Maximise the benefits of slurry and manure

Storing and applying slurry and manure wisely makes good sense, whether or not a farm lies within a nitrate vulnerable zone (NVZ).

This was the message given to farmers by David Ball, AHDB’s technical manager.

Ensuring nitrogen stays in soil and is made available to the growing crop will help save money on fertilisers and reduce the risk of it reaching watercourses, he added.

Mr Ball pointed to software and apps which could help farmers when completing calculations to comply with NVZ requirements: “The AHDB Slurry Wizard will enable you to calculate how much slurry and dirty water is produced and the minimum storage requirement for your farm to meet NVZ requirements.

“It will estimate the nutrient content of slurry and manure and the effect different application methods will have on availability of nutrients to the growing crop.

“The Slurry Wizard can predict how much money can be saved if different investments are made to reduce the amount of water entering the slurry store.”

Mr Ball highlighted recent EU legislation relating to ammonia emissions, which will be implemented in the UK in July 2018.

He said: “Our Government is keen to implement this legislation, so even when the UK leaves the EU, it is likely to remain in some form.

“The Government is currently tackling emissions from cars, but agriculture is likely to be next in the firing line.

“Agriculture is responsible for 83 per cent of ammonia emissions and, of this total, livestock farming accounts for 80 per cent. The remaining proportion is mainly from fertiliser spreading.”

The EU legislation requires an 8 per cent reduction in ammonia emissions by 2020 and 16 per cent reduction by 2030, which could be a challenge.

Mr Ball said: “There are several areas where farmers can influence ammonia emissions, such as the design and construction of housing, storage of manures, method of slurry and manure application and the way we feed our cows, as lower protein diets result in lower emissions.”

Choosing an application method for slurry, which minimises losses of ammonia to the atmosphere, also results in a higher proportion of nitrogen reaching the growing crop.

This reduces the need for bagged fertiliser, according to Mr Ball: “Adopting a shallow injection system reduces ammonia emissions by 70 per cent. Up to 80 per cent of the nitrogen content of slurry is lost to the external environment if a splash plate is used, so opting for an umbilical system, a dribble bar or a trailing shoe could significantly increase the amount of nitrogen made available to the crop.

“An average application of 30cu.metres/hectare of slurry is worth the equivalent of £33.84/ha as inorganic fertiliser, so increasing the percentage of nitrogen retained in soil translates into a lower fertiliser bill.”

When applying slurry, Mr Ball reminded farmers of the worm population in soil, advocating spreading ‘little and often’ to avoid any adverse effects on them.

Silage effluent should not be forgotten, Mr Ball said, adding it was ‘very polluting’ and ‘should be treated the same way as slurry’.

He said: “Farmers must advise the Environment Agency when building a new slurry or silage store. They may wish to inspect the store after construction and you must give them at least 14 days notice of when you are planning to start using it.”