Production of potato crisps and chips in organic farming: effect of sprinkler irrigation, manure and preceding crop management of clover grass on yield and quality

In contrast to conventional agriculture the nutrient supply in organic potato production must be secured by preceding crop or organic fertilization. On lighter sites nitrogen mineralisation of organic fertilisation depends highly on water supply. Over two years field experiments with sprinkler irrigation relating to different manure fertilization and varied clover grass management systems (mulching, cut mowing) has been conducted and effects on yield, grading and qualitative properties of processing potatoes has been surveyed. The tested clover grass management systems showed only a low effect on yield and quality on the following crop potato. In 2003 a small yield increase was achieved by the mulching system. In the dry year 2003 the sprinkler irrigation had a great effect on yield, grading size and starch content of the potatoes for processing, especially in combination with manure.