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海拔高、温度低是制约康北一熟区土壤供氮的主导因子,故其氮素潜在含量高、供氮量少,对青稞亩平供氮8 kg,约占青稞丰产需氮量的59.6%。常规碱解氮量与该区土壤供氮能力不吻合,用低温(10～20℃)碱解法得到的碱解氮量能较好地反映其土壤供氮能力,测定值约为其常规碱解氮量的三分之一,即也可用常规碱解氮量换算。该区氮素丰缺指标用常规碱解氮量表示时,<75ppm为极缺,75～130ppm为缺,130～170 ppm为中,>170ppm为丰;氮素临界值为140ppm。
High altitude and low temperature are the main factors restricting soil nitrogen supply in the first cropping area of North Hebei Province. Therefore, the potential nitrogen content is high, nitrogen supply is low, nitrogen supply is about 8 kg per acre, about 59.6% %. The amount of available nitrogen for conventional hydrolysis does not coincide with the capacity of nitrogen supply for the soil in this area. The amount of available nitrogen can be well reflected by the amount of available nitrogen at low temperature (10 ~ 20 ℃) One-third of the amount of nitrogen, that is, can also be used to convert conventional nitrogen base conversion. The nitrogen deficiency index in this area is less than 75ppm, less than 75ppm and less than 75ppm, and more than 170ppm is abundant in the range of 130-170ppm. The critical value of nitrogen is 140ppm.