| Crop production and sustainable agricultural development in the dryland farming area of central Gansu Province is restricted by less rainfall,serious soil erosion,and low utilization efficiency of water resources.Therefore,it is imperative to study the soil water dynamics in the root-soil interface,improve the water use efficiency and the ecological environment.In this paper,a long-term experiment made up of different tillage practices including(conventional tillage without mulch,conventional tillage with plastic film mulch,no tillage with straw removed,no tillage with plastic film mulch,no tillage with straw mulch,and conventional tillage with straw),were studied.The effects on the water dynamics in the root-soil interface and water use efficiency under the different tillage practices systems were evaluated.The main mechanism about water dynamics in the root-soil interface under different tillage practices under dynamic changes of soil water content,soil physical properties,the growth and spatial distribution of spring wheat and field pea roots,and the changes of root soil water potential gradient were explored.The main results are as follows:1.The tillage measure affected the amount of water in the root-soil interface.Compared with conventional tillage,no tillage with straw mulch and no tillage with mulch significantly increased the amount of water migration of root-soil interface of spring wheat and field pea.In the whole growth period of spring wheat,the water migration increased by 17.58%~74.48%,the total migration increased by 34.88% and43.30%;In the whole growth period of field pea,the water migration quantity increased by 11.93%~99.35%,the total migration quantity increased by 27.46% and35.66%.2.The appropriate tillage practices improved soil physical properties and increased soil moisture content.No tillage with straw mulch reduced soil bulk density in the 0-30 cm soil layer.Compared with conventional tillage,the soil bulk density decreased by 6.35%~8.06%,and 4.58%~8.13% in the spring wheat and field pea plots,respectively.The total porosity(0-30cm)of spring wheat and field pea plots increasedby 6.9%~11.7% and 4.6%~9.4%,respectively,compared with the conventional tillage.No tillage with straw mulch improved soil saturated hydraulic conductivity and soil infiltration,compared with conventional tillage;the soil saturated hydraulic conductivity increased by 27.88% and 38.81%.No tillage with straw mulch and no tillage with plastic mulch increased soil moisture at the different growth stage of spring wheat and field pea in the upper soil layers;reduced soil water evaporation,and promoted water absorption and utilization in deeper layers at the vigorous growth period of the crops.No tillage with plastic mulch restrained the evaporation of water at the surface layer at late growth stages,which had good preservation of soil moisture.The soil moisture content of spring wheat significant correlated with total root-soil moisture migration in different growth periods.3.Tillage measure affected the root characteristics of crops and improved the distribution of deeper roots.No tillage with straw mulch and no tillage with plastic mulch promoted the growth and improved the spatial distribution of root system significantly.To some extent,the root length of spring wheat and field pea was increased compared with conventional tillage;spring wheat was increased by35.8%~92.6%,and field pea was increased by 35.9%~121.9%.No tillage with straw mulch and no tillage with plastic mulch increased root surface area of spring wheat and field pea by 29.6%~162.5% and 44.1%~187.4%,respectively.The dry weight of root was increased by 10.1~47.1%(spring wheat)and 40.0%~191.7%(field pea).No tillage with straw mulch and no tillage with plastic mulch increased the distribution of root in 0-10 cm soil layer at the seedling stage of spring wheat and field pea.The maximum root population occurredat flowering stage,and the 10-30 cm soil layer.No tillage with straw mulch and no tillage with plastic mulch increased root distribution in the 10-30 cm soil layer at the same time,and improved the ratio of root in the deeper layers.Spring wheat and field pea root length,root surface area had significant positive correlation with total root-soil moisture migration.4.Tillage measures had effect on total migrat[]ion mainly by affecting the water potential gradient of root-soil interface of spring wheat and field pea at different growth stages.No tillage with straw mulch,respectively,increased the water potentialgradient from 2.23 MPa to 2.48 MPa at the tillering and flowering stages of spring wheat in the root-soil interface,compared with conventional tillage,it increased by54.75%~19.01%.The water potential gradient at the branching stage of field pea was the highest with 0.29 MPa under no tillage with plastic mulch;the flowering and podding stage was the highest with 0.49 MPa under no tillage with straw mulch,compared with conventional tillage,it increased by 96.59%~354.08%.The water potential gradient of these growth periods was closely related to the total water transport at the root-soil interface,and had a significant positive correlation..5.With respect to the grain yield and water use efficiency,no tillage with straw mulch and no tillage with plastic mulch significantly increased crop grain yield and water use efficiency;compared with conventional tillage,spring wheat yield increased by 30.0% and 23.4%,water use efficiency increased by 20.4% and 14.8%;field pea yield increased by 38.7% and 27.9%,water use efficiency increased by 29.7% and16.2%.The crop yield and water use efficiency with the total root-soil moisture migration had a significant correlation.Therefore,appropriate conservation practices were found to improved soil physical properties and improved the shallow soil moisture content,promote crop root growth,build a reasonable root distribution,and affected soil water supply and root water absorption.The soil water potential gradient changes at crop growth period in root-soil surface.This promoted water transport processes in soil-root surface,increase the amount of water transport,which is conducive to improve crop yields and achieve efficient use of water. |
PDF Full Text Request