The Courier & Advertiser (Fife Edition)
Research into benefits of green manures
CROPS: SRUC carrying out field trials to assess how they can be used on farms
The wider uses and environmental benefits of green manures are being investigated by Scotland’s Rural College (SRUC).
Some growers already use green manures in their rotational cropping systems and they are an integral part of organic systems for the benefit of the soil.
However, interest has grown since greening rules changed and they can now be used in Ecological Focus Areas (EFAs).
To help Scottish farmers use these green manures more effectively, SRUC initiated a research programme in 2015 into a wide range of potential species at sites in Aberdeenshire and Midlothian.
Replicated field trials are taking place over multiple years, with funding from the Scottish Government and the Mains of Loirston Charitable Trust.
The trials on EFA nitrogen-fixing crops are using straights of black medic, field beans, red, white and crimson clover, lucerne, lupin, peas, vetch and five, three-way mixtures of these crops.
According to SRUC, an important feature of species mixtures is that they have built-in redundancy. If one species fails, another can take its place, which improves resilience to poor conditions.
Some research results already show a clear benefit of mixtures in terms of the dry matter yield of a first silage cut, with mixtures having four of the five greatest measured yields.
The two highest-yielding mixtures both contained a grain legume, peas or field beans, and it is anticipated that this will also give higher silage protein contents.
All of the straights of the less familiar species gave yields as good as or greater than that of a standard grass/clover mixture, and pollinating insects such as bees and hover flies have been shown to benefit from crop mixtures, with later-flowering species being a particularly valuable food source during the breeding period.
The ultimate aim of the research is a comprehensive assessment of green manures, practical recommendations for their use on Scottish farms and to inform Scottish Government policy.
Work is also looking at the impact of green manures on following cereal crops to assess how they contribute to the performance in rotational cropping systems.