Horticulture Week Bulletin

Study finds no health risks in compost use

by Rachel Sixsmith
Horticulture Week
12 March 2010

Be the first to comment Growers who use compost can feel doubly confident about its benefits after research commissioned by the Waste & Resources Action Programme (WRAP) showed that it poses no health risks to humans, animals or the environment.

The independent study, work on which started two years ago, showed that even when compost was applied to cropped land at what is considered to be its "maximum" rate - 50 tonnes per hectare of green composts and 45t/ha of green/food composts - no risks were identified.

Dr David Tompkins, an agricultural specialist for WRAP, told Grower: "We are hoping that the outcome of this work demonstrates that the material is quite safe and that growers should not have any concerns about using it."

He added that the research was carried out to help "keep the confidence in the market" after some livestock farmers expressed concern that compost used on grasslands may pose a risk to their grazing animals.

Three independent risk assessments were therefore carried out by Cranfield University's Centre for Resource Management & Efficiency, with help from the Macaulay Land Use Research Institute and ADAS.

The first assessment looked at the risk green compost posed to arable crops and livestock while the second looked at the risk posed by food waste-based compost to livestock.

Both assessments showed that both types of compost were safe to use on arable crops and livestock grazing land and they would only pose a risk in extremely unlikely circumstances.

For example, the chances of cattle catching foot-and-mouth disease through surface-applied food waste compost were estimated to be one in 10 billion.

The third, and most pertinent to horticulture, assessment examined the risks of applying compost to cropped land. No risks were identified even though a wide range of cropping scenarios was considered.

Tompkins said: "We are extremely pleased with the results, particularly as we estimate that there will be around 500kt of green/food composts available for use in agriculture and horticulture by 2015 (up from 250kt today)." He added: "We would like to see more growers take advantage of the benefits of compost."

WHAT WAS TESTED?

Potentially toxic elements that could pose risks to humans eating salad crops when PAS100 green compost is applied at 50t/ha.
Polychlorinated biphenyl and dioxin risks in salad crops, when PAS100 green compost is applied at 50t/ha.
E. coli risks to humans eating salad crops when PAS100 green/food compost is applied to 45t/ha.