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No-tillage (NT) and reduced tillage (RT) systems are well-known management tools for reducing soil erosion and improving soil fertility. NT and RT may improve the environmental and economic performance of organic farming, but they are still not common practice among organic farmers. This paper presents the effects of tillage [RT versus conventional tillage (CT)], fertilization (slurry versus manure compost) and biodynamic preparations (with versus without) on soil fertility indicators such as soil organic carbon (C org ), microbial biomass and microbial activity, soil nutrients and nutrient budgets in an organic farming system during the first six-year crop rotation period of a long-term experiment on a clayey soil in a temperate climate. RT caused stratification of soil organic carbon (C org ), microbial properties and soil nutrients in the soil profile. Under RT, C org in the 0-10 cm soil layer increased from 2.19 to 2.61% (w/w) from 2002 to 2008, whereas it remained constant under CT. In both tillage treatments, C org remained constant in the 10-20 cm soil depth. Microbial biomass C increased by 37% under RT in the 0-10 cm soil depth and microbial activity [dehydrogenase activity (DHA)] was enhanced by 57%. Soil microbial biomass C and DHA in the 10-20 cm soil depth were also higher under RT (+ 10 and + 17%, respectively). Soluble soil P and K were 72 and 40%, respectively, higher in 0-10 cm soil depth under RT when compared with CT. Fertilization showed no effects on the measured soil properties. Biodynamic preparations increased solely the C mic -to-N mic (soil microbial biomass C to soil microbial biomass N) ratio by 7% in the 0-10 cm soil depth. Nutrient budgets for P were balanced in all treatments, but N and K exports were higher under RT compared to CT. We conclude that RT is a suitable method for increasing indicators of soil fertility in organic farming systems. The combined effects of RT and an organic farming system with a diverse, ley-based crop rotation and organic fertilization merit further promotion and it may be considered for supporting actions by the agricultural policy schemes.

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Green manure catch crops promote the sustainability of agricultural systems by reducing soil erodibility and by nutrient uptake and transfer to the following main crops. This effect efficiently reduces the risk of nitrate leaching. Biological nitrogen fixation by legume catch crops is an additional benefit, mainly in organic farming. Such crops may, however, reduce nitrogen uptake from the soil and increase nitrate leaching. Additionally, under drought conditions, their extra water consumption may outweigh the beneficial effects. To determine the best catch crop management in stockless organic farming under dry, Pannonian site conditions in eastern Austria, four treatments were compared in 2002 and 2004: (1) legumes: field pea, common vetch and chickling vetch, (2) non-legumes: phacelia, oil radish and turnip, (3) a legume and non-legume mixture (all mentioned components), and (4) a bare fallow control. Our results show that catch crop biomass and N yield, biological N fixation, and crop N uptake from the soil were about 4 times higher under moderately dry conditions in 2002 than under drought conditions in summer and autumn 2004. In 2002, the legume/non-legume mixture had the highest biomass and N yield and the highest biological N fixation. Both the legume/non-legume mixture and the non-legumes were more efficient than legumes in N uptake from the soil (+32 kg N ha −1 ); and in reducing both soil inorganic N contents by -45 kg N ha −1 and nitrate concentrations in soil solution by -20 mg N L −1 . These findings show that the legume/non-legume mixture combined the positive effects of non-legumes and legumes. In 2004, catch crop effects did not differ except for their above-mentioned effect on inorganic N contents. The only pre-crop effect was that of legumes compared with non-legumes on spring barley grain dry matter of +0.6 Mg DM ha −1 and grain N yield of +17 kg N ha −1 in 2005. The water consumption of catch crops never adversely affected the following crops. green manure / biological nitrogen fixation / nitrogen conservation / drought / legume catch crop

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