Effect Of Tillage Practices And Organic Material Application On Soil Physical Properties And Maize Growth In Sloping Farmland Of Mollisol

The sustainable utilization of sloping farmland in the Mollisol region has a great significance for the food security in the Northeast area and even the whole country.In recent years,due to the decentralized management of land,shallow tillage practices like rotary and plow have been long-term used by farmers in the agricultural production,which cause many problems such as shallowing the tillage layer,thickening the plow pan and moving upwards the hard layer,then the soil water storage capacity is deteriorated and the crop roots are limitted,finally affect crop growth and yield formation.Therefore,it is urgent to adopt reasonable tillage practice to ensure the sustainable utilization of sloping farmland in Mollisol region.This study relies on one field experiment which set in Hailunn City,Heilongiang Province and investigate the effect of tillage practices and organic material application on soil physical properties and maize growth,these tillage practices included no-till（T0）,rotary tillage to the depth of 15 cm（T15）,plough tillage to the depth of 20 cm and 30 cm（T20,T30）,subsoiling to the depth of 30 cm（ST15,ST20）.These organic material application treatments included no material application（NO）,maize straw application（St）and cattle manure application（Cm）.These research conclusions are as follows:（1）Compared with conventional rotary tillage,no-till was not conductive to improving soil physical properties of the tillage layer.Subsoiling and deep plow could significantly reduced soil compaction,improved soil structure and soil porosity,increased soil water content and soil saturated hydraulic conductivity of the deeper soil layer,the increased effect could maintain the entire maize growth stage.Plough to 20 cm with subsoiling（ST20）was the best treatment for soil physical properties improvement.（2）The application of organic material could stabilize the soil structure,increase the stability of the aggregate,soil water content,porosity and soil saturated hydraulic conductivity.The increased effect of straw application was greater than cattle manure application.The straw application could affect soil physical properties of the depth to 20 cm soil layer under conventional rotary tillage treatment and 30 cm under subsoiling and deep plow tillage treatment,which could maintain the entire maize growth stage.Cattle manure application only affected the soil physical properties in the 0¹0 cm soil layer,it increased soil water content and soil saturated hydraulic conductivity,the duration time of the effect was only in the later stage of maize growth.（3）Tillage practices and organic material application significantly changed the growth of maize stem and roots.Compared with conventional rotary tillage,no-till treatment was not conducive to maize stem and roots growth,subsoiling and deep plow treatment had no significant effect on maize plant height,but promoted the growth of maize roots.They could increase root volume,root number and root dry weight,but reduced root width.The treatment of plow to 20 cm with subsoiling（ST20）was the most affected.The effect of organic material application on maize roots was less than that of tillage practice,straw application could increase root angle,but reduce root dry weight,cattle manure application could increase root dry weight and root-shoot ratio,but the difference was not significant.（4）The yield components of maize under different tillage practice were as follows:no-tillage increased the emergence rate and number of maize panicles,but significantly reduced the number of kernels;Subsoiling and deep plow had no significant effect on emergence rate,panicle number and 100-grain weight.The yield of maize between different tillage practice was 9699¹0093 kg·hm^-1,and there was no significant difference.Straw application could reduce number of maize panicles and maize yield,with a decrease of 6.8%and 8.5%,respectively.Cattle manure application could increase maize yield,but the difference was not significant.On the whole,the treatment of plow tillage to 20 cm with subsoiling and applying cattle manure（ST20-Cm）was the most suitable method of maize production for sloping farmland,which could improve the structure of tillage layer and create a suitable tillage layer environment.