Water companies start taking cover crop benefits seriously

A growing number of water companies are paying farmers to protect river catchments from run-off and nutrient leaching by planting cover crops.

Anglian Water has been working with the Lincoln Institute for Agri-Food Technology and local farmers to look at catch crops in the arable rotation. Supported by the Innovative Farmers project, the trial has assessed the benefits of cover crops over bare land.

Other companies – including Cambridge Water and Affinity Water – have also introduced cover crop schemes, recognising that healthy soil, leads to a healthy crop which requires fewer inputs, leading to better water quality.

Independent soil and carbon specialist Neil Fuller says there are numerous benefits associated with multi-species cover crops – both in terms of improved farm productivity and reduced environmental risks.

“Many water authorities are beginning to reap the reward of sponsoring farmers to grow cover crops, not just in sensitive catchments but across the broader agricultural landscape,” says  Mr Fuller.

‘Early indications are that cover crops significantly reduce the amount of nitrogen and phosphorus that leaves arable fields over winter, actively preventing these nutrients from working their way into watercourses. 

“There are also indications that the way cover crops can re-structure soil has a positive impact on root development and biological activity, which in turn alters the way water is held within the soil profile.

The cost of making cover crop seed available to growers is relatively small compared to the benefits it delivers. It can improve infiltration, drainage and tolerance to drought, while holding on to some of our more mobile nutrients and pesticide residues.

Biggest benefits

Fast-growing cover crops can work to a degree when grown between winter wheat or oilseed rape and a following winter barley, for example, but the biggest benefits result from when they are grown between winter and spring crops, Neil Fuller points out.

“Trials suggest a good cover crop mix will produce 20-50t/ha of fresh matter above ground. This could contain more than 80kgN/ha, with a similar amount of potash and about a third of this amount as phosphate.”

As synthetic N accounts for roughly 75% of the carbon footprint of current combinable crop production, cover crops could be delivering a big reduction in emissions at farm level that would travel all the way from soil to supermarket, says Mr Fuller.

“Farmers that are growing cover crops supplied by water companies are reporting increases in spring cereal yield that would be equivalent to applying an additional 20kgN/ha. 

“On shallow and sandy soils, some of this yield uplift is coming from increased water holding, but tissue testing shows plants are also picking up more nutrition.

“That’s great for most arable crops but our work has also shown that simple adjustments to agronomy can ensure this extra nutrition goes into yield rather than grain nitrogen in the case of malting barley crops. 

“Getting climate-smart by integrating cover crops in the rotation at every opportunity, and really focusing on good soil and crop management, can provide a stack of environmental gains and real agronomic savings that increase over subsequent years.”

Smaller carbon footprint

Cover crops also draw down a significant amount of atmospheric carbon and this can help decarbonise the production emissions of agricultural feedstocks such as cereals, oilseeds, grain legumes and potatoes.

“There are biodiversity benefits too, with cover crops creating respite habitat for pollinators and predators which can help in the suppression of aphids and take growers further on their journey to being insecticide-free.

“The governmnent’s Sustainable Farming Incentive will contribute £129/ha for cover crops to be grown and that more than covers the cost of the seed and the management of the crop,” adds Mr Fuller.

With growing interest in cover crops as part of sustainable agricultural practices for the future, KWS is launching a range of multi-species mixes designed to deliver specific benefits in a range of situations.

“The Fit4Next is a range of cover crops specifically tailored to complement following crops and add real benefit to the rotation,” says the company’s Kate Cobbold

“Work in Germany has shown such mixes add significantly to biomass growth and organic content of soils whilst preventing soil erosion at the same time.

“KWS catch crop mixtures have also been shown to actively bind carbon in the soil with a far-reaching benefit to future sustainability.”