Soil Water Balance Measurement in Field Scale
摘要
A 5－year experiment on water balance has been conducted in a flat rainfed wheat field with an area of 66×100m^2 in Fengqiu,Henan Province in China.Based on the analysis of semi-variance functions conducted with soil moisture samples taken from 77 nodes of a 10×10m^2 grid,the soil moisture distribution in the field was structural with a temporal stability.According to the autocorrelation range of the semi-variance function,6 sites were selected for the determination of soil water conditions.The characteristic of probability density function of the differences of water storage in two sets of measurements showed that the distribution of these variables in the field was a normal one.The error in the estimation of the average of 5 random samples was 14% (α=0.10),and the errors of water consumption by wheat during the experiments were estimated to be 6-13%.Sime the experimental field was large enough to avoid any edge effect,the results obtained should tally with the actual situation.Yet the soil system was heterogeneous,so we must follow the principles of statistics and geostatistics when describing the system's status with the average of the samples.