渭北旱塬小麦不同栽培模式对土壤硝态氮残留的影响

Effects of Different Wheat Cultivation Methods on Residual Nitrate Nitrogen in Soil in Weibei Dryland

在陕西渭北旱塬进行了4年田间小麦试验，研究了旱地不同栽培模式、施氮量睇Ⅱ种植密度对土壤硝态氮残留累积的影响。结果表明，种植小麦4年后，0-200cm土壤剖面中残留硝态氮为29．87-462．59kg／hm0，且主要积累在80-160cm土层，土壤氮库不仅明显．且残留比前3年土壤剖面显著下移（前3年主要累积在100cm），差异达显著和极显著水平；不同栽培模式和种植密度0-200cm土层硝态氮残留累积规律及其小麦籽粒吸氮量基本相似，排序均为：地膜覆盖〉常规种植〉秸秆覆盖〉垄沟种植；随施氮量的增加土壤硝态氮残留量也相应增加．N0处理0-200cm土壤平均硝态氮残留量为57．69kg／hm^2．N120处理平均为97．04kg／hm^2，虽然高于无氮处理，但两者差异未达到显著水平．N240处理平均为355．43kg／hm^2，比前者增加的幅度更大，其差异达到极显著水平。因施氮肥而增加的土壤硝态氮残留量为14．9～401．18kg／hm^2．平均占4年施氮量的19．59％，其中地膜覆盖占26．07％，常规种植占20．98％，秸秆覆盖占17．46％，垄沟种植种植占13．87％。

A field experiment was conducted for 4 years in Weibei Highland of Shaanxi province to investigate the effects of different cultivation methods on residual nitrate nitrogen in black loessial soil in winter wheatfallow system. The study concerned about four cultivation modules （no mulch, straw mulch, plastic film mulch and furrow planting）, three nitrogen fertilizer levels （0, 120 and 240 kg N/hm2） and two wheat densities （seed rate of 180 and 225 kg/hm2）. Furrow planting was the combination of plastic film mulch and straw mulch, with the ridge covered by plastic film and furrow covered by crop straw. It was a special cultivation module in semi-arid and semi-humid area of North China. The results showed that 29.87-462.59 kg residual nitrate N per hectare were found in the depth of 0--200 cm of soil after 4 years cropping and considerable residual nitrate N in the depth of 80--160 cm of soil. It was an important part in soil nitrogen bank in dryland and depth of residual nitrate N in the profile of soil is significant decline than depth of the first season, the second season and the third season. Differences came up to significant average and very significant aver）,. The regularity of distribution of residual NO3^--N in the depth of 0--200 cm of soil and N uptake by wheat under different wheat cultivation modules and densities were similar basically. Order was：plastic film mulch 〉 no mulch〉 straw mulch 〉furrow planting. Accumulated nitrate N in 0--200 cm of soil of N240 treatment was significantly higher than that of No and N120 treatments. While No and N120 treatments had no significant differences. Increase of residual NO3^- --N due to application of N fertilizer was 14.9-401.18 kg/hm^2 ,Averrage was 19.59% in amount of 4 years N fertilizer applied, plastic film mulch was 26.07%, no mulch was 20.98% ,straw mulch was 17.46%, furrow planting was 13.87%.