Field Trials

Trials with UK composts and anaerobic digestates

The aim of Cambridge Eco is to help pave the way for efficiently recycling organic materials. So, in addition to teaching farmers about compost and digestates, advising regulators about health and safety aspects and talking to major European food industry stakeholders, we also set up and manage field trials. Below are some of the projects we are currently working on on behalf of WRAP.
   

Growing perennials on brownfield sites for use in AD (WRAP funded programme OMK004)

Growing herbaceous plants suitable for anaerobic digestion on brownfield sites using compost and digestate as a soil improver

This project is part of a wider WRAP funded two year programme to investigate the potential for utilising brownfield sites by planting energy crops. All projects within this programme will use digestates from anaerobic digestion (AD) as a fertiliser, and compare this to more standard fertilisers. All projects are starting in spring 2012, and will finish in spring 2014.

Project aims

This project is investigating the effects of the application of digestate and compost on the growth of a mix of perennial flowering plants, tailored to the UK climate, on two brownfield sites in England over two years.  The harvested material will be assessed for its potential use as a feedstock in anaerobic digestion to produce biogas and more digestate.

This project commenced in spring 2012 and is investigating the effects of the application of digestate, compost and standard inorganic fertiliser on the growth of a mix of perennial flowering plants on several brownfield sites in England over two years. The harvested material will be assessed for its yield and potential use as a feedstock in anaerobic digestion.

Trial site in September

Why use perennials as a feedstock for AD?

In Germany there are significant areas of maize grown for AD. Recent German research has found that a range of mixes of perennials can be grown instead of maize as an energy crop for use in AD plants. These mixes offers a much greater source of pollen and nectar than maize, greater biodiversity and also soil protection, as the mix can remain in the ground for up to five years. Fewer fertilisers and pesticides are required compared to maize, and so the perennial mix has a lower carbon footprint and lower agricultural inputs, whilst producing significant quantities of biogas.

For this WRAP funded trial, we are using a perennial seed mix which is very similar to the German mixes. Our seed mix is based on species generally grown in the UK, and includes legumes to enhance the fertility of the nutrient poor brownfield sites.