Tailoring nitrogen applications to optimise response

Tailoring nitrogen applications to optimise response

1 April 2021

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Help is at hand to get the most out of nitrogen fertiliser under new rules.

Applying nitrogen (N) fertiliser uniformly across different management areas on farm can be inefficient.

“With N cap rules starting in July 2021 for the 2021/22 season, tailored N applications are recommended to get the best response from your fertiliser,” says Ballance Agri-Nutrients Science Extension Officer Jessica Hollever.

Under the Essential Freshwater rules, no more than 190 kilograms of N per hectare per year (kg N/ha/year) can be applied to each grazed ha in pasture. The average across grazed pasture and forage crops must also not exceed 190 kg N/ha/year.

“Different management areas on farm have varying levels of soil N available for plants to use, and this is, in part, why plants respond differently if N fertiliser is applied uniformly,” Jessica explains.

Uniform applications of N fertiliser across a farm can result in N being applied where pasture response is low, leading to both economic and environmental impacts.

“The new N fertiliser cap rules mean using N wisely and getting the best pasture response from N applications is more important than ever.”

Total N soil test

The first step in optimising the placement and rate of N is to identify the varying levels of N in the soil across the farm’s different management areas. This is done via a Total N soil test.

“As the name suggests, the test measures the total pool of N in the soil – the combination of mineral N, available N and immobilised (mainly organic) N pools. Although not often used, it provides valuable information on the potential pasture response rate to applied N,” Jessica says.

The Total N test can be incorporated into a regular soil testing regime, and involves testing each different management block on farm to a depth of 75 millimetres (mm). It only needs to be repeated every four to five years as results change slowly over time depending on changes in land management.

Using the Total N test results

How do the Total N test results help to optimise N application?

This is where My Pasture Planner – a decision support tool incorporating scientific expertise from AgResearch – comes in.

“My Pasture Planner uses Total N soil test information to identify strategic N fertiliser applications so you can tailor both N fertiliser placement and rates on a monthly basis. Ballance Nutrient Specialists can use My Pasture Planner to guide annual N fertiliser plans and show where response is likely to be less and greater,” Jessica says.

The tool uses the Total N soil test, a digital farm map and regional pasture growth data to predict pasture response, so N can be used more efficiently – in the right places and at the right rates and times – with less impact on the environment. This could translate into lower N leaching as modelled by Overseer.

Farmers can easily access outputs from My Pasture Planner which is integrated with the MyBallance platform. The mapping capability makes it easy to create an annual plan, and the MyBallance integration means easy access to a fertiliser recommendation mapped out for the farm.

My Pasture Planner was developed in collaboration with AgResearch, and partly funded by the Ministry for Primary Industries’ Primary Growth Partnership. Used exclusively by Ballance, it is available via a Ballance Nutrient Specialist to customers registered with MyBallance.

To find out more, contact your local Ballance Nutrient Specialist or visit ballance.co.nz/my-pasture-planner.

Article supplied by Ballance Agri-Nutrients.