| Tillage directly or indirectly affects the physical,chemical and biological properties of soil.The reasonable tillage measures can effectively improve soil structure,physicochemical and ecological environment,and realize the sustainable utilization of farmland soil,promoting high and stable yields of crops.The destruction of soil structure,the decline of fertility and the reduction of crop yield caused by traditional tillage have been paid more and more attention.In recent years,no-tillage,subsoiling and more protective tillage measures have been popularized and applied.In order to study the effects of different tillage measures on soil microbial community functional diversities and soil organic carbon in dark loessial soil of Weibei plateau.The study was based on a field experiment with different tillage measures in dark loessial soil on Weibei high land.A split plot design was developed in the research,with three fertilizer applications as main treatments(balanced fertilization,low fertilization and conventional fertilization treatment).In addition,there were six tillage measures as sub-treatments(conventional tillage(CC),no-tillage(NN),subsoiling(SS),no-tillage-subsoiling(NS),subsoiling-conventional tillage(SC),conventional-no-tillage(CN)).This study investigated the effects of tillage methods on soil nutrient,soil organic carbon and its fractions and microbial community functional diversity.With a view to understanding the relationship between soil organic carbon and its fractions and microbial community functional diversity.The experiment provides a theoretical and technical support for reasonable tillage and topsoil structure in Loess Plateau and black loessial soil areas.The results were as follows: 1.Effects of different tillage and fertilization on content and distribution soil nutrientsUnder the three fertilizer levels,the total nitrogen content of 0～10 cm and 10～20 cm soil layers were CF>BF>LF.The available nitrogen content of 0～10 cm soil layer was BF>LF>CF,and in the 10～20 cm soil layer of BF were higher than LF and CF significantly.The total phosphorus content of 0～10 cm soil layer was BF>CF>LF,and there were significant difference among the three fertilization levels.The total phosphorus content of 10～20 cm soil layer was CF>LF>BF,and the CF was higher than LF and BF significantly.The available phosphorus content of 0～10 cm soil layer was CF>BF>LF,and the available phosphorus content of 10～20 cm soil layer were higher under BFand CFthan LF.The total potassium and available potassium content of 0～10 cm and 10～20 cm were BF>LF>CF,and there were significant difference among the three fertilization levels.From different tillage measure under the balanced fertilization,the total nitrogen content of 0～10 cm were NS>SS>NN>SC>CN>CC,and the other tillage measure were higher than CC treatment.The total nitrogen content of 10～20 cm were NN>CC>NS>CN>SC>SS,compared with CC treatment,the NN treatment was increased by 17.07%,the SS treatment was decreased by 18.84%.The available nitrogen content of 0～10 cm were NS>NN>SS>CN>CC>SC.But the available nitrogen content of CC treatment was the highest in the 10～20 cm soil layer,and the NN treatment was the lowest,and increased by 32.58% compared with the CC treatment.Compared with CC treatment,in the 0～10 cm soil layer,the total phosphorus content were SC>NN>NS>CC>SS>CN,the SC treatment was increased by 12.94%.In the 10～20 cm soil layer,The NN treatment was increased by 6.49%,the NS treatment was decreased by 41.97%.The available phosphorus content of 0～10 cm were NS>CN>NN>SC>CC>SS.In the 10～20 cm soil layer,the available phosphorus content of CC treatment was the lowest,and the CN treatment was the highest,which was increased by 39.68% significantly compared with CC.The total potassium content of 0～10 cm were SS>NS>CN>NN>SC>CC.Compared with CC treatment in the 10～20 cm soil layer,the total potassium content of NN treatment was the highest,which was increased by 15.63%,and the SS treatment was the lowest.The available potassium content of 0～10 cm were SC>NN>SS>CN>NS>CC,and the content of 10～20 cm were CN>SS>NS>SC>CC>NN,compared with CC treatment,the CN treatment was increased by 14.39%,the NN treatment was decreased by 38.42%.In different tillage measures,the stratification phenomenon of soil nutrient were great difference in available nutrient.Compared with CC treatment,the NS,NN and SS treatments improved the stratification ratio of available nutrient under three fertilizer levels.The NS and SC improved the stratification ratio of total phosphorus significantly,decreased the stratification ratio of available phosphorus.The SS treatments improved the stratification ratio of total potassium and available potassium.2.Effects of different tillage and fertilization on soil organic carbon and its fractionsUnder the three fertilizer levels,the soil organic carbon content in the 0～10 cm soil layer was BF>LF>CF,and it was BF>CF>LF in 10～20 cm.The contents of soil microbial biomass carbon and easily oxidized organic carbon in the 0～10 cm and 10～20 cm were BF>LF>CF.The dissolved organic carbon in the 0～10 cm and 10～20 cm were BF>CF>LF.It showed that the balanced fertilization increased the soil organic carbon and its fractions in the 0～10 cm and 10～20 cm soil layers.From different tillage measure under the balanced fertilization,the content of soil organic carbon,microbial biomass carbon,dissolved organic carbon and easily oxidized organic carbon in the 0～10 cm soil layer were higher than CC treatment,which were increased by 9.12%～22.57%、14.74%～44.62%、7.84%～24.07%、11.85%～41.23%,and the NS,NN treatments were higher than other treatment.The NS and NN treatment of microbial biomass carbon and easily oxidized organic carbon content were higher than other treatment in the 10～20 cm,and the NN treatment was the lowest,which decreased by 25.32%和 44.83% significantly than CC treatment.The stratification ratio of different tillage treatments showed that,compared with CC treatment,the other treatment all increased the stratification ratio of soil microbial biomass carbon,and the NS and NN treatments increased significantly.And the NS,SC,NN and SS treatment increased the stratification ratio of easily oxidized organic carbon,the NS and NN treatments also increased the stratification ratio of dissolved organic carbon.3.Effects of different tillage and fertilization on microbial community functional diversity.Under the three fertilizer levels,the AWCD value(average well color development),carbon conversion ratio and functional diversity index of balanced fertilization were higher than low fertilization and conventional fertilization.Compared with CC treatment,the AWCD value of the other treatments were increased,and the NS treatment increased significantly by 63.79%,64.10%,121.05% in three fertilizer levels.The NN treatment increased significantly by 32.76%,89.74%.In balanced fertilization,the NS and NN were higher than CC treatment in carbon conversion ratio.The carbohydrate and amino acids were main carbon sources for soil microbial utilization in the region.For the functional diversity index,compared with CC treatment,all the tillage treatment enhanced the richness index and shannon index,the NS and NN treatment increased by 35.17%,4.05% and 11.11%,4.39%.The evenness index and dominance index were no significantly difference.Principal component analysis showed that soil microorganism had the different partiality on carbon utilization.The NS and NN treatments presented great comparability in model of microbial communities utilizing C sources.Redundancy analysis showed that total nitrogen,available nitrogen,total phosphorus and available phosphorus had great influence.And the positive correlation between soil organic carbon and its fractions and the carbon utilization ability of soil microorganisms.And the soil organic carbon and soil organic carbon had great influence,the easily oxidized organic carbon had relatively little influence.In general,the tillage of NS under balanced fertilization was the most suitable measure for Weibei highland. |
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