Search

The mechanized seeding operation is an important part in modern agricultural production, and the net operating time utilization rate of the seeder is an important indicator to impact the efficiency of seeder unit. According to machinery unit application principle, the new term of seasonal net time utilization rate was determined in this paper, each consumed time items of seeder unit was distinguished and relevant mathematic models were established based on mechanized seeding practice and sufficient survey, such as net operating time, turning time and time of adding fertilizer and seeds and so on. Based on this, three mathematical models of net operating time utilization rate of seeding machinery units were established according to different adding fertilizer and seed ways. The experiment scheme was designed, which uses the method of multi-point synchronous tracking measurement to test the time items in the seeding process without disturbing the normal seeding process. Data of each time items of 4 typical seeding machinery units were obtained during the experiments. The statistic principle of 3ᓂ was used to distinguish and eliminate invalid experiment data. Based on the models established and effective tested data, Matlab 2012b was used to analysis the net operating time utilization rate of the 4 seeding machinery units changing with plot length and area under 3 different ways to add fertilizer and seed, the test results were expressed using Sigmaplot 12.5 software, and th quantitative correspondence between the different typical seeding machinery units and suitable operating plot area and length under the aimed net operating time utilization rate were determined. The results showed that when the aimed net operating time utilization rate of seeding machinery units is greater than 0.6, the John Deere 7 830 unit is suitable for the plots with areas no less than 6 hm² and the plot length is 1 200-1 400 m. The Valtra 171 unit is suitable for the plots with area no less than 6 hm² and the plot length is 1 000-1 200 m. The suitable plots for Changfa 504 unit are that area is no less than 1 hm²and the plot length is 500-1 500 m. The plots with area no less than 0.3 hm² and the plot length is 200-1 500 m are suitable for Huanghai 254 unit. The results can provide scientific accordance to select seeding machinery units for different plots. [ABSTRACT FROM AUTHOR]

Differential pressure tank is a widely used fertilization device in the application of fertilization in China and many other countries. However, the fertilizer concentration in the tank continuously decays with the inflow of water. The decay feature of fertilizer concentration can easily lead to excessive fertilization at the head and insufficient fertilization at the end of the irrigation system. An analytical solution was proposed in this paper to achieve uniform fertilization based on differential pressure tank with constant fertilizer concentration and flux. The relationship between the uniform fertilization analytical solution and the fertilizer continuity equation was obtained based on differential pressure tank. The analytical solution was expected to control the flux flowing into the differential pressure tank and the flux directly flowing into the irrigation system through the main pipe according to 4 parameters: Uniform fertilizer concentration, initial fertilizer concentration, the volume of differential pressure tank and the total fertilization flux of the main pipe. Based on the analytical solution, the fertilizer continuity equation and the incompressible continuity and momentum equations of water were used for describing the movement of mixture in the differential pressure tank. The numerical model for mixed water and fertilizer flow in the differential pressure tank was determined by experimental data. The fertilizer concentration simulated by numerical model was nearly uniform in the tank and the fertilizer concentration at tank outlet obtained by numerical model decayed with a negative exponential pattern as described by Feng’s theory. The numerical simulation results directly verified the accuracy of the basis of Feng’s theory. The differential equation was also the basis of the uniform fertilization. The mean absolute error between the differential equation and the experimental data was less than 0.041 when the boundary condition of traditional fertilization method was substituted into the differential equation, which indirectly proved the rationality of uniform fertilization method satisfying the boundary conditions of constant fertilizer concentration and flux. The analytical solution’s feasibility in the uniform fertilization process based on differential pressure tank was simulated by the numerical model of fertilizer solution in determining the uniform fertilizer concentration and the fertilization time. The fertilizer concentration at tank outlet simulated by the numerical model decayed almost linearly and agreed with the uniform fertilization analytical solution. The fertilizer concentration simulated by the numerical model at drip irrigation system inlet was almost uniform and in agreement with the analytical solution of uniform fertilization. The relative bias of fertilizer concentration between the analytical solution and computation calculated by the numerical model was less than 15%, which verified the feasibility of uniform fertilization method based on differential pressure tank. The results showed that the application of uniform fertilization method and the uniform fertilization method could basically achieve constant fertilizer concentration and flux based on differential pressure tank. According to the actual product, the relationship between valve opening and time could be obtained in order to realize the control of valve opening process by computer. Approximately 70% to 80% of fertilizer in the normal operation was within range of the excessive or insufficient amount, whereas the uniform fertilization method could effectively avoid the waste of excessive fertilization and the lack of insufficient fertilization. [ABSTRACT FROM AUTHOR]

Carbon trading is the market mechanism to reduce global greenhouse gas (GHG) emissions. Soil testing and formulated fertilization play an important role in reducing the fertilizer application and GHG emissions in intensive agricultural production area of China. In this paper, the methodology of upland GHG emission reduction in soil testing and formulated fertilization was proposed according to the basic process of carbon trade methodology. Huantai County, Shandong Province was chosen for the case study of tradable carbon calculation. The main conclusions were as follows: 1) Boundary of the project included the geolocation of upland crops and the production process of chemical fertilizers. Baseline of the project was CO2 emission in chemical fertilizer production and N2O emission in upland crop planting without soil testing and formulated fertilization, while the project activities were GHG emissions in above processes under soil testing and formulated fertilization. 2) In Huantai County, too much nitrogen and phosphorus fertilizer were added to the cropland, while potassium fertilizer was suitable. The average application amounts of nitrogen, phosphorus and potassium in wheat-corn rotation system were 515.1, 289.5 and 145.7 kg/hm2, respectively. The investigation of nitrogen fertilizer production enterprises showed that the average CO2 emission for the production of 1 t urea was 2.23 t (CO2 equivalent, the same as below). 3) The tradable carbon from soil testing and formulated fertilization was 26 485.8 t, and the farmland emission reduction, nitrogen fertilizer production reduction and phosphatic fertilizer production reduction accounted for 35.3%, 58.3% and 6.8%, respectively. Potassium production increased by 110 t emission, accounting for -0.4%. The situation was different in every town of the county because of the different crop area and fertilization. GHG reduction for Suozhen Town and Qifeng Town was 4848.6 and 6 180.3 t, respectively. The main reason was that too much fertilizer was used in these 2 towns. GHG reduction in Tianzhuang, Jingjia, Chenzhuang, Xincheng, Zhoujia and Guoli was between 1 700 and 2 300 t. GHG reduction in Xingjia, Maqiao and Tangshan was lower than 1 700 t, mainly because less fertilizer was used in these towns. 4) According to the carbon price of Shenzhen carbon trading market in March 2016, the emission reduction projects of soil testing and formulated fertilization in Huantai County could reach 12.86 million yuan, with 1.286 million yuan every year, which met the project requirement of small carbon trade. 5) The carbon trading methodology system that adopted the Denitrification and Decomposition (DNDC) model as the main measurement tool could achieve the carbon emission reduction calculation. The study has great significance to the implementation of GHG carbon emission reduction project from soil testing and formulated fertilization. [ABSTRACT FROM AUTHOR]