旱地冬小麦不同栽培模式、施氮量和种植密度土壤水分利用状况

Effect of cultivation methods,N fertilizer rate and winter wheat planting density on soil water utilization in dryland

通过3年田间试验,研究不同栽培模式、不同施氮量及种植密度对冬小麦田土壤水分特征的影响,结果表明：无论何种栽培模式,冬小麦生长期间水分动态变化具有相似的规律,播前贮存在土壤中的水分经过一个生长季后都会有大量消耗,消耗深度延伸到2 m及其以下土壤深层。小麦收获后,各种处理土壤在40-80 cm和120-160 cm深度均出现两个低水层。覆盖栽培措施对水分利用的影响表现出较大的年度变异性,原因可能主要与生育期降水量和播前土壤贮水量有关系：与无覆盖相比,秸秆覆盖在降水较少的年份可显著提高水分生产效率;地膜覆盖具有稳定的促进水分有效利用的作用;垄沟种植没有表现出预期的增产增效的效果。施用氮肥显著促进土壤水分的消耗,这种作用随着种植年限的增加而增大,这种作用在0-200 cm整个土壤深度都有反映,而且深层比表层更显著,低水土层（40-80 cm和120-160 cm）比其它深度土层更显著。施氮显著提高水分生产效率。适当增加小麦种植密度有利于提高旱地水分生产效率。

Field experiment of winter wheat has been conducted for three years to investigate the effect of cultivation methods, rate of nitrogen fertilizer and planting density on soil water utilization, The results indicated that different cultivation methods showed the similar trend of fluctuation of water content through the soil profile during the stage of winter wheat growth. Large amount of water stored in the depth of 0 -200 cm or even deeper soil before wheat sowing was consumed during the stage of winter wheat growth. Two soil layers （40- 80 cm and 120 - 160 cm） with lower water content through the 0- 200 cm soil profile were found after wheat harvest no matter what kinds of cultivation methods was applied. Effect of mulching on water utilization varied in different years, probably due to the water content before wheat sowing and precipitation during the stage of wheat growth. Straw mulch could increase significantly water use efficiency （WUE） in drier year, comparing with no mulch. High WUE could often be found when plastic film mulch was applied. Furrow planting （with plastic film covered on ridge and straw covered on furrow and wheat planted on furrow） was expected to increase wheat yield and WUE comparing with no mulch, straw mulch or plastic film mulch. However, we failed to see it. N fertilizer increased remarkably water consumption through 0 - 200 cm of soil profile. The effect became more obvious with the time, More water lost in deep soil layer than topsoil, and more water lost in the depth of 40 - 80 cm and 120 - 160 cm than any other depth of soil. N fertilizer increased significantly WUE. Appropriate increase of wheat planting density could lead to increase of WUE in dryland as well.