EverGraze - Simulating beef production in Manjimup WA using GrassGro

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1 EverGraze - Simulating beef production in Manjimup WA using GrassGro Paul Sanford, DAFWA, Albany WA Introduction This modelling work is part of the WA research component of a national project entitled EverGraze which has the goal in the high rainfall zone of southern Australia of increasing profit from livestock while improving NRM outcomes. In WA the focus is on increasing profitability by around 50% while reducing groundwater recharge, waterlogging and soil erosion by introducing deep rooted perennials into a substantial proportion of the farm. With the completion of EverGraze phase 1 which demonstrated a perennial based livestock system in the Albany Eastern Hinterland the decision was made by the funders, industry and researchers to increase the geographic spread of the investigation to an area from Manjimup across to Esperance. Consultation with producers and consultants via workshops held in Katanning and Albany found that one of the highest priorities in the industry was the investigation of the economic benefits of introducing perennials into the feed base. This field validated modelling analysis compares the on-farm performance of kikuyu, tall fescue and lucerne pastures to that of annual pastures as the basis for a beef enterprise in the high rainfall environment (900mm) of Manjimup WA. Hypothesis: A perennial based system will increase gross margins from beef production in Manjimup compared to an annual system by providing more feed during out-of-season feed gaps. It is hoped that the findings of this investigation will allow producers to make informed decisions regarding how the adoption of perennials will influence the profitability of their farm. Methods Validation The GrassGro model version (Moore et al. 1997) was validated using annual, tall fescue, lucerne and kikuyu pasture growth data collected from John and Danielle Mottram s beef enterprise near Manjimup ( me, mn) from 2010 to Cattle movements for much of this period were recorded to paramatise the models grazing management module. Soil parameters were derived from observations and measurements taking during the calibration of neutron moisture meter tubes on the property. The climate file was constructed using SILO and Western Australian Department of Agriculture and Food local weather stations. Local weather station data was given preference over SILO data and historical SILO data was corrected based on the relationship between SILO and weather station data. A mix of standard and custom plant parameter sets were used in the validation. A digital construct of the Mottram farm (300 ha) including paddock sizes and type was entered into the model for the purposes of validation and simulation analysis (see appendix). Simulations All the simulations presented in this report were generated using the cattle, pasture, soil and climate parameters used in the validation process unless otherwise stated. A digital construct of the Mottram farm (300 ha, 22 paddocks) was used as a basis for all of the analyses the only exception being a 3 paddock system used to explore the optimum ratio of tall fescue, lucerne and kikuyu. For further detail regarding parameters used in simulations refer to appendix. All simulations were initialised for five years prior to the data recording period of 40 years from 1973 to

2 To evaluate the impact of perennials on gross margins for a beef enterprise the following simulations were run; 1. Annual pasture 100% x two soil fertility scalers (0.4 & 0.8) x time of calving (Mar, May, Jul, Sep, Nov & Jan) x stocking rate (0.4, 0.8, 1.2, 1.6 & 2 cows/ha) 2. The Mottram farm system (87% annual, 5% tall fescue, 5% lucerne & 3% kikuyu) x time of calving (Mar, May, Jul, Sep, Nov & Jan) x stocking rate (0.8, 1.2, 1.6 & 2 cows/ha) 3. Varying percentages of tall fescue, lucerne or kikuyu (0, 25, 50 & 100%) x Sep calving x stocking rate (0.8, 1.2, 1.6, 2 & 2.4 cows/ha) 4. Tall fescue 100% x time of calving (Mar, May, Jul, Sep, Nov & Jan) x stocking rate (0.4, 0.8, 1.2, 1.6 & 2 cows/ha) 5. Varying perennial mixtures (each perennial in a separate paddock) x Sep calving x stocking rate (0.8, 1.2, 1.6, 2 & 2.4 cows/ha) Results Validation Monthly rainfall for the period including model validation is presented in figure 1. Overall there is good agreement between simulated and observed pasture growth rates in all pasture types (figure 2). For the annual pasture the largest discrepancies between observed and simulated occurred in spring 2011 and winter It is possible that in the case of winter 2012 that the actual season break (April, figure 1) was earlier than that modelled leading to a smaller leaf area index and as a consequence lower winter growth rates. In the case of tall fescue the largest difference occurred in the autumn and winter of 2011 with the model overestimating growth rates for this period. One possible explanation is the model overestimates growth during wet cold winters given that this was the wettest of the three years used to validate the model (figure 1). The discrepancies between observed and simulated for both lucerne and kikuyu pastures were relatively small as such the models ability to simulate pasture growth rate for these two pasture types is excellent. Based on this validation GrassGro was able to provide a credible simulation of the Mottram farm pastures from 2010 to 2012 as such it can be expected to provide useful comparisons of their performance as part of different livestock systems over many seasons. Figure 1. Monthly rainfall (mm) from 2009 to 2012 at Manjimup WA. 2

