Experimental Study On Effects Of Conservation Tillage On Soil Moisture

Water is the main limiting factor of agriculture in (semi-) arid region. And the efficient utilization of water resources is an agricultural sustainable development direction in this region. In this paper, I choose the Lou soil of Guanzhong Region as the research object. The impact of wind, straw-mulching and irrigation quotas are set up as treatment factors and the effect of these factors were analyzed, while accumulative soil water evaporation was established with various factors. Our research also put forward on the anti-erosion effects under different crop stubble. The main results are as follows:(1) The wind speed and straw-mulching can make an obvious effect on soil water evaporation. When the water content was 70% of the field moisture capacity and straw- mulching (0, 4120 kg/hm2) were the same, the soil water evaporation with wind speed 1.5m/s was higher than other treatments significantly; when the water content was higher than 55% of the field moisture capacity, the cumulative soil water evaporation with no mulching and wind speed 1.5m/s was far more than that of other treatments.(2) Under enough moisture treatment, soil water evaporation with 6h winding is higher than the control treatment, while the soil water evaporation with straw-mulching (4120, 8240 kg/hm2) was no significant change. When there is no straw- mulching and enough moisture, the cumulative soil water evaporation with 6h winding is higher than the control treatment and 3h winding significantly.(3) Under different irrigation quotas, soil water evaporation with enough moisture and no straw-mulching is a higher increase, but soil water evaporation with straw-mulching is a gradual increase. The relative cumulative evaporation decreased gradually with the increase of irrigation quotas, and it means that the straw-mulching has better moisture retention with the increase of soil moisture.(4) Under different straw-mulching, wind and irrigation quotas, there lies an exponential relationship between the cumulative soil water evaporation (EI) and time (t), and parameters (a and b) have clear differences among the treatments of straw-mulching levels and irrigation quotas.(5) We analyzed the conservation tillage to reduce the range of the wind speed range by changing the central wind speed, as well as the height of crop stubble. The experimental results show that: crop stubble can reduce the wind speed by building protection zone, as the wind speed increased, the capacity of the crop stubble to reduce the wind speed will decrease. From the vertical direction along the surface, with the distance further, the rate on reduce of the wind speed become lower. The maximum reduce rate of weed speed was 25% in 100 cm distance, and there was less protection in 200 cm distance. The 10cm crop stubble treatment has less protection. The have significant difference with different horizontal direction. The height of crop stubble between 15cm to 25cm, which can paly an ideal protective role in soil wind erosion.