A Devon composting scheme
claims to boost yields and
improve soil structure – for
free. Brendan James
examines what sounds like
an attractive offer
FARMERS in Devon are queuing to join a free on-farm composting scheme set up two years ago. EcoSci, the company involved, is already handling over 30,000t/yr of green waste and composting two-thirds of it at 45 separate on-farm sites.
Based at the Wolfson Laboratory on the campus of Exeter University, EcoSci delivers the green waste, pushes it up into windrows, monitors the composting process, takes soil samples for analysis and screens and spreads the finished product. It also does all the legislative paperwork – and the service is free.
Incoming green waste from waste management companies and local authority parks and gardens is tipped at one of EcoScis five shredding sites. Gate charges are normally below the cost of tipping to landfill and once on site EcoSci shreds it in a 300hp mobile shredder. After shredding, piles of about 1000cu m each are picked over by hand and checked for heavy metals and other contaminants before being delivered to farms.
On-farm, EcoSci pushes the green waste up into Toblerone-shaped windrows that are turned two or three times during a composting period of about six months. Temperature is monitored during composting and the end product is screened to a suitable size before spreading or stacking for future use. Over-size material can be recycled into the next composting cycle.
Farmers receiving the green waste only have to provide space for the windrows. In cases where farmers do their own on-farm work EcoSci pays them a fee designed to cover costs. "By using their existing farm equipment to turn and spread the compost some farmers are actually able to earn a small profit," says EcoSci operations manager Matthew Lawson.
Working arrangements vary from farm to farm. Some, like Brian Chidley of Parkhayne Farm near Honiton, Devon, do paid contract work for EcoSci. Others, like John Broome of nearby Logshayne Farm, simply supply space for windrows and use the free compost. The amount of work done under contract also varies and Mr Chidley turns and aerates green waste that he has hauled to his own and several other farms including Mr Broome at Logshayne.
Mr Broome, who farms his own mixed 160ha (400 acres) plus land rented from Mr Chidley, is an enthusiastic convert to compost. Contrary to popular belief, he finds that it is particularly good for the light sandy soil of his hilltop grazing where the nutrients are washed out of the soil. "Used up here on the hungry ground you see the improvement and the change in the colour of the grass almost straight away," he says.
Reduced fertiliser use
In the first year it was applied at about 50t/ha inorganic fertiliser use was reduced by 50%. On the hills it was screened with a fine mesh and spread onto the grass. On medium loams lower down the valley it was screened with a coarser mesh and ploughed in prior to sowing maize. Anything over after doing the selected fields was put onto the farmhouse vegetable garden.
"The maize fields gave a good crop, but because it was mixed with FYM you cant really say that it was entirely due to the compost. But in the garden we used no fertilisers or herbicides and the vegetables were the best we had ever had with no more weeds than usual, " he says. "That proves that the heat generated during composting really does kill the weed seeds."
Although only a personal view, these observations are broadly in line with commercial field trials carried out over four-year periods in Coventry, Somerset and Devon. In these trials, yields from land previously treated with normal amounts of inorganic fertilisers were compared to land treated with inorganic fertilisers plus compost and compost only.
Results indicate that progressively increasing or maintaining yields with reduced applications of inorganic fertilisers combined with compost applied at both high (750kg N/ha) and low (250kg N/ha) is possible.
Although low application rates improved yields, pH levels and the overall health of the soil, these effects often didnt manifest themselves until year two or three. By contrast, EcoSci says the higher application rates gave an immediate improvement in plant disease suppression. This has been confirmed by other research where the compost applied at these higher rates (at least 750kg total N/ha) showed no measurable increases in nitrate leaching or concentrations of heavy metals in the soil.
Using green waste compost is clearly an eco-friendly way to keep agricultural land in good heart. Nonetheless, its production is subject to the all-embracing Waste Licensing Regulations 1994. Drafted to regulate recycling activities, the Act is not really relevant to composting, however the DETR is presently applying it in a way that would be a strong deterrent to any farmer hoping to do it without help.
EcoSci has, however, developed a protocol to ease applications under the 1000cu m exemption rule that allows farmers to make compost heaps of around 500t on their own land for their own use. In many cases, multiple exemptions for different sites on one farm are possible. The company looks after all the paperwork and obtains all the permissions needed to do on-farm composting. Before work starts the farmer is assured that he is complying with all environmental and planning laws and health and safety regulations.
Preliminary on-farm checks look at the proximity of ground and surface water, nearby buildings and other aspects that could affect local residents or the environment. Further considerations include siting windrows as close as possible to roads to reduce travelling costs and avoiding compaction of agricultural land.
EcoSci funds the whole operation out of gate fees. Because transport costs have to be kept low, the scheme is presently available only to farms located within a six or seven-mile radius of the EcoSci shredding sites. These are all currently in Devon, but this and similar no-cost schemes should spread as more local authorities move towards EU landfill targets.
Holding back popularity
At present the main factors holding back the popularity of green waste composts are probably costs and lack of confidence in an untried product. So far, most of it is made at large centralised sites remote from the farm. Transport from site to farm and the difficulties encountered when disposing of huge quantities push up costs.
Made this way, the composts cost farmers about £200/ha to buy and spread. Obviously, a less attractive proposition than a free product made in situ and tailored to suit the circumstances of a particular area on a specific farm.
Left: Shredding green waste at one
of EcoScis sites
Above: Constructing windrows at Logshayne Farm. Right: Windrows at Logshayne Farm.
EcoSci can be phoned on 01392 424846
or e-mailed at firstname.lastname@example.org
The concept of on-farm composting was developed by EcoSci as the most cost-effective means for farmers to derive the maximum benefit from compost produced from recycled green waste. Provided these benefits can be demonstrated, the regulations allow farms to compost up to 1000cu m (about 500t) of green waste at any one time for use on their own land.