Effect Of Subsoiling On Yield And Water Use Efficiency Of Summer Maize

As a result of perennial rotary tillage in Shandong province,the plow sole is thickened,the plough layer becomes shallow,the plough layer construction deteriorated,and the continuous improvement ability of grain yield declines.Subsoiling method has the advantages of breaking plow sole,improving soil structure,preventing drought and flood.This method is of great significance to construct rational tillage layer.The current studies of Shandong province mainly focus on soil organic carbon,crop growth and grain quality,and lack of research on soil moisture.In addition,the depth of subsoiling is mostly concentrated in the range of 30-40 cm in Shandong province,and there is no corresponding depth specification,which is likely to cause waste of resources and economy.In order to explore the best depth suitable for Shandong province,we have carried out field experiment of summer maize for two years,hoping to provide theoretical support for extension of subsoiling technology and sustainable development of agriculture in Shandong province.The experiment adopts single factor design method.It contained 3 treatments under the condition of straw mulching,including rotary tillage 15 cm(CK),subsoiling 40cm and subsoiling 35 cm respectively(Subsoiling before sowing of winter wheat).Each treatment has3 replicates.There are 9 neighborhoods.There is no other variable except the independent variable of tillage method.The experiment results show that:1?Compared with traditional rotary tillage,subsoiling40cm treatment can improve soil infiltration rate,speed up the infiltration of rainfall into the soil,and accelerate the growth rate of soil water storage in the soil layer.With the increase of rainfall,the soil depth of this phenomenon gradually deepens.The subsoiling 40 cm treatment increased the soil moisture content in the soil layer of 50-130 cm and the soil water storage capacity in the soil layer of 0-130 cm,which was more significant in the drought period.The performance of subsoiling 35 cm was better than that of traditional rotary tillage,but not as good as that of deep pine treated with 40 cm.2?Compared with traditional rotary tillage,subsoiling treatment can increase leaf area index(LAI)and chlorophyll content in ear leaf of summer maize.In addition,this treatment could increase the dry matter accumulation of summer maize.In dry period,subsoiling treatment can increase the photosynthetically active radiation interception rate of summer maize,reduce the transmission rate,and promote the growth and development of summer maize.Compared with the subsoiling 40 cm treatment,the leaf area index of subsoiling 35 cm decreased slightly in the later growth stage of summer maize,with higher photosynthetically active radiation interception rate and lower transmission rate,which effectively alleviated the senescence of summer maize leaves.In addition,this treatment had a higher content of chlorophyll in the ear leaf in the later growth stage,increased the late dry matter accumulation and the proportion of dry matter in spike and reduced the proportion of stem,which was more conducive to the growth and development of summer maize and the improvement of maize yield.3?Compared with the traditional rotary tillage treatment,the whole growing period farmland water consumption of subsoiling 40cm average increased by 10.1%and subsoiling 40 cm average increased by 4.0%in the two years.The effect on farmland water consumption in the whole growing period is mainly reflected in the increase of farmland water consumption in joining-filling stage.Because the yield of subsoiling increased greatly,the water use efficiency was higher than that of traditional rotary tillage.The water consumption of subsoiling 40 cm treatment was significantly higher than that of subsoiling 35 cm treatment and rotary tillage,and the yield was not significantly different from that of subsoiling 35 cm treatment.Therefore,the water use efficiency of subsoiling 35 cm treatment was 13.5%higher than that of subsoiling 40 cm treatment in the two-year experiment.4?Compared with rotary tillage,the yield of summer maize was significantly increased by subsoiling 35cm treatment.The main reasons for the increase yield were the significant increase in kernels number per row and 1000-grain mass.The treatment of subsoiling could increase the economic benefit of summer maize,and the effect of subsoiling 35 cm treatment was better than that of subsoiling 40cm treatment,with an average increase of 844.5 yuan/hm~2 in two years.In addition,the subsoiling 35 cm treatment reduces the working resistance of agricultural machinery,reduces fuel consumption and exhaust emissions.It is more conducive to the sustainable development of agriculture.The subsoiling 35 cm treatment could increase the dry matter accumulation in the later growth stage of summer maize,thus increasing the yield of summer maize and improving the water use efficiency and economic benefits.Therefore,compared with the subsoiling 40 cm treatment,the subsoiling 35 cm treatment is more conducive to the sustainable development of agriculture and should be regarded as an appropriate depth for the promotion of subsoiling technology in Shandong province.