不同砂石覆盖量对土壤水分及冬小麦生长过程的影响

为探讨不同砂石覆盖量对土壤水分运动和冬小麦生长的影响,进行了2014—2015年和2015—2016年遮雨棚下4种砂石覆盖量(0,23,46,69kg/m~2)的土箱试验研究。采用精度较高的重力传感器建立小型蒸渗仪观测系统,测定土壤水分动态变化。无麦和有麦情况下砂石覆盖量从0~69kg/m~2的处理名分别记为NW0、NW23、NW46、NW69及W0、W23、W46、W69。结果表明:(1)土壤贮水量随着砂石覆盖量的增加而增大,逐月土壤蒸发量、逐月蒸腾量、累积土壤蒸发量和累积蒸发蒸腾量均随砂石覆盖量的增加而减小。有麦的各处理土壤贮水量整体比无麦的低,有麦的各处理逐月蒸发蒸腾量比无麦的逐月土壤蒸发量高,累积蒸发蒸腾量亦比无麦的累积土壤蒸发量高。无麦情况下,第一、二年度3个覆盖处理比不覆盖处理的累积土壤蒸发量分别减少了11.6%~18.1%和28.5%~47.5%;有麦情况下,累积蒸发蒸腾量分别减少了2.2%~3.7%和0.7%~3.6%。(2)冬小麦的株高、叶面积指数、有效穗数、产量及水分利用效率均随着砂石覆盖量的增加而增大。第一、二年度3个覆盖处理比不覆盖处理的最大株高分别增长了5.3%~17.2%和1.0%~5.8%,最大叶面积指数分别增大了17.9%~74.6%和7.9%~28.2%,产量分别增大了6.6%~14.2%和12.3%~44.6%,水分利用效率分别增大了8.0%~16.2%和15.6%~67.1%。最适宜冬小麦生长的砂石覆盖量为69kg/m~2。进行砂石覆盖能够将冬小麦生长前期增加的土壤储水有效用于生长后期,从而对提高冬小麦产量和水分利用效率做出了重要贡献。

Effects of Different Sand-gravel Mulching Amounts on Soil Water Storage and Winter Wheat Growth Processes

In order to investigate the effects of different sand-gravel mulching amounts on soil water movement, soil water storage, evapotranspiration processes and winter wheat growths, two-year experiments were conducted in 24 soil containers which were put under a rain shelter at four sand-gravel mulching amounts (0, 23, 46 and 69 kg/m2). The soil water dynamic change was observed by a micro-lysimeter which contained a high-precision weighing transducer connected with a data logger. For the no-wheat and with-wheat conditions, when the sand-gravel mulch amounts increased from 0 to 69 kg/m2, the treatments were named NW0, NW23, NW46, NW69 and W0, W23, W46, W69, respectively. The results showed that: (1) Soil water storage increased with the increase of sand-gravel mulch amounts, the monthly soil evaporation, monthly evapotranspiration, cumulative soil evaporation and cumulative evapotranspiration decreased with the increase of sand-gravel mulch amounts. Soil water storages under the with-wheat conditions were lower than the values of the no-wheat conditions. The monthly soil evaporation, monthly evapotranspiration, cumulative soil evaporation and cumulative evapotranspiration under the with-wheat conditions were a little bit higher than the values under the no-wheat conditions, especially at the later winter wheat growth stages. Under the no-wheat conditions, in the first and second years, the total evaporations of the three coverage treatments were less than the non mulching treatment from 11.6% to 18.1% and 28.5% to 47.5%, respectively. Under the with-wheat conditions, in the first and second years, the total evapotranspiration of the three coverage treatments was less than the non mulching treatment from 2.2% to 3.7% and 0.7% to 3.6%, respectively. (2) All of the plant heights, leaf area indexes, productive panicle number, yields and water use efficiencies of the winter wheat increased with the increase of sand-gravel mulching amounts. In the first and second years, the maximum plant height of the three coverage treatments was more than the non mulching treatment from 5.3% to 17.2% and 1.0% to 5.8%, respectively. The maximum leaf area index of the three coverage treatments was more than the non mulching treatment from 17.9% to 74.6% and 7.9% to 28.2%, respectively. The yields of the three coverage treatments were more than the non mulching treatment from 6.6% to 14.2% and 12.6% to 44.6%, respectively. The water use efficiency of the three coverage treatments were more than the non mulching treatment from 8.0% to 16.1% and 15.6% to 67.1%, respectively. From the results, the most suitable sand-gravel mulching amount was 69 kg/m2, the sand-gravel mulch can effectively prevent soil water evaporation, the increased soil water storage at early crop growth stages could be utilized for later stages of crop growth, which highly contributes for improving crop yields and water use efficiency.