| There are more and more researches on improving crop yield by using ridge and furrow planting in sub-humid areas in China in recent years.These researches have effectively promoted the further research on rainwater harvesting planting and the further optimization of technical models.However,whether the white pollution problem covered by plastic mulch can offset the effect of crop yield increase in the field and ultimately achieve the effect of crop yield increase remains to be discussed.Based on previous research,could we replace the plastic mulch covered in ridges with liquid mulch and no mulch,and by using natural precipitation to compensate for the seasonal shortage of summer maize or the shortage of water within a certain range? In addition,the effects of ridge and furrow planting patterns combined with different ridge and furrow structures on soil hydrothermal,crop growth and development,yield and water use efficiency in summer maize season remain unclear.Therefore,this study conducted two consecutive years of field experiments in Yangling,Shaanxi Province from 2021 to 2022.Taking summer maize in winter wheat-summer maize double-cropping mode as the research object and traditional plain cropping(CK)as the control,six ridge and furrow planting treatments were set up as follows: the ridge and furrow mulching systems with ridge coverage liquid plastic film and ridge-furrow ratios of 40cm:40cm(L40),40cm:60cm(L60)and 40cm:80cm(L80);and the ridge-furrow without mulching and furrow ratios of 40cm:40cm(S40),40cm:60cm(S60)and 40cm:80cm(S80).The regulation effects of ridge and furrow mulching systems with ridge coverage liquid plastic film combined with different ridge and furrow structures on soil hydrothermal,canopy radiation interception ability and crop yield of summer maize in winter wheat-summer maize double-cropping system were analyzed,and the main research results were obtained as follows:(1)Ridge and furrow planting reduces the soil water content in 0-60 cm soil layer in the early growth stage of summer maize(sowing stage to jointing stage),so that crops consume the surface soil water content and increase the deep soil water content.It reduces the soil water content in the soil layer below 100 cm in the late growth stage of summer maize(silking stage to maturity stage),so as to enhance the utilization of deep soil water by crops.The ridge and furrow mulching systems with ridge coverage liquid plastic film(L40,L60,L80)significantly reduced the water consumption during the growth period of summer maize,so as to achieve the effect of water storage and moisture conservation.The average soil temperature of 10 cm soil layer in the whole summer maize growth period under the ridge and furrow mulching systems with ridge coverage liquid plastic film and the ridge-furrow without mulching treatment was 2.3-3.0℃ and 0.4-1.2℃ higher than CK treatment,respectively.And the soil temperature showed an increasing trend with the increase of furrow width.(2)The contents of nitrate nitrogen and available phosphorus in soil decreased with the deepening of soil layer.The contents of nitrate nitrogen and available phosphorus in0-60 cm soil layer were increased by ridge and furrow planting.Compared with CK,the nitrate nitrogen content increased by 17.9%-28.3% and 1.1%-15.7%,and the available phosphorus content increased by 19.4%-37.0% and 2.5%-17.2%,respectively,in the ridge-furrow mulching systems with ridge coverage liquid plastic film and the ridge-furrow without mulching.(3)Ridge and furrow planting promoted the growth and development of the upper part of summer corn field,optimized the canopy structure,significantly reduced the canopy transmittance,and improved the canopy light environment.Plant height,stem diameter,leaf area index(LAI)and SPAD of summer maize were all improved by changing planting methods and ridge-furrow structure,and thus dry matter accumulation and grain yield of summer maize under different treatments were increased.L60 treatment was the best in wet year(2021)in all aspects,and L40 treatment was the best in dry year(2022).The canopy light transmission ratio of furrow width of 80 cm treatment was higher than CK,and the other treatments were lower than CK.In different ridge and furrow structures,as the furrow width gradually narrowed,the light transmission ratio at the bottom of the canopy decreased,and the intercepted photosynthetically active radiation in the canopy increased by 3.6%,3.7%,3.1%,1.8%,2.1% and 0.9% compared with CK,respectively.Among them,L60 treatment had the strongest intercept ability of photosynthetic active radiation.(4)Based on the results of two years of experiments,the number of grains per ear and 100 grain weight of summer maize were increased by ridge and furrow planting,and compared with CK,the average grain yield of summer maize under ridge and furrow planting(L40,L60,L80,S40,S60 and S80)was increased by 8.3%,13.9%,10.0%,2.7%,3.1% and 2.4%,respectively.The average water use efficiency increased by 31.9%,35.9%,30.2%,14.8%,16.8% and 11.2%,respectively,compared with CK.With the increase of furrow width under different ridge and furrow structures,the grain yield and water use efficiency of summer maize increased first and then decreased,and the grain yield and water use efficiency were the highest when the furrow width was 60 cm.In conclusion,in the sub-humid areas of Guanzhong plain,ridge and furrow planting can improve soil water distribution and nutrient content,regulate soil temperature,promote the growth and development of summer maize,optimize canopy structure,and improve the intercept ability of photosynthetic active radiation.Ridge and furrow with liquid mulching can deepen this effect,and finally improve the grain yield and water use efficiency of summer maize.All things considered,L60 treatment can achieve the effect of water saving and stable yield in the summer maize under winter wheat-summer maize double-cropping system. |
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