| The ecological environment of the Loess Plateau is weak,rainfall is scarce and the soil is barren.Corn is an important food crop in this area,straw mulching and plastic film mulching have become the main cultivation mode of spring maize in Weibei Dryland because of the better eco-environment effect and agricultural production effect.In this experiment,by studying the dynamic distribution of soil moisture and nutrients in spring maize,soil enzyme activities and their spatial distribution,and the responses of microbial carbon,nitrogen and phosphorus restriction to different mulching cultivation modes were analyzed by ecological enzyme kinetics and stoichiometry in order to provide theoretical basis for high yield and high efficiency of spring maize in Weibei Dryland.The main conclusions are as follows:(1)Compared with the treatment without mulching,the water use efficiency of straw mulching and plastic film mulching were increased by 7.6% and 17.9%;the yield was increased by 10.1% and 24.7%,and increased the partial productivity of nitrogen fertilizer.Cover cultivation can significantly improve water and fertilizer use efficiency and achieve high yields.(2)Covering cultivation significantly increases the water consumption in the early stage of spring corn,reduces the water consumption in the later stage of flowering,and adjusts the ratio of water consumption before and after the spring corn flowers..Mulching cultivation can reduce water evaporation consumption,improve soil water storage in winter fallow period,and ensure normal water demand of spring maize in pre-flowering period.(3)Compared with no mulching,the accumulation of nitrate nitrogen respectively decreased by 22.8% and 44.8% in straw mulching and plastic film mulching 100-200 cm,and the ammonium nitrogen accumulation in 0-200 cm section decreased by 33.1% and34.8%.Plastic film mulching and straw mulching reduced nitrogen leaching and soil available nitrogen accumulation.The content of soil organic carbon under straw mulching increased with the increasing of mulching years,and tended to be stable.After 4 years of plastic film mulching,the content of soil organic carbon began to decrease.Compared with2015,soil organic carbon content decreased by 0.3% in 2016 and 1.7% in 2019 under plastic film mulching,and increased by 4.7% in 2016 and 25.8% in 2019 under straw mulching.(4)The ratio of soil hot spot enzyme activity to root surface enzyme activity and hot spot area of straw mulch C-enzyme were the highest.The ratio of the root surface enzyme activity of N-and P-enzymes to the soil hot spot enzyme activity under the mulching film was the highest.Straw mulching had positive effects on C-,N-and P-enzyme activities,film mulching only had positive effects on P-enzyme activities.The critical values of BG and LAP enzymatic reaction speed and saturation concentration were increased by surface mulching during vegetative growth period,and the affinity of LAP enzyme and LAP substrate was increased when LAP complex was formed during reproductive growth period.Film mulching had positive effect on P-enzyme activity,accelerated the decomposition of soil organic carbon and available phosphorus during maize reproductive growth period by inducing higher P-enzyme activity.Straw can be used as a continuous input of carbon source to supplement soil organic carbon and available phosphorus,weaken the limitation of microbial phosphorus.To sum up,plastic film and straw mulching can adjust stage water consumption,reduce inorganic nitrogen accumulation,increase soil enzyme activity and hot spot area The content of soil organic carbon increased steadily with the increase of straw mulching years,which was beneficial to increase the content of soil nutrients.Therefore,straw mulching cultivation is suitable for spring maize production in Weibei Dryland. |
PDF Full Text Request