Occurrence of a herbicide resistant acetyl
65. wards for any one year it is based on the product of the long term interest rate 7 as in the rates 24 ECONOMIC EQUATIONS of price amp yield increase table in the Prices amp rates sheet and the running total balance at the end of the previous year Tax is paid on interest earned In RIM the tax system is represented simply because there is so much variability between farmers in their tax arrangements RIM allows the user to specify a single marginal tax rate which should be the rate of tax he or she would pay on any additional income earned above current income Tax costs T ha are based on the marginal tax rate MTR as specified in the rates of price amp yield increase table in the Prices amp rates sheet For any one year 2 Ti MTRx TRi TVC Ii In year 1 the running total RT ha is the addition of the adjusted gross receipts TR and interest Z minus the adjusted costs TVC and tax T for that year In all other years the running total for the previous year RT is added to the equation RT TR TVC 1 T RT TR TVC 1 T RT The final balance after 10 years FB ha is the running total in year 10 This is used to calculate the equivalent opening balance EOB ha If a bank account began in year 1 and earned interest at a rate r minus tax MTR over 10 years the EOB would be the opening balance that would give the FB9 10 EOB o FB o x es ee 1
66. y calculate which strategy is best Users evaluate strategies using experimentation and trial and error RIM does not represent year to year variation in weather potential yield or herbicide performance Yields in the model do vary from year to year due to the sequence of crops and pastures selected and the level of weed competition Climatic conditions do not rule out any of the treatment options Users can self impose constraints on the use of different treatments Some strategies may involve changes in machinery or livestock management that have impacts at the whole farm level However as RIM represents only a single field the model does not automatically allow for such changes Similarly RIM makes particular assumptions about the way that investments in machinery are financed Therefore it may be appropriate to consider the whole farm cash flow implications of strategies outside of RIM before making adoption decisions based on output from this model Despite considerable effort being expended on data collection it is inevitable in such a comprehensive model that there will be areas where the available information is not strong Sensitivity analysis as described by Pannell 1997 is an important approach for evaluating the significance of data deficiencies A related issue is the variation in biological and economic parameters that occur between farms The values included in the standard version of RIM are representative of a typical
67. ypo Ywre x 1 YP x 1 YPys x 1 Boy x Dp In the case of lupins a yield penalty occurs when the break between lupin crops is only one year YP There is also a yield penalty if lupins are sown into a burnt crop stubble YP YF Yup X I YP s x I YP x I YP x 1 YBou xD Depending on whether use high seeding rate is selected in the Select strategy sheet either the relevant crop plant density corresponding to standard density or high density options in the Crops amp weeds sheet is transferred into the Biological results sheet The procedure is the same for finding the plant density plants m for wheat PD barley PDs canola PDQ and lupins PD_ These parameters are used in the following equation The yield of a crop depends on the relative competitive abilities of that crop and of ryegrass and the densities of each The proportion of weed free yield with weeds for each of the crops gives the proportion of the weed free yield that is achieved after competition from weeds is accounted for In the case of wheat the proportion of weed free yield with weeds actual crop density PY plants m is found using the following equation l a PD x Pow a PDy facw X Gres PY xM 1 M where a is the background competition factor Poy is the standard wheat density not actual density a standard level for comparison plants m2 fraw is the ryegrass competition factor in wheat and Gpp is the ryegr

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