Growing Futures

Optimising nitrogen in wheat crops

Optimising nitrogen in wheat crops

New tools support optimal use of nitrogen to increase yield

In New Zealand, wheat is primarily planted on mixed cropping farms, where different cereal and vegetable crops are rotated depending on soil health and season. Farmers produce more than 400,000 tonnes of wheat each year, for use in milling or as feed for animals, from around 50,000 hectares of land.

The key targets for the wheat industry are increasing yields whilst optimising inputs, such as nitrogen and water, to ensure maximum profitability of farms and maintaining environmental sustainability.

The Wheat Calculator is a decision support tool that allows farmers and farmer organisations to calculate the amount of nitrogen fertilisers to apply to wheat crops to optimise productivity. The tool is based on modelling of cultivar performance under different scenarios – including soil type, sowing date and weather – allowing growers to make the decisions that best meet the needs of their own crop.

The tool allows farmers to see the impact on their wheat crops of changing amounts and timings of nitrogen application, and the optimal point where application of nitrogen delivers maximum economic benefit. It also uses information on the nitrogen supply from the soil, along with weather and irrigation data, to predict the best windows for nitrogen application that optimise productivity and minimise the risk of nitrogen leaching.

The Foundation for Arable Research has used data from the Wheat Calculator in the development of a series of farm guidelines, which are now used by around 80% of the 1,700 farmers operating mixed cropping farms around New Zealand. Trials have shown that, through optimal nitrogen application, wheat yield can be increased by an average of 40%, with potential margin over nitrogen costs for some cultivars of up to $2,700 per hectare.

The development of the Wheat Calculator was funded by the Ministry for Primary Industries' Sustainable Farming Fund with support from the Foundation for Arable Research and Ballance Agri-Nutrients.

Created: September 2014

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