3 Figure 2. Simulated (-) and observed ( ) pasture growth rate for a) anuual pasture b) tall fescue and subclover, c) lucerne, ryegrass and subclover and d) kikuyu and subclover pasture at Manjimup, WA from 2010 to Note soil fertility scaler for validation; annual pasture 0.4, tall fescue 0.9, lucerne 0.7 and kikuyu Optimising time of calving, stocking rate and soil fertility for a beef enterprise consisting of entirely annual pastures For comparative purposes analysis was undertaken to establish the optimum returns achievable for a production system based entirely on annual pastures by varying time of calving, stocking rate and soil fertility. The results are presented in figure 3. A soil fertility factor of 0.4 (figure 3a) represents the productivity of the pastures measured on the Mottram property for the purposes of model validation (figure 2) a fertility factor of 0.8 (figure 3b) represents the potential production of annual pastures in the Manjimup environment. A beef enterprise based on current annual pastures is largely unprofitable irrespective of calving time or stocking rate (figure 3a). Only a September calving at stocking rates of 0.4 and 0.8 cows/ha provided positive gross margins of $19 and $39/ha respectively. However annual pastures are potentially quite profitable if their productivity could be raised to approximate that of the modelled pastures at a fertility factor of 0.8 (figure 3b) given that the cost to achieve this is reasonable. Time of calving and stocking rate made a substantial difference to gross margins with a September and November calving providing the highest gross margins at all stocking rates. Given the risk associated with higher stocking rates represented in the model output as a large variation in returns over 40 years (data not presented) the optimum stocking rate was 1.2 cows/ha as it returned the highest average gross margin of $332/ha without a negative return in any one year. 3

4 A September calving consistently returned a higher gross margin irrespective of soil fertility or stocking rate as less supplement was required to fatten calves and maintain cows compared to other times of calving (figure 4). With a September calving cows are joined in December when they are in good condition following spring pasture growth and calves are weaned in May and fattened within the pasture growing season leading to a lesser requirement for supplementary feed particularly for calves. By contrast for a May calving weaning takes place in January with a much larger need for supplementary feed. Figure 3. Relationship between stocking rate (cows/ha) and average gross margin ($/ha) for various times of calving at soil fertility factor 0.4 (a) and soil fertility factor 0.8 (b) at Manjimup WA. 4

5 Figure 4. Relationship between stocking rate (cows/ha) and supplement fed (kg/ha/yr) for various times of calving at soil fertility factor 0.8 at Manjimup WA. Has the introduction of perennials on the Mottram property increased gross margins? The Mottram property used to validate the model and provide the basis for all the simulations has a small area of tall fescue, lucerne and kikuyu pastures (see methods and appendix). This analysis sought to determine if the current feedbase has lifted gross margins in comparison to the properties historical feedbase made up of entirely annual pastures. Results are presented in figure 5. Note the results presented are for a September calving other calving times were assessed but proved to be less profitable (data not presented). Figure 5. Relationship between stocking rate (cows/ha) and average gross margin ($/ha) September calving for the Mottram property feedbase, including perennials, compared to a feedbase made up entirely of annuals with the soil fertility factor set at 0.4 at Manjimup WA. 5

