红壤丘陵区油茶林需水关键期土壤水分变化特征研究

Characteristics of Water Content in Red Soil Profile during the Key Water Requirement Period of the Oil Camellia Trees in Hilly Region

基于南方红壤丘陵区油茶树具有“七月干果，八月干油”的敏感需水期特征，本试验采用传统钻土取样——烘干法，选择在典型油茶林地连续定位抽样监测7—9月份油茶林地需水关键期的土壤含水量，分析了油茶林地土壤水分动态变化特征及其水分有效性。结果表明：土层0～10cm范围土壤含水量受大气气候及灌溉等因素影响强烈，波动幅度比较大，较长时间含水量低于植物凋萎点以下；油茶树吸水根系分布密集的土层30～100cm范围内土壤平均含水量相对高，土壤含水量大多数高于凋萎点且波动幅度小，仍随着季节性缓慢波动；但有个别时段深层土壤含水量低于凋萎点，油茶树可能处于亏水胁迫期。这有可能导致油茶挂果率、出油率等产量降低。

Based on the saying ＂the fruit dried in July and the oil dried in August＂, the oil camellia trees have the principle characteristics of the sensitive water required period in the red soil hilly south region. Soil water content in the typical oil camellia trees land were monitored continuously during the period from July to September by the use of the traditional method of earth-drilling, sampling and drying in this experiment. And the dynamic characteristics and effectiveness of soil water were investigated during the critical periods. The results indicated that soil water contents from the surface to 10cm soil depths were highly affected by such factors as the climate and irrigation, resulting in a big fluctuation and water contents less than plant wilting point in a longer time. Average wa- ter contents from 30cm to100cm soil depths with the dense distribution of water-absorbing roots of oil camellia trees were relatively high, beyond the wilting point and with small fluctuation, still fluctuating slowly with seasons. However, water content in deep soil depths during individual intervals was lower than the wilting point. That shows that the oil camellia trees were probably in the period of water deficit stress, which was likely to reduce fruit output and oil extraction.