Manure fertilization for soil organic matter maintenance and its effects upon crops and the environment, evaluated in a long-term trial

Summary

The effects upon soil organic matter and crop yield of applying farmyard manure, both with and without biodynamic preparations, as compared to treatments receiving mineral fertilizer (and straw) have been studied in a field trial starting in 1980. The site has a sandy orthic luvisol, 590 mm precipitation per year and 9.5̊ C annual mean temperature. Since 1985/86, crop rotation is red clover, spring wheat, potatoes and winter rye. Soil organic matter (SOM) content in the topsoil has been found to be higher with manure than with mineral fertilization. The highest SOM content of 1.00 % Corg has been observed in the treatment with biodynamic preparations. Increasing applications gave higher SOM contents only with manure, but not with mineral fertilization. SOM levels in all treatments have been fairly constant for more than 10 years. Crop yield does not show the same pattern as SOM content. Winter rye has 33 % higher yields (37.7 instead of 28.3 dt ha-1) and potatoes have 10 % higher yields (271 instead of 247 dt ha-1) with mineral as compared to manure fertilization. Spring wheat has the same yield with all types of fertilizer (approx. 40 dt ha-1). Biodynamic preparations increased potato yields by 15 dt ha-1 (6%) on average over all years. In spring wheat yield stability is greater, i.e. fluctuation over the years is smaller, with manure than with mineral fertilization.