Farmers’ use of renewable fertilisers to be revolutionised by new research

9th February 2016

Farmers’ and growers’ confidence in digestate and compost has been given a welcome boost, as new ground-breaking research published today,  shows smart use of these renewable fertilisers can increase yields and reduce bills with no negative impact on crop quality or safety.

The programme of field experiments, ‘Digestate & Compost in Agriculture’ (DC-Agri),  confirms that food-based digestate - a product of anaerobic digestion - is a valuable source of readily available nitrogen; the single most important nutrient influencing crop yields. This new data will enable farmers to predict how much nitrogen the digestate will supply their crops, allowing them to confidently reduce the amount of bagged fertiliser without affecting yields.

For compost – made from recycled green garden waste and food waste – the research shows it builds levels of soil organic matter1 more quickly than other organic materials, such as farmyard manure, which will help deliver stronger and more resilient crops.

In addition, both digestate and compost provide crops with a measured boost of phosphorus, potassium and sulphur, helping to maintain soil fertility.  Crops grown with an integrated nutrient plan combining bagged fertilisers and digestate or compost resulted in higher yields2 and better financial returns. 

The five year research programme3, led by resource efficiency charity WRAP, demonstrated that the timing and method of digestate application is critical if the maximum value is to be gained. If digestate is used in the spring on actively growing crops, or other times when there is a crop nitrogen requirement, farmers and growers can significantly increase its nitrogen value. For best results digestate should be applied using precision application methods such as band spreading and shallow injection.

With compost use, the research confirmed that it should be seen as a means to build up long term soil nitrogen rather than a short term replacement4.  The value in compost lies in its ability to build soil organic matter more quickly than other organic materials; retention of the organic matter in soils supplied by green compost was almost double that of farmyard manure indicating it’s more resistant to decomposition. 

DC-Agri’s robust scientific evidence has now been brought together in WRAP’s guides to good practice, also published today. The guides explain how to use these products safely and help farmers and growers make the most of renewable fertilisers economically and environmentally.

Dr. Richard Swannell, Director at WRAP, said: “Digestate and compost are valuable renewable products of our food and garden waste recycling processes. These new findings show the benefits that using the products correctly can bring, and for the first time farmers and growers have the evidence to make informed decisions about their fertiliser use. This is a significant step forward for both the anaerobic digestion and composting industries and for farmers and growers.”

Defra’s Resources Minister, Rory Stewart, said: “Sustainable farming is increasingly important for our environment and food supply. I welcome this report which will allow farmers to make better decisions about renewable fertilisers, helping to grow crops more smartly and efficiently."

Review the DC-Agri summary and full reports at

Read the good practice guides at


Notes to editors

Follow on Twitter @WRAP_UK and use #DCAgri

Supporter quotes: 

Martin Rogers, Environment Policy Advisor, NFU, said: “Digestate is an excellent biofertiliser which can help farmers to reduce their costs. With the recent rapid growth in AD infrastructure, it is becoming increasingly available to farmers across the UK. It is therefore important that anaerobic digestate is managed appropriately to maintain quality standards and achieve the best results. The DC-Agri experiments provide evidence to help farmers make informed decisions about its use.” 

Sajjad Awan, AHDB Research Manager, said: “The industry is always looking at new ways of working to improve businesses resilience in an increasingly tough market place. And there is a real hunger for good quality information. Not only has DC-Agri produced this information but it has also worked hard, through its programme of knowledge exchange, to get the results out to growers.”

Additional info: 

A vital objective of the DC-Agri project is to make the research results accessible to farmers and growers.  A strong programme of knowledge exchange has been developed to deliver this through guidance tools, events and learning materials. Find out more at

Media contact: Clare Usher, PR Officer, WRAP – 01295 819619 / 


  1. High levels of organic matter in soil bind soil mineral particles together to deliver a workable, crumb-like structure and produce soil aggregates that make cultivation easier.
  2. The research found that combining digestate or compost with bagged fertilisers in nutrient management plans can lead to higher yields.  At the experimental sites, grain yields from winter cereal crops increased by 7-10%.
  3. From 2010-2015 
  4. The amount of readily available nitrogen delivered with the first application of compost is negligible, however the experiments have shown that repeated applications over time will increase the nitrogen supplied naturally from the soil.

About WRAP: WRAP’s vision is a world where resources are used sustainably. It works in partnership with governments, businesses, trade bodies, local authorities, communities and individuals looking for practical advice to improve resource efficiency that delivers both economic and environmental benefits. @WRAP_UK

Our mission is to accelerate the move to a sustainable resource-efficient economy through: 

a. re-inventing how we design, produce and sell products,

b. re-thinking how we use and consume products, and

c. re-defining what is possible through re-use and recycling.

First established in 2000, WRAP is a registered charity.  WRAP works with UK governments and other funders to help deliver their policies on waste prevention and resource efficiency.  WRAP is a registered Charity No 1159512 and registered as a Company limited by guarantee in England & Wales No 4125764. Registered office at Second Floor, Blenheim Court, 19 George Street, Banbury, Oxon, OX16 5BH.


Clare Usher

PR Officer
01295 819678