Vinasse rate, time of application and compaction effect on soil properties and durum wheat crop

The results of an experiment studying the effects of vinasse (an alcohol industry waste) recycling in agriculture are reported in this work. Vinasse was applied in a durum wheat crop by a trailed vinasse sprayer system compacting about 10% of the field. The experiment was carried out in Central Greece, on two soils (a clay and a silty clay loam) with three levels of vinasse rate (one fully covering N requirements of the crop, one covering half the N requirements, the rest covered by chemical fertilizers and a control without vinasse and use only of chemical fertilizers) and three times of application (Summer, Autumn before ploughing and Autumn before drilling). The middle strip of the plots was compacted by three passes of the tractor-trailed vinasse sprayer producing the compacted treatment. During the experiment, the physical and chemical properties of the soil were measured as well as the plant growth and yield. It was found that the compacted plots had higher dry bulk density and soil strength, while vinasse rate and time of application effects were not significant. An increase in N, exchangeable Na+, K+ and available Mn was caused by vinasse application. Compaction had a significant effect on plant growth, while vinasse rate and time of application effects were not significant. Yields were affected by weather conditions. In the compacted plots, the yields were generally lower but in the wet years they were also significant. Yields were higher at higher vinasse rates and lower for the application before ploughing in the autumn, indicating an adverse effect of that treatment. The combined analysis of the yields for the four years showed a significant adverse effect of compaction in the clay soil, while in the silty clay loam the effect was not significant. Vinasse application significantly increased yields, while an adverse effect was observed for the applications before ploughing. The work proved the beneficial effects of vinasse recycling as a substitute for chemical fertilizers and the feasibility of using of a spraying system, which compacts only the 10% of the field, to reduce any adverse economic effect of soil compaction on the crop. (C) 1999 Silsoe Research Institute.