| In order to select the appropriate tillage practices,improve soil physical and chemical properties,increase soil fertility,soil water conservation and crop grain yield of Huang-Huai lime concretion black soil farmland,two tillage experiments were set in winter wheat-summer maize rotation system.The first experiment was conducted in farmland with no tillage in maize season and rotary tillage in wheat season formerly to research the effects of 3 winter wheat season tillage practices(no tillage,rotary tillage and deep tillage)on soil bulk density,soil organic carbon,soil inorganic nitrogen and grain yield of winter wheat.The second experiment was conducted in farmland with 5 long term fix-point annual tillage practices(no tillage-rotary tillage,no tillage-deep tillage,subsoiling tillage-rotary tillage,subsoiling tillage-no tillage,no tillage-no tillage)to research the effects of annual tillage practices on soil organic carbon,soil nutrient,soil bulk density,soil water content and crop grain yield.The results showed:(1)In the tillage practices experiment of wheat season,compared with rotary tillage,deep tillage practice could significantly decrease soil bulk density in 10-30 cm soil layer.There were no significant differences among three tillage practices of soil organic carbon content in 0-20 cm soil layers,but deep tillage could increase soil organic carbon content in 20-40 cm soil layers compared with rotary tillage.In20-40 cm soil layers,the order of the content of ammonium nitrogen was deep tillage > rotary tillage > no tillage during the whole growth period of winter wheat.Compared with rotary tillage,deep tillage could significantly increase grain yield of winter wheat,but no tillage decreased the grain yield.(2)In the fix-point annual tillage practices experiment,compared with no tillage-rotary tillage,no tillage-deep tillage,subsoiling tillage-rotary tillage,and no tillage-no tillage all increased annual soil organic carbon and total nitrogen content in 0-20 cm soil layer.No tillage-deep tillage,subsoiling tillage-rotary tillage,and notillage-no tillage significantly increased soil available phosphorus content in 0-20 cm soil layer during the whole growth period.Subsoiling tillage-no tillage significantly increased 0-20 cm soil layer available phosphorus in anthesis and harvest period of winter wheat.Subsoiling tillage-no tillage increase annual soil available potassium content in 0-20 cm soil layer during the whole growth period.In20-40 cm soil layer,subsoiling tillage-no tillage and no tillage-no tillage significantly increased soil available potassium content in seedling,trumpeting,anthesis and filling stage of summer maize season.(3)In the fix-point annual tillage practices experiment,compared with no tillage-rotary tillage,subsoiling tillage-no tillage and subsoiling tillage-rotary tillage significantly decreased soil bulk density in 15-40 cm soil layer during maize harvest period and in 20-25 cm soil layer during wheat harvest period.No tillage-deep tillage,subsoiling tillage-rotary tillage and subsoiling tillage-no tillage significantly increased soil water storage in 0-40 cm layer during maize harvest period.Subsoiling tillage-no tillage increased soil water content in 20-40 cm soil layer during the whole growth period.Compared with no tillage-rotary tillage,subsoiling tillage-rotary tillage and subsoiling tillage-no tillage significantly increased annual grain yield by 7.67% and 10.21%,respectively.No tillage-deep tillage and no tillage-no tillage decreased annual grain yield by 0.44% and 2.19%,respectively.To sum up,in farmland with no tillage in maize season and rotary tillage in wheat season formerly,transformation from rotary tillage to deep tillage in wheat season could decrease soil bulk density,improve the content of organic carbon and ammonium nitrogen,and also increase grain yield of winter wheat in the end.Compared with no tillage-rotary tillage,subsoiling tillage-rotary tillage and subsoiling tillage-no tillage could decrease soil bulk density,improve the content of soil nutrient and increase annual grain yield.Especially,subsoiling tillage-no tillage could improve the potential of soil water conservation,and the effect of subsoiling tillage-no tillage on increasing grain yield is optimal.Therefore,Subsoiling tillage-no tillage should be selected as an appropriate tillage practice in Huang-Huai lime concretion black soil farmland. |
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