Nitrogen - how to meet the need?

For an environmental sound nitrogen management, meeting the right application rate is of crucial importance. Several precision farming methods and tools exist to calculate the N demand. How to derive optimum nitrogen rates?

N uptake indicated by biomass

Total nitrogen uptake and yield are closely related for oilseed rape. Therefore the principle of deriving optimal N rates is to define the achievable yield and to calculate the total required amount of nitrogen. Growers arrive at the optimum nitrogen rate for spring application by deducting the actual N uptake from the totally required N amount. A widely accepted method developed in France calculates the nitrogen forecast for spring by weighting the above ground biomass at the end of autumn or the beginning of spring. The biomass based estimation of actual N uptake together with the yield expectation provides a reliable estimate of the required nitrogen in spring. The method, however, is destructive and time consuming.

The Yara ImageIt app

ImageIT is a digital App. It determines nitrogen uptake of rapeseed based on images of the actual crop development. The application sends the photos over the network for automated analysis. A detailed recommendation based on yield objective, actual nitrogen uptake and mineralization potential of the soil is returned instantly. To download the App, scan the QR code or search your store for Yara ImageIT.

Cost efficient application

The economic optimum of nitrogen application is reached when revenues from crop yield minus fertilizer cost reach a maximum. It depends on actual market prices for rapeseed and fertilizer. In general, nitrogen application increases returns, as demonstrated by field trials in Germany (figure 6), with an economic optimum at about 150 - 200 kg N/ha applied in spring.