Effects Of Different Tillage Methods On Black Soil Fertility In Jilin Province

Black soil is a valuable land resource in China.Due to the influence of tillage mode and the excessive use of land,the black soil layer becomes thinner,nutrient deficiency,fertility decline,structural deterioration and other defects.In view of the above problems,this experiment studied the effects of traditional tillage(CK),continuous deep tillage + straw returning(T1),deep tillage + straw returning every other year,no-tillage + straw mulching(T2),deep loosening +straw mulching(T3),deep loosening + straw leaving(T4)on the physical properties,nutrient status,enzyme activity and carbon sequestration of black soil through 5 years of continuous field positioning test.The purpose of this experiment is to find a tillage method that can improve soil water and fertilizer retention,reduce nutrient deficit and maintain sustainable soil development,and provide theoretical basis and technical support for black soil protection and national food security.The main results show that :1.Compared with CK,each treatment could reduce soil bulk density,increase soil porosity,water content,saturated water content and capillary water content in 0-80 cm soil layer,among which T1,T3 and T4 treatments reached a significant level.Each treatment could reduce the soil three-phase structure distance(STPSD),T1 and T3 treatments reached a significant level,and each treatment could increase the structure index(GSSI).In 0-20 cm soil layer,T1 treatment was significantly higher than CK,T2,T3 and T4 treatments,and there was no significant difference between treatments in 20-80 cm soil layer.However,T1 treatment had the highest increase(3.68 %-5.20 %).T1 treatment can significantly increase the content of > 0.25 mm aggregates,reduce the content of micro-aggregates and silt-clay aggregates,greatly improve the stability of water-stable aggregates and reduce the damage rate of aggregates.2.Compared with CK,in the 0-80 cm soil layer,each treatment could increase the content of available nitrogen,phosphorus and potassium in the soil to varying degrees.Compared with CK,T1 significantly increased the content of soil available nitrogen by 38.36 % ～ 123.29 % and available phosphorus by 47.79 % ～ 411.43 %.T1 ～ T4 treatments could significantly increase the content of soil available potassium,among which T1 increased the most(17.60 % ～53.35 %).3.Compared with CK,in the 0-80 cm soil layer,each treatment could improve soil enzyme activity to varying degrees.Compared with CK,T1 significantly increased soil acid phosphatase activity by 35.29 %-221.74 %,neutral phosphatase activity by 90.91 %-130.00 %,catalase activity by 17.65 %-22.65 %,sucrase activity by 24.26 %-88.41 %,and urease activity by73.44 %-98.41 %.4.Compared with CK,in the 0-80 cm soil layer,T1 treatment significantly increased soil total organic carbon content by 29.19 % ～ 117.20 %,carbon pool management index(CPMI)by 41.51 % ～ 152.18 %,and organic carbon content of aggregates by 23.15 % ～ 149.77 %.Each treatment can increase the contribution rate of organic carbon in soil > 0.25 mm aggregates to varying degrees,indicating that the carbon sequestration capacity of soil macroaggregates is enhanced.In summary,continuous deep tillage + straw returning(T1)treatment can effectively improve soil structure,coordinate the relationship between soil solid,liquid and gas phases,enhance the stability of soil water-stable aggregates,increase soil available nitrogen,phosphorus and potassium content,enhance soil enzyme activity,and improve soil carbon sequestration performance.It is an effective measure for black soil conservation and fertility improvement in this area.