Study On Soil And Water Erosion And Soil Physical Properties Of Conservation Tillage In Loess Hilly And Gully Region

Loess plateau of China is one of the most serious soil erosion areas in the world.Soil and water loss of sloping fields is one of main reasons for the shortage of waterresource, decline of soil fertility, and reduction of crop output lead to the increase ofthe cost of agricultural production and the reduction of food supplies seriously affectthe development of agricultural production. In order to reduce soil and water lossesin sloping fields and improve sustainability on fragile slopes, the field experiment wascarried out to investigate the effects of conservation tillage on soil and water erosionin2007-2010in western loess plateau6°⁷°sloping fields. Six treatments in genuinemedicinal materials conservation tillage, i.e. radix isatis/glycyrrhiza intercroppingwith conventional tillage(T_IL), wheat/glycyrrhiza intercropping with conventionaltillage (TwL), radix isatis/glycyrrhiza intercropping with no tillage and no stubbleretention(NT_IL), wheat/glycyrrhiza intercropping with no tillage and no stubbleretention(NT_WL), radix isatis/glycyrrhiza intercropping with no tillage and stubbleretention(NTSIL), wheat/glycyrrhiza intercropping with no tillage with no stubbleretention(NTSwL); and six treatments in strip intercropping of grain-grass-legumeconservation tillage, i.e. wheat/alfalfa intercropping with conventional tillage(T_WL),potato/alfalfa intercropping with conventional tillage (T_PL), chickpea/alfalfaintercropping with no tillage and no stubble retention(T_CL), wheat/alfalfaintercropping with no tillage and no stubble retention(NTSWL), potato/alfalfaintercropping with no tillage and stubble retention(NTSpL), chickpea/alfalfaintercropping with no tillage and no stubble retention(NTScL). In this paper, weinvestigate the effects of conservation tillage under different rainfall condition on soiland water erosion, and soil physical properties, runoff amount and soil erosionamount was analyzed. The main results were obtained as the following:(1)Soil bulk density is increasing with the increasing of soil depth in genuinemedicinal materials conservation tillage and strip intercropping of grain-grass-legumeconservation tillage. No tillage and stubble retention could decrease soil bulk density and damage rate of soil aggregate, but total soil porosity and soil saturated hydraulicconductivity was increased. Wheat/glycyrrhiza intercropping and potato/alfalfaintercropping could improve soil physical properities.(2)Runoff and sediment amount was increasing with the increasing of naturalrainfall in genuine medicinal materials conservation tillage and strip intercropping ofgrain-grass-legume conservation tillage. Rainfall had significant positive correlationwith runoff and sediment, the relationship between runoff and sediment indicatedthat runoff and soil erosion amount had correlation of quadratic equation curve withrainfall, runoff and rainfall had correlation of linear equation curve with sediment.(3)In the genuine medicinal materials and strip intercropping ofgrain-grass-legume conservation tillage study, runoff of conventional tillage wasgreater than no tillage treatment; the results indicated that NTS and NT treatmentscould effectively reduce runoff amount, erosion amount and soil nutrients loss.(4) total runoff and erosion of conventional tillage was greater than no tillagetreatment in genuine medicinal materials and strip intercropping ofgrain-grass-legume conservation tillage, soil srosion of T_WL, T_WL﹡, NTSILand NTS_PLwas5.12t/hm2,14.82t/hm2,1.09t/hm2and2.81t/hm2, respectively. Soil erosion inthe same planting pattern was shown as NTS<NT<T. Soil erosion of wheat/alfaflaintercropping treatment was NTSWL<T_WL, chickpea/alfafla intercropping treatmentwas NTS_CL<T_CL, and potato/alfafla intercropping treatment was NTS_PL<T_PL.(5)The time of producing runoff with no tillage and no tillage and stubbleretention had significant differences with increasing in artificial simulation ofprecipitation intensity in genuine medicinal materials conservation tillage. with theprecipitation intensity of6.97mm,9.71mm and22.23mm, runoff volume of differenttreatment with different precipitation intensity was T_IL>T_WL>NT_IL>NT_WL>NTSIL>NTSW.The surface runoff consists of four processes: runoff producing, peak value, stabilityand disappear; with the precipitation intensity of6.97mm,9.71mm and22.23mm,sediment production of different treatment was shown as:T_IL>T_WL>NT_IL>NT_WL>NTSIL>NTSWL. The soil erosion consists of three processes:occurrence, peak value and reduction. (6)In genuine medicinal materials conservation tillage study, the runoff volumeof no tillage was decreased by15.28%³8.75%than conventional tillage, the runoffvolume and sediment production of no tillage with stubble retention was decreasedby20.38%⁵6.25%and38.13%⁷6.83%than conventional tillage,5.00%²8.57%and12.96%⁵2.36%than no tillage respectively. In strip Intercropping ofgrain-grass-legume conservation tillage, the runoff volume of T treatments wasshown as: T_WL>T_CL>T_PL, and NTS treatments was shown as: NTS_PL>NTS_CL>NTSWL; Theerosion volume of T treatments was shown as: T_WL>T_CL>T_PL, and NTS treatments wasNTSWL>NTS_CL>NTS_PL.