Effects Of Different Approaches Of Corn Straw Mulchingon Soil Evaporation Evapotranspiration And On Soil Temperature Of Winter Wheat Field

The straw mulching is a highly effective and water-saving technology of cultivation, which has distinctive function to change the quality of soil surface and energy balance, and to regulate soil temperature and soil moisture, fulfilling the purpose of improving economic yield and the rate of water utilization, and reducing water evaporation. This article mainly studied the effects of different corn straw mulching approaches on soil evaporation, evapotranspiration and soil temperature of winter wheat field. The results will be able to offer the theoretic basis to prevent soil evaporation and improve water use efficiency in the Loess plateau, especially in Guanzhong area.The experiments were conducted on No. 1 Station in Northwest University of Agriculture and Forestry. The crop used in the experiment is Xi-nong 979 (winter wheat). The field experiment comprises three treatments: heavy corn straw mulching:6000 kg; light corn straw mulching:3000 kg; non corn straw mulching:0 kg. Some main conclusions of the study on effects of different corn straw mulching approaches on soil evaporation, evapotranspiration and on soil temperature of winter wheat field can be summarized as follows:1.The effect on inhibition efficiency of soil evaporation under mulching treatments is distinctive, among which the effect on heavy mulching is the best. It is in the middle ten days of the first ten days of October 2005, the last ten-day of March 2006 and the first ten days of June 2006 that daily variations of soil evaporation of winter wheat are more than other stages; whereas, it is in December2005, January 2006 and February 2006 they are less than other stages. The maximum of soil evaporation in the whole day is between 12p.m. to 2p.m..2.The effect of inhibition efficiency of soil evaporation under much mulching is the best. The inhibition efficiency of soil evaporation between heavy mulching treatment and non-mulching from seeding to tilling and from elongation to tassel is higher than other stages. The inhibition efficiencies of soil evaporation are as follows: 64.32% and 58.22%. The effect on inhibition efficiency of soil evaporation under between mulching treatment and non-mulching is: from seeding to tilling is the best and from overwinter to recovering is lower than other stages. 3.The total water demands of winter wheat during all growth stages under heavy mulching, light mulching and non-mulching are 449.92 mm, 477.11 mm and 519.35 mm respectively. and at the same time, the percentages of water demand between elongation to maturity under non-mulching, light mulching and heavy mulching are 73.42%, 76.01% and 78.43%. The ratios(E/ET) of soil evaporation to evapotranspiration in the whole growth stage under heavy mulching, light mulching and non-mulching are 19.63%, 26.41% and 32.91% apart, and the treatment of heavy mulching decreases 40.35% than the treatment of non-mulching.4.The relationship between E/ET and LAI can be shown as a form of function, and the formulas of relationship are as follows: Non- mulching E/ET=0.7915LAI-1.0971 R2=0.9552 Light mulching E/ET=0.7536LAI-1.2054 R2=0.9379 Heavy mulching E/ET=0.7041LAI-1.3899 R2=0.94655.There is no evident effect on ground temperature under mulching in Oct and Nor under mulching; mulching treatment can raise ground temperature in December, January and February; the ground temperature of mulching treatment during recovering stage is lower than no mulching treatment, which has obvious effect on decreasing temperature in summer. At the depth of 5cm, the highest day soil temperature appears at 3p.m., and the appearance of the highest day soil temperature at the depth of 10 cm postpones 1 to 2 hours than that of 5cm. It can be found that the soil temperature at 10 cm depth changes more mildly than that of 5cm, which demonstrates that the deeper soil reacts to changes sluggishly and can be slightly influenced by outer circumstances. The adjustment ability of mulching to ground temperature becomes feeblish when LAI is high. The sequence of soil total accumulating temperature of 0cm, 5cm and 10cm is: non- mulching>light mulching>heavy mulching.6.The sequence of yield and WUE under heavy mulching, light mulching and non- mulching is: heavy mulching> light mulching> non-mulching. Compared the yields of treatments of heavy mulching and light mulching with non-mulching treatment, the yields increase 56.6 kg and 40.9 kg respectively. Compared the WUEs of treatments of heavy mulching and light mulching with non- mulching treatment, there are 16.36% and 9.46% increases respectively.