6 At the optimum stocking rate of 0.8 cows/ha the part perennial feedbase (Mottram property) increased the gross margin of an annual based system from $39 to $86/ha an increase of a 120%. As expected profit partly increased due to lower demand for supplementary feed (figure 6) as the perennial feedbase partly filled the out of season feed gap. The remaining increase in gross margin was the result of the tall fescue and lucerne pastures producing more feed compared to the annual pastures. Figure 6. Relationship between stocking rate (cows/ha) and supplement fed (kg/ha/yr) September calving for the Mottram property feedbase, including perennials, compared to a feedbase made up entirely of annuals with the soil fertility factor set at 0.4 at Manjimup WA. What is the optimum proportion of a farm to sow to either tall fescue, lucerne or kikuyu? For the following analysis perennials were compared to annual pastures at the level of productivity measured on the Mottram property (soil fertility factor set at 0.4) and potential production (soil fertility factor set at 0.8). This approach was taken to determine whether perennials could also provide benefits when compared to highly productive annual pastures. The kikuyu pasture was also run at a fertility factor of 0.8 compared to its validation setting of 0.35 to explore its potential as a high yielding pasture. Tall fescue The results for tall fescue are presented in figure 7. Based on the current levels of farm productivity (figure 7a) sowing tall fescue would provide increases in gross margins at all of the stocking rates tested. To realise maximum returns as more tall fescue is sown stocking rate needs to be increased. For example with no tall fescue a stocking rate of 0.8 cows/ha returns the highest gross margin of $39/ha however once the feedbase consists of 50% tall fescue the optimum changes to at least 1.2 cows/ha with a gross margin of $311/ha. With a 100% tall fescue the stocking rate required to produce the highest gross margin of $561/ha is 2 cows/ha. Given that the optimum stocking rate is around 1.2 cows/ha based on a sensible balance between profit and risk (see earlier section) a highly profitable beef system would contain at least 50% tall fescue. In this case the general trend of higher gross margins with greater proportions of tall fescue is easy to understand as tall fescue substantially produces more dry matter than the current annual pasture driving higher stocking rates, less supplementary feed and therefore more profit. The fact that it can also partly fill out of season feed gaps simply lifts gross margins even further. If annual pastures were yielding close to their potential the benefits of sowing tall fescue are reduced and there is a consistently linear relationship between stocking rate and gross margin (figure 7b). At stocking 6

7 rates equal to or greater than 0.8 cows/ha sowing tall fescue results in an increase in gross margins. In the case of 0.8 and 1.2 cows/ha there is little or no increase in gross margin above 25% tall fescue. For example at 1.2 cows/ha the gross margin increased from $332/ha to $379/ha by sowing 25% of the feedbase to tall fescue yet with a 100% the gross margin had only increased to $400/ha. While the biggest increase in gross margins at higher stocking rates (1.6 to 2 cows/ha) also occurred up to 25% tall fescue higher proportions provided larger increases than those for lower stocking rates. Figure 7. Relationship between the percentage of farm sown to tall fescue and average gross margin ($/ha) for a) soil fertility factor annuals 0.4, tall fescue 0.9 and b) soil fertility factor annuals 0.8, tall fescue 0.9 at Manjimup WA. All September calving. Lucerne The findings for lucerne are summarised in figure 8. Sowing lucerne into the current annual pasture base like tall fescue consistently increases gross margins at all stocking rates (figure 8a). Once the feedbase consists of 7

8 more than 50% lucerne stocking rate needs to be increased to between 1.2 and 1.6 cows/ha to maximise gross margins. At a stocking rate of 1.2 cows/ha gross margins increase at a steady rate from minus $34/ha with no lucerne to $434/ha with 75%. A stocking rate of 2 cows/ha appears to be too high for lucerne in terms of providing the best financial return. While lucerne as simulated in the model is lower yielding than tall fescue within the growing season it does have higher growth rates in summer. As a consequence the benefit of lucerne in reducing supplement is greater in proportion to its yield benefit. Interestingly when compared to very productive annual pastures lucerne only provides increases in gross margins when it consists of 50% or more of the feedbase at stocking rates between 1.2 and 1.6 cows/ha (figure 8b). A good example of this difference can be seen at a stocking rate of 1.6 cows/ha with the increase in gross margin from $372 to $523/ha when going from no lucerne to 75%. Overall the maximum returns achievable from introducing lucerne into the feedbase were similar to that of tall fescue, $523 verses $561/ha respectively (figure 7 and 8). Figure 8. Relationship between the percentage of farm sown to lucerne and average gross margin ($/ha) for a) soil fertility factor annuals 0.4, lucerne 0.7 and b) soil fertility factor annuals 0.8, lucerne 0.7 at Manjimup WA. All September calving. 8

