Nitrate Leaching from Tillage Lands

There is a high risk of nitrate leaching from free draining tillage fields in the autumn/ winter and early spring period of the year due to low crop growth rates and high rainfall levels. Farmers can help reduce these losses by carefully managing fertiliser applications and targeted establishment of catch or cover crops. This factsheet was produced as part of a series of factsheets by the Agricultural Sustainability Support and Advisory Programme (ASSAP).

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Tips for reducing nitrate leaching from tillage fields

• Maximising Nutrient Use Efficiency (NUE) on your farm is the best way to minimise nitrogen losses to waters and also to improve crop profitability.
• Ensure soil pH, Phosphorus and Potassium are at optimum levels. Soils at correct pH, P and K status will result in a higher nutrient uptake by the crop thereby reducing the risk of loss.
• Nitrate leaching risk can be reduced by matching fertiliser application to the crop demand. Adjusting the timing and rate of application to match crop requirements, will ensure best return on money invested as well as reduced losses through leaching. There may be opportunities to reduce Nitrogen rates without impacting the yield of the crop.
• Ensure soil temperatures are consistently at 6 degrees or above before applying chemical Nitrogen. Low soil temperatures that do not support crop growth will increase risk of leaching to groundwater. Avoid application when rain is forecast within 48 hours or on wet or waterlogged soils.
• To ensure efficient and accurate application of fertiliser, calibrate fertiliser spreaders and use GPS equipment where available.

Summary

There is a high risk of nitrate leaching from free draining tillage fields in the autumn/ winter and early spring period of the year due to low crop growth rates and high rainfall levels. Farmers can help reduce these losses by carefully managing fertiliser applications and targeted establishment of catch or cover crops. Improved utilisation of chemical nitrogen by tillage crops will improve the financial return to the farmer but also reduce the risk to water quality.

For more information please visit www.teagasc.ie/water-quality or view the other factsheets in the series here