What a difference a year makes for living mulches

Well-managed leguminous living mulches have been shown to provide ‘multifunctional’ biotic and abiotic benefits in broad-acre arable production, with many positive impacts on soil health, crop protection, weed suppression and biodiversity. Several key management challenges remain to be overcome in order to optimise living mulch systems and increase uptake within industry.

One such key challenge in the management of clover living mulches is the achievement of good establishment of the chosen clover type to under-sow with the crop, and subsequent persistence of the clover into future growing seasons. This can be maximised with considered selection of the clover type, as different types have varying characteristics and requirements which may affect not only ease of establishment, but also whether the living mulch can be expected to last long-term given climactic conditions. These are important aspects which, in turn, can also feed into weed management strategies.

As part of the TRUE Case Study at STC, which aims to evaluate management options of in-crop clover living mulches, white, red and berseem clover living mulches were under-sown in a fodder maize crop in the 2018 growing season. Despite dry, challenging weather conditions, the clovers established readily, most likely aided by shading effects from the maize crop which may have protected the soil from rapid drying, thus improving conditions for establishing clover seedlings.

In the 2019 growing season, the same area was sown with sugar beet using strip-tillage and precision agriculture techniques, with an aim to evaluate the recovery of the clover sown in the previous season. The 2019 spring, however, was warm and dry, leading to a slow start for the clover following drilling of the sugar beet. Through the subsequent season, the red and white clover plots did recover somewhat, though this was significantly patchy with poor overall ground coverage levels. This, combined with a summer punctuated by good rainfall and warm weather spells, led to poor weed suppression and consequently to challenges in managing the weed pressure in the crop. Data has not yet been analysed, but initial observations suggest that top-up sowings of clover after the first growing season may be of benefit to maximise clover coverage across growing seasons, thus reducing the likelihood of significant weed challenges and potentially mitigating the vagaries of the weather!