Two leading water companies in the UK; Affinity Water and Portsmouth Water are funding an innovative study to understand the rotational and environmental impacts of nitrogen captured by autumn/winter cover crops. The Nitrogen release from Cover Crops (NiCCs) project, being delivered by ADAS, will focus on the effect that cover crop species choice and different destruction methods have on nitrogen release into the following crop and beyond. The results will be used to underpin advice for growers on the appropriate management of cover crops, both in terms of maximising the nitrogen available to the next crop and minimising long-term nitrate leaching.

The study will compare two cover crop mixes (kindly supplied by RAGT seeds UK) and assess the quantity and timing of nitrogen being released into the soil. Different destruction methods (glyphosate vs. chopping or rolling), will then be used to better understand the potential of growing cover crops without glyphosate. Experiments will be conducted over two years in Hertfordshire and West Sussex.

“Understanding when nitrogen captured by a cover crop is released and how this impacts subsequent crop nitrogen fertiliser requirements and over-winter nitrate leaching was identified as a key knowledge gap by the AHDB Maxi Cover crop project. It’s great to be working with Affinity and Portsmouth water on this collaborative project to begin to explore this, and help farmers and growers potentially improve nitrogen use efficiency, reduce fertiliser use and improve water quality”
Dr Anne Bhogal Bhogal – Principal Soil Scientist, ADAS

“This is a great opportunity to collaboratively work with ADAS and Affinity Water to look in to the effects of nitrogen releases from Cover Crops after they have been destroyed. It will help understand water quality impacts and look into what solutions to reduce this could be made,” said Simon Deacon, Catchment & Environment Manager Portsmouth Water

“We encourage farmers in our catchments to grow cover crops as the evidence is clear on how they can reduce nitrate leaching in the autumn and winter. However, a question I am often asked by farmers is should they adjust their nitrogen rates following a cover crop to make use of the nitrogen that the cover crop has held onto. This study will hopefully shed some light on this knowledge gap and help farmers further refine their nitrogen use and build on the benefits that cover crops deliver for soils and water quality,” said Shaun Dowman, Agricultural Advisor, Affinity Water.