| Weibei highland is an important base for winter wheat production in Shaanxi province,where is the typical rainfed agricultural region, with surface and underground water resourcescarcity and low precipitation use efficiency. Meanwhile, the soil fertility is low, whichrestricts the further improving of winter wheat yield. Therefore, with the aim of seeking ansuitable cultivation pattern for winter wheat to guarantee a stable and high yield, improve soilfertility, maintain fertility level and sustainable development of local agriculture, a locatedfield experiment for winter wheat was carried out in Changwu County, Weibei Highland ofShannxi province from2008to2010. The experiment consisted of five treatments:(1) thecontrol treatment (CK),(2) manure application (MA),(3) straw mulch (SM), and twofurrow-ridge cultivations,(4) plastic film mulched the ridges (PM),(5) plastic mulched onsoil ridge+straw mulch (PM+S). The experiment mainly studied the soil moisture of0-200cm, the dynamic variation of topsoil temperature, yield components and water use efficiency,and the soil carbon pool and soil nutrient conditions after winter wheat harvest of the lastseason. Results obtained were as follows:(1) Dynamic variation of soil moisture and topsoil temperature during the winter wheatgrowing season was studied to explore the effect of soil hydro-thermal conditions underplastic mulch ridges cultivation patterns on winter wheat production. Results showed that,compared to the CK treatment, plastic mulch ridges cultivation increased the soil moisture of0-100cm by15%. With soil depth increase, the PM+S treatment maintain more soil moisturethan the PM treatment, and the SM treatment was lower than the PM+S and PM treatments.During the growing stage of2008-2009, the soil moisture in the PM treatment of tablelandand PM+S treatment of terrace was21.0%and21.5%higher than the CK. In the2009-2010,the PM and PM+S treatment in the tableland increased the soil moisture by28.0%and31.0%,respectively. While, in the terrace was8.03%and20.9%. Under suitable fertility condition,more soil water storage could increase the grain yield of winter wheat in this area, which wasperfectly sealed by the wheat grain yield of2008-2009and2009-2010. And the water useefficiency in the PM and PM+S treatments were also higher. Compared to the CK treatment, PM and PM+S increased the grain yield by16.6%,18.4%in the tableland, and97.2%,96.5%in the terrace of2008-2009, respectively. Besides, plastic mulched on the ridges couldeffectively regulate the topsoil temperature. According to daily range of plough layertemperature, it showed that PM and PM+S dramatically improved the soil temperature underlow air temperature, meanwhile, decreased soil temperature under high air temperature. Thedaily range of surface soil temperature in PM+S treatment was significantly lower than othertreatments, and compared to CK treatment, four daily ranges decreased by69.3%,62.1%,71.9%and64.2%, respectively. That was benefit for the growth of root system, reduction ofsoil water evaporation, and increase of the grain yield. Because only half area was used toplant winter wheat in the ridge-furrow cultivation pattern, so the spike numbers per1m2waslower than other treatments. However, the grain per spike and the1000grain weight wereboth maximum. So the grain yield of winter wheat in PM and PM+S treatments wereobviously higher than the CK treatment. Above all, the ridge-furrow cultivation couldeffectively improve soil moisture of growing stage of winter wheat and water use efficiency,regulate the soil temperature of plough soil, and then increase the grain yield of winter wheatin Weibei highland. So, it was a suitable cultivation pattern for winter wheat production inthis area.(2) Effects of different mulch patterns on soil carbon pool and correlation with the soilnutrient was studied to verify whether the soil labile organic carbon (LOC) and carbonmanagement index (CMI) could be regarded as a criteria to evaluate the soil fertility. So, thefollowing results was analysed only for the topsoil. Results showed, different cultivationpatterns had significant effects on topsoil carbon pool, while less significant in the20-40cmsoil depth. The SM and MA treatments improved the soil total organic carbon (TOC), LOCand CMI, whereas, the plastic mulched ridges cultivation resulted in decrease of TOC andLOC. Total organic carbon: compared to the CK treatment, the PM and PM+S treatmentsdecreased it by11.4%and3.3%, and MA and SM treatments increased by6.4%and7.8%,respectively; Labile organic carbon: MA and SM treatments increased LOC by40.6%and27.1%. The PM+S treatment increased LOC by56.3%compared to the PM treatment. Carbonpool management index: because of the TOC and LOC in the manure application and strawmulch treatments were higher than other treatments, so was the CMI. Plastic mulch resulted inthe significant decrease in soil CMI, whereas, plastic mulch combined with straw mulchtreatment effectively relieved this situation, so as to maintain and gradually improve the localsoil fertility levels. Otherwise, no obvious difference was showed in no-labile organic carbonby straw mulch, plastic mulch and manure application. Total nitrogen and readily availablepotassium had significant relation with CMI (P<0.05), but no significant relation with TOC. Therefore, the soil LOC and CMI could be used as the indices to assess the ecological effectsof plastic mulch, straw mulch and manure application. At the same time, we should noticethat the plastic film mulched the ridges cultivation must be combined with straw mulch,manure application or other ways of improving the soil fertility, to guarantee the sustainabledevelopment of local agriculture.(3) By studying effects of different mulch conditions on different kinds of potassium of0-40cm soil layer after the winter wheat harvest, the aim was to evaluate the ability ofsupplying potassium from different soil layer. Results showed: There were significant effectson soil readily-available potassium and available potassium among different treatments, whileless effects on total potassium, mineral potassium and slowly-available potassium. The MAtreatment could significantly increase readily-available potassium and available potassium, sothe supplementary intensity of potassium was improved. To some content, the SM treatmentalso increased the readily-available potassium, available potassium and supplementaryintensity of potassium, while, this trend was less significant than the MA treatment. However,the content of readily-available potassium and available potassium in plastic mulch ridgescultivation patterns were lower than MA and SM treatments, which resulted in the decrease ofsupplementary intensity of potassium. Compared to the PM treatment, the PM+S treatmentdid not significantly improved soil potassium supply capacity. There was no obvious effectson soil potassium efficiency among different treatments. The electrical conductivity (EC)showed opposite trend to soil pH. So the EC in the MA and SM treatments were lower thanthe CK treatment, while the plastic mulch ridges treatments were higher than CK treatment,but not significantly. Therefore, under the conditions of this experiment, straw mulch andmanure application showed significant supplementary capacity of readily available potassiumand available potassium, while, less significant effects on total potassium andslowly-available potassium. To some content, plastic mulch ridges resulted in decrease inreadily-available potassium and available potassium. Compared to the PM treatment, thePM+S treatment did not significantly improve soil potassium supplementary capacity. |
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