A soil mineral nitrogen test, as part of an appropriate, calculated justification should be used at a point in the rotation where crops are grown using heavy applications of nitrogen (>200kg/Ha) or incorporating large quantities of FYM. A soil N balance sheet approach based on crop requirements and soil N-supply should then be introduced. All nitrogen applications should also take account of the P, K, Mg and S element of farmyard and organic manures applied.

Where crops requiring high levels of nitrogen are grown on light soils, particular care is required to match the amount and timing to crop needs to minimise leaching risks. Additionally, care should also be taken in areas which are designated Nitrate Vulnerable Zones. These are areas where water resources are limited and vulnerable, and growers are asked to observe a programme of measures designed to reduce nitrate loss from the land and help reduce nitrate levels in water.

Consideration should be given to the use of liquid rather than solid fertiliser. It is more accurate to apply liquids and the risk of buffer zone inclusion is less. Under dry conditions, the efficiency of uptake of Nitrogen is usually increased from using liquids rather than solid fertilisers. However, there are additional risks to consider when using liquids, e.g. prevention of spillage, as there may be little opportunity for ‘mopping up’. Therefore, siting of loading for liquid fertilizer requires care. Consideration of the fertilisers’ chemistry and its release mechanisms should be given. Thus, increases in the efficiency of use of fertiliser may be gained e.g. from using fertiliser with a steady release over time, as opposed to a rapid release.

Target Nitrogen Application

The choice of crop, autumn crop cover, cultivation, organic manure use and grassland management all have a major impact on the quantity of nitrogen lost.