旱地不同栽培模式下土壤水分和矿质氮含量的时空变化

Effects of different cultivation patterns of the dryland farming on the spatial-temporal variations of soil moisture and mineral nitrogen in soils

以田间试验为研究手段连续两年研究了旱地不同栽培模式和施用氮肥对冬小麦生长期间土壤水分、硝态氮和铵态氮含量时空变化的影响。结果表明：与常规相比,覆膜和覆草均显著增加了0-5、5-10和10-20cm土层水分含量,而施用氮肥却是0-20 cm各土层水分含量均有所降低。不同栽培模式对土壤贮水量的影响因作物各生育时期的不同而不同,返青期覆膜和覆草模式土壤贮水量显著高于常规对照,拔节期覆草模式土壤贮水量显著高于覆膜模式,灌浆期各模式之间土壤贮水量的差异未达显著水平。冬小麦生长期间不同处理的土壤铵态氮含量均较低,时空变化较小;而不同处理的土壤硝态氮含量的时空变化较大,其含量的时空变化与施氮量、栽培模式和不同时期有密切关系。增加氮肥用量明显提高0~20 cm土层硝态氮含量和矿质氮的累积量,随着生长时期的推进,土壤硝态氮含量降低明显。0-100 cm土层中硝态氮的累积量为覆草〉常规〉覆膜。

A long-term field experiment was used to research the spatial-temporal variations of NH4^- -N, NO3^- - N and water in soil under winter wheat cultivation at the different N levels and different cultivating patters in two continual years （2004 and 2005）. The results showed that, compared to the conventional cultivation method （without any mulching methods）, plastic mulching and straw mulching significantly increased the water content in soil depth of 0-5, 5-10 and 10-20 cm; however, the application of nitrogen fertilizer decreased the water contents in the above soil depth. The effects of different cultivating methods on the water contents in 0-100 cm soil depth varied with the growth period of winter wheat. The water contents in 0-100 cm soil depth under plastic mulching and straw mulching cultivation was significantly higher than that of the conventional cultivation method at reviving stage; at the shooting stage, the water contents in 0-100 cm soil depth under straw mulching cultivation was significantly higher than that of the plastic mulching cultivation method; and there were not significant differences on the water content in 0-100 cm soil profile among the different cultivating methods at the grain-filling stage. The level of NH4^＋ - N in soil of different treatments remained at a very low level during the whole growing period of winter wheat, while the variations of NO3^- - N content in soil was very high. The spatial-temporal variations of soil NO3- - N had close relationships with N application level, cultivation methods and growth stage. The content of NO3^- - N and the accumulation of mineral nitrogen in 0-20 cm soil increased with the increase of N rate added, and decreased as the growing of winter wheat. The accumulation of NO3^- - N in 0-100 cm soil were in the following order, straw mulching 〉normal cultivation 〉 plastic mulching.