Nitrogen Management

Farmers supplement the soil’s natural nutrient level with fertiliser to improve the land’s production potential. The key is to convert nutrient inputs into product efficiently and profitably while minimising losses within the system.

Overseer is a modelling tool used to measure the movement of nitrogen through the dairy farm system on an annual basis.  Our aim is to minimise modelled nitrogen loss per hectare.

The journey to date:

To achieve the reductions to date we have:

  • Improved feed conversion efficiency by reducing stocking rate from 2.95 cows/ha to 2.8 cows/ha, and increasing production per cow from 396 kg MS/cow/year to 440 kg MS/cow/year
  • Changed to earlier calving to match feed supply, culling cows early in autumn and completing lactation in early May to meet Average Pasture Cover (APC) and Body Condition Score (BCS) targets
  • Reduced the total amount of N fertiliser used annually from 161 kg N/ha to 138 kg N/ha
  • Utilised fertiliser technology like SustaiN and PhasedN and Smartfert
  • Monitored soil moisture and growth rate data to determine optimum times for fertiliser application
  • Carried out annual block soil testing along with Total N tests to address the most limiting nutrient for pasture production first
  • Reduced the amount of nitrogen applied in May (for new grass only), and no applications in June and July each year
  • Constructed a 3000 m3 effluent storage pond that is emptied every May to avoid the need to apply effluent during June and July
  • Extended the effluent spreading area from 44 ha to 52 ha (36% of the milking area) which has reduced the N loading from effluent to 43 kg N/ha/year on this block. In 2021 we also used umbilical effluent spreading to apply effluent over areas of the farm outside the effluent block
  • Reduced herd replacement rate from 23.4% to 22.9%

 

The journey continues:

To achieve further reductions we have developed a strategic approach to nitrogen fertiliser in conjunction with Ballance Agri-nutrients using Total N soil test results, and My Pasture Planner to determine the most effective use of 120 kg N/ha in our pastoral system.

  • 30 kg N/ha in August to fill a feed deficit
  • 30 kg N/ha in October/November during cropping and silage making
  • 20 kg N/ha in December to extend rotation length and push feed into summer
  • 40 kg N/ha in April/May for summer dry recovery and following new grass grazings

Effluent management is a critical part of our nitrogen management strategy.  Effluent is a valuable source of nutrients to recycle.  In October 2021 we invested in further infrastructure to allow us to irrigate effluent over a total of 61 ha (42% of the farm). 

In 2021 we committed to planting all new permanent swards with 4 kg/ha of Ecotain plantain to further reduce nitrogen losses in our system, and two species of white clover and one red clover to provide nitrogen fixation for plant growth.

Dairy Insights report from Fonterra 2020-21