湘南丘陵红壤持水特征及水分状况的研究

在湘南丘陵坡地第四纪红壤上连续定位测定土壤含水量，研究了湘南丘陵红壤的周年土壤水分状况。采用压力膜技术，测定了实验区红壤的土壤水分特征曲线，分析了红壤的持水和保水特征。结果表明：湘南丘陵第四纪红壤，质地粘重，水稳性微团聚体发育，持水性强，释水力差；湘南丘陵红壤区，降水丰富且季节性变化大，土壤含水量季节性变化明显。坡地红壤的土壤水分状况可划分为四个土壤水分时期：土壤潮湿期（冬-春季）、土壤水分耗损期（夏初）、土壤干旱期（夏季-秋初）和土壤水分补充恢复期（秋末）。湘南坡地红壤普遍存在季节性土壤干旱，多表现为夏秋连旱，对作物生产危害很大。文中还提出了旱地农业土壤水分调控原则。

WATER RETENTION AND MOISTURE REGIME OF A SLOPING RED SOIL IN SOUTHERN HUNAN HILLY AREA

Field experiments were conducted on a hilly red soil at Qiyang Red Soil Experi mental Station of Chinese Academy of Agricultural Sciences (CAAS) during 1985.3-1986.3, to monitor soil water contents in the profites with or without a naturally recovering vegetation cover by using gypsum soil moisture sensors. The main physical properties in relation to soil water retention were also analysed. The results indicate that: (1) The red soil in the southern Hunan is heavy in texture, rich in microaggregates, and has large water retention and weak water releasing ability; (2) The preciptation in southern Hunan is abundant, but very erratic, inducing marked seasonal fluctuations in soil water content; (3) The red soil water regime found in the study could be divided into four distinct periods: moist period in spring and early summer, water depletion period in mid-summer, drought period in late summer and early fall, and water recharging period in late fall and winter; (4) There exists a severe soil drought occuring in late summer to early fall on the sloping red soil in southern Hunan. The findings in the study have implications to the development of upland agriculture and the improve ment of ecological conditions in southern Hunan hilly area.