稻草覆盖对红壤旱地土壤温度和水分的调控效应

Effects of Rice Straw Mulching on Soil Temperature and Moisture Regulation in an Upland Red Soil

利用雨养玉米田间小区试验,研究了稻草覆盖调节旱地红壤温度和水分动态的作用及其降低玉米干旱胁迫的效应。结果表明,稻草覆盖能显著降低高温时段(15:00)10cm以内土层的温度,降幅可达1.6-4.1℃,降温效应随覆盖量增加而增加。稻草覆盖能明显提高0-5cm表土层的水分保持能力,当覆盖量为5000-10000kg·hm-2时,高温干旱期表土层的最低含水量平均可提高3.3%-3.6%;稻草覆盖量为15000kg·hm-2时,表土层最低含水量平均提高6.1%。由于稻草覆盖的降温保墒效应,玉米拔节期叶片的光合速率提高了8.34-17.77μmol·m-2·s-1(提高率60.3%-128.4%),喇叭口期(雌花发育期)光合速率提高4.46-11.27μmol·m-2·s-1(提高率16.3%-41.3%),子粒产量增加7.6%-13.1%。就土壤降温保墒和玉米增产效应而言,可选择5000kg·hm-2的稻草覆盖量。

Based on a field plot experiment of rainfed summer maize, the influences of rice straw mulching on soil temperature, moisture dynamics and reducing drought stress effects of the maize plants were studied in a upland soil derived from the Quaternary red clay earth. Straw mulching could reduce soil temperature significantly within the 10 cm top layer in the high air temperature period （15：00）. The extent of reduction ranged from 1.6 ℃ to 4.1 ℃ averagely, and the effect of temperature reduction was enlarged with the amount of rice straw mulching increasing. There was also a measurable increase of water holding capacity at the 0～5 cm soil layer in treatments with straw mulching. In the high air temperature and drought period, the lowest content of soil moisture in the 0～5 cm layer increased by 3.3%～3.6% averagely when 5 000～10 000 kg·hm^-2 of rice straw was mulched, while the moisture content increased by 6.1% when amount of straw mulching increased to 15 000 kg·hm^-2 averagely. Because of the effects of straw mulching on decreasing soil temperature and increasing water hold capacity, the photosynthesis rate of the maize plants increased by 4.46～11.27 μmol·m^-2·s^-1 （i.e. 16.3%～41.3%） at the elongation stage, and 4.46～11.27 μmol·m^-2·s^-1 （i.e. 16.3%～41.3%） at the female flower initiation stage, compared with the non-mulching control. And the grain yield increased by 7.6%～13.1% with straw mulching. Considering the acceptable effects on reducing soil temperature and protecting soil moisture, a dose less or more than 5 000 kg·hm^-2 of rice straw could be chosen as mulching of upland soil in the subtropical hilly area of Hunan province.