9 Kikuyu The results for kikuyu are presented in figure 9. Based on field measurements the kikuyu pasture produced a similar amount of dry matter to that of the annual pasture reflecting the 0.35 fertility scalar used for model validation (figure 2). However kikuyu does provide pasture growth in summer (figure 2). As a consequence there are no yield benefits from kikuyu within the growing season only the potential to partly fill the summer/autumn feed gap thereby reducing supplementary feed. Figure 9. Relationship between the percentage of farm sown to kikuyu and average gross margin ($/ha) for a) soil fertility factor annuals 0.4, kikuyu 0.35 and b) soil fertility factor annuals 0.8, kikuyu 0.8 at Manjimup WA. All September calving. Introducing kikuyu into the current annual pasture only provides modest increases in gross margins at 0.8 and 1.2 cows/ha at a proportion between 25 and 50% (figure 9a). At a stocking rate of 0.8 cows/ha the gross margin went from $39/ha with no kikuyu to $76/ha with 25%. Annual and kikuyu pastures with the current level of productivity are simply not profitable at stocking rates of 1.6 cows/ha or above. 9

10 When annual and kikuyu pastures are simulated close to their potential production (figure 9b) it restores the positive linear relationship between stocking rate and gross margins. Due to its summer activity kikuyu provided benefits in comparison to highly productive annual pastures at stocking rates of 0.8 cows/ha or higher. The highest gross margins were recorded with systems containing between 25 and 50% kikuyu. For example at a stocking rate of 1.2 cows/ha sowing 25% of a feedbase to kikuyu increased gross margins $61 from $332 to $392/ha. Do perennials change the optimum time of calving? Once it had been determined that perennials could lead to higher gross margins with a September calving the question arose as to whether the optimum time of calving had changed with the addition of out of season feed. The simulated Mottram property sown entirely to tall fescue pastures was chosen to investigate the relationship between gross margin and time of calving for a feedbase with summer green feed. The results are presented in figure 10. A September time of calving returned the highest gross margin as it did with annual pastures and the order from highest to lowest gross margin (May) remained the same (refer to figure 3). As a consequence a September time of calving was used in all analysis which included perennials. Figure 10. Relationship between stocking rate (cows/ha) and average gross margin ($/ha) for various times of calving for tall fescue at soil fertility factor 0.8 at Manjimup WA. Is it possible to increase gross margins further with a feedbase made up of a number of different perennials? The simplest approach to answering this question was to firstly determine whether a livestock system comprising of two types of perennial pasture could provide higher gross margins than that containing just one. The findings of this analysis are presented in figure 11. In the case of tall fescue and lucerne it is only at stocking rates of 1.6 and 2 cows/ha that a combination of both pastures results in a higher gross margin than either tall fescue or lucerne alone (figure 11a). For example the highest gross margin of $621/ha was achieved at 1.6 cows/ha with 25% tall fescue and 75% lucerne compared to $523 and $496/ha for lucerne and tall fescue respectively. It was not possible to increase gross margins when combining kikuyu with either tall fescue or lucerne (figure 11b and 11c). However in both cases systems comprising of 25% kikuyu did not return lower gross margins at stocking rates from 0.4 to 1.2 cows/ha. One such example is a system stocked at 1.2 cows/ha 10

