Research On Key Technologies Of Constructing High-Quality Maize Seedbed And Its Inter-Row Till-Planter

Maize(Zea mays L.)is the largest food crop in China and plays an irreplaceable role in the national economy.The Northeast China is the main producing area of maize,accounting for more than 35% of the planting areas of food crops in China.And the precision planter is widely used to sow maize in this area.In the past few decades,the black earth area of Northeast China has been overexploited,and the disadvantages of traditional farming are gradually being exposed.The black earth has been irreversibly damaged and the black soil layer is thinning.In order to protect and restore the black earth,the conservation tillage techniques and black earth protection were written in the Central No.1 Document.With the development of modern agriculture,we are increasingly demanding the seeder.We are no longer satisfied with the seeding function of the seeder,but rather to achieve high quality sowing,creating a high-quality seedbed environment for the seed to increase yield.To this end,we have proposed the key technologies of constructing high-quality maize seedbed: Shallow rotation of seeding strip is carried out to loosen the soil,creating a good seed furrow for the seeds to improve the quality of the seeding,providing a suitable seedbed environment for germination of seeds and growth of seedlings.Aiming at the conservation tillage model in Northeast China,through theoretical analysis,mathematical model,experimental analysis and other methods,we broke through the key technologies of constructing high-quality maize seedbed,investigated the effects of the various components on the sowing quality and the effects of different seedbed characteristics on the emergence and growth of maize.Finally,the inter-row till-planter was designed to solve the problems of poor sowing quality,weak drought resistance,poor consistency of emergence and serious soil adhesion.(1)Furrow compaction device with openingAfter the double-disc opener operation,there will be many unfavorable phenomena such as a W-shaped bottom,returning a lot of soil,rough furrow sidewall,and large soil blocks in the furrow bottom.These phenomena will cause the problems of poor sowing depth consistency and seed spacing uniformity.In order to solve the problems,the furrow compaction device with opening was designed to compact and reshape the original seed furrow,eventually forming a smooth and flat V-shaped seed furrow.Through theoretical calculations and kinematic analysis,the main structural parameters of the device were limited to a small range: the spring stiffness coefficient k=0.96~4.19 N/mm and the angle of furrow compaction wheel φ=30°~60°.In the soil-bin experiment,the optimal structural parameters obtained were: the spring stiffness coefficient k=4.0 N/mm,and the angle of furrow compaction wheel φ=42.4°.The furrow compaction device with opening provides key component support for the inter-row till-planter study.(2)Seed furrow water spraying deviceThe drought at seedling stage seriously affects the emergence percentage of maize,and eventually reduces the grain yield.To ensure that the seeds can root and germinate under drought conditions,and to further improve the quality of sowing,the seed furrow water spraying device was designed,which was used in conjunction with the furrow compaction device with opening.The test results revealed the effects of factors on the indicators,and showed the optimal parameters of the device: 0.4~0.6 L/m of the spraying water volume and conical nozzle.The seed furrow water spraying device provides key component support for the inter-row till-planter study.(3)Profiling elastic press device and anti-adhesion mechanism of its surface structureIn order to reducing soil adhesion of press device and find anti-adhesion mechanism of its surface structure,based on the characteristics of earthworm motion,we designed the anti-adhesion structure of a press roller.(1)The geometrical parameters of the earthworm surface were measured.The width-height ratios of the head and body were obtained.Based on the data,the surface structure was optimized and the rubber bulge was determined.The range of rubber bulge height was 16~26 mm.The performances of surface structure were tested in an indoor soil bin.The test results showed the optimal parameters: rubber bulge height 16mm(h2)and load 450N(F1).(2)Each rubber bulge covered an angle of 60° on the surface of the press roller,and pictures were taken every rotation of 10°.The broken lines of curvature radius of rubber bulges were obtained in MATLAB.Similarly,we also obtained the broken lines of curvature radius at the earthworm head and body.By comparison,the result showed the broken line h2 is most similar with that of earthworm.(3)Theoretical analysis was carried out to reveal the anti-adhesion mechanism of the rubber bulge structure.The profiling elastic press device provides key component support for the inter-row till-planter study.(4)Effects of soil physical properties of seedbed on maize growthThe effects of seed furrow treatments,surface compaction pressures,water spraying treatments and their interactions on maize growth were evaluated.Two seed furrow treatments were: bottom compaction(BC)and no bottom compaction(NBC).Each seed furrow treatment included the combination of three levels of surface compaction pressures(25,50 and 75 kg)and four levels of water spraying(0,0.2,0.4 and 0.6 L/m),thus forming 12 combinations of surface compaction pressures and water spraying.We measured soil cone index,soil moisture content,mean emergence time,percentage of emergence,mean seedling height,root biomass,aboveground biomass and root shoot ratio.The results of this study showed that the surface compaction pressure of 25-50 kg is the most suitable for the chernozems in Northeastern China.The optimal spraying water volume is 0.4-0.6 L/m in the experimental plot,but for the other different plots,the spraying water volume needs to be determined according to the soil moisture content before operation.This study provides a reference for constructing high-quality maize seedbed,and data basis for the innovation design of the inter-row till-planter.(5)Design and test of the inter-row till-planter constructing high-quality seedbedThe key technologies and components of constructing high-quality maize seedbed were integrated into the whole machine,forming the inter-row till-planter which was suitable for the conservation tillage mode of Northeast China.In order to verify the performances of the machine,the field test was carried out.We studied the effects of key components on the sowing quality,operation performance,emergence and yield.The results showed that the comprehensive performance of the whole machine was significantly better than the traditional till-planter.