Effect of the Nitrification Inhibitor on Nitrification of Ammori Fertilizer and Yield of Rice Sown Directly on Unflooded Paddy Field Part : 1. Effect of 2-〔（N-nitro）methlylamino〕-1，3，4-thiodiazole

The purpose of this study is to evaluate the effect of a nitrification inhibitor, 2-[(N-nitoro) methylamino] -1, 3, 4-thiodiazole (NAT), on the nitrification of nitrogen applied to rice culture by direct sowing on unflooded field, and the yielding effects on the plant growth and grain yield thereby. In addition to this, to get a fundamental information to establish an application method of the inhibitor containing fertilizer in the rice culture, which is most profitable to increase the yield with less labor requirement, is also the other purpose. The results obtained were as follows: 1. NAT exhibited distinguished effect on the control of nitrification of applied nitrogen, and NH_4-N concentrations in soils ÷NAT plots were higher than those in the soils of -NAT plots during the early period of unflooded state. The inhibitory effect of NAT on nitrification, however, terminated within 25 days. ....