Die Wirkung einer Schwefeldüngung auf Ertrag und Qualitätsparameter von Kleegrasbeständen im ersten und zweiten Hauptnutzungsjahr
At the Experimental Farm of the Thünen Institute of Organic Farming the effect of sulphur fertilisation in form of MgSO4 and CaSO4 of a red clover-grass mixture was tested in the years 2013 -2015. At the beginning of the vegetation period clover-grass plots were fertilised in the first and second year of usage with 30 and 60 kg S ha-1 and were compared to unfertilised plots. The fertilisation resulted in significantly higher fresh weight and - with one exception of thew second year usage in 2013 - higher dry matter yields. The forage quality was significantly increased by sulphur fertilisation. Due to higher sulphur contents in the fertilised plots in the N/S-ratios showed values below the threshold of 15 for an adequate sulphur supply. The N-withdrawals increased in the fertilised plots in the first year of usage by 14 -25%, in the second year by 12 -45%. S-withdrawals were also increased by fertilisation and reached 20 - 40 kg S ha-1 compared to 12 - 15 kg S ha-1 in the unfertilised plots. In the majority of cases neither the level nor the kind of fertilzer showed significant effects on the parameters. Therefore a sulphur fertilisation of 30 - 60 kg ha-1 can be considered sufficient.