Effect Of Tillage Practice On Soil Quality And Carbon Emission And Their Relationship In Loess Soil

The dryland agriculture area in western Loess of Plateau is a typical region for dryland farming system.However serious soil erosion,limited water resources and low fertilizer use efficiency has led to low agroecosystem productivity.The issue has become the main challenge for the sustainable development of agriculture in this region.Hence,there is the need to improve soil quality,enhance soil carbon pool function,reduce carbon emission and continuously improve land productivity level.They are of great significance for the sustainable development of agriculture in the region.The present study was conducted at a long-term field experiment with wheat-pea rotation which was established at the central part of Gansu province in2001.The experiment included four treatments,with three replicates:T?conventional tillage?,NT?no-tillage?,TS?conventional tillage with straw?,and NTS?no-tillage with straw?.The environmental factors including soil carbon emission,soil quality and established the system of quality evaluation were examined.The objective of this study was to determine the main mechanism underlying the effects of different tillage practices on carbon emission based on changes in the soil quality.The main findings were summarized as followed:1.No-tillage with straw improved loess soil quality.The tillage practices effect on soil physical quality index were:NTS?0.82?>TS?0.63?>NT?0.53?>T?0.20?in wheat field;and NTS?0.86?>TS?0.56?>NT?0.37?>T?0.21?in pea field;The tillage practices effect on soil chemical quality index were:NTS?0.60?>TS?0.53?>NT?0.50?>T?0.26?in wheat field;and TS?0.59?>NTS?0.41?>NT?0.38?>T?0.23?in pea field;The tillage practices effect on soil biological quality index were:NTS?0.79?>NT?0.72?>T?0.48?>TS?0.44?in pea field.The soil quality comprehensive evaluation index was NTS?0.70?>TS?0.53?>NT?0.48?>T?0.30?.2.No-tillage and no-tillage with straw reduced carbon emission in loess soil and enhanced soil carbon sink function.The pattern of soil carbon emission under the different tillage practices were TS>T>NT>NTS in wheat field.Compared with T,NT and NTS treatments reduced soil carbon emission by 10.03%and 12.15%,respectively.The primary productivity?NEP?of spring wheat ecosystem under different tillage practices was positive,and the NEP under NTS treatment was the highest,with 81.37%higher than under traditional tillage.Soil carbon emissions under different tillage practices in pea fields were T>TS>NTS>NT.Compared with T,soil carbon emissions under NT and NTS decreased by 22.96%and 21.58%,respectively.And the primary productivity?NEP?of pea field ecosystem under NTS treatment was positive and highest,with 114.18%higher than under traditional tillage.3.CO₂ emissions significantly correlated with most soil quality indicators of loess soil,but not with the soil quality comprehensive index.There was no significant correlation between soil carbon emissions and soil physical quality index?SPQR?,chemical quality index?SFQI?,biological quality index?SBQI?and soil quality comprehensive index?SQI?.However,the indicators of soil physiochemical and biological quality have a significant correlation with soil carbon emission during crop growth period.Carbon emissions of farmland soil was positively correlated with soil water content?0.716**?,organic carbon?0.660**?and negatively correlated with soil total nitrogen?0.698**?,microbial Chao index?0.753**?,Observed index?0.782**?,Shannon index?0.765**?and soil microbial biomass carbon?SMBC??0.745**?.In conclusion,the conservation tillage within no-tillage with straw retention could improve soil quality,reduce soil carbon emission,and enhance soil carbon sequestration in western Losses Plateau of China.Different tillage practices effected soil carbon emissions and farmland ecosystem carbon balance by regulating soil moisture content,organic carbon,total nitrogen,abundance and composition of soil microbial community,and soil microbial biomass carbon.Therefore,within global climate change,no-tillage with straw practice could be considered as a reasonable agricultural management which was beneficial for the continuous improvement of farmland productivity in the arid land agricultural areas.