Demand for compost made from recycled garden materials, such as grass cuttings and leaves, has expanded rapidly in recent years as farmers and growers have begun to recognise its sustainable and commercial benefits.
The compost production industry is experiencing unprecedented growth. In 2003, the industry was producing just 340,000 tonnes of compost each year. Now, in 2007, more than two million tonnes of quality BSI PAS 100 compost is being produced across the UK for use in a range of sectors.
WRAP has been instrumental in this growth and has partnered with organisations such as TCA (The Composting Association) to introduce quality standards and raise awareness of the many benefits of compost, in order to develop potential markets.
The growth of the commercial composting industry began in earnest in 2002 with the introduction of the BSI PAS 100 quality assurance certification scheme, the national specification for the production of quality compost. PAS 100 certification ensures that compost producers are manufacturing a product that is consistent, safe and reliable, and provides the foundation on which producers can develop their products further for different markets.
The scheme has been a lynchpin in the development of the industry over the past few years, a fact recognised by its inclusion as the chosen standard in the recently launched Quality Protocol for Compost.
The Quality Protocol - which was developed by WRAP, the Environment Agency, the Environmental Services Association and the Composting Association - provides a clear framework for the production and supply of compost and means that, provided its requirements are complied with, compost can be classed as a product and no longer a waste. The Quality Protocol makes it easier than ever before for the industry to supply more quality compost while further increasing the confidence of compost users, such as farmers and growers. Indeed, since the Protocol was published in March, there has been an increase in PAS 100 applications of over 36 percent.
Of course, increased production capacity and assurances of compost quality alone would not be enough if compost could not also offer significant benefits.
To this end, long-term scientific trials have been run in the UK to demonstrate the benefits of compost in a range of situations.
One set of scientific trials has been assessing the benefits of using compost made from recycled green waste as part of a fertiliser programme to assist crop growth. The project has proven numerous benefits and recent extensions to the field-scale trials have been funded by WRAP. The research, which has been running for more than six years, has shown a reduced need for inorganic fertilisers, an improvement in the soil’s water holding capacity, and an increased yield on a range of crops.
The project, managed by Enviros Consulting, started on Park Farm over six years ago. Now managed by Westrope Farming, the trials initially involved two quarter hectare sites growing sugar beet and potatoes.
This was followed by expansion into five more sites in 2002 and the assessment of the benefits of compost to different crops such as barley, wheat and carrots.
Each trial involved eight different treatments to compare the benefits of applying compost. Two trials with compost applied respectively at 30 tonnes per hectare annually and 60 tonnes per hectare biennially were compared with an untreated control trial, a trial using standard NPK fertiliser, and trials of compost in conjunction with both standard and reduced levels of Nitrogen.
All treatments were replicated four times to ensure that conclusions were based on statistically significant data.
The trials concluded that compost in conjunction with reduced levels of nitrogen was as effective as compost with standard levels of nitrogen and both were more effective than NPK fertiliser.
The key result from the six year project was an average increase of seven percent crop yield - for example, the potato crop, growing at 50 tonnes per hectare, increased to 53.5 tonnes per hectare over the period of the trial. This increase has been attributed to a long-term change in the soil structure caused by the repeat application of compost.
Compost adds organic matter to the soil which improves crumb structure making it more workable, allowing for better seedbed conditions and supporting the retention of both nutrients and moisture for longer periods.
Commercial benefits can also be derived from the lower costs of using compost. For example, comparing the cost of using standard NPK fertiliser to the cost of applying compost with a reduced nitrogen application over a five-year rotation, the average net gain is £116 per hectare per year. This is based on a farmer paying £2.50 per tonne for delivered compost and £1.50 per tonne for spreading.
Phil Wallace, technical director at Enviros Consulting, says: “Because of the long-term change in the soil structure, there has been a marked improvement in both water infiltration and retention rates, and far less need to apply phosphate, potash or nitrogen fertilisers. The compost is helping the soil hold moisture and nutrients for longer periods which means a healthier bed for crops all year round.”
The use of compost also addresses the environmental issues of soil erosion and depletion of nutrients.
As organic matter helps create the humic substances which bind soil particles, soil becomes much more resistant to erosion, allowing efficient crop production without threatening its future productivity.
Phil Wallace continued: “These trials are a landmark for both farmers and the composting industry. They prove the commercial value-add that compost can provide, both reducing fertiliser cost and increasing yield, while also providing a range of environmental benefits.”
The success of the trials has led to a continuation of field-scale trials currently underway on Westrope Farms. More than 3,000 tonnes of compost has been applied so far to 100 hectares over nine fields that are currently growing onions.
Compost is the perfect solution for increasing productivity and at the same time working in harmony with the natural environment. As the sustainable and commercial benefits of quality compost continue to become more widely known, both organic and conventional farmers are set to play a pivotal role in the growth of its use.
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