Quality compost plays a crucial role on organic farms across the UK, supplying both nutrients and improving soil quality. Recently however, conventional farms have started to recognise the benefits of using compost, reports WRAP Organics.
While most UK farmers are used to just using artificial fertilisers for a ready supply of nutrients, some are now starting to complement their application of fertilisers, or even replace it, with compost produced from recycled garden material such as grass cuttings, prunings and leaves, as its many benefits become more evident.
Long-term scientific trials have been run in the UK to assess the benefits the application of compost can have in a range of situations. The trials have shown that compost can have a very positive effect on soil structure; the organic matter contained in compost increases the soil’s ability to hold moisture, facilitates the slow, steady release of crucial nutrients, and makes the soil more workable over a period of time.
Organic farmers have known this for some time as they are only permitted to use certain products as fertilisers on their farms, and compost is one of a few limited options for fertility enhancement. As a result they have seen the benefits compost brings to their growing schemes, and that is why farms with mixed conventional and organic growing schemes have been the first to start applying compost across both.
Langmead Farms, a quality salad supplier with 550 ha of organic farm land and 2,000 ha of conventional farm land in West Sussex, started using compost on its organic farms more than six years ago. As a major supplier to big retailers, they have to be sure that their produce is always of the highest quality.
Scott Phillips, development manager at Langmead Farms, explained: “Compost is the most effective way of guaranteeing consistent fertility rates. Without compost it would be very difficult to maintain rates of production and get the levels of NPK right.”
Langmead’s organic farms produce a wide range of crops for retail. Major retailers are supplied with whole head lettuce varieties including Iceberg, Romaine and Continental; brassicas including cauliflower and broccoli; celery; carrots; and, just introduced in 2007, strawberries.
The farm applies quality compost made from recycled garden waste in two out of every four years. For the other two years there is a year with no treatment and a year where composted animal manure is applied to ensure the right balance of nitrogen in the soil.
Having witnessed the natural soil structure benefits that compost has had on its organic farms, Langmead began using compost on its conventional farms in 2004.
Phillips said: “While we have not used compost to replace artificial fertilisers, we do believe that our conventional farms benefit from the application of compost as it helps to ensure steady growing conditions by supplying organic matter to the soil on our farms.
“We need to ensure that everything we produce is of the absolute highest quality, consistently. We want to do everything possible to manage the appropriate rates of moisture and nutrients in our soils, so if the organic matter that compost contains can help then we’re going to use it.”
In 2006, Langmead applied approximately 12,000 tonnes of compost on its organic farms and 8,000 tonnes of compost on its conventional farms. Compost was applied on every organic field but chosen selectively for particular fields on the much larger conventional farm.
Phillips continued: “We took a pragmatic approach to applying compost on the conventional farm by applying it to those fields that had been intensively cultivated over the past few years as these were more likely to benefit from compost application.”
Langmead produces a large amount of its own compost from the leftovers that it produces within its own salad factory where they make bagged salads for supermarkets.
The salad factory produces nearly 10,000 tonnes of waste each year which they transport to their own compost production facility. They use an open-windrow system to produce the compost - where waste material is shredded and turned for aeration over a period of between 12 to 16 weeks and then screened to get the right product size.
The site at which processing takes place is currently in the process of attaining BSI PAS 100 certification and is also certified by the Soil Association.
All of the 10,000 tonnes of waste collected on farm is turned into compost and used back on Langmead’s farms. They also buy additional compost from other producers in East and West Sussex including the Woodhorn Group, Veolia and KPS Composting to meet their requirements.
“One of the biggest barriers to using compost is transportation and bulk supply. The compost we produce is used on the farms closest to our own production site but there are other compost producers in or around the county whose products we can use if it’s more convenient. There’s also bound to be more and more compost available as the industry grows,” Phillips explained.
Always innovating, Langmead Farms has found further outlets for the compost it produces. Not only does it supply some compost for use as a growing media component at its own nursery, Brinham’s, it has also started bagging its compost for sale in Tesco stores in and around East and West Sussex.
Phillips said: “Until now our compost production site has not provided a direct revenue stream. However now that gardeners across the UK are beginning to see the value of compost as an inexpensive and environmentally friendly soil conditioner and improver there’s a real market opportunity.”
Langmead is also beginning trials on its conventional farms with WRAP (Waste & Resources Action Programme) to assess whether compost application can improve nutritional values by increasing the nitrate, folic acid and vitamin levels in spinach and Romaine lettuce.
“Water retention rates and levels of organic matter in the soil are helped by compost but a wide range of factors can affect this, however strict the trial context is,” Phillips said. “We’re trying to pick out specific nutritional benefits which will show that crops grown using compost are actually better for you with higher levels of healthy nutrients.”
The trials, which will compare the levels of nutrients in baby spinach grown with compost and without, are in their early stages and will conclude in autumn 2007.
“While there has been much talk about compost in the last few years, we’re proud to be one of the first farms in the UK to really make the most of the opportunities that compost provides,” Phillips concluded.
If you are thinking about using compost and would like to know more, visit the WRAP Organics website at www.wrap.org.uk/composting.
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