Pros and cons of cover crops revealed in ADAS/ NIAB TAG study

Sentry cover crop demonstration at Hill House Farm, Hedenham.

Sentry cover crop demonstration at Hill House Farm, Hedenham. - Credit: Archant

The pros and cons of planting cover crops have been outlined in a comprehensive scientific review funded by levy-payers.

The nine-month review, carried out by environmental consultancy ADAS and plant scientists at NIAB TAG (National Institute of Agricultural Botany), claims to provide the most comprehensive analysis to date of the benefits of using beneficial plants in between commercial crops..

Four broad objectives were identified by the review – to improve soil fertility, to benefit soil structure, to tackle weeds and pests, and to manage the environment.

Ensuring cover crops are established early – with a clear objectives in mind – and considering benefits over an appropriate time-frame are among the key recommendations in the report.

Lead author Dr Charlotte White of ADAS said when assessing a cover crop's direct financial benefit, the benefits should be measured beyond the next cash crop.

She said: 'Conducting a long-term cost-benefit analysis is not easy, but the practical guidance in the review will help growers make relatively robust assessments of a cover crop's potential value to find the one that fits their system best.'

The scientific basis of reported cover crop functions and cover crop agronomy was also reviewed, including cover crop choices, establishment methods, starter fertiliser requirements, pest management and cover crop destruction.

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In terms of agronomy, getting cover crops established in the late summer to early autumn period was considered to be the most important key to success.

Analysis of nitrogen (N) uptake information revealed that cover crops typically take up 30-100kg of nitrogen per hectare (N/ha), with 10-100kg N/ha released in the following crop. Nitrogen fixation was also determined to be most effective between 7°C and 20°C. Organic matter increases following a cover crop were also determined, which ranged from 0 to 42 per cent.

It was also recommended that a target canopy cover of at least 30pc is required for the purpose of reducing soil erosion risks.

The review, funded by Cereals and Oilseeds division of the Agriculture and Horticulture Development Board (AHDB), includes information on how to evaluate cover crops, case studies and recommendations for further research.

To see the review, click here.