11 made up of 25% kikuyu and 75% lucerne which returned $452/ha compared to $467/ha for lucerne alone (figure 11c). The highest gross margin achieved in simulations to this point is $621/ha for a system made up of 25% tall fescue and 75% lucerne (figure 11a) compared to the potential for annual pastures at $393/ha (figure 3b). To determine if it was possible to push gross margins higher a 3 paddock simulation was designed with the ability to vary the areas of tall fescue, lucerne and kikuyu and therefore able to test if a 3 perennials would result in further improvements. The results of this analysis is presented in figure 12. As expected perennial combinations return higher gross margins than annual pastures alone and at stocking rates lower than 2 cows/ha, perennial combinations also result in higher gross margins than tall fescue alone. Interestingly all combinations of tall fescue and lucerne with 10% or less kikuyu return similar gross margins below a stocking rate of 2 cows/ha. Proportions of kikuyu above 10% reduce gross margins. No combination tested increased gross margins substantially higher than that achieved with 25% tall fescue and 75% lucerne however this analysis does demonstrate that this ratio is flexible as systems with up to 40% tall fescue and as low as 60% lucerne can return similar gross margins. Discussion Validation of the model suggests that the simulations used in this analysis are credible particularly for comparative purposes across a range of pasture systems and livestock management. The hypothesis that a perennial based system will increase gross margins from beef production in Manjimup compared to an annual system by providing more feed during out-of-season feed gaps is accepted however when this hypothesis was developed prior to the study the investigators did not expect tall fescue and lucerne to produce more feed within the growing season this result was unexpected. Very little research has been undertaken on perennials in the Manjimup region. However, one such study undertaken by Omedii (see references) between 2007 and 2009 showed that stocking rates on tall fescue were double that on annual pasture (24 DSE verses 12 DSE/ha respectively). A similar comparison from this analysis would be annual pasture fertility scaler 0.4 verses 25% tall fescue/75% lucerne with respective stocking rates of 11 and 24 DSE/ha (data not presented). While there is not a large body of independent evidence for Manjimup to support the statement that tall fescue and lucerne can significantly increase gross margins, this study and Omedii s make compelling cases to encourage beef producers to consider and trial them as more profitable alternatives to annual pasture. Part of the reason for higher returns with tall fescue and lucerne is the relatively low productivity of the annual pastures that were monitored on-farm to validate the model. If this level of productivity is typical for annual pastures in the Manjimup region it is likely that beef enterprises return at best a low profit. This analysis suggests that there is a need to investigate low cost ways to increase annual pasture productivity particularly for parts of the landscape that are not well suited to tall fescue or lucerne. Apart from their measured higher yield tall fescue and lucerne lift gross margins by filling the summer/autumn feed gap allowing higher stocking rates and reduced supplementary feeding. These simulations suggest that September is the optimum time of calving for both annuals and perennials as this time of year required the least amount of supplementary feed to finish young stock to market specifications. Other viable options include August, November and January. It is possible that beef producers in the region have alternative calving times that can equal or better September however they most likely manage and market their stock differently to that used in this analysis. It is proposed to meet with local beef producers to discuss time of calving and get their feedback on these findings. The modelling results supported the Mottram s decision to sow perennials on their property (5% tall fescue, 5% lucerne and 3% kikuyu) and even though the farm only had a relative small area under perennial pastures it was sufficient to increase gross margins above that for their annual pastures. This finding is encouraging as it demonstrates that at least for Manjimup producers can get benefits from sowing perennials even with the first few paddocks. 11

12 Figure 11. Relationship between stocking rate (cows/ha) and average gross margin ($/ha) for varying amounts of a) tall fescue and lucerne, b) tall fescue and kikuyu and c) lucerne and kikuyu at Manjimup WA. September calving. 12

13 Figure 12. Relationship between stocking rate (cows/ha) and average gross margin ($/ha) for varying amounts of tall fescue, lucerne and kikuyu at Manjimup WA. This investigation looked extensively at the question of what is the optimum proportion of tall fescue, lucerne and kikuyu to maximise gross margins. The results clearly show that tall fescue and lucerne could substantially lift profit. If compared to the measured annual pastures on-farm this increase could be as much as $582/ha (annuals 0.4 fertility scaler stocked at 0.8 cows/ha verses 25%tall fescue/75% lucerne stocked at 1.6 cows/ha) or $228/ha if you compare highly productive annual pastures to the same perennial system. Encouragingly the findings suggest that producers can achieve these high gross margins with a reasonably wide range of proportions of tall fescue and lucerne, as a consequence producers should choose either tall fescue or lucerne based on which is best suited to the paddock in question. Kikuyu as measured on-farm was relatively unproductive and only provided a modest benefit in the analysis by providing green feed in summer and autumn. A more productive kikuyu pasture was modelled and the findings suggest that it could return substantially higher gross margins than annual pastures particularly if it comprised 25 to 30% of the feedbase. Methods to increase kikuyu pasture yields in this environment warrant further investigation. Small proportions of kikuyu (5 to 10% of the feedbase) combined with tall fescue and lucerne appear to be quite profitable. This suggests that beef producers should sow kikuyu if they have soils suited to it but not tall fescue or lucerne eg deep sand. Other reasons include areas to feed stock in autumn and paddocks that are at risk of soil erosion. A final note of caution regarding stocking rates. The gross margin values presented in this report are averages, given the number of simulations undertaken it was not possible to present the year by year variation around these averages. Typically as stocking rates are increased the variation in annual gross margins also increases to a point at 2 cows/ha where this represents too high a risk. For productive pastures it is the authors judgment that for the risk adverse producer 1.2 cows/ha is the optimum stocking rate in this environment and for those more comfortable with higher risk and higher returns 1.6 cows/ha. The findings of this analysis strongly recommend the sowing of tall fescue and lucerne on suitable soil types for the purposes of lifting productivity and profit. The results also suggest growers should not be too concerned from an investment perspective with how much of their property should be sown to these species given they can be established at a reasonable cost. The challenge for annual and kikuyu pastures is to 13

