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在半湿润易旱地区红垆土上进行的大田试验表明，连续施用氮肥显著影响硝态氮在土层中的残留累积、０～２０ ｃｍ 土层微生物体氮和矿物固定态氮。当每作施氮量达到１１２５ ｋｇ／ｈｍ ２ 时，则发生残留硝态氮的累积，并随施氮量增加，残留量增加，当每作施氮量低于 ７５０ ｋｇ Ｎ／ｈｍ ２ 时，不会出现硝态氮的残留累积。补充灌水后，作物产量、吸氮量和氮肥利用率提高，则累积的残留硝态氮显著下降。微生物体氮和施氮水平及作物产量之间的关系：施肥加灌水，作物地上、地下部分生长量增加，土壤中作物残体增加，能源物质充分，微生物体氮相应增加。施肥和灌水对矿物固定态氮的影响与对残留硝态氮和微生物体氮的影响不同，与试验开始时相比，不施氮，矿物固定态氮显著下降，施氮后却保持着试验开始时的水平，表明施用氮肥对维持土壤矿物固定态氮库的稳定具有重要意义。
Field experiments on red loess soil in semi-humid and drought-prone areas showed that continuous application of nitrogen fertilizer significantly affected the residual accumulation of nitrate nitrogen in the soil layer and the nitrogen and mineral nitrogen in the 0-20 cm soil layer. When the amount of nitrogen application reached 1125 kg / hm 2, the accumulation of residual nitrate nitrogen occurred. With the increase of nitrogen application amount, the residual amount increased. When the nitrogen application rate was less than 750 kg N / hm 2, there will be no accumulation of nitrate nitrogen. After supplementary irrigation, crop yield, N uptake and N use efficiency increased, then the residual nitrate nitrogen accumulated decreased significantly. Nitrogen and Nitrogen Levels in Microbial Organisms and Crop Yield: The relationship between fertilization and irrigation of fertilizers and fertilizers increased the aboveground and belowground parts of crops, increased crop residues in soil, sufficient energy sources and corresponding increase in microbial nitrogen. The effect of fertilization and irrigation on the fixed nitrogen in mineral was different from the effect on residual nitrate and microbial nitrogen. Compared with the beginning of the experiment, the fixed nitrogen in the mineral decreased significantly after the application of nitrogen and the experiment started , Indicating that the application of nitrogen fertilizer is of great significance to maintain the stability of soil mineral nitrogen pool.