Effects Of Rotation Tillage Modes On Soil Physical Properties And Wheat Root And Shoot Characteristics In Fluvo-aquic Soil In Northern Henan Province

Rotary tillage in wheat season and no-tillage in the maize season is the major tillage practice in Fluvo-aquic soil in northern Henan province,which results in the shallow cultivated soil layer and deeper plow pan.To solve this problem,the experiment was carried out with three tillage combinations of deep tillage,strip rotary tillage,and rotary tillage,in a 3-year cycle.Five treatments were set as:（1）Continuous Rotary Tillage（RT-RT-RT）;（2）Deep tillage-Rotary tillage-Rotary Tillage（DT-RT-RT）;（3）Deep tillage-Rotary tillage-Strip rotary tillage（DT-RT-SRT）;（4）Deep tillage-Strip rotary tillage-Strip rotary tillage（DT-SRT-SRT）;（5）Deep tillage-Strip rotary tillageRotary tillage（DT-SRT-RT）.The soil aggregate characteristics,water characteristics,nutrient content,microbial characteristics,wheat root cap characteristics,photosynthetic characteristics,full plant nutrients,yield and constituent factors in the0-40 cm soil layer were measured and analyzed.The main results were as follows:（1）Compared with RT-RT-RT,the soil aggregate stability,macroaggregate proportion,organic carbon content（SOC）,contribution rate and SOC storage of each particle level were improved under the treatments with rotation tillage mode.The macroaggregate decreased with the increasing of soil depth.Compared with RT-RT-RT,the macroaggregate proportion in the 20-40 cm soil layer was significantly increased by rotation tillage treatment.In the 0-40 cm,DT-SRT-SRT had the largest macroaggregate proportion,with the highest proportion of 46.3%-51.9%.DT-SRT-SRT increased the mean mass diameter（MWD）,geometric mean diameter（GMD）and water stability aggregate（R0.25）in the 0-40 cm soil layer,with 1.11 mm,0.56 mm and 47.73%,respectively,and reduced the fractal dimension（D）.DT-SRT-SRT and DT-SRT-RT significantly increased soil large aggregate organic carbon content in the 0-40 cm soil layers,with 12.24 g·kg^-1 and 14.54 g·kg^-1,respectively.The macroaggregate organic carbon contribution rate was increased,with an increase of 60.30% to 88.29%,respectively.The large aggregate organic carbon reserve was increased,with 5.38 t·hm^-2 and 6.14 t·hm^-2,respectively.The macroaggregate aliphatic organic carbon content was increased,with the highest 2920 cm-1/1630 cm-1peak area ratio of 56.67 and 51.96,respectively.（2）Compared with RT-RT-RT,the soil moisture content and water capacity were increased under rotation tillage treatments,and the highest increment was under DTSRT-RT.DT-SRT-RT significantly increased the soil volume water content（16.38%）,water storage（530.46 mm）,field water holding capacity（36.92%）,water storage capacity(2595 m³·hm^-2),total water storage capacity(3565 m³·hm^-2)and available water storage capacity（33.90 mm）in the 0-30 cm soil layer in the wheat season,and decreased the soil wilting coefficient（30.94%）.Besides,DT-SRT-RT improved the soil moisture content and available water storage capacity in the maize season.（3）Compared with RT-RT-RT,soil physical and chemical properties were improved under rotation tillage treatments,and all indexes decreased with the increasing of soil depth,except for bulk density.DT-SRT-RT significantly improved the soil porosity（40.47%）,total nitrogen(1.06 g·kg^-1),organic matter(19.80 g·kg^-1),alkaline nitrogen(83.38 mg·kg^-1),available phosphorus(27.22 mg·kg^-1),available potassium(116.68 mg·kg^-1),active organic carbon(4.07 g·kg^-1),dissolved organic carbon(57.08 mg·kg^-1)and dissolved organic nitrogen content(31.57 mg·kg^-1)reduced soil bulk density(1.49 g·cm^-3).In addition,tillage mode has less impact on nutrient in maize season.（4）Soil enzyme activity,microbial biomass carbon（SMBC）and microbial biomass nitrogen content（SMBN）were increased under rotation tillage treatments,and all indexes decreased with the increasing of soil depth.In wheat and maize season,DTSRT-RT significantly increased urease(1.83 [NH3-N mg·（kg·24h）^-1]),sucrase(43.51[Glu.mg·（kg·24h）^-1]),alkaline phosphatase activity(1.43 [Phenol mg·（kg·24h）^-1]),SMBC(230.40 mg·kg^-1)and SMBN content(58.39 mg·kg^-1)in the 0–20 cm soil layer.（5）The root architecture and root/shoot ratio of main growth stage of wheat were improved under treatments with rotation tillage.DT-SRT-RT significantly improved the wheat root architecture at jointing,flowering and filling stages,among which root length（RL）,root volume（RV）,branch number（RF）and root/shoot ratio（R/S）were the highest,reaching 396.68 cm,1.36 cm³,2262 and 0.14,respectively.The net photosynthetic rate,transpiration rate and stomatal conductance in 2021 were shown as flowering stage> filling stage > jointing stage.DT-SRT-RT significantly increased the net photosynthetic rate(27.61 μmol·m^-2 s^-1),transpiration rate(5.38 mmol·m^-2 s^-1)and stomatal conductance(0.55 H2 O m^-2 s^-1)at the main wheat growth stage.DT-SRT-RT had the highest contents of total nitrogen,total phosphorus and total potassium in plant parts,and the contents of total nitrogen was 0.44-0.76 g·kg^-1.The highest total phosphorus content was 0.18-0.28 g·kg^-1.The highest total potassium content was 1.18-4.90 g·kg^-1.DT-SRT-RT had the highest yield in wheat season and maize season was9630 kg·hm^-2 and 12140 kg·hm^-2,respectively.In summary,DT-SRT-RT was beneficial to reduce soil bulk density for current and subsequent crops.DT-SRT-RT improved soil porosity,macroaggregate content,organic carbon content,contribution rate and organic carbon storage of each particle-level aggregate,soil moisture content,soil nutrient content,soil microbial mass and soil enzyme activity.It is recommended as the optimum rotation tillage mode in this area.