Wood chips used for weed control in Organic Farming
Journal of Plant Diseases and Protection
The effect of wood chips mulch on weeds and yield was tested in a long-term experiment within a crop rotation in Organic Farming. The wood chips originated from hedgerows and trees of the Experimental Station Kleinhohenheim of the University of Hohenheim. The material consisted for 25% of bark and had a C:N ratio of 47. After annual mulching of crops with 0 (control), 80 and 160 m(3) ha(-1) in spring, any mechanical weed control was omitted. There was no effect of mulching on yield in the years 2002-2006. In the season 2007, when the investigations were intensified, winter wheat yielded 7.0-7.2 t ha(-1) or 607-626 ears m(-2), and had protein contents of 10.8-10.9%, all without significant differences between the treatments. N-min after harvest 2007 ranged from 83 and 104 kg ha(-1). The water content of the soil after harvesting winter wheat 2007 was highest in the treatment with high application of wood chips. There was a quantitative effect of mulch application on weed infestation in field and model experiments. The application of wood chips significantly reduced weed infestation in lucerne/grass, and also significantly reduced volunteer lucerne in the following crop winter wheat. The highest number of annual weeds was found in winter wheat in the treatment 80 m(3) ha(-1). A germination test with wood chips extract for an investigation of potential allelopathic effects resulted in lowest germination rates of oilseed rape (Brassica napus), blackgrass (Alopecurus myosuroides) and field poppy (Papaver rhoeas) seeds when the highest eluate concentration was used. As a conclusion, wood chips are suitable to contribute to weed control in Organic Farming, and they additionally close the total farm's nutrient cycle. An increase of soil organic matter and higher water storage capacity can be expected in future due to the high input of C and N by wood chips in the further run of the experiment. Wood chips application can additionally be a flexible tool to control erosion on fields with a slope, and in crops with wide inter-row distance.
Author(s): Gruber, S; Acharya, D; Claupein, W
Journal: Journal of Plant Diseases and Protection