Autumn v spring spreading

Published 13 February 14

Autumn v Spring application of slurry?


Key messages

  • Altering the timing and method of slurry application will help reduces losses of nitrogen (N) increasing the amount of N available to the plant
  • Moving slurry applications from autumn to spring can improve nitrogen use efficiency by 10%
  • Applying slurry to grassland using low emission techniques, eg bandspreading or injection, can improve nitrogen use efficiency by 10-15%
  • MANNER-NPK software will help calculate the most effective times to apply slurry to maximise nitrogen use efficiency by taking account of postcode-specific climate patterns and soil types.

Cattle slurry has half its total nitrogen in readily available ammonia form. After application, this ammonia nitrate is readily available for crop uptake but is also at risk of loss from nitrate leaching and volatilisation (losses to the atmosphere).

The timing and method of slurry applications can mean major reductions in these losses, explains Dr Lizzie Sagoo in a new DairyCo video on maximising manure application efficiency.

Where slurry is applied to the land in the autumn, when plant growth is slow, some of the readily available ammonium will leach over winter. The amount of nitrogen leached depends on the amount of rainfall after application and soil type.

MANNER-NPK software estimates drainage volumes and nitrate leaching losses by using postcode-specific climate data and soil type information, and can help you plan manure applications to minimise these losses.

It estimates that manure applied to grass in October, before the NVZ closed period, in a high rainfall area, would leach 20% of the available nitrogen. However, moving slurry applications to the spring will typically improve nitrogen use efficiency by between 5 and 10%.

Following application some of the readily available ammonia nitrogen will be lost into the atmosphere by volatilisation. The most effective way to reduce this is by applying slurry, using an injector or band spreader. This also has the benefit of applying the slurry evenly, reducing odour and minimising contamination.

For more information, about MANNER-NPK and to download the latest version of the software, click here.