Effects Of No Tillage And Pre-sowing Irrigation On Carbon Emission And Water Use Efficiency Of Summer Maize Field

This study was carried out in the water pool of Shandong Agricultural University agronomy experimental station in 2018 and 2019.The experimental design method is split area experimental design.There are two cultivation methods in the main area:Annual no tillage?NT?and wheat season conventional tillage?CT?no tillage in summer season.There are three irrigation quantities before sowing in the sub area:30 mm,70 mm and 110 mm,a total of 6treatments,each treatment 3 times repeated,a total of 18 cells,random block arrangement.In this paper,the soil respiration rate,soil carbon emission,soil water and carbon components,growth and yield of summer maize,carbon emission efficiency and water use efficiency were studied.The results are of great significance to the efficient use of farmland water and the mitigation of greenhouse gas emissions.The test results are as follows:1.Soil respiration rate and carbon emissionWith the development of the growth period,the soil respiration rate of Summer Maize Farmland showed two peaks in 2018 and a single peak in 2019.Among them,the soil surface temperature and moisture showed a very significant correlation with soil carbon emissions.During the two years,no tillage in wheat season inhibited soil respiration in summer maize field,which decreased soil carbon emission compared with that in wheat season;soil respiration rate increased with the increase of pre-sowing irrigation,and soil carbon emission also increased.2.Soil moisture and carbon componentsWhen sowing,pre-sowing irrigation can significantly affect the soil moisture content of the first 80 cm soil layer,no uniform law on the soil moisture content of 80-120 cm soil layer for two years,and no effect on the soil moisture content of 120-160 cm soil layer.With the development of summer maize,the water content between different irrigation amounts tends to be the same.Among all soil layers,no tillage in wheat season can keep soil water better.Under the same tillage method,the increase of irrigation amount before sowing can improve the content of organic carbon,microbial biomass carbon and easily oxidized carbon in 0-10 cm soil layer;Under the same irrigation treatment,no tillage treatment in wheat season can increase the content of organic carbon,microbial biomass carbon and easily oxidized carbon in 0-10 cm soil layer.There is no significant difference between the components in 0-10 cm and 10-20 cm soil layers in wheat season ploughing treatment,which has a certain uniformity of soil layer.The content of three carbon components in 20-40 cm soil layer is significantly lower than that in 0-10 and 10-20 cm soil layer.3.Growth and yield of summer maizeIn two years,to a certain extent,with the increase of pre-sowing irrigation,the photosynthetic performance and leaf area index of summer maize increased significantly,so as to increase the dry matter accumulation and ultimately increase the yield of maize.There was no significant rule between 110 mm pre-sowing irrigation and 70 mm,but the yield of 70 mm pre-sowing irrigation was 13.57-39.82%higher than that of 30 mm.At the same time,no tillage in wheat season could also promote the growth of summer maize.Under the same pre-sowing irrigation condition,the yield of summer maize was 7.16-34.3%higher than that of conventional tillage in wheat season.4.Carbon emission efficiency and water use efficiencyThe increase of irrigation amount before sowing can promote the growth of summer maize,and improve the water use efficiency and carbon emission efficiency of summer maize,but the improvement is limited.The water use efficiency and carbon emission efficiency of 70 mm irrigation amount before sowing are significantly higher than that of 30 mm and 110 mm irrigation,but the single water consumption and carbon emission are not consistent in two years.Compared with ploughing in wheat season,no tillage in wheat season has lower soil carbon emission and evapotranspiration,so no tillage has higher water use efficiency and carbon emission efficiency,and lower unit water consumption and carbon emission.In conclusion,no tillage and pre-sowing irrigation in wheat season can improve summer maize yield,reduce soil CO₂ emission,increase soil moisture and carbon content,and improve carbon emission efficiency and water use efficiency of summer maize,but on the whole,70mm pre-sowing irrigation under no tillage is a more reasonable pre-sowing irrigation.