Effects of Green Manure, Organic Fertilizers and Urea on Yield and Grain Quality of Spring Wheat

Effects of two green manure crops—persian clover and persian clover/Westerwolth ryegrass—and three fertilizers—liquid manure, meat bone meal and urea-on subsequent spring wheat yields and quality characters were studied in four field experiments. No significant differences between green manure crops in production or effects on wheat were found. The yield was up to 2500 kg/ha higher after the green manure crops than after oats, but the effect on wheat protein content was less pronounced. Fertilization did not increase the yield as much as green manuring, but significantly increased protein content in two of the experiments. In a partial least square regression (PLSR) model, the wheat yield was largely explained by the amount of green manure herbage ploughed in during the autumn and the amount of mineral N in the soil in spring. The prediction model of protein content was weak.