Responses Of Soil Properties,Crop Growth And Yield To Tillage And Residue Management In A Wheat-maize Cropping System On The North China Plain

Crop residue removal and subsoil compaction are limiting to yield improvement in the North China Plain(NCP).We conducted a field study composed of six consecutive crop growing seasons from 2010 to 2013 in Henan province,China,to determine responses of soil properties,crop growth and yield to tillage and residue management in a wheat-maize cropping system under irrigated conditions.Tillage practices comprised rotary tillage(RT)to a depth of 15-cm,deep mouldboard ploughing(DMP)to a depth of 30-cm,and chisel ploughing(CP)to a depth of 30-cm.Crop residue management included crop residue retained(AS)and crop residue removed(NS).The main results are as follows:1.Soil tillage mainly changed the soil structure and residue retained mainly improved the soil fertility.DMP and CP could significantly improved soil structure and nutrient availability,influenced the the distribution of soil organic matter and total nitrogen in the tilled layer,but no significant influence on soil organic matter and total nitrogen stocks.Residue retained had no significant effect on the soil bulk density and total porosity,but significantly increased the soil nutrient content and the stocks of soil organic matter and total nitrogen.Compared with RT,DMP and CP treatment significantly reduced soil bulk density at 10-30 cm soil layer and penetration resistance at 10-40 cm soil layer,increased soil porosity at 10-30 cm soil layer.In the three tillage practices,CP had the best soil water storage capacity and the water retention.Compared with RT,DMP and CP improved the soil nutrient availability,such as the available P and available K;increased soil nutrient content in the subsoil,such as organic matter,total nitrogen,available P and available K;reduced the soil carbon and nitrogen ratio,but had no significant influence of soil organic matter and total nitrogen stocks in the tilled layer.Although residue retained had no significant effect on the soil bulk density and total porosity,but significantly increased the soil water,then significantly reduced penetration resistance at 10-40 cm soil layer.Residue retained not only significantly increased soil organic matter,total nitrogen,C:N ratio,available P and available K,but also the stocks of soil organic matter and total nitrogen.In the six treatments,DMP+AS had the lowest soil bulk density and penetration resistance,the highest total porosity;CP+AS had the best soil water storage capacity and the water retention.DMP+AS and CP+AS significantly increased soil organic matter,total nitrogen,available P and available K.2.Increase the tillage depth and residue returned could increased crop root biomass and improved the function of root system.Compared with RT,the wheat and maize root biomass in the 0-100 cm soil layer under DMP were increased by 13.56%and 17.93%respectively,under CP treatment were increased by 13.84%and 13.84%respectively.DMP and CP improved the soil structure and promoted the crop root growth,and significantly increased RLD and RMD of wheat at 0-70 cm soil layer and RLD and RMD of maize at 0-60 cm soil layer.Compared to RT,DMP and CP increased the root activity of wheat and maize,enhanced the root-bleeding sap and mineral ions(K,P,NH4+ and NO3-,?g plant-1 h-1)of root-bleeding sap.Compared with NS,the wheat and maize root biomass in the 0-100 cm soil layer under AS were increased by 10.84%and 8.87%,respectively.In addition,AS significantly increased the RMD and RLD,but the practice resulted in a different spatial distribution of wheat and maize roots.Residue incorporation increased RMD and RLD of wheat across 0-60-cm soil depth,while residue mulching increased RMD and RLD of maize only at 0-30-cm soil depth.This may be because of the higher SMC in the top soil as a result of the residue mulching.Compared to NS,AS increased the root activity of wheat,but decreased the root activity of maize due to higher root-rot incidence of maize;and enhanced the wheat and maize root-bleeding sap and the root-bleeding sap and mineral ions(K,P,NH4+ and NO3-,?g m-2 h-1)of root-bleeding sap.In the six treatments,DMP+AS and CP+AS resulted in higher root biomass,root-bleeding sap and mineral ions(K,P,NH4+ and NO3-)of root-bleeding sap,then for higher yields.3.Increase the tillage depth and residue returned could delayed plant senescence and improved crop photosynthetic performance.In our study,soil tillage and residue returned had no significant effect on wheat seedling emergencerate,however significant effect on tillering,LAI,SPAD,photosynthetic rate and the process of leaf senescence.Increase the tillage depth and residue returned could increased tillering,LAI,SPAD,photosynthetic rate,and SOD,POD and CAT of the flag leaf,and slowed protective enzyme activity decline rate and the accumulation of MDA content,delayed leaf aging process.For maize,soil tillage and residue returned had no significant effect on maize seedling emergencerate,plant height,ear height and leaf number per plant;however significant effect on stem diameter,leaf length and width,LAI,SPAD,photosynthetic rate and the process of leaf senescence.Increase the tillage depth and residue returned could increased stem diameter,leaf length and width,LAI,SPAD,photosynthetic rate,and SOD,POD and CAT of the flag leaf,and slowed protective enzyme activity decline rate and the accumulation of MDA content,delayed leaf aging process.4.Increase the tillage depth and residue returned could increased plant nutrient uptake and dry matter accumulation.For wheat,relatived to RT+NS,DMP+AS and CP+AS significantly increased the plant NPK uptake and dry matter accumulation,enhanced NPK and dry matter translocation after anthesis,but reduced NPK and dry matter translocation ratio after anthesis,and significantly increased NPK and dry matter accumulation after anthesis and contribution of NPK or dry matter accumulation after anthesis to grains.For maize,relatived to RT+NS,DMP+AS and CP+AS significantly increased the plant NPK uptake and dry matter accumulation,reduced NPK and dry matter translocation after anthesis and translocation ratio,and significantly increased NPK and dry matter accumulation after anthesis and contribution of NPK or dry matter accumulation after anthesis to grains.Although,DMP+AS and CP+AS redued the nutrient use efficiency,but increased fertilizer partial factor productivity for wheat and maize.5.Increase the tillage depth and residue returned could increased grain yield of wheat and maize.In this study,increase the tillage depth and residue returned had a consistent effect on wheat and maize grain-filling characteristic,namely improved grain-filling rate and extended the filling duration,and then higher grain weight.For wheat,soil tillage and residue returned had no significant effect on number of grain per spike,however significant effect on spike number per plant and 1000-grain weight.This results shown that spike number per plant and 1000-grain weight were probably the most direct reason for winter wheat yield increase in this study.From the analysis of wheat production,we could known that the highest wheat grain yield was found under CP+AS with average annual 9.76 t·hm-2,next was under DMP+AS with average annual 9.62 t·hm-2,and the lowest was under RT+NS with average annual 8.86 t·hm-2.Compared with RT+NS,the wheat grain yield under CP+AS and DMP+AS were increased by 8.58%and 10.16%,respectively.For maize,soil tillage and residue returned had no significant effect on ear rows and the longof bare top,however significant effect on 100-grain weight and grain number per ear.This results shown that grain number per ear and 100-grain weight were probably the most direct reason for summer maize yield increase in this study.From the analysis of maize production,we could known that the highest maize grain yield was found under CP+AS with average annual 8.65 t·hm-2,next was under DMP+AS with average annual 8.50 t·hm-2,and the lowest was under RT+NS with average annual 7.67 t·hm-2.Compared with RT+NS,the maize grain yield under CP+AS and DMP+AS were increased by 12.81%and 10.86%,respectively.From the analysis of yearly productivity,we could known that the highest wheat+maize grain yield was found under CP+AS,next was under DMP+AS,and the lowest was under RT+NS.Compared with RT+NS,the wheat+maize grain yield under CP+AS and DMP+AS were increased by 10.91%and 8.33%,respectively.