Scope for more efficient use of fertilizer nitrogen

About 1.6 million tonnes of fertilizer N are applied to UK crops each year. In net terms, 10–60% of this is not taken up by the crop to which it was applied. Fertilizer N commonly doubles crop yield, but in the short term at least more than 90% of current production would be possible with only half normal use of N. However, costs of crop production other than fertilizer N are a large proportion of gross returns, so profits are sensitive to adjustments in N use and controls on N use could affect land values. Survey data show that compliance with current recommendations is good; recent improvements have come through restricting the use of N applications in autumn. Further improvements are possible by adjusting N use more fully for the extent to which past N applications have exceeded crop removal, and by better targeting the N used to improve protein concentrations of wheat grain. Research now in progress may provide insights into minimizing the crop N necessary for yield formation and the crop N left in the field at harvest, specifying the growing conditions which result in efficient N uptake from soil.