[Change characteristics of soil moisture and nutrients in rain-fed winter wheat field under different fertilization modes in Southern Shanxi of China during summer fallow period].

In 2009-2011, a field experiment was conducted in a rain-fed winter wheat field in Southern Shanxi of China to study the effects of different fertilization modes on the change characteristics of soil moisture and nitrate-N contents in 0-200 cm layer and of soil available phosphorus (Oslen-P) and potassium contents in 0-40 cm layer during summer fallow period (from June to September). Three fertilization modes were installed, i. e., conventional fertilization (CF), recommended fertilization (RF), and ridge film furrow planting (RFFP) combined with straw mulch. The results showed that the rainfall in summer fallow period could complement the consumed water in 0-200 cm soil layer in dryland wheat field throughout the growth season, and more than 94% of the water storage was in 0-140 cm soil layer, with the fallow efficiency ranged from 6% to 27%. The rainfall in summer fallow period caused the soil nitrate-N moving downward. 357-400 mm rainfall could make the soil nitrate-N leaching down to 100 cm soil layer, with the peak in 20-40 cm soil layer. Straw mulching or plastic film with straw mulch in summer fallow period could effectively increase the Oslen-P and available K contents in 0-40 cm soil layer, and the accumulative increment in three summer fallow periods was 16-45% and 36-49%, respectively. Among the three modes, the binary coverage mode of RFFP plus furrow straw mulching had the best effect in maintaining soil water and fertility. The accumulative water storage and mineral N in 0-200 cm soil layer in three summer fallow periods were up to 215 mm and 90 kg x hm(-2), and the accumulative Oslen-P and available K contents in plough layer were increased by 2.7 mg x kg(-1) and 83 mg x kg(-1), respectively, being significantly higher than those in treatments CF and RF. There were no significant differences in the change characteristics in the soil moisture and nutrients between treatments CF and RF.