The multifunctionality of living mulch systems was the underlying research question for field trials with cauliflower (Brassica oleracea L. convar. Botrytis) and leek (Allium porrum L.). Field trials were conducted at the Hessian Research Estate Frankenhausen over 3 years, parallel demonstration plots were established over 2 years on commercial pilot farms for entomological investigations in a big scale mode, plots of 1000 m². In all trials white clover (Trifolium repens L.) was used as a single species living mulch. In the years 2012 and 2013 the experimental design consisted of a 2-factorial approach for the test of 3 cultivars and the effect of additive and substitutive system for the establisment of living. The cultivars of cauliflower were Chambord F1, Belot F1, and White ball, of leek Herbstriesen Hannibal, Axima, and Catcher F1. For the substitutive system of living mulch each third row was replaced by clover with the potential of common weeding in the areas covered by vegetables. The establishment of clover took place between 4 weeks after planting or later. In 2014 a one year trial was added for the investigation of different sowing dates of living mulch, 2 and 4 weeks after planting, towards the performance of cauliflower and leek, cultivated with one cultivar. The two year pilot farm activities were located at two organic field vegetable farms in Northrhine-Westfalia, each site in one year.
Crop yields were mainly influenced by the fact that the Substitutive system had a plant density which was 2/3 of the figures in control and Additive system. Therefore all figures found were significantly lower. Opposite to these findings the data referred to single crops showed an advantage for the Substitutive system. With regard to the second system tested the addition of clover into the vegetable system did not cause reductions of yields in any case. This was obvious on the levels of nutrient yields of the crops.
The samples of pit fall traps were measured over a time span between August and midth of September in 2013 and midth of August till end of September in 2014. The estimates were done on a family level. The main groups were found at each site, in each crop as dominant: Carabidae >> Staphilinidae > Arachnidae. The abundance was significantly different on the species level according to Kruskal Wallis evaluations, statistical distinctions on the system could not be found due to small diffenrences and partly inconsistent results