Field Plot Specific Analysis Of 32 Organic Farms In Saxony: Crop Rotation Management

Plot card records of crop rotation arrangements from 32 organic farms in the German federal state of Saxony were analyzed according to field plot and farm over a six-year period. In total, a data set of 810 organically cultivated field plots from over 4.800 harvests was available. First, a suitable assessment procedure was developed for the crop rotation management, in which easily recordable and checkable criteria for the field plot-specific estimation of the degree of performance were established for basic crop rotation rules. The crop rotation criteria results were summarized in tabular form, which appeared useful with regard to the expansion of crop rotation consulting services in organic farming.The farm-based analyses initially showed that a weed suppressing effect of crop rotation was supported by a widespread, regular alternation between the cultivation of spring and winter main crops. Deficits in cultivation were found in just 20 % of the arable field plots. The share of cereals in the crop rotation was over- or understated in some 40 % of the plots. The field fodder cropping share, mostly comprising legumes, was also overvalued for about 40 % of plots. The disease and pest suppressing effect of crop rotation typically occurred through observance of the necessary crop intervals for potatoes and oilseeds. However, on 50 % of the farms, potatoes were excessively used in the rotation. On average, the recommended interval of cultivation for potatoes was not observed on 17 % of the arable plots.The recommended crop interval for grain legumes failed to be met on 26 % of the plots, with the too frequent cultivation of grain peas being a particular problem. The high proportion of legumes in field fodder cultivation with a focus on only a few species increased the risk of facilitating specific crop rotation diseases (legume exhaustion). On 41 % of arable plots, the crop intervals failed to be observed. Effects of the examined crop rotation on soil fertility were assessed, amongst other aspects, by the extent of field fodder and catch crop cultivation. On the one hand, the share of legumes in the crop rotations was too high on the majority of farms. On the other hand, on 49 % of the plots, there was no optimal use of the nitrogen left behind by the legumes, due to the unfavorable configuration of cropping sequences after the legume crops.Overall, it could be established that an optimal crop rotation arrangement was practiced on 7 farms only. However, when all farms were included, a sum effect of nearly 40 % of the arable field plots examined displayed potentially yield limiting deficits, mainly because basic intervals of cultivation for the crop species were not observed in the cropping sequences. From these results it can be concluded that increased efforts need to be undertaken by farms to improve crop rotation arrangements in order to preserve soil fertility and better avoid losses of crop yield and quality in the future. For this purpose, research and teaching should also include extensive experimental activity, especially in the form of long-term trials, in order to be able to present the latest consulting materials for practical crop rotation and nutrient management, respectively.