Abstract
This study dealt with the influence of application of the digested slurry and bagasse charcoal to the Shimajiri-maji soil on sugarcane growth and the nitrate nitrogen losses to groundwater. Two kinds of organic fertilizers, compost and digested slurry, and bagasse charcoal were incorporated into the Shimajiri-maji soil. Sugarcane and sorghum were cultivated on Shimajiri-maji soil. Changes in concentrations of nitrate nitrogen in percolating water, specific gravity and available moisture in soil between planting and harvesting were observed. The indexes of the Sugarcane and sorghum growth, such as the stem diameter and length, yield, Brix, and root condition of sugarcane in each experiment were clarified.
The results indicated that application of organic fertilizers and bagasse charcoal to Shimajiri-maji soil increased the yields and sugar content of sugarcane, ultimately increased the sugar beet produced. In addition, the nitrate nitrogen losses were controlled by applying bagasse charcoal and practicing cultivation rotation of sugarcane and sorghum. It may be concluded that the applying bagasse charcoal and practicing cultivation rotation of sugarcane and sorghum can reduce the environmental loads in Miyako Island.
