Fate of fertilizer nitrogen applied in an area with high precipitation in southern Kyushu [Japan]
1994
Kobayashi, Y. (Kyushu National Agricultural Experiment Station, Chikugo, Fukuoka (Japan)) | Niimi, H. | Ohshima, H. | Hasegawa, I.
Contamination of shallow groundwater by nitrogen, which has been of great concern recently in souther Kyushu, a region with high precipitation, is mainly considered to be brought about by the return of a large amount of livestock waste to arable land. As a result, the fate of excess nitrogen applied to arable land is now being monitored to solve this problem. The results obtained in this study were as follows: 1) The amount of eluviated N ranged from 4 to 28 kg/10a for the year examined, with a negative correlation between precipitation and crop yields. 2) Eluviation of N in regions with high precipitation was mainly dependent on precipitation factors and involvement of soil factors was limited to low precipitation years. 3) When the amount of applied slurry barnyard manure increased, the rate of N lost (due to volatilization and denitrification) increased. The N concentrations in the soil solutions collected from the plots where a large amount of slurry barnyard manure had been applied decreased with time. In addition, a high concentration of nitrous oxide remained in the subsoils. It was suggested that microbial decontamination of excess N occurred in soil
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