Study on the potential of farmland soils as non-point sources of nitrogen and phosphorus in Japan.
The amounts of N and P accumulated in farmland soils of 50 cm depth were equivalent to the amount of chemical fertilizer supplied for 50-70 years. The values of N/P of surface soils in farmlands were 1.0-4.3, lower than expected. The median diameter of soil particles in run-off waters was generally less than 10 microm. The mean values of particulate fractions over 1 microm and over 0.22 microm were 19% for N, 27% for P, and 39% for N, 64% for P respectively. Fine particles of soil containing concentrated phosphorus should be carefully monitored as potential sources related to eutrophication.
Ukita
M
M
Department of Civil and Environmental Engineering, Faculty of Engineering, Yamaguchi University, Tokiwadai, Ube 755-8611, Japan. mukita@yamaguchi-u.ac.jp
Shi
X
X
Higuchi
T
T
Arkin
Y
Y
Fukada
M
M
D000383:Agriculture; D004784:Environmental Monitoring; D005068:Eutrophication; D005308:Fertilizers; D007564:Japan; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012987:Soil; D012989:Soil Pollutants; D014867:Water; D014872:Water Movements; D014873:Water Pollutants
D005308:Fertilizers; D012987:Soil; D012989:Soil Pollutants; D014873:Water Pollutants; D014867:Water; D010758:Phosphorus; D009584:Nitrogen