Farming

Supporting farm sustainability through the use of digestate

Digestate produced as a result of anaerobic digestion is a nutrient-rich substance that can be used on agricultural land as a fertiliser, replacing raw manures, synthetic fertilisers and soil conditioners. Digestate contains major plant nutrients such as nitrogen, phosphorous, potassium, magnesium, sulphur and trace elements.

Plant uptake of nitrogen from digestate is similar to that of commercial fertiliser and a more predictable source of nitrogen than raw slurry.

Studies have shown that the use of digestate can enhance crop growth more than the use of conventional fertilisers with the use of liquid digestate enhancing nutrient penetration through the soil.

The spreading of digestate enhances soil quality more than conventional fertilisers. Digestate has a high biological component, which enhances soil moisture retention and reduces erosion and compaction by improving soils health and creating microscopic biofilms within the soil.

Anaerobic digestion reduces the volatile organic content of organic material, such as raw manure, and stabilises it. This reduces the potential for odorous greenhouse gas release during spreading.

Digestate is easier to spread than raw slurries, owing to the decomposition of solids and reduction in viscosity, reducing cost, energy and impact on the environment (see video).

Weed seeds that are commonly found in raw slurries are destroyed during the AD process. This reduces the requirement for use of herbicides. In addition, pathogens such as salmonella and e.coli and parasites such as tapeworm, that can be naturally present in raw slurries, are destroyed during the AD process.