Effects Of Different Covering Cultivation Modes On Soil Water And Heat Dynamic Change And Wheat Root Growth

A widespread measure for soil water storage in the semi-arid region of China is theridge-furrow planting system combined with mulching. However, it is not well understood,how and to which extent the water and heat flow regime in this manmade field is herebymodified. In this study, we analyzed the effects of mulching of crop residues and plastic filmon coupled soil water and heat flows in the dry highland of Loess Plateau. Using thecontinuous monitoring data of profiled soil moisture and temperature, as well as thedetermination of soil properties in the laboratory, the differences in soil water and heatdynamics under crop residues in the furrow and plastic film in the ridge were described, andfurther verified by a physical-based HYDRUS model. To further estimate the actualevapotranspiration (ET) and also water use efficiency. At the same time, we used the monitorimages in situ with the help of CI-600root system, in order to provide theoretical basis forecological research of winter wheat roots and improve dryland wheat production potential.The experiment consisted of four treatments: conventional fertilization (CK), recommendedfertilization (JN), recommended fertilization+straw mulching (JN+S), recommendedfertilization+plastic film mulching on soil ridges and straw mulching in furrows(JN+PFM+S):(1) The results showed that there are significantly different in soil moisture contentsamong all the treatments, and soil water content of different soil layers fluctuated with rainfalland was influenced by different covering modes. Among the four treatments, JN+PFM+Streatment had the highest water storage both in wet and dry years;(2) Soil daily mean temperature differences were very small among all the treatments. Inthe seeding to over winter stage, soil daily mean temperature at5cm soil layer: CK> JN>JN+S> JN+PFM+S, and in the reviving to maturity stage, soil daily mean temperature at5cm soil layer: CK> JN> JN+S> JN+PFM+S. However, the changes of intraday temperaturewere significantly different, and diurnal temperature range of different treatments were JN>JN+S> JN+PFM+S;(3) In the wet year, compared with CK treatment, the yield of JN、JN+S�'�JN+PFM+Streatments respectively increased8.86%、8.60%and5.25%, and water use efficiency respectively increased6.93%、11.23%and42.06%. In the dry year, JN+S�'�JN+PFM+Streatments had a falling trend in crop yields, but JN+PFM+S treatment still had the mostwater use efficiency;(4) HYDRUS model is capable of simulating soil water content dynamics well, so as to itcan be used for analyzing soil water and heat processes between different covering modes.Especially, HYDRUS-2D model can successfully predict the lateral water and heat flowbetween ridge and furrow positions, mirrored the strong and complicated interactions ofcoupled soil water and heat in the ridge-furrow planting system combined with mulching;(5) Winter wheat root length and root tips number during the observation period had“rotating S by90degree” change trend, and in the heading stage, root growth was the mostvigorous. However, there is no significant difference in the average root diameter, and all thetreatments were between0.15to0.20mm. Diameter classes of the live root length and roottips number of winter wheat under different covering modes were basically the same. Withthe increase of diameter class, the live root length and root tips number increased rapidly andthen gradually reduced. The largest proportion of the live root length and root tips numberwith diameter between0.1mm and0.2mm were55.5%~89.5%and41.9%~89.5%,respectively;(6) Root length density was the least in the over winter stage, then increased rapidlyafter the reviving stage and reached the maximum in the heading stage. During theobservation period, the root length density with diameter between0.1mm and0.2mm wasthe largest, accounting for52.7%~52.7%of total root length density. And the root lengthdensity with diameter greater than0.4mm was minimal. In the reviving to jointing stage, thegrowth of winter wheat root was positive, but in the heading to filling stage, the growth ofwinter wheat root was negative.