14 improve their productivity closer to the potential. However small amounts (5 to 10% of the feedbase) of kikuyu appeared in simulations to be financially beneficial which means producers can be confident in sowing on deep sands that are at risk of erosion. One deficiency in this study that could be addressed in the future is how sensitive these findings are to varying costs of perennial pasture establishment and variations in the length of perennial pasture persistence. References Moore, A. D., Donnelly, J. R. and Freer, M. (1997). GRAZPLAN: Decision support systems for Australian grazing enterprises. III. Pasture growth and soil moisture submodels and the GrassGro DSS. Agricultural Systems 55; p Omedii, P. Manjimup EverGraze Supporting Site. 14

15 Appendix. Details for Mottram Farm GrassGro simulation September Calving. Note: For other feedbase systems simulated the pasture species and soil fertility scaler in paddocks were changed appropriately Location me, mn Paddocks (all level) Paddock Paddock Fertility Soil Pasture species area (ha) scaler profile Kikuyu & subclover Subclover, capeweed & annual ryegrass Tall fescue (summer-active) fixed legume at 15% Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Lucerne (winter-active), subclover, annual ryegrass & capeweed Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Tall fescue (summer-active) fixed legume at 15% Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Tall fescue (summer-active) fixed legume at 15% Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Subclover, capeweed & annual ryegrass Total 300 Soil Profile 1 (Mottram kikuyu paddock soil type) Soil description Sandy loam over clay loam Soil albedo 0.17 Soil evaporation 3.5 mm/d ½ SCS runoff curve no. Use default Topsoil Subsoil Cumulative depth (mm) Field capacity (m 3 /m 3 ) Wilting point (m 3 /m 3 ) Bulk density (Mg/m 3 ) Saturated conductivity (mm/hr) Initial water (m 3 /m 3 ) Soil Profile 2 (Mottram kikuyu paddock soil type with more clay) Soil description Sandy loam over light clay Soil albedo 0.17 Soil evaporation 3.0 mm/d ½ SCS runoff curve no. Use default 15

16 Topsoil Subsoil Cumulative depth (mm) Field capacity (m 3 /m 3 ) Wilting point (m 3 /m 3 ) Bulk density (Mg/m 3 ) Saturated conductivity (mm/hr) Initial water (m 3 /m 3 ) Soil Profile 3 (Mottram lucerne NMM tube5 bottom soil) Soil description Sandy loam over light clay Soil albedo 0.17 Soil evaporation 3.0 mm/d ½ SCS runoff curve no. Use default Topsoil Subsoil Cumulative depth (mm) Field capacity (m 3 /m 3 ) Wilting point (m 3 /m 3 ) Bulk density (Mg/m 3 ) Saturated conductivity (mm/hr) Initial water (m 3 /m 3 ) Soil Profile 4 (Mottram lucerne NMM tube5 top soil) Soil description Sandy loam over light clay Soil albedo 0.17 Soil evaporation 3.0 mm/d ½ SCS runoff curve no. Use default Topsoil Subsoil Cumulative depth (mm) Field capacity (m 3 /m 3 ) Wilting point (m 3 /m 3 ) Bulk density (Mg/m 3 ) Saturated conductivity (mm/hr) Initial water (m 3 /m 3 ) Soil Profile 5 (Mottram tall fescue NMM tube 12 soil) Soil description Sandy loam over light clay Soil albedo 0.17 Soil evaporation 3.0 mm/d ½ SCS runoff curve no. Use default Topsoil Subsoil Cumulative depth (mm) Field capacity (m 3 /m 3 ) Wilting point (m 3 /m 3 ) Bulk density (Mg/m 3 ) Saturated conductivity (mm/hr) Initial water (m 3 /m 3 )

