| The area of cultivated land in China accounts for 9% of the world,but it consumes 30% of the chemical fertilizer in the world.The average use of chemical fertilizer is far higher than that of other countries in the world.The utilization rate of fertilizer is low and the utilization rate of nitrogen fertilizer in paddy field is 30%-35%,while the fertilizer utilization rate of developed countries is 10% higher than that of our country.In order to solve the problem of low fertilizer utilization rate,this paper designed an airflow stratified fertilization system,which can put the fertilizer needed in the whole growth period of rice into the ground in one time,in order to ensure the supply of growth nutrients in the early and late stages of rice,and carry out field experiments.The main research results are as follows:1)The physical properties of fertilizer were studied.The physical characteristics of fertilizers were studied,and the physical properties of 4 kinds of compound fertilizers commonly used in rice production were determined.The compound fertilizer of Norway is more than 90%,the grain size of 1.5-4MM is greater than 90%,the density of accumulation is 834g/L,the sliding angle is 23.5 degrees,the grain size 2-3mm is more than 90%,the accumulation density is 870g/L,the sliding angle is 23.8 degrees,the island rice special fertilizer,the fertilizer grain size 3-4mm is more than 90%,the accumulation density is 845g/L,the sliding angle is 24.9;ten thousand valley.The particle size of particle compound fertilizer is 2-3mm greater than 90%,the packing density of fertilizer is 850g/L,the slip angle is 23.9 degrees,and the fertilizer box is designed according to the determination results.2)An airflow layered fertilizer allocation system is designed.According to the requirements of rice growth matching,a method of layered fertilization was put forward,and the position and amount of fertilizer applied in shallow and deep layers were determined.When sowing,a shallow fertilization ditch was opened synchronously on the side of the rice sowing ditch.The depth of the ditch was 4cm and the distance from the sowing ditch was 5cm.The shallow fertilization amount was about 40% of the total fertilizer amount.A deep fertilization ditch was opened in the middle of the two rice sowing trenches.The depth of the ditch was 8cm,and the deep fertilization amount was about 60% of the total fertilizer amount.The amount of shallow fertilizer and deep fertilization can be adjusted according to actual needs.Stratified fertilization can provide nutrients for rice seedling stage,middle stage and late stage.On this basis,the airflow layered fertilization system was designed,and the minimum wind speed was determined through fertilizer suspension test and starting test.Through analysis,it is determined that the inner diameter of the air conveying fertilizer pipeline is 38 mm,and the fan type and relevant parameters of the system are also determined.The negative pressure of the inlet air inlet and the mixed outlet of the airflow fertilizer at the different cross section height of the air and fertilizer mixer was simulated with SolidWorks simulation.The simulation results show that the maximum of the cross section of the air and fertilizer mixer is 20 mm when the cross section height of the air flow and fertilizer mixer is at the variable cross section is most satisfied with the requirements of the current air and fertilizer mixer.The experimental design verifies the result of the simulation analysis.3)A single factor test was carried out on 6 factors affecting the airflow stratified fertilization system.The results showed that the system wind speed,the length of fertilizing pipe,the water content of fertilizer and the amount of fertilizer were all influenced on the effect of fertilization,and the wind speed,the amount of fertilizer and the length of the fertilizer pipe were more significant.Through single factor test,it can be found that the system wind speed is 16m/s to 20m/s,the amount of fertilizer is 30 kg to 60 kg,and the length of the fertilizer pipe is 50 cm to 150 cm,the air flow stratified fertilization system can work normally,and the proportion of deep fertilization and the proportion of shallow fertilization is small.The orthogonal experiment was carried out with three factors which had significant influence.The results showed that the effect of the stratified fertilizer distributor effect was the system wind speed > fertilization length > fertilizer amount.The optimum scheme was: wind speed was 20m/s,the amount of fertilizer was 50 kg,and the length of the tube was 50 cm.4)A delamination fertilizing ditching device was developed.The stratified fertilization ditching device of this system was determined by the ectopic fertilization.The shallow layer used the ship shaped shovel opener,and the deep fertilization adopted the core share ditching device.The field experiments were carried out on the delamination fertilizer ditching device.The experimental results showed that the depth of furrow opening and the distance from the rice line were satisfied with the design requirements.5)Field performance tests were carried out on the airflow layered fertilization system.The results of field experiment on the ratio stability of deep fertilization and shallow fertilization showed that the error of shallow fertilization and deep fertilization was greater than that in bench test,but the overall error was small.The result of the test of fertilization broken bar showed that,under the condition of normal operation,the amount of fertilizer was 30 kg ~ 60 kg mu,and when the wind speed was 16m/s to 20m/s,no fertilization broken strip was found. |
