Nitrogen and phosphorus effluent loads from a paddy-field district adopting collective crop rotation

• Published in: Water science and technology Vol. 66; no. 5; pp. 1074 - 1080
• Main Authors: Hama, T., Aoki, T., Osuga, K., Sugiyama, S., Iwasaki, D.
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.01.2012
• Subjects: Agricultural practices; Agriculture - methods; Ammonium nitrogen; Cereal crops; Crop rotation; Crops; Crops, Agricultural - metabolism; Effluents; Fertilizers; Fertilizers - analysis; Glycine max; Japan; Load; Mineral nutrients; Nitrogen; Nitrogen - chemistry; Nitrogen - metabolism; Nutrient loading; Oryza; Oryza sativa; Outlets; Phosphorus; Phosphorus - chemistry; Phosphorus - metabolism; Rain; Rice; Rice fields; Rotation; Runoff; Soybeans; Surface runoff; Triticum; Triticum aestivum; Vegetables; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Wheat; Japan
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2012.292

Japanese paddy rice systems commonly adopt the rotation of vegetables, wheat and soybeans with paddy rice. Crop rotation may, however, increase the nutrient load in effluent discharged from the district because more fertilizer is applied to the rotation crops than is applied to paddy crops. We investigated a paddy-field district subject to collective crop rotation and quantified the annual nutrient load of effluent from the district in three consecutive years. The total annual exports of nitrogen and phosphorus over the investigation period ranged from 30.3 to 40.6 kg N ha–1 and 2.62 to 3.13 kg P ha–1. The results suggest that rotation cropping increases the effluent nutrient load because applied fertilizer is converted to nitrate, and surface runoff is increased due to the absence of shuttering boards at the field outlets.