Abstract
Introducing buckwheat to acid soil region is expected to reduce soil erosion in subtropical Japan. We examined whether the amount of chemical fertilizer applied can be reduced by applying composted manure, which is produced locally in large amounts, since manure substantially improves grain yield of buckwheat grown on acid soil. When 1 kg m-2 of composted manure from pig and cow was applied, grain yield, yield components, shoot weight, and the concentrations of phosphorus and potassium in the shoot were not lowered even when phosphorus and potassium fertilizer were not applied. When 1 kg m-2 of composted manure of pig was applied, omittion of phosphorus, potassium and nitrogen lowered the nitrogen concentration in shoot and grain, but did not lower grain yield or yield components. Even when chemical fertilizer was omitted, the nitrogen, phosphorus and potassium contents of soil after buckwheat harvest were not lower than before sowing buckwheat. These results indicate that application of nitrogen, phosphorus and potassium fertilizers can be reduced by application of 1 kg m-2 of composted manure.
