Responses Of Soil Moisture Characteristics And Spring Maize Seedling Quality To Straw Returning

Inner Mongolia is one of the main corn producing areas in my country.Drought stress and unscientific farming measures restrict the development of local agriculture.Therefore,this experiment aimed at the shortage of water resources,low water use efficiency and poor stability of maize under traditional farming methods in Inner Mongolia.It is based on three different ecological zones in Inner Mongolia Tumochuan Plain Irrigation Area,Loess Gully Irrigation Area and Lingnan Dry Farming Area.Five kinds of straw returning methods were set up respectively:Conventional plowed(CK),Deep ploughing returning(DPR),Subsoiling stirring returning(SSR),No-tillage returning(NTR)and Strip tillage returning(SCR).The response mechanism of spring maize soil structure and water to different straw returning methods was systematically analyzed.The purpose is to optimize the farming measures and improve the moisture conservation and water storage capacity of the farmland in Inner Mongolia.The main results are as follows:(1)In the three ecoregions,DPR and SSR treatments significantly reduced soil bulk density.In the Tumochuan plain irrigation area,the loess gully irrigation area and the Lingnan dry farming area,the soil bulk density decreased by 8.1%～4.6%,3.2%～6.5%and0.4%～7.9%respectively compared with the CK in three years,and the soil porosity was increased.soil water storage capacity.DPR and SSR treatments can also adjust the soil three-comparison.The three-year deviation value of soil three-comparison in Tumochuan plain irrigation area,loess gully irrigation and Lingnan dry farming area treated by SSR and DPR is 24.6%lower than that of CK on average in three years～43.2%,29.7%～46.6%and 7.8%～23.7%.(2)In the three ecological regions,different straw returning methods can increase the content of soil water-stable macroaggregates and improve the stability of soil aggregates.The content of soil water-stable aggregates(>0.25 mm)increased under DPR treatment was the highest,which was 21.5,21.4,and 18.5 percentage points higher than CK in the three ecoregions,respectively.Body stability is poor.NTR treatment has the strongest soil aggregate stability due to less soil disturbance,with MWG and GWD increased by30.8%-44.1%and 29.7%-48.7%compared with CK.Different straw returning methods can increase the fractal dimension of soil water stability agglomeration,and each treatment decreases by 2.48%-4.16%compared with CK.(3)DPR is a suitable method of returning fields to improve soil water content in the irrigation area of??Tumochuan plain and loess gully irrigation area.Compared with CK,the soil infiltration was increased by 12m L and 8.6m L,and the field water holding capacity was increased by 24.08%～26.39%and 27.05%～29.14%.The soil water content at the seedling stage,silking stage and grain filling stage increased by 9.3,2.5 and 5.2 compared with CK,respectively.Percentage points;three-year average increase of water storage before sowing by 27.3mm and 21.6mm.The emergence rate increased by 9.9 and 8.0percentage points,and the uniformity increased by 4.0 and 5.7.The water use efficiency was increased by 18.1%and 14.5%,the average yield was 12.6t/hm~2and 13.1t/hm~2,and the yield was increased by 18%and 16%.(4)NTR has outstanding ability to maintain moisture and heat preservation,and it is a suitable way to return to the fields in Lingnan dry farming areas.Compared with CK,NTR increased soil water content by 1.97 percentage points,increased water storage before sowing by 34.3 mm,and could achieve sufficient moisture to sow on schedule.There was no significant difference in seedling emergence rate and CK supplemented sowing.10.3t/hm~2,an increase of 3%.It has good application prospects by improving the technology in dry farming areas.