Design and Experiment of Layered Deep Fertilization Device of Different Fertilizers Based on Pneumatic Distribution

Abstract

Northeast black soil region is an important commercial grain production base in China, which plays an important role in ensuring national food security and promoting national economic development. Protecting the security of arable land resources in the black soil region of Northeast China is of great significance to maintaining the bottom line of the strategy of "basically self-sufficiency in grains and security of rations". However, the black-soil cultivated land has begun to degenerate significantly, and soil fertility has been declining year by year. In addition, due to long-term over-cultivation, high-intensity output and lack of protective measures, some serious problems, including black soil layer became thinner, organic matter decreased sharply, and plow bottom thickened were observed. All the aforementioned problems seriously affected the sustainable development of agriculture in the black soil area in Northeast China, since the large-scale reclamation of black soil. Therefore, changing the farming system and transforming conventional reclamation into conservation tillage was the key to solve the degradation of cultivated land quality in the black soil areas of Northeast China. A layered deep fertilization device combining ordinary compound fertilizer and slow-release fertilizer application method was proposed according to the demand of no-tillage or less-tillage sowing and fertilization of corn in the black soil region of Northeast China. Moreover, the problems of single type of fertilizer applied and non-obviously effect of existing layered fertilization devices were resolved under layered deep fertilization approach. The structure and working parameters were obtained through theoretical analysis and parameter's calculation. Main factors affecting the fertilization performance of the layered deep fertilization device were analyzed and determined. The backward and downward tilt angle of the wing shovel, and forward speed of fertilization were selected as the test factors, and the amount of fertilizer deviation stability coefficient in each layer was taken as the test index. A quadratic-regression orthogonal combination simulation test was carried out by the coupling simulation method of discrete element method (DEM) and computational fluid dynamics (CFD). A regression model between test index and influencing factors was established. Through the fitting and optimization analysis of the results, it was obtained when the backward and downward tilt angle of the wing shovel and the speed of fertilization was 58.11°, 52.84°and 3.38 km/h, the corresponding fertilization amount deviation stability coefficient of the upper, middle and lower layers was 8.50%, 6.54% and 9.10%, respectively. The layered deep fertilization device was processed with the optimized parameters and verified in field test. The results showed that field experiment had a similar tendency with the simulation test under the optimized parameters, which can meet the fertilization requirements.