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Being dollar wise about using N

Being dollar wise about using N. Rex Webby, AgResearch Ruakura. Various studies. Sensitivities around cost of N, product value, response rate, amount of N applied and N leaching For a mixed sheep and cattle farm Ewes scanned twins set stocked for lambing Improving efficiency using N.

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Being dollar wise about using N

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  1. Being dollar wise about using N Rex Webby, AgResearch Ruakura

  2. Various studies • Sensitivities around cost of N, product value, response rate, amount of N applied and N leaching • For a mixed sheep and cattle farm • Ewes scanned twins set stocked for lambing • Improving efficiency using N

  3. For a mixed sheep and cattle farm • Study based on: • Farm size 1000 ha • Potential annual pasture production 8324 kg DM/ha/year • Lambing % 125% • N timed to give most benefit

  4. Product per ha and amount of N applied

  5. Results for the mixed farm analyses • Farm stocking rate and production increased with higher N • Financial return was highest at 20 and 40 N rates • N leached increased in a curvilinear fashion as N application rate increased

  6. N and twining ewes • N applied 31 July • Ewes scanned twins set stocked at 6.5 ha • Based on 40 kg N/ha at 15:1 • North facing steep hills • Weaning 155% • Amount of N applied decreases or increases depending on response rate • All lambs at weaning valued $/kg live weight • Cost of N was set at $1.40/kgN applied

  7. Relative returns from differing response rates (kgDM/per kg N) and varying lamb values ($/kg live weight) at weaning

  8. Relative returns from differing response rates (kgDM/per kg N) and varying lamb values ($/kg live weight) at weaning

  9. Other sensitivities • Lamb survival • At 15:1 if weaning 165% add another $35/ha at $2/kg LWT • At 10:1 if weaning 165% breaks even at $1.50/kg LWT • Stocking rate • With no N the stocking rate is 5.6 ewes/ha (with 6.5) • If adjusted stocking rate instead of amount of N result the same • Cost of N • At 40kg/N ha a 10c change in cost of a kg N applied is equal to a $4 change in per ha cost.

  10. Improving efficiency using N • Aim • To maximise the use of late spring pasture growth • Improve utilisation of total feed grown on farm • Improve feed quality throughout the year • Produce more • Make more money • Achieved by • Increasing stocking rate by using N strategically • Improving animal performance/efficiency of production • Systems need to be designed for one application of N in spring

  11. Pasture cover profile no N vs N

  12. Results • Utilisation of feed grown increased from 80 to 90% • Lower pasture covers throughout year • Improved pasture quality throughout year • 30 kg more product per ha • An extra $37/ha gross margin

  13. Summary • Highest returns at 20 to 40 kg N/ha • N leaching increases curvilinear with increasing amounts of N • Little point in applying more than 80 kg N/ha per year on sheep and cattle farms • Responses rate (kg DM/kgN) important to profitability • Animal performance (lambing% and LWG) important to profitability and economics of using N • The strategic use of N can improve efficiencies with flow on benefits improving pasture utilisation and quality leading to higher animal performance

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