Auteurs : E. Erhart, W. Hartl, B. Putz

Organic wastes should be recycled from an ecological as well as from an economical point of view. To integrate compost into the crop rotation, however, the availability of nutrients should be known. Therefore, when municipal composting operations attained a large scale in Vienna in 1992, the present field trial was set up to investigate the performance of the biowaste compost in agriculture on a fertile soil under relatively dry climatic conditions, as is typical for eastern Austria. This paper presents the yields and crop quality results of the first 10 years. The experiment included three treatments with compost fertilization (9, 16 and 23 t ha−1 year−1 fresh matter (f.m.) on average of 10 years), three treatments with mineral nitrogen fertilization (25, 40.5 and 55.9 kg N ha−1 year−1 on average), five treatments with combined fertilization and an untreated control in a latin rectangle design with a practical local crop sequence.
The yield in the compost treatments increased for 8%, 7% and 10% compared to the unfertilized control (average of 10 years). Yield response to the compost applications was very low in the beginning and increased slightly with the duration of the experiment. This is likely due to the dry climatic conditions (552mmprecipitation), to the average C/N ratio of 23 in the composts used, and the high level of fertility of the Fluvisol on the site. The analysis of the yield components of the cereals showed that the plants in the compost treatments were sufficiently supplied with nitrogen in the early growth stages and after pollination, but at booting, when N-uptake is highest, the N-supply in the compost treatments was comparable to that with mineral fertilization at up to 30 kg N ha−1. Crop quality was not affected by compost fertilization, but in some cases even improved. The results suggest that on fertile soils in the pannonic climate the fertilizer effect of biowaste compost is small, but increasing with time. The yields as well as the results concerning nitrogen availability during the vegetation period and crop quality show that the compost acted as a slow-release source of nitrogen on a medium level.

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