| Aiming at the problem that the synergistic relationship between soil water,salt,nutrients distribution,the root system of sunflower and the growth of the aboveground is still unclear under the condition of straw interlayer with different thickness in Hetao Irrigation Area.In this paper,through the indoor root box control test combined with the field micro verification test,four treatments with straw interlayer thickness were set up(CK: no straw interlayer;S3: straw interlayer thickness of 3 cm;S5:straw interlayer thickness of 5 cm;S7: straw interlayer thickness of 7 cm).The effects of different thickness of straw interlayer on soil water and salt transport,nutrient distribution,microbial community,root system and biomass of sunflower were simulated to clarify the synergistic relationship between soil ecological factors and sunflower growth under different thickness of straw interlayer.The main results are as follows:(1)The effect of straw interlayer thickness on the distribution characteristics of soil water,salt and was clarified.Straw interlayer could enhance the water retention and salt leaching capacity of 0-40 cm soil layer after irrigation,and S5 treatment had the best effect,the soil water content increased by11.0 % and the salt content decreased by 4.0 % compared with CK(P<0.05).With the development of sunflower growing period,evaporation increased,straw interlayer had a great influence on the 40-60 cm soil layer.The soil water content increased with the increase of interlayer thickness.And the difference between soil water and salt content and CK treatment gradually increased with the extension of growth period.However,straw interlayer treatment had no significant effect on soil p H.In addition,compared with CK,straw interlayer treatment decreased soil nutrient content in 0-40 cm soil layer(except alkaline hydrolyzable nitrogen and available potassium),but increased soil nutrient content in 40-60 cm soil layer,with S5 treatment increasing the most,in which available potassium was significantly increased by 15.0% compared with CK(P<0.05).(2)The synergistic relationship between the thickness of straw interlayer and the growth of sunflower and soil ecological factors was clarified.Straw interlayer treatment could increase the stem diameter,leaf area,and ground dry matter of the sunflower,and promote the growth and development of the sunflower root system,increase the root dry weight,and then increase sunflower yield,among which the effect of S5 treatment was significant.The total root length,total root surface area,root tip number and root dry weight in 0-40 cm soil layer were 3.6,2.9,3.5 and 2.4 times of those in CK treatment,respectively.With the increase of straw burying years,the differences among treatments gradually decreased.In addition,the distribution of root morphology in the first year of straw planting was affected by the content of soil water,salt and organic carbon(20-40 cm soil layer),and the accumulation of aboveground dry matter was affected by the content of soil water,salt and available potassium(0-20 cm soil layer).With the gradual decomposition of straw,a lot of nutrients were released.In the third year,the yield of sunflower was mainly affected by the content of water and salt in0-40 cm soil layer and nutrients in 40-60 cm soil layer.(3)The effect of straw interlayer thickness on soil microbial community was explored.Straw interlayer treatment significantly changed the composition of soil microbial community.In terms of bacterial community composition,S3,S5 and S7 treatments increased the relative abundance of Actinobacteria,Chloroflexi,Verrucomicrobia and Firmicutes,Among them,the relative abundance of Chlorobacteria,Verrucobacteria and Firmicutes was the highest under S5 treatment.In terms of fungal community composition,interlayer treatment significantly increased the relative abundance of Rozellomycota,which was as follows: CK<S3<S5<S7(P<0.05).Redundancy analysis and correlation analysis showed that soil bacterial community structure was mainly affected by soil water,salt and organic carbon.Soil fungal community structure was mainly affected by soil water and salt.In conclusion,the growth of sunflower in the year when the straw was buried was mainly affected by the contents of water,salt,SOC content of 20-40 cm and soil available potassium content of 0-20 cm.After the second year,with the gradual decomposition of straw,the,and nutrient accumulation in 40-60 cm soil layer,which was beneficial to the absorption and utilization of sunflower,and then increased the yield.Considering soil microenvironment and sunflower growth,5 cm thick straw interlayer was the best.This study provides an important theoretical basis for improving saline soil and increasing crop yield in Hetao irrigated area. |
