The Effect of Gravel-sand Mulched Field Degradating on Soil Temperature and Evaporation

The soil content in the mulched gravel-sand layer increased with the elogation of cultivated years of field.There were six treatments of soil content proportion to gravel sand in the simulating experiment on effect of gravel-sand muched field degradation to soil temperature and evaporation:t1-5%，t2-10%，T3-20%，T4-25%，T5-30%,，T6-40%；two checks：CK1pure gravel-sand mulched layer and CK2,non-muched layer.

The results show that soil temperature in 5cm and 10cm depths at 8:00 and 20:00 decrease with the aggravation of mulched layer degrading,and appear a transversely placed 〝S〞shape at 14:00.In comparsion with CK1,the function of delaying the daily maximum ground temperature weaken as the degradation level increase,companying with daily accumulated temperature decreasing,daily temperature range increasing,and evaporation intensifying.The evaporation rate of CK2 is three as that of CK1,but that of treatment T5 or T6 is two times.