Effects of Successive Application of Cattle Manure Slurry on Chemical Properties of Grassland Soil and Grass Quality

Abstract

On grasslands where aerobically digested slurry and methane-fermentation-digested slurry had been applied for up to 8 years, the chemical properties of the surface soil layer and the quality of the grass produced were investigated. The overall mineral balance was found to be favorable and the potassium content in the grass was found to be within an appropriate range, although the potassium content in the surface soil layer was markedly high. The magnesium content of the grass was only slightly above the lower limit of standard magnesium levels. Excessive potassium in the surface soil layer may have inhibited the grass from absorbing magnesium from the soil. The soil analysis suggests that the application of chemical fertilizer should be reduced. It is estimated that on grasslands where aerobically digested slurry and methane-fermentation-digested slurry are applied, zinc and copper tend to accumulate in the surface soil. However, the zinc and copper content levels of the grassland to which slurry had been applied were not significantly different from those of the grassland where only chemical fertilizer had been applied.