不同种植年限蔬菜大棚土壤盐分累积及硝态氮迁移规律

通过对关中地区泾阳等地32个蔬菜大棚土壤分析,表明:该区大棚土壤盐分表聚和酸化现象明显。耕层(0~20cm)平均全盐量为3.2g/kg,20~40cm土层平均也达2.8g/kg,40~60cm和60~80cm土层在2.0g/kg左右;耕层土壤PH值比对照下降0.61,60~80cm土层比对照下降了0.27;耕层硝态氮含量平均高达63.3mg/kg,是对照的5.5倍,硝态氮深层下迁趋势明显,可达80cm以下,仅60~80cm土层的平均含量为27.3mg/kg;耕层平均有机质含量仅为16.0g/kg。随棚龄延长盐渍化和酸化程度加重,硝酸盐下迁损失愈多。其主要原因是偏施化肥,不重视有机肥,常年连作,不合理灌溉等。建议采取增施有机肥、限制化肥用量、改进施肥技术、科学灌排、轮作倒茬等措施。

Study of the Regularity of the Salt Accumulation of Topsoil and NO3-- N Migration in Greenhouse Soil and Years of Vegetables Cultivation

The analysis on 32 soils sample of greenhouse in the area GuanZHong, the results that the soil salt accumulation and acidulation of topsoil are obviously showed. The average total salt content of topsoil is 3.2 g/kg, 20~40cm depth of soil is 2.8 g/kg, almost 40~60cm and 60~80cm depth of soil are 2.0 g/kg; both PH-value of topsoil lower 0.61 and 60~80cm soil layer lower 0.27 than the check sample ; the average NO3-- N content is 6.3 mg/kg,it is 5.5 time of the check sample , NO3--N down-ward migration is total soil profile ,even the average NO3--N content is 27.3 mg/kg of 60~80cm soil layer ; the average content of organic matter is 16.0 g/kg of topsoil ;all the salt content is increasing and PH-value is down and NO-3-N is leaching loss of deep level more and more serious with cultivated year. The reasons are over-fertilizer, poor organic manure, continuous cropping, illogical irrigation etc. We suggest to increase the input of organic manure, to limit mineral fertilizer application rate, to improve fertilizer practice, to irrigation and drainage scientifically, crop rotation.