作　　者： ; (杨青）; (王毅勇）;

机构地区： 华南农业大学

出　　处： 《中山大学学报（自然科学版）》 2000年第S2期262-266,共5页

摘　　要： 中子法与烘干法相结合定期定位观测发现，三江平原低湿地旱田土壤的水分分布具有明显的垂直差异性，呈“Ｓ”型分布，大约在 ４０－７０ｃｍ土层存在一个明显的少水层， ８０－１００ｃｍ以上土壤含水率的垂直梯度较大，再往深层土壤含水率缓慢下降，差异微弱．土壤含水率水平空间异质性与地块的海拔高度、相对地势、耕种类型等因素有密切关系．地块内微地貌差异对土壤水分含量影响显著．定位动态观测结果显示浅层土壤水分散失较快，散失量随深度增加而减小的短期动态变化特点，土壤水分含量的波动幅度随土层的加深而减小．农田生态系统土壤的水分条件对气候的依赖性十分严重，其动态变化与降水和蒸发具有高度相关性． The study demonstrate that "Neutron Methed" is an objective, accurate and convenient away to measure soil moisture content below 40cm. Unless special screen is equipped, the result of the measurement above 40cm in soil is unreliable. Comprehensive measurement on soil moisture percentage with the methods of "Neutron Method" and "Drying over.Heat Method" shows that the verticaldistribu tion curve of soil moisture percentage is a "s" -shaped curve. There is an obviously drier layer of soil between 40cm and 70 cm. The vertical gradient of soil moisture percentage between 80cm and 100cm is relatively high and, in deeper layers, the soil moisture content declines slowly along with the increase of depth. The horizontal distribution of soil moisture percentage is highly related with topgraph ical situahons and farming types. At the same time, the topographical situation plays an important rile in effecting the soil moisture percentage within a farmland. Measurement at fixed positions shows that the fluctuating range and speed of surface layers soil moisture is bigger and higher than deeper layers. In addition, the dynamic state of the soil moisture percentage is closely related to rainfall and evapo transpiration. In Conclusion, the situation of soil moisture content is an important factor to the productvity of crops in Sanjiang Plain dry farmlands which almost completely depends on the weather.

关 键 词： 三江平原 旱田 土壤含水率 中子法 动态变化

领　　域： [自然科学总论]