17 Pastures Max rooting depth (mm) Initial seed DM (kg/ha) Subclover, capeweed & annual ryegrass Subclover Capeweed Annual ryegrass Tall fescue (summer-active) fixed legume at 15% Tall fescue Lucerne (winter-active), subclover, annual ryegrass & capeweed Lucerne (winter-active) Subclover Annual ryegrass Capeweed Kikuyu & subclover Kikuyu Subclover Livestock Breed Standard reference weight (kg) Angus 570 kg Bull breed Hereford (Mature bull: 700 kg) Death rate: adults (%/yr) 1 Death rate: weaners (%/yr) 1 Management policy: Beef Cows Stocking rate Rate 0.6/ha (was varied for SR analysis) Replacement rule Purchase Cast for age Self-replacing each 12 May Sell stock aged 9 to 10 years on 11 May First join at Mating date Conception at CS 3 Reproduction rule 01 years 16 Dec 100% Birth date Castration Weaning date One bull per Keep bulls for 25 Sep yes 10 May 45 cows 5.0 years 17

18 Sell young heifers Sell young steers Sell 0 year old animals as they reach a weight of 370 kg after 11 May; sell any remaining 1 year old animals on 1 Dec Sell 0 year old animals as they reach a weight of 370 kg after 11 May; sell any remaining 1 year old animals on 1 Dec Maintenance Feeding rule Description Main flock/herd Mature Females Feed in paddock, applying the rule: If animal condition falls to 3.0 during 1 Jan to 31 Dec feed to maintain condition of the thinnest animals Immature Females Feed in paddock, applying the rule: If animal condition falls to 3.0 during 1 Jan to 31 Dec feed to maintain condition of the thinnest animals Immature Males Feed in paddock, applying the rule: If animal condition falls to 2.5 during 1 Jan to 31 Dec feed to maintain condition of the thinnest animals Weaner flock/herd Weaners Feed in paddock, applying the rule: If animal condition falls to 3.0 during 1 Jan to 31 Dec feed to maintain condition of the thinnest animals Supplement Ingredient Supplement: Hay Hay Proportion of mix (%) 100 Supplement Dry matter content (%) 86 Dry matter digestibility (%) 61 ME:DM (MJ/kg) 8.7 Crude protein (%) 14 Rumen-degradable protein (%) 65 18

19 Feeding rule Supplement Production Feeding rule Ad libitum, in paddock from 1 Jan to 30 May Start feeding when available green DM < 600 kg/ha End feed when available green DM > 600 kg/ha Ingredient Supplement: Silage Silage Proportion of mix (%) 100 Dry matter content (%) 27 Dry matter digestibility (%) 66 ME:DM (MJ/kg) 9.6 Crude protein (%) 17 Rumen-degradable protein (%) 80 Grazing management Cows From 1 Jan to 31 Dec Heifer Weaners Same as Heifer yearlings Same as Steer weaners Same as Steer yearlings Same as Grazing rule: 20 paddock movements Withhold: 1 day. Then check every 1 day. Move when average daily wt gain can be improved by 0.01 kg Paddock 1, Paddock 2, Paddock 3, Paddock 4, Paddock 5, Paddock 6, Paddock 7, Paddock 8, Paddock 9, Paddock 10, Paddock 11, Paddock 12, Paddock 13, Paddock 14, Paddock 15, Paddock 16, Paddock 17, Paddock 18, Paddock 19, Paddock 20, Paddock 21, Paddock 22 Cows Heifer weaners, cows Heifer yearlings, Heifer weaners, cows Steer weaners, Heifer yearlings, Heifer weaners, cows Cattle costs Cow Husbandry $3.37 /head Calf Husbandry $4.10 /head Cow Replacement $702 /head Bulls $1173 /head Cattle sales commission 5 % Cattle sales cost $17.30 /head Pasture cost $80.00 /ha Supplement costs Hay $211 /t Silage $211 /t 19

20 Cattle prices Cow sales Base price 116 c/kg Steer sales Base price 167 c/kg Heifer sales Base price 167 c/kg 20