| Wheat is one of the main grain crops in China.Because of its flat terrain,deep tillage and good light-heat conditions,Huang-Huai-Hai region is the largest winter wheat production base in China.Drill-seeding is widely used in wheat planting patterns in this region.At present,there are some shortcomings of bare and crowded seedlings in the drill-seeding planting pattern.On the other hand,there are still some problems in the wheat production management,such as excessive fertilizer application and low efficiency of fertilizer utilization.To solve these problems and shortcomings,agronomic experts put forward the production managements of wheat wide-boundary sowing and fertilizer stratified application.Many experimental studies have shown that these production managements have good effects on increasing yield and reducing fertilizer application.To promote the deep integration of agricultural machinery and agronomy,this paper studied the key technologies of wide-boundary sowing and base-fertilizer stratified application combined operation for winter wheat.These key technologies mainly include precise depth delivery method of materials,wide-boundary sowing method for wheat,key structural parameters optimization of fluted roller fertilizer apparatus,precision fertilization/sowing control technology,wide-boundary sowing and base-fertilizer stratified application combined operation technology.Based on the research results of the above key technologies,a combined equipment of wide-boundary sowing and base-fertilizer stratified precision application for winter wheat was developed.This study can provide equipment support for wide-boundary sowing of winter wheat and fertilizer stratified application in Huang-Huai-Hai region of China,and in the further,the study can improve the quality of wheat sowing and fertilizer stratified application,reduce amount of chemical fertilizer application and improve efficiency of fertilizer utilization in China.The main research contents and conclusions of this paper include five parts:(1)According to the agronomic management requirement of wheat sowing and basefertilizer stratified application,this paper present a materials precisely depth-setting delivery application method by rearward covered soil.This method can make traditional material depthsetting delivery process get rid of the dependence with ditch opener.From the kinematics analysis of rotary blade and soil block respectively,a mathematical model of the positions of materials outlet orifice of steel pipe and the depth of materials target delivery depth was established.In order to validate this mathematical model,a precision rotary tillage seeding and fertilization test platform was set up,and two groups of progressive experiments were designed The experiment results showed that the maximum offset deviation of materials actual delivery depth was 9mm,and the maximum deviation ratio of materials actual delivery depth was 8.75%.The results of these experiments show that the established mathematical model of the positions of materials outlet orifice of steel pipe and the delivery target depth of materials was trustworthy.This study can provide a theoretical basis for the design of layered seed and fertilizer delivery mechanism in the future.(2)In order to improve the wheat transverse uniformity effect of wide-boundary sowing device,this paper designed a spherical wide-boundary sowing device.Discrete element simulation technology,soil tank test and orthogonal test were used to study structural innovation and parameters optimization of wide-boundary sowing device.The mathematical structure model of seed separated plate is established in this paper.Spherical radius,installation angle and span were three key structural parameters of mathematical structure model.The results of single factor simulation test showed that wide-boundary sowing device had relatively small coefficient variation of wheat transverse uniformity when spherical radius,installation angle and span at 130～150 mm,30～40° and 70～90° respectively.The orthogonal result showed that the main and secondary factors affecting coefficient variation of wheat transverse uniformity were installation angle,spherical radius and span.There was a certain interaction between installation angle and span.When spherical radius,installation angle and span were 141.26 mm,35.53° and 90.72° respectively,the coefficient variation of wheat transverse uniformity was the least,and the coefficient variation of simulation test and bench test were 9.21% and 13.40%,respectively,and the deviation was only 4.19%.This results can provide references for optimizing the structural parameters of seed separated plate of wide-boundary sowing device and improving the performance of the wide-boundary sowing.(3)On the basis of considering factors interaction,this paper optimizes the structural parameters of fluted roller fertilizer apparatus to improve its fertilizer delivery stability.This paper used the discrete element simulation technology,3D rapid prototyping technology and orthogonal test.4 key structural parameters of groove wheel radius,groove number,effective length and section of groove were analyzed the influence rules on its fertilizer performance.The test results of the interaction of 4 factors showed that there were not interaction between the groove wheel radius and the groove number,and between effective length and groove number,and there was a certain interaction between groove wheel radius and groove number.The groove number was very significant on the performance of the fertilizer,and the groove wheel radius was significant on the performance of the fertilizer.When the groove number was7,the groove wheel radius was 30 mm,the effective length was 20 mm,and the section of groove was circular-arc,the performance of the fluted roller fertilizer apparatus was the best,and the variation coefficient of the fertilizer for this type of fluted roller fertilizer apparatus at simulation test and bench test were 1.75 % and 5.48 %.Considering that there may be some errors in the bench test,the results of the bench test was basically consistent with the simulation results.This research results can provide references for optimizing the structural parameters of fluted roller fertilizer apparatus and improving the performance of the fertilizer.(4)A three-path precision fertilizer/seed control system with real-time monitoring function of machine attitude was developed.The control system is mainly composed of vehicle control terminal,three-path hydraulic motor electronic control drive module,machine attitude analysis module,machine position and speed analysis module,storage battery and hydraulic cylinder.According to the functional requirements of the control system,a human-computer interaction software interface is developed.The machine attitude analysis module monitored the pitch angle of lower link of three-point suspension mechanism in real time,which could be used to judge whether the machine is working or not.The rotational speed of fertilizer/seed axis is controlled in real time by integrating the machine attitude analysis module and the algorithm of machine position and speed analysis module.The precision fertilizer/seed control system developed can improve the intelligence and automation of wheat seeding and fertilization combined operation equipment.(5)The equipment of wide-boundary sowing and base-fertilizer stratified precise application combined operation for winter wheat was developed.The combined equipment is mainly composed of frame,rotary tilling device,mechanism of complete fertilizer and seed layered device,precise fertilizer/seed control system,compacting device,depth-controlled component and three-point suspension mechanism.The combination of rotary tilling device and mechanism of complete fertilizer and seed layered device can achieve the layered delivery technical effect of deep fertilizer,shallow fertilizer and wheat seed.In order to improve the operation stability of combined equipment,the inclination angle of the bracket of depthcontrolled component is be set 15°,which could increase the horizontal distance between depth limiting wheel and rotating center of rotary tilling device by 115 mm.The upper suspension point of three-point suspension mechanism was improved to a horizontal long-hole type to compensate the pitch angle of combined equipment.The combined equipment can provide equipment support for popularization and application of combined operation technology of wide-boundary sowing and base-fertilizer stratified application.(6)The field application effect of wide-boundary sowing and base-fertilizer stratified precise application combined equipment for winter wheat was studied.In this paper,the field application effects of stratified fertilization,precision fertilizer/seed control and wide-boundary sowing of winter wheat were tested.The results of stratified fertilization showed that the depth qualified rates of wheat seed,shallow fertilizer and deep fertilizer were 83.33%,86.67% and90% respectively,and the qualified rates of the actual stratified distance between wheat seed and shallow fertilizer,shallow fertilizer and deep fertilizer were all 100%.The results of precision fertilizer/seed control showed that the variation coefficients of wheat seed,shallow fertilizer and deep fertilizer were 3.0%,3.5% and 3.8%,respectively.The variation coefficients of three fertilizers and seeds were less than 5.0%.The results of wide-boundary sowing of winter wheat showed that the actual width of seeds band and seedlings band after sowing were basically same as the target width.The coefficient variation of wheat transverse uniformity of winter wheat seeds was 14.5%,and the theoretical yield per hectare was 7668.8 kg,which was8.8% higher than the traditional drilling mode.The field application effect test results showed that the combined equipment could be satisfied the relevant operational testing standards. |
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