Nitrogen tool a starting point for valuable on-farm conversations

N-Guru is decision support software designed in a partnership between AgResearch and Ballance Agri-Nutrients to improve the efficiency of nitrogen use on pastoral farms.

AgResearch testing of pasture nitrogen fertiliser response rates led to a hypothesis that the higher the soil organic matter content the lower the fertiliser nitrogen response. In 2008 AgResearch used seed funding to confirm this with further field trials.

“The experiments confirmed the negative relationship between soil organic content and fertiliser response,” says AgResearch Senior Scientist Mark Shepherd.

“Basically in areas of high organic matter you are getting more from the soil so therefore you don’t need as much fertiliser.

“Ballance knew that this was valuable information for farmers, so they funded some more nitrogen response trials to test the results in locations throughout New Zealand (Northland, Waikato and South Island) and in different seasons. Using that work and the previous research we worked with Ballance to come up with a simple software tool. The Ballance team did the software design and AgResearch supplied the underpinning equations to go into that software.”

It is the first product from Ballance Agri-Nutrient’s $19.5 million, seven-year Clearview Innovations Primary Growth Partnership programme, jointly funded by the Ministry for Primary Industries. The programme aims to develop a range of new products, including biological products, which will improve nitrogen and phosphorus use efficiency and reduce losses to the environment. The programme will also help farmers adopt these new products and services through a best-practice extension programme which aims to improve on-farm management and reduce environmental footprints while increasing efficiency.

Soil total nitrogen tests were not a routine aspect of soil testing prior to this research and software tool. Where total nitrogen varies sufficiently across the farm the model can be used to determine the benefit from variable nitrogen use instead of applying nitrogen at uniform rates. Launched in 2014 Ballance offers  N-Guru as part of a soil test regime, which then informs the rate of nitrogen application and/or where the nitrogen is applied to maximise nitrogen use efficiency.

“This is another step forward in our ability to give expert advice, adapted to each part of the farm and firmly based on knowledge gathered from a large number of pasture response trials carried out nationally,” says Warwick Catto, Science Strategy manager for Ballance Agri-Nutrients.

“By improving nutrient use efficiency through the strategic and targeted use of nitrogen the risk of associated nitrogen loss is reduced and the cost-benefit of fertiliser nitrogen application increases.”

“The major turning point for the project was getting Ballance around a table and identifying how what we had found could be of practical value to a farmer,” says Dr Shepherd.

“We had this idea that you get less fertiliser response on high organic matter soils, but couldn’t really see how farmers could use that information. It took the partnership in 2011/12 with Ballance, who know the market and know the farmers, to turn it into something that farmers and rural advisors could use.

Dr Shepherd says that this is a particularly useful tool in low payout seasons or for farms operating under environmental constraints.

“If a farmer has limited fertiliser resources through budget limits or through an environmental cap this tool will help farmers make those strategic decisions about where best to deploy their fertiliser for the best production. The most benefit will be in those farms that have a wide range of organic matters and soil types as the tool can identify which area will respond more and which will respond less.

“It is great conversation starter for farmers and their rural advisors. It gets everyone to think about how and where they can get the best production from nitrogen fertiliser.”

Development of the N-Guru software is ongoing, based on feedback from farmers.

Benefit to New Zealand

Using the dairy sector as an example, the ability for N-Guru to enable analysis for differential N application recommendations across a farm based on soil test data will derive calculated economic benefits on-farm.  Ballance advisor calculations have shown that matching N fertiliser application to N soil levels can result in increased N use efficiency from 10:1 to 13:1, and 30% additional dry matter production for the same amount of fertiliser, when compared to a generic practice of whole farm N application rates.  On a 100ha farm this equates to an additional milk solids production of 643 kg produced from the generation of an additional 9651 kg DM.  Obviously the impact of N-Guru use will be farm specific; nevertheless as the on-going science extension strategy for N-Guru is developed and adopted nationally, significant economic and nutrient management sustainability benefit gains to the dairy sector would be anticipated.