Abstract: The advantages and disadvantages of traditional water balance method were discussed. The principle and modeling method of balance diagnostic model of soil moisture based on initial soil water content, time-period precipitation and time-period “evapotranspiration, leakage and runoff” were emphatically introduced. The model was established by the data of 87 monitoring sites in 23 counties in 7 provinces during 2012-2014, and validated by the data of 2015. The results showed that the balance diagnostic model had only about 50% qualification rate in diagnosis and prediction. The main reason for the low qualification rate was the small amount of data based on the subsection prediction of the sum of precipitation and soil water content, which led to an inadequate prerequirement for parameter determination. The balance diagnostic model established as a soil moisture diagnostic model needs to be further studied.

Key words: yam, leguminous crop, soil biological property, soil comprehensive fertility., soil chemical property, intercropping