Rotorainer with water

Understanding new rules on spreading slurry and dirty water


New rules on spreading manure, slurry, digestate, inorganic fertilisers and other forms of “agricultural pollutants” came into effect early in April.

The Farming Rules for Water fulfil the UK’s obligations on diffuse pollution under the EU’s Water Framework Directive. They set out “reasonable precautions” to prevent runoff, soil erosion and pollution of water courses. The new rules have the force of law and are part of a bigger 25 year environment plan.

We believe farmers who already adopt best practice have little to fear from the new regulations. Forward planning, sensible risk assessment, following guidelines on when and where to irrigate and regular monitoring are all that is required. Our equipment has always been designed to help minimize risk.

However, we asked defra to provide clarification of the definitions of “agricultural pollutants” in Regulation 2, which makes no mention of ‘dirty water’. Agricultural pollutants have a wide ranging definition under the new Regulations and include anaerobic digestate, silage effluent, sludge and slurry capable of being pumped or discharged by gravity. Moreover, they cover just about anything that contains substances found in organic manure. In most cases dirty water falls under the regulations.

Each application needs to be assessed in advance so that the total quantity of nutrients added to the soil does not exceed the needs of the soil or crop. Therefore, if you know that the nutrient value of the organic material in the dirty water will have very little impact on the total amount of nutrient being applied, its effect under the Regulations will be minimal.

So, to comply with the new Regulations it is important to know what you are doing, which may mean some extra testing. Just in case there is a problem, good records could also be useful.

The AHDB Nutrient Management Guide (RB209) was updated in May 2017 and continues to recognise dirty water. The total nitrogen content of dirty water is listed as 0.5 kg N/m3 or /t, which is one third the strength of thin cattle slurry separated by a strainer box. Of the N in dirty water, half is available to the crop when applied in the Spring and somewhat less (10% - 35%) when applied at other times of the year.