Can cover crops justify their establishment cost and are there any potential benefits to the following crops?

摘要

In recent years there has been an increasing interest in cover crops in the UK. Generally, cover crops are grown between the harvest of one winter crop and the drilling of a spring crop. In most of the cases the intention is to minimise soil erosion,prevent nitrate and other nutrient leaching, supply organic matter, improve soil biology and suppress weeds. From a farmer point of view, cover crops should have positive effects on the succeeding crops in terms of yield or reduction in the application of nitrogen fertiliser. The trial reported in this paper showed that cover crops such as Oil Radish, Fodder Radish and a mixture of Vetch + Crimson had the potential to accumulate nutrients in particular soil nitrogen which might return a large amount ofnitrogen in the form of organic matter back to the soil. This organic matter may release 60 to 90 kg ha~(-1) of nitrogen during the season, depending on the cover crop species, which can be utilised by the main following crop. This organic matter can also improve soil structure, water holding capacity and soil biology which in most cases can result in high grain yield and justify the cost of cover crop establishment. Fodder production can be another possible outcome for cover cropping that may result inan economical benefit for the farmer. This benefit can be even larger than the fertiliser savings attributed to green manuring. The cover crop residues left on soil may reduce weed infestation such as black-grass, provided that the crop is drilled withminimum soil disturbance. Further trials are required to confirm the short and long term benefits of cover crops on a wide range of soil types and crop rotations.