Effects Of Different Mulching Measures On Soil Moisture And Growth Process Of Winter Wheat

The surface of the straw mulching,plastic mulching or sand-gravel mulching,not only can effectively preserve soil moisture,inhibit soil evaporation,raising temperature,control salinity,reduce soil erosion and improve crop quality.To investigate the growth pattern of winter wheat under different mulching conditions and study the applicability of various evapotranspiration estimation methods.the first two-year experiments were conducted in 24soil containers which were put under a rain shelter at four sand-gravel mulching amounts?0,23,46 and 69 kg/m2?.The soil water dynamic change was observed by a micro-lysimeter which contained a high-precision weighing transducer connected with a data logger.For the no-wheat and with-wheat conditions,when the sand-gravel mulch amounts increased from 0to 69 kg/m2,the treatments were named NW0,NW23,NW46,NW69 and W0,W23,W46,W69,respectively.In addition,the experiments which were put under a rain shelter at different mulching.The mulching treatments are corn stalk?The lengths are 1mm,1cm,5cm and 10cm,respectively?,black plastic?the thickness is 0.006mm?,white plastic?the thickness is 0.006mm?and sand-gravel mulching?the thickness is 4cm?,respectively.Using Penman-Monteith model,single crop coefficient approach,dual crop coefficient approach and R-K model to estimate winter wheat ET_c.Improvements and corrections to the dual crop coefficient approach and R-K model based on the Winter Wheat measured ET_c of the sand-gravel mulching and the different mulching in two years.The following main conclusions:?1?Soil water storage increased with the increase of sand-gravel mulch amounts,the monthly soil evaporation,monthly evapotranspiration,cumulative soil evaporation and cumulative evapotranspiration decreased with the increase of sand-gravel mulch amounts.Soil water storages under the with-wheat conditions were lower than values of the no-wheat conditions.The monthly soil evaporation,monthly evapotranspiration,cumulative soil evaporation and cumulative evapotranspiration under the with-wheat conditions were a little bit higher than the values under the no-wheat conditions,especially at the later Winter Wheat growth stages..Under the no-wheat conditions,in the first and second years,the total evaporations of the three coverage treatments were less than the non-mulching treatment from11.6%to 18.1%and 28.5%to 47.5%,respectively.Under the with-wheat conditions,in the first and second years,the total evapotranspiration of the three coverage treatments was less than the non-mulching treatment from 2.2%to 3.7%and 0.7%to 3.6%,respectively.?2?All of the plant heights,leaf area indexes,productive panicle number,yields and water use efficiencies of the Winter Wheat increased with the increase of sand-gravel mulching amounts.In the first and second years,the maximum plant height of the three coverage treatments was less than the non-mulching treatment from 5.3%to 17.2%and 1.0%to 5.8%,respectively.The maximum leaf area index of the three coverage treatments was less than the non-mulching treatment from 17.9%to 74.6%and 7.9%to 28.2%,respectively.The yields of the three coverage treatments were less than the non-mulching treatment from 6.6%to 14.2%and 12.6%to 44.6%,respectively.The water use efficiency of the three coverage treatments were less than the non-mulching treatment from 8.0%to 16.1%and 15.6%to67.1%,respectively.From the results,the most suitable sand-gravel mulching amount was 69kg/m2,the sand-gravel mulch can effectively prevent soil water evaporation,the increased soil water storage at early crop growth stages could be utilized for later stages of crop growth,which contributes much for improving crop yields and water use efficiency.?3?A good linear relationship was obtained between single crop coefficient and sand-gravel mulching amounts at the three different growth stages of Winter Wheat.The equation can better simulate ET_c of Winter Wheat under the sand-gravel mulching conditions.The ranges of coefficient of determination?R²?between measured ET_c and ET_cS?ET_c estimated by the single crop coefficient method?were 0.77⁰.80?in the first year?and0.73⁰.76?in the second year?,respectively;There was a good linear relationship between dual crop coefficient and sand-gravel mulching amounts.This relationship was introduced to modify the dual crop coefficient under sand-gravel mulching conditions.The modified dual crop coefficient approach can also better simulate ET_c of Winter Wheat under different sand-gravel mulching amounts compared to the measured ET_c.The ranges of R² between the measured ET_c andthe simulated ET_c were 0.83-0.88?in the first year?and 0.87⁰.92?in the second year?,respectively;The single crop coefficient approach simulated average evapotranspiration better than the dual crop coefficient approach,although the dual crop coefficient approach was more accurate on daily ET_c.In conclusion,the single and dual crop coefficient approaches were still applicable for estimating the ET_c of Winter Wheat under the sand-gravel mulching conditions,but it needed revision using the measured data.?4?Comparison between mulching processing and non mulching processing in two years,effectively inhibiting the soil moisture evaporation and increase soil water storage.The surface mulch can significantly increase the effective panicle number,grain weight,yields and water use efficiency of the Winter Wheat.Under mulching condition,yield and yield components of winter wheat increased to different extent.Black and white plastic mulching f is better than straw mulching and sand-gravel mulching.Surface mulching can effectively increase soil water storage in the early stage of Winter Wheat growth and make significant contributions to improving winter wheat yield and water use efficiency.?5?The R² of the empirical coefficient x and y obtained from the measured values are not less than 0.706,indicating that x and y can be used for estimating the evapotranspiration of Winter Wheat under different mulching measures.80 days after sowing,the estimated value of ET_cR-KR-K is quite different from that of ET_cM.80-240 days after sowing,ET_cR-KR-K can estimate ET_cMM well.R² is greater than 0.771,NSE is in the range of 0-1,D is greater than 0.774.R-K model can be used to estimate the evapotranspiration of Winter Wheat different mulching measures.?6?Estimation of Winter Wheat ET_cDD by the improved dual crop coefficient approach in two years of has the same variation with ET_{c M}.The changing trend of the crop transpiration T_r and soil evaporation E_s under different mulching conditions is same.The evapotranspiration of the Winter Wheat was dominated by crop transpiration,and the soil evaporation was supplemented.In two years,the R² of ET_cDD under different mulching measures were all greater than 0.883,RMSE was less than 0.511,NSE was close to 1,D was greater than 0.911.Indicating the ET_cDD could well describe daily variation of ET_cM,and the estimation result was accurate and credible.Therefore,the improved dual crop coefficient approach can accurately estimate and distinguish evapotranspiration of the Winter Wheat under different mulching measures.on the whole,the improved dual crop coefficient approach in estimate and distinguish evapotranspiration under different mulching measures has strong applicability.Provide the basis for revealing the evapotranspiration variation of the Winter Wheat under different mulching measures.