Analysis of the nitrogen pollution load potential from farmland in the Tedori River Alluvial Fan Areas in Japan.

摘要

A nitrogen balance study was carried out by setting up a test paddy in order to estimate the nitrogen pollution load potential (NPLP) from farmland in the Tedori River Alluvial Fan Areas and the load from the entire area under consideration was estimated using the cropping record and fertilizer application rate (FAR). The total NPLP was estimated to be 261 tons/year and the load from the paddy 79 tons/year for 5,704 ha, which would translate to an intensity of 14 kg/ha, while the load from the vegetable field was estimated to be 118 tons/year for 215 ha, which would equate to an intensity of 549 kg/ha. The pollution loads for the vegetables were significantly greater than those for the rice. The load for the barley was 57 tons/year for 261 ha (216 kg/ha) and that for the orchards was 23 tons/year for 64 ha (359 kg/ha). The estimation of soybean load was a negative 15 tons/year for 717 ha (-21 kg/ha), which meant that the nitrogen in the yield was greater than the FAR. The results also confirmed the yield absorption ratio in relation to the FAR. The load from the paddy for the entire area was also estimated using the percolation rate and the water quality load underneath the farmland was estimated to be 89 tons/year.