Study on the relationship between fertilization,yield and soil desiccation in the Loess Plateau region

Fertilization is a key measure to get high yield in the cropland,and it can increase the consumption of water in the deep soil.The water concentrations were determined under different fertilization conditions in the vertical soil profiles before wheat seeding in 2007.The results showed that the changes of water concentration in the 0～100 cm soil layer were slight on different fertilization conditions,and the range of moisture storage was 14.7 mm.The changes of moisture storage were very great in the 100～300 cm soil layer,and the range of moisture storage was 130.1 mm.The phenomenon of soil desiccation was observed in the 100～260 cm soil layer and the degree of soil desiccation increased with the addition of fertilizer application rates.However,the water concentration in soil rose again below 260 cm depth in the vertical soil profile.The water concentration in the dried soil layer was the highest in plots where N and P2O5 were applied together,which was higher than the water concentration in plots where N or P was applied alone.The water concentration was the lowest in the dried soil layer in unfertilizered soil.But,the differences of water concentration were not significant between CK and P treatments in the dried soil layer.In the term of yield,the yield of winter wheat was significantly negative correlated to the water concentration of dried layer as line type.There was no dry layer in deep soil when the yield of winter wheat was less than 1 354 kg/hm2,and the degree of desiccation in deep soil was slight when the yield of winter wheat was among 1 355 to 2 406 kg/hm2,and the degree of desiccation in deep soil was moderate when the yield of winter wheat was among 2 407 to 3 458 kg/hm2.