2011 Volume 46 Issue 4 Pages 167-177
To develop a cropping system for corn production without using N fertilizer, a crop rotation with hairy vetch (Vicia villosa Roth, HV) was examined over a 3-year period (2007-2009). The experiment consisted of four treatments (incorporation of HV biomass, mulching of HV biomass, fertilization with mineral fertilizer, and control without application of nutrient source) carried out in triplicate. The HV biomass was managed according to each treatment in May, followed by cultivation of silage corn in June. Corn dry weight and N uptake were measured during the growth season. The HV biomass accumulated 260-300 kg N ha-1 year-1, and approx. half of this N seemed to be available in an inorganic form to corn plants. In the second and third years, above ground biomass (AGB) in both HV-treated plots exceeded that of the control, which was almost equal to that of the fertilized plot. N uptake by corn was 330-400 kg N ha-1 when AGB reached 25 Mg ha-1. It was estimated that 40% of the N required to achieve this yield could be sup-plied by HV. The difference in N uptake between HV-treated and control plots was 20-25 kg N ha-1 in the first year, 100-140 kg N ha-1 in the second year, and 40-50 kg N ha-1 in the third year. Thus, HV was an important N source, in spite of the annual fluctuation. There was no difference in corn yield between the incorporation and the mulching treatments.
