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The existing studies of threshing process of combine harvesters adopt the assumption of constant mass, which is contradictory to the phenomenon of separation of grains and short stalks in actual threshing process. Therefore, the characteristics of threshing and separation are not accurately described. Aiming at this problem, this study established the tangential-longitudinal threshing and separation test-bed with tangential-flow device, auxiliary feed beater, and longitudinal-flow device of tangential-longitudinal-flow combine harvester and conducted experiments and analysis of rice threshing with feed rates of 5, 6, and 7 kg s^-1. The results showed that the changes in rates of material flow along the arc-length of concave in tangential-flow device and longitudinal-flow device were equal to the changes in rates of material density with time. In the process of variable-mass and constant-mass rice threshing, when the feeding rates were 5, 6, and 7 kg s^-1 in the test-bed, the flow rates from the tangential-flow device were 4.07, 5.01, and 5.95 kg s^-1, respectively. The average power consumption of the tangential-flow drum in variable mass threshing process was higher than that in the constant mass threshing process by 2.16, 2.73, and 3.09kW, respectively. The flow rate at the outlet of the longitudinal-flow device was 3.34, 4.04, and 4.72 kg s^-1, respectively. The average power consumption rate of the longitudinal-flow drum in variable mass threshing process was lower than that in the constant mass threshing process by 7.32, 10.44, and 12.17kW, respectively. The results of material flow rate and power consumption would offer the basis for the design of longitudinal-tangential flow threshing and separation device.

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The effects of banana continuous cropping on soil quality and chemical properties and crop yield were investigated under continuous cropping for 1, 3, 5, 7, 10, and 15 years in Hainan province, China. The results indicated that the contents of total N, total K, available K, NH₄-N, exchangeable Ca, and available Cu tended to increase, while total organic C (TOC), available S, and available Zn tended to decrease with the increase of continuous cropping years at the four sampling stages. The contents of exchangeable Mg and available Fe and Mn were higher in the 3, 5, 7, and 10 years than in the 1 and 15 years at the four sampling stages. The values of pH, the contents of total P and available P decreased from 1 to 5 years and increased from 7 to 15 years at most of the sampling stages. Overall, average banana yield increased from 1 to 3 years and decreased afterwards. In conclusion, banana continuous cropping deteriorated soil quality as evidenced by increase of soil acidity, decrease of total organic C, accumulation of N, P, K, Ca and Cu, deficiency of Mg, S, Fe, Mn, and Zn and accompanying decline in banana yield. In order to improve the soil environment and sustain higher productivity under continuous-banana cropping system, application of balanced rate of fertilizers is of considerable importance.

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The negative impact of excessive fertilization on the sustainable development of agriculture has become the focus of universal attention. Thus, the aim is to maximize the yield of rice without imposing too much damage on the environment. This paper uses data regression analysis based on the statistical data (from 1990 to 2020) of a certain region to explore the impact of fertilizer application on rice yield, and adopts the sensitivity analysis to study the sensitivity of rice yield to the applied amount of chemical fertilizer. The results show that the average rice yield increased with increasing Nitrogen (N) and potassium (K) fertilizers application within the statistical data range; while the average rice yield decreased as Phosphorus (P) fertilizer application increased. Simultaneously, increasing the application of N and K fertilizers improved the average rice yield. Reducing the amount of P fertilizer and increasing the proportion of K fertilizer positively affected the average rice yield. The sensitivity analysis indicated that the average rice yield was most sensitive to K application amount. The sensitivity value maximized at a small amount of N fertilizer (11.25 kg hm^-2) and a large amount of P fertilizer (6 kg hm^-2). The findings reveal the interactive effect of multiple fertilizer application rates on grain yield and address the unclear mechanism of single fertilizer application on grain yield in the existing research. This paper provides a theoretical basis for scientific fertilizer use, agricultural quality, efficiency improvement, and sustainable development of agriculture.