不同栽培模式及施氮对玉米-小麦轮作体系土壤肥力及硝态氮累积的影响

以在陕西关中土垫旱耕人为土区进行的连续6年定位试验为对象,研究了长期覆盖栽培及施氮量对玉米?小麦轮作体系下土壤有机质、全氮及土壤剖面硝态氮残留量和分布的影响。结果表明,不同栽培模式对土壤有机质和全氮含量的影响为覆草垄沟常规节水,其中覆草模式影响达显著水平。增施氮肥不同程度地提高了土壤有机质和全氮含量。经过12季玉米-小麦的轮作,不同栽培模式0～200cm土壤剖面硝态氮残留量为垄沟节水覆草常规,垄沟和节水栽培模式与常规栽培硝态氮累积量差异达显著水平。随种植年限和施氮量增加,0～200cm土壤中硝态氮累积量明显增加,施240kg·hm-2N(N240)处理0～200cm土壤硝态氮累积量显著高于施120kg·hm-2N(N120)处理。不同施氮量下硝态氮在0～200cm土壤剖面的分布存在差异,与不施氮(N0)和N120处理相比,N240处理下各栽培模式在120cm以下的土壤硝态氮含量随深度增加而显著增加。

Effect of cultivation pattern and nitrogen application rate on soil fertility and nitrate accumulation under maize-wheat rotation system

A field experiment was conducted in Guanzhong of Shaanxi Province to study the effects of long-term cultivation patters and fertilization on organic matter, total soil nitrogen, and the quantity and distribution of nitrate N in soil profile under maize-wheat rotation system. The results indicate that the order of effect of the different cultivation patterns on soil organic matter and total nitrogen contents is: straw mulching > furrow planting > conventional cultivation > water-saving cultivation. Straw mulching has the most significant effect on soil organic matter and total nitrogen contents. Nitrogen application significantly influences soil organic matter and total nitrogen. After 6 years of maize-wheat rotation cropping, the order of residual nitrate N in the 0~200 cm soil profile under different cultivation patterns is: furrow planting > water-saving cultivation > straw mulching > conventional cultivation. There are significant differences in nitrate N accumulation among furrow planting, water-saving cultivation and the conventional cultivation. Nitrate N accumulation in the 0~200 cm soil profile increases with longer cultivation periods and increasing nitrogen application rates. Accumulated nitrate N under 240 kg(N)·hm^{-2 (N240) treatment is significantly higher than that under 120 kg(N)·hm-2 (N120) treatment. The pattern of nitrate N distribution across the soil profiles differs with differing nitrogen application rate. Under N240 treatment, nitrate N content below the 120 cm soil depth increases with soil depth.}