2 August 2018

Optimising your digestate spreading and storage tactics

Spreading digestate on land has been recognised across the industry as promoting crop growing capabilities, offering high levels of nitrogen and proving a great alternative to artificial fertilisers.

Ahead of spreading digestate, it is important to understand how this product will work in tangent or replace your current fertilisation activities whilst also establishing a firm grasp on best practice to yield the highest output from this activity.

What is digestate?

Digestate is the term attributed to the material which remains following anaerobic digestion of biodegradable feedstock, alongside the remaining biogas. Digestate is produced through two different processes; acidogenesis and methanogenesis. Each of these processes has different characteristics.

Acidogenesis is typically fibrous and contains plant matter such a cellulose and lignin. It contains remnants of bacteria and minerals which can be beneficial to crop growth. Methanogenesis is the liquid or liquor digestate and is often referred to as a sludge. This product is high in nutrients, including; phosphates and ammoniums.

Technically, digestate matter is not compost, despite being similar in appearance and it’s chemical characteristic breakdown. Compost differs in that it is a product that is produced through means of aerobic digestion-decomposition by aerobes, including bacteria and fungi, which allow the cellulose and lignin to be broken down to a further extent.

The digestate product is a nutrient-rich substance which has been favoured in recent years to be used as an effective fertiliser. Not only this, it makes use of materials which are indigestible and microorganisms, to create a more economically sound fertiliser, which can be used in place of artificial composts and stored for long periods of time.

Optimum spreading times

Opting to use digestate over synthetic fertilisers offers farmers the opportunity to save energy, reduce their consumption of fossil fuels, minimise their carbon footprint and simultaneously save money, particularly through investment in a bespoke digestate storage tank or lagoon.

Digestate contains all of the nitrogen, phosphorous and potassium present in the feedstock; furthermore, the nutrients available are typically present at a much higher level when compared to a raw slurry. This allows plants to absorb the nutrients more effectively and improve crop production.

It is also important for farmers who are considering utilising digestate for a boosted crop production, to understand the optimum times for spreading the product on the land. Failure to adhere to restrictions in line with digestate spreading advice can result in an excessive run-off, soil failing to absorb the nutrients and the possibility of causing pollution to the local areas when weather conditions and land structure have not been considered.

It is advised that you do not plan to or undertake digestate spreading in the following conditions:

  • On waterlogged soil or land
  • During periods of heavy rainfall or when this is forecast within 48hours
  • On top of the frozen ground or during periods of snow covering
  • Where soil has cracked down to the field drains
  • Where a field has been pipe or mole drained
  • When a field is sub-soiled over drains within the past 12 months

Where digestate spreading cannot be carried out due to changes in weather or where crop growth is determined to not be at the peak of its maximum growth, farmers should hold off and instead invest in digestate storage solutions, such as tanks or lagoons, to effectively store the matter until such time.

Understanding nutrient levels

In order to most effectively utilise your digestate, you should regularly test the nutrient levels of the product and align these with the nutrients present in the soil on your land. Gaining a deeper understanding of the soil and digestate can ensure that the application is carried out at the most optimum time as well as ensuring the right amount of material is used.

Measurement of soil levels and digestate nutrient levels will also ensure that you do not cause oversaturation within the soil, bombard the land with excess nutrients and avoid the possibility of run-off of excess phosphorus and nitrogen. If run-off does occur, it can result in damage to the local environment and air and pollute nearby water sources.

For more information on digestate spreading services and digestate storage solutions, get in touch with AWSM Farming today.