Search

This study aimed to assess the feasibility of a novel weeding and fertilization scheme, namely, mechanical weeding plus a one-time deep application of a reduced amount of slow-release fertilizer for rice cultivation. The effects of the weeding and fertilization method on rice yield and quality were investigated using a split plot test as the research method. Two weeding methods, namely, chemical weeding (CW) and mechanical weeding (MW), and four fertilization methods were tested, including the conventional fertilization method (quantitative split broadcast application of fast-release N fertilizer (CK)), the quantitative split broadcast application of 80% fast-release N fertilizer (LCK), the one-time base application of slow-release fertilizer (SR), and the one-time deep application of 80% slow-release fertilizer (LSR). The results showed that the rice yield under MW with LSR treatment can maintain a high level—higher than 9.2 t ha−1 per year. This was attributed to the slow-release fertilizer and deep fertilization, which increased the number of stems and tillers in the pre-fertility and spike rate, respectively, resulting in a high panicle number with a 20% reduction of N fertilizer. Furthermore, mechanical weeding improved the seed-setting rate, resulting in a higher number of grains per panicle, a higher panicle number, and an increased thousand-grain weight, thereby maintaining a high yield. At the same time, the quality of rice under MW with LSR treatment improved, specifically reflected in the significant improvement of the processing and appearance quality of rice, a slight increase in protein content, and a reduction in the amylose content, thereby improving its nutritional quality while maintaining good cooking quality. [ABSTRACT FROM AUTHOR]

• Fertilizer distribution depends on the speed at the outlet of the mixing cavity. • Uneven dispersion of fertilizer granules due to directly falling from blade gaps. • Fertilizer mixed by double-blade has lower outlet speed than that of single-blade. • Mixing effect of multi-fertilizers by air blowing & double-blade stirring is best. In proportional variable-rate fertilization, improving the uniformity of multi-fertilizer mixing helps to improve the overall utilization efficiency of fertilizers. In this paper, a multi-fertilizer mixing by air blowing and blade stirring was presented. Using fertilizer granules mixing uniformity as an indicator, the method optimized the structures and working parameters of single-blade group stirring, double-blade group stirring and air blowing & double-blade stirring. EDEM and Fluent software were used for the simulation and the results were verified by experiments. The simulation results showed that the appropriate speed range of single-blade group stirring was 600 ∼ 900 r⋅min−1 and the highest mixing uniformity was achieved with the blade mounting angle α of 20°. The best structure of double-blade group stirring was achieved with an upper blade mounting angle β of 20°, a lower blade mounting angle θ of −20° and a spacing h of 89 mm. For the air blowing & double-blade stirring method, the best results were achieved when the input air velocity v a was 8.4 m⋅s−1 and the blade speed of agitator n b was 740 r⋅min−1. The mixing uniformity of nitrogen (N), phosphate (P) and potash (K) fertilizer granules reached 98.41%, 98.12% and 98.31%, respectively. The bench test results showed that the mixing uniformity by air blowing & double-blade stirring was better than that by double-blade group, and the mixing uniformity by double-blade group was better than that by single-bladed group, which were consistent with the simulation results. Meanwhile the differences between experimental values and simulation values were within 2%, which showed that the simulation models were reliable. Results from this study can be used as reference for the design of mixing devices of variable-rate fertilization. [ABSTRACT FROM AUTHOR]