Effect Of Soil Water Repellency On Evapotranspiration And Grwoth Of Summer Maize

Soil water repellency(SWR)is a common soil physical property,which has a direct or potential negative impact on the ecosystem,and has an impact on the crop growth process and the final yield and soil water movement process,which is not conducive to sustainable development of the environment.Studying the impact of SWR on crops can provide some references for optimizing irrigation technology,improving water resources utilization efficiency,and preventing land degradation in arid and semi-arid areas where rainfall is scarce.In this paper,the effects of a certain degree of water repellent soil on the growth of crop and the surface of evapotranspiration were tested.The slightly water repellent soil with different WDPT values was tested.With the hydrophilic soil as a control,the germination rate of different species of plants,the growth process of summer maize under the canopy and the soil under the canopy of SWR were discussed.The main results of water dynamic change and evapotranspiration of summer maize are:(1)SWR has an effect on the germination time of plants.The germination time of flower and vegetable seed in the hydrophilic soil is relatively early,but it is greatly influenced by soil water repellency,and the time of germination is late in the soil with larger WDPT value.The germination time is relatively late in the soil with large WDPT value;the crop plants are rejected by the soil.When the water-borne effects were less than the other three plant types,they germinated in different WDPT values and the germination time was relatively early.The initial germination time of the tree-like plants seeds was not significantly affected by soil water repellency.In addition,SWR has a significant effect on the germination rate of plants.The germination rate of seeds of vegetables,flowers,trees,and crops in hydrophilic soil was higher than that in the soil with slightly water repellent treatment with WDPT values of 7s,9s,12s,and 16s.The overall water repellency was found.The results showed that the stronger the soil water repellency,the lower the germination rate of plant seeds.(2)SWR has a great influence on soil moisture changes.The water repellency of the soil changes with the sowing time and the number of irrigations.The WDPT value increases significantly with the increase of the sowing time,and reaches the peak value before the next irrigation.After the first two irrigations,the CK treatment of hydrophilic soil also showed a certain degree of water repellency.The WDPT value reached a maximum of 31s and showed a slight water repellency.The maximum WDPT values of the four water repellent treatments after the first irrigation reached 2000,2200,2300 and 2355s,respectively,showing a severe water repellency,after the final irrigation of the final corn WDPT value after the final corn harvest WR4 after irrigation and crop growth WDPT value is still the largest.The WDPT value and volumetric moisture content?_v of each treated soil were affected by irrigation.For the CK treatment,the WDPT value of the soil changed only after the first two irrigations,and the maximum value was 31 s.For the water repellent treatment,the WDPT value increased by more than 5 s.The WDPT value showed a negative correlation with?_v.(3)It has been found through experiments that multiple irrigations will reduce the degree of soil water repellency,which is helpful for soil restoration and plant growth.However,this process is long and requires long-term accumulation.In addition,the relationship between the soil surface WDPT values and?_v also suggests that similar changes may exist between deeper soils,suggesting that during the growth of summer maize,the soil water repellency may also be related to changes in soil moisture content.It will increase to more lasting conditions.SWR can inhibit deep soil evaporation.Comparing daily evapotranspiration,cumulative evapotranspiration,?_v,and total soil water storage,it was found that the evapotranspiration of the water repellent treatment was small,but the?_v and total soil water storage were large,and the water-saving effect was significantly better than that of the CK treatment.(4)SWR has a delayed effect on the growth period of summer maize.The stronger the SWR,the slower the growth rate of summer corn.Compared with CK treatment,the plant height,stem diameter,and leaf area index of summer corn showed a stronger SWR and a smaller physiological index.With the increase of SWR,the dry matter quality of summer maize decreased significantly and the yield decreased in turn,and the water use efficiency and water consumption also decreased in turn.(5)The evapotranspiration of summer corn in different treatments can be accurately calculated based on the single crop coefficient method recommended by FAO-56 and the dual crop coefficient method.The calculated value and measured value of the single crop coefficient method during the summer corn growth period after correction were in line with each other.In the initial stage of growth,the relative deviation of each treatment was small,and the relative deviation increased during the development period,mid growth period and late period.Introducing SWR into the traditional dual crop coefficient method can make a reasonable estimation of the evapotranspiration of summer corn in different growth stages.After the correction,the calculated values of the two-crop coefficient method are similar to the measured values.The relative deviation between the calculated and measured values of the two-crop coefficient method for each treatment in the two years is relatively small;during the development period,the relative deviation of 2016 is less than 2017.In the middle and late growth stages,the relative deviations of the two years are relatively large.The modified single and dual crop coefficient method is also applicable to crops in soils with a certain degree of water repellency,but the comparison shows that the CK processing results are the most accurate,indicating that the presence of SWR causes certain deviations in the calculation results.After comprehensive comparison,it was found that the dual crop coefficient method can more accurately estimate the evapotranspiration of summer corn in different treatments.