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据1980年统计,我国氮肥年施用量略高于一千万吨(以纯氮计),但我国氮素化肥的利用率一般仅30—50％,低者在10％以下,高者在80％以上,这就说明我们施到田里去的氮肥有相当多的肥料没有真正发挥增产作用,因此合理施用氮肥,潜力很大。现在我们从土壤角度来谈谈提高氮素化肥利用率的施用技术。就全国范围来说,从北到南土壤pH值有逐渐降低的趋势,大体上以北纬33度为界,33度以北的土壤,因降水量少而蒸发强烈,土壤盐分不但得不到淋洗,而下层和地下水的盐分反而向表层集中,土壤表现为碱性反应。在北纬33度以南的长江中下游和华南地区气候温暖湿润,矿物风化和雨水淋洗均很强烈,地带性土壤呈酸性反应。土壤的酸碱度不同,土壤供肥能力就有很大的差异,因而我国南北方施用氮素化肥的技术就应有所不同。
According to the statistics of 1980, the application amount of nitrogen fertilizer in our country is slightly higher than 10 million tons (in terms of pure nitrogen), but the utilization rate of nitrogenous fertilizer in our country is generally only 30-50%, the lower is below 10% and the higher is above 80% Above, this shows that we applied to the field of nitrogen fertilizer has a considerable amount of fertilizer did not really play a role in increasing production, so the rational use of nitrogen fertilizer, great potential. Now we talk about the application of nitrogen fertilizer to improve soil fertility. Nationally, the pH value of soil from north to south tends to decrease gradually. Generally speaking, the soil at 33 degrees north latitude and the soil north of 33 degrees evaporate strongly due to the small amount of precipitation, and soil salinity can not be leached Washed, while the lower groundwater and salinity instead concentrated to the surface, the soil showed a basic reaction. The climate is warm and humid in the middle and lower reaches of the Yangtze River and the southern part of the Yangtze River south of latitude 33 degrees north latitude. Mineral weathering and rainfall showering are very strong, and the zonal soil is acidic. Different soil pH, soil fertility have great differences, so our country north and south fertilizer application of nitrogen technology should be different.