河北平原区农田硝态氮分布规律研究

Experimental study on nitrate nitrogen distribution characteristics in the Hebei Plain

通过在冉庄实验站进行耕作与非耕作对比田间试验,获得河北平原区土壤中硝态氮的空间分布规律。结果表明:土壤中硝态氮主要来自施肥,硝态氮的分布受降水、灌溉影响很大,氮肥深层淋溶现象明显。玉米生育期土壤中硝态氮含量随深度变化较大,呈现双峰现象。根层土壤(0～100cm)硝态氮含量随深度增加,在80～100cm呈现第1个峰值,在200cm左右出现第2个峰值,且较前1个峰值更大。第1个峰值主要是玉米苗期施肥所致,第2峰值是小麦生育期施肥随雨季降水下移所至。350cm土层以下土壤含氮量随深度减少并稳定在20mg/kg左右。不同耕作条件下土壤硝态氮的分布情况差别明显,耕作区的土壤中硝态氮的含量远高于非耕作区,并且在深层土壤中仍有分布。为此,提高氮肥利用效率并减少氮素对水体的污染需从施肥灌溉管理方面采取措施。

A comparative field experiment was conducted at farming field and non-farming field in Ranzhuang Experiment Station to obtain the soil NO^--N distribution characteristics. The results showed that soil NO^--N mainly come from fertilization, nitrate nitrogen distribution is influenced by precipitation and irrigation. Nitrogen fertilizer leached into deep soil obviously. Soil NO^--N content changed with depth largely in maize growth period, which presented bi- modal phenomena. Nitrate nitrogen content also increased with depth. In root layer soil （0 - 100 cm）, the first peak occured at 80 - 100 cm, and the second emerged at 200 cm, and the val- ue of the second peak was bigger than the first. The first peak was mainly caused by the fertili- zation at the corn seedling stage; the second peak was mainly caused by the nitrogen deep transportation in the wheat growth period. The soil nitrogen content reduced with depth and stabilized on 20 mg/kg below 350 cm soil layer. The soil nitrate nitrogen distribution characteristics