The importance of crop rotation, catch crop and manure in organic farming.

The role of crop rotation, catch crop and manure can be very important in organic farming since synthetic mineral fertilizes are not permitted. Experiment was carried out in organic certified field of the Experimental Station of the Lithuanian University of Agriculture in the period of 2003-2008. The complex of all investigated effects was evaluated in the year when the same main crop was cultivated in all crop rotations. Soil type – LVg-p-w-cc(sc)Calc(ar)i-Epihypogleyic Luvisol and LVg-pw-cc(sc,ah)-Calc(ar)i-Epihypogleyic Luvisol. The experiment factors were as follows: A – crop rotations with a different ratio of nitrogen fixing crops (I 43%; II 43%; III 29%; IV 14%), B – animal manure (without and with animal manure), C – catch crop (without and with catch crop). The aim of this investigation was to evaluate complex effect of crop rotation with a different ratio of nitrogen fixing crops, catch crop and animal manure on cereals yield in organic agriculture. Grass-clover of the first year is considered the best preceding crop in organic agriculture. Grass-clover of the second year is a lower quality precrop because over-wintering of red clover is not always successful. The crop rotation II with 43% of nitrogen fixing crops (grass-clover > winter wheat > peas > spring barley > grass-clover > winter wheat > spring barley) was the most effective one. Peas are also an effective pre-crop. Manure was established to have positive influence on grain yield. This influence was significant for winter wheat. Effect of farmyard manure used at rate 30 Mg ha does not last more than two years. White mustard used as catch crop for green manure in organic agriculture has no positive effect on the yield of cereals. In some years catch crop emerging problems occur, sparse crop stand determinates weed infestation and subsequent decrease of the crop yield. Crop rotation, catch crop, manure, organic farming.