Effects Of Returning Straw To Field On Soil Physical And Chemical Properties And Organic Carbon Components In Hilly Area Of Central Sichuan Under Different Tillage Methods

In order to explore the effects of straw returning on soil physical and chemical properties and organic carbon components in the pea-maize two-maturity area in the hilly area of central Sichuan,this study was conducted in Tashui Village Experimental Station,Zhujia Town,Renshou County,Meishan City,Sichuan Province in 2017.Rotary tillage straw crushed mixed return to field(RTM),tillage straw return to field(CTB),deep pine straw cover return to field(STC),no-till straw cover return to field(NTC)and blank control no-till straw were set up respectively 5 treatments without return to the field(NT).This paper mainly studies the effects of different treatment methods on soil physical and chemical properties,total organic carbon and active organic carbon during the growth period of winter pea-summer corn in 2018-2019,and uses Duncan multiplicity comparison to make significant differences in the annual changes of various indicators.Analysis,the correlation analysis and principal component analysis of soil total organic carbon and soil physical and chemical indicators and active organic carbon component indicators,and a comprehensive score for each treatment factor.The main results are as follows:(1)The effects of returning straw to the field on different soil layers have different effects on soil physical properties under different tillage methods,and are mainly concentrated in 0-30 cm soil layers.Among them: RTM and CTB treatments are more conducive to significantly reduce the soil bulk density of the 0-30 cm soil layer and increase its total soil porosity,and RTM treatment reduces the soil bulk density of the5-30 cm soil layer and the total soil porosity.The increase is more significant than other treatments,while STC,NTC and NT treatments will increase the bulk density of the soil in the 15-30 cm soil layer and reduce the total soil porosity.(2)Under different tillage methods,the effects of returning straw to the field on soil nutrients are mainly concentrated in the 0-30 cm soil layer,and the overall impact on the soil layer larger than 30 cm is small.Among them: STC and NTC treatment can effectively increase the content of total nitrogen,alkali-decomposed nitrogen,available phosphorus and available potassium in the soil of 0-5cm soil layer,the impact is more significant,and the impact on the soil nutrient content of the soil layer of 5-30 cm is relatively gentle.It has no significant effect on the soil nutrients of the 30-50 cm soil layer;under the CTB treatment,the soil nutrient content of the 15-30 cm soil layer is higher than the STC,NTC and NT treatments,and slightly higher than the RTM treatment;The effect of the soil nutrient index content of the 5-15 cm soil layer is significantly higher than that of the STC,NTC and NT treatments,and the RTM is higher than the CTB treatment;while for the30-50 cm soil layer,the difference in soil nutrient content between different treatments is not obvious.The soil nutrient content under the treatment of RTM and CTB was slightly higher than that of STC and NTC.The effect of straw returning to the field on total organic carbon and active organic carbon components in the soil of 0-50 cm in different tillage methods has the same trend,showing a vertical distribution law that gradually decreases with the increase of soil depth,and in the 30-50 cm soil The SOC content of different treatments in the layer changed little,and the difference was not significant.Among them: under the treatment of STC and NTC,the content of SOC,LOC,DOC and POC in the soil of 0-5cm soil layer is significantly higher than the corresponding index content of the soil layer of 5-50cm;RTM and CTB treatment on the soil SOC,LOC,Compared with STC,NTC and NT treatments,the content of DOC and POC has a significant improvement effect,and under RTM treatment,the content of soil between 0-30 cm soil layers changes more uniformly,and the SOC,LOC,DOC of 30-50 cm soil layers Compared with other treatments,the influence of POC content is slightly improved,but the overall difference is not large;CTB treatment has a significantly higher effect on the content of LFOC in the 15-30 cm soil layer than other treatments.(4)Soil nutrient indicators,total organic carbon and various active organic carbon components under STC and NTC treatments have obvious enrichment phenomena and time accumulation effects on the soil surface,and RTM treatment can effectively avoid the above-mentioned relevant indicators only on the soil surface Enrichment.At the same time,in addition to individual indicators,the content of nutrient indicators and activated organic carbon components in the 5-30 cm soil layer of the RTM treatment is more significant than the overall improvement of the other treatments,and the content changes between the soil layers are also more significant Evenly.(5)There is a certain degree of mutual conversion between different types of activated organic carbon.Soil particulate organic carbon affects the volume density and porosity of the soil to a certain extent,which is closely related to the soil structure and the soil active organic carbon There is a certain interaction between carbon and soil nutrient elements.At the same time,whether it is the winter pea planting season or the summer corn planting season,the RTM treatment factor score is the highest,and the RTM treatment factor is the first principal component,indicating that RTM treatment The soil physical and chemical indicators,total organic carbon and active organic carbon components under the index can reach a better level than other treatments.In summary,compared with other treatments in this experiment,RTM treatment has more obvious soil improvement effect in the central Sichuan hilly area,and it is also more suitable for mechanized farming and straw return to the field technology.