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SCI论文目录 |
稻草覆盖对红壤旱地土壤水分、温度的影响 |
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| 出 版 社：中科院硕士学位论文 |
| 发表时间：2007.07 |
| 台 站：
桃源农业生态试验站
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| 作 者：苏衍涛 |
| 点 击 率：5016 |
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| 关 键 字：稻草覆盖；红壤旱地；土壤温度；土壤水分；光合速率；玉米 |
| 摘 要：红壤旱地土壤有效养分和有机质含量匮乏，生产力水平普遍偏低，加之受季节性干旱影响，作物产量低而不稳，严重制约着红壤丘陵区复合农业生态系统综合生产力的提升。将丰富的稻草资源转移到红壤旱地，作为有机肥或生物覆盖材料，是旱地快速培肥和缓解作物季节性干旱胁迫的技术途径之一。本文依托中国科学院桃源农业生态试验站稻草覆盖红壤旱地的试验，探讨不同稻草覆盖量对调节红壤旱地土壤温度和水分的效应，为有效利用稻草资源，缓解红壤旱地系统季节性干旱胁迫提供科学依据。主要结果如下：
桃源县具有季节性干旱特征的天气主要出现在5月~9月，其主要变现为气温较高并且降雨较少，0~2.5 mm的日降雨量占83.59 %，随着降雨量等级的增大，其降雨天数基本上是随之降低，直至最大降雨量>27.5mm占2.95 %；并且日平均温度以25.0~32.5 ℃为主。另外，尤以7月为代表月份，0~2.5 cm日降雨量为主(占94.79 %)，气温高于30 ℃(占84.38 %)这样的极端高温少雨的天气不多，其出现频率为1.59 %。
稻草覆盖能有效调节旱地土壤耕作层（0~20 cm）的温度变化，显著降低高温时段（15 pm）5cm和10 cm以上土层的温度水平，平均降温效应达2.7~4.1℃。覆盖量之间的差异主要表现在5cm和10cm两个层次，其他土壤层次的温度没有受到明显的影响；高温时段以覆盖15000 kg/hm2 减低土壤温度的效果最明显。通过稻草覆盖，降低高温干旱期白昼的土壤温度，对减少土壤水分蒸散，缓解土壤和作物干旱将具有积极意义。
稻草覆盖对土壤水分动态的调控效果主要体现在0~5 cm的表土层，当稻草覆盖量为5000~10000 kg/hm2时，高温干旱期表层土壤的最低含水量平均可提高3.3 %~3.6 %；当稻草覆盖量增加至15000 kg/hm2时，表层土壤最低含水量平均可提高6.1 %。稻草覆盖对土壤水分的调控机理主要是削减太阳辐射对表层土壤的增温效应，降低土壤水分蒸发势。稻草覆盖能调节0-20 cm土层水分变化动态，提高干旱期土壤水分含量，降低水分变化幅度，对20 cm以下土层水分变化影响较小。
在玉米生长前期，覆盖对提高夏玉米光合同化速率有明显的效果，其中以覆盖15000 kg/hm2的最明显，后期玉米冠层相对削减了覆盖的作用，并且小的降雨过程频繁，处理间的差异并不明显。稻草覆盖调节土壤温度和水分动态，对缓解玉米生长前期的高温干旱胁迫、提高叶片光合作用速率的效果非常明显。
通过太阳辐射参数，大气累积温度、>2m/s的平均风速等气象因子，联合作物株高及作物需水要求，可以对土壤水分含量的变化进行预测，这种预测是可行的。
我国红壤丘陵区双季稻田秸秆的年平均生产量可达15000 kg/hm2，扣除根茬直接还田之后，剩余秸秆资源可转移分配到旱地农作系统，发挥其培肥土壤和提高作物抗干旱胁迫的双层效应。就覆盖的降温保水效应来说，红壤旱地稻草施用15000 kg/hm2左右能达到较好的效果。
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| 关 键 字(英文)：Rice straw mulching; Upland red soil; Soil Temperature; Soil moisture; Photosynthesis efficiency; Maize |
| 摘 要(英文)：Available nutrients and organic matters were lacking in upland red soil, and the prolificacy of those fields are in a low levels. Moreover the seasonal drought in the red soil of the middle subtropical zone makes this situation worse, which becomes a restricted key to makes it hard to improve the productivity of the complex agro-ecosystem in this zone. One of the technical approaches of fertilizing the soil fast and releasing seasonal drought pressure is to transfer the redundant straw resources from the rice fields to the upland soil fields as organic matters and biological mulching materials. This experiment was carried out in the National Observation Station of Taoyuan Agro-ecology System, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, which to discuss the regulating differences of 4 straw mulching quantities to the upland red soil water and temperature. Some evidences is provided for further research of releasing the seasonal drought to the upland red soil and improved the efficiency of utilizing the straw resources. The main results showed as followed:
The climate which was characterized by that mean daily rainfall of 0~2.5 mm would be in 83.59 %, and the maximum rainfall level of as the quantities of >27.5mm would be in 2.95 %, and as rainfall increased, the numbers of rainy day decreased, while the mean temperature mainly between 25.0~32.5 ℃ as the typical seasonal drought in Taoyuan county frequently appeared from May to September. Furthermore, the extremely climate, July as a representative month, showed as that the frequency of rainfall quantities between 0~2.5 cm was 94.79 %, and that of the temperature higher than 30 ℃ was 84.38 %, was in lower frequency of 1.59 %.
Straw mulching could regulate the soil temperature effectively in cultivated horizon(0~20 cm), and significantly reduced the soil temperatures of 5 cm and 10 cm soil layers in high temperature stage(15pm) average to 2.7~4.1℃, but less significance in other layers. Mulching treatment of 15000 kg/hm2 reduced soil temperature more significant than the other treatments’ in time of high temperature. Straw mulching could be good for that reducing the soil temperature; decreasing the evaporation of soil water in daytime of high temperature and arid period.
Straw mulching effectively regulated the soil moisture in 0~5 cm soil layer. When the rice straw quantity was between 5000~10000 kg/hm2, the lowest soil moisture increased 3.3 %~3.6 % in arid time, while the quantity increased to 15000 kg/hm2, increased 6.1 %. The regulating mechanism of straw mulching was to weaken the heating effects of solar radiation, so that the evaporation potential reduced. The mulching effectiveness of increasing the soil moisture, minimizing their ranges was more effective in 0-20 cm soil layers than that under 20 cm soil layers.
There were significant effects of straw mulching releasing the pressure in the high temperature and arid periods. By regulating the soil temperature and stabilizing soil moisture status. In prophase of maize establishment, straw mulching could minimized the physiological damages of maize in upland red soil fields from that pressure, increased photosynthesis efficiency significantly in arid time, and the treatment of 15000 kg/hm2 was the best. These effects were less than that after the canopies were established and frequent rainy day.
It is feasible that a predicting model could be established through several factors such as parameters related to the solar radiation, air temperature accumulation, and >2m/s mean wind speed as input fields.
The productivity of rice straw in dual seasonal rice crop system could be 15000 kg/hm2 in the red soil of the middle subtropical zone. After the stubble return, it is good for fertilizing the barren upland soil and releasing the pressure from the high temperature and arid period that transferring the redundant straw to the upland fields’ crop system and mulching with them. Considering the acceptable effects on reducing soil temperature and protecting soil moisture, a dose less or more than 15000 kg/hm2 of the straw could be applied in the upland red soil area.
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