| China has large rice cultivation area, and rice planting patterns varied very much. Rice planting mechanization is one of the technical difficulties to realize full mechanization in rice production. Mechanization of direct-seeding is a light and simplified rice cultivation technique pattern with the advantages of saving labor, time and energy. Due to fact that it is susceptible to area, rice variety, crop rotation and cultivation custom, mechanized rice direct-seeding can be only applied in appropriate areas. According to the problems of full seedling, lodging, weeding and yield in manualrice seeding, this research proposed a precision rice hill-drop drilling technology with synchronous furrowing and ridging. Combined with improvement of the machines and devices, this study researched two key technologies, precision hill-drop drilling and furrowing and ridging. Main research contents are as follows:(1) A precision rice hill-drop drilling technology with synchronous furrowing and ridging was researched to meet the requirements of rice planting in orderly columns and rows. In one single pass, it creates a ridge, opens the drilling furrow on the ridge and water furrow in between the ridges, and sows pre-germinated rice seeds in the drilling furrow synchronously. Basic theories of main technical features of precision hill-drop drilling and furrowing and ridging were discussed in this paper. To match the seeding density of different rice varieties, the machines can be adjusted with different row spacing, mainly including 20 cm or 25 cm. The hill spacing can be adjusted from 10 cm to 20 cm. The amount of sowing seeds pre hill can be adjusted from 3 to 10 grains or from 10 to 20 grains. According to the relationship between the water content and plastic range in paddy soil, better water content range is determined to be 40-50% for the precision rice hill-drop drilling machine, which can open seed furrows(Upper width 5cm, lower width 3cm, depth 3cm) and water furrows(Upper width 7cm, lower width 5cm, depth 6cm). To meet the technological requirements of precision hill-drop drilling, furrowing and ridging, and seeding and spraying, two types of precision rice hill-drop drilling machines were designed in this study.(2) Precision hill-drop drilling is one of the most effective ways to achieve reasonable growth of rice groups. Comparison experiments were carried out from different ways of rice planting and different ways of rice direct seeding. Results show that precision rice hill-drop drilling can improve the lodging resistance and reduce the lodging index. The mechanized rice drilling technology has advantages of promoting rice individuals, optimizing the allocation of rice groups, such as increasing some individuals growth duration roots, dry weights and other indicators. Therefore, the mechanized precision hill-drop drilling technology is beneficial to achieve high and stable rice yields.(3) In order to solve the problems such as seedling miss, shallow root and lodging etc., contrast tests were conducted between machines with opening furrows and forming ridges synchronously and without opening furrows. Results show that precision rice hill-drop drilling technology with seed furrowing can guarantee a good seedling emergence in orderly columns and rows and improve the seedling emergence rate by up to 14.9%. Precision rice hill-drop drilling technology with seed furrowing and water furrowing cannot only reduce the effect of rice lodging index, but also improve the root morphology index and dry weight accumulation of some parts of the growth period. Thetechnology with furrowing and ridging synchronously has no significant effect on the rice yield. However, different rice varieties had some differences in the response to three furrow opening methods.(4) A weeds control technology with synchronous seeding and spraying was proposed in order to solve the technical problems of weeding which support the rice mechanical hill-drop drilling technology. Its adaptability on field production and the active ingredients of herbicide residues and dynamic rule of herbicide degradation in the soil, water, and plant were studied as well. Three kinds of herbicides,Pendimethalin, Sofit(pretilachlor) and Zhibojing(pretilachlor), were applied in this study to support rice mechanical hill-drop drilling technology. The phytotoxicity residuals were undetectable in the rice plants and degradation rate of active ingredients in soil and water was above 95% after 20 days. Compared with Pendimethalin, Sofit(pretilachlor) had a better adaptability and a smaller influence to rice germination, growth and yield. There were more active ingredients of herbicide by using the approachwithsynchronousseeding and spraying than that with spraying three days after seeding. Herbicide residue time in the water was found to belonger than that in the soil, and Sofit(pretilachlor) had higher content of active ingredients than Zhibojing(pretilachlor) in both soil and water. Obviously, it is better to spray herbicide synchronously while seeding, but it still needs to further study the suitable spraying concentration which should be adjusted based onsoil moisture content of the paddy field.(5) Application and extension of the designedrice mechanical hill-drop drilling technology has been carried out throughout the country from 2006 to 2015. Application effects in different parts of China were investigated and analyzed, including rice yield, rice quality and economic benefit. Results show that precision rice hill-drop drilling technology with synchronous furrowing and ridging can guarantee the rice yield to a certain extent. Compared with the manual broadcasting, precision rice hill-drop drilling can increase rice yield by more than 16.7%. Compared with the other rice transplanting technologies, there was no significant difference between them. Precision rice hill-drop drilling technology is beneficial to improve head rice yield. Rice planted with precision rice hill-drop drilling has been proved to have 9.11%, 27.02%, 4.08%, and 11.11% higher head rice yield than that with mechanical transplanting in Nanling Anhui, Mianzhu Sichuan, Wensu Xinjiang, and Gaoqing Shandong, respectively.Precision rice hill-drop drilling technology can save the cost of production by 14.4%, 7.7% and 7.9%, compared with the manual transplanting, manual seedling broadcasting and mechanical transplanting, respectively. It also can increase the average income by 80.0%, 46.6%, 36.0%,18.1% and 6.1%, compared with the manual transplanting, manual seedling broadcasting, manual broadcasting, mechanical transplanting and mechanical drilling, respectively.Overall results of this research show that precision rice hill-drop drilling technology can achieve rice planting in orderly columns and rows withbetter ventilation and lighting. This technology can also improve seedling emergence rate and lodging resistance of direct-seeding rice. It has better grain yield, rice quality and economic benefit as well. This research can not only provide theoretical basis for improving design of precision rice hill-drop drilling machines with synchronous furrowing and ridging, but also provide technical reference for production of rice mechanical hill-drop drilling technology. |
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