Effects Of Fertilization Methods On Root Growth, Nutrition Absorption Of Rice And Soil Nutrition Distribution

Rice took outstanding position in food production in China. Along with the large-scale rural labor force shift, rice production should shift to mechanization and simplification. Fertilization method is one of the important factors influencing the fertilizer use efficiency. The effect of different fertilizer placement on the growth of crop roots and absorption of nutrients was significant. In this paper, we carried out investigation and pot experiment to study suitable fertilization method and location combining with the rice root characteristics. All of them would provide the basic knowledge and technical parameters for the mechanized application, and the main conclusions are as follows:(1) It was found that numerous problems of rice production including rural labor shortage, rice planting area reduction, time consuming traditional planting way, simple and crude fertilization and unbalanced nutrient application. The article points out countermeasures for the existing problem including light simplified, mechanization and rationalization of fertilization. Eventually it summarized that reasons for the low level of mechanization of rice production in the prevalent Mechanization background, and proposed the advantage and research progress of improving mechanical integration.(2) The effect of different fertilization depths on rice seedling growth was obvious. The results showed that root biomass and nutrition absorbing of 1 cm treatment were significantly higher than those of others. The root biomass of each soil layer in the fertilization treatments was higher than that of no fertilization treatment. The lower root biomasses of 1 cm treatment were significantly increased. Inorganic nitrogen, available phosphorus and potassium content of 1 cm and 5 cm showed significantly higher than others in 0 ~ 10 cm soil layer. The method of appropriate fertilizer in shallow soils kept available nutrients mainly concentrated in the upper soil. The 1 cm treatment could improve the root activity; increase the proportion of the lower root and benefit of the root architecture building. The effect of fertilization methods(1 cm and 5 cm of focus methods, 0~5 cm and 0~10 cm of mixed methods) and nitrogen fertilizer application(N0, N0.3, N0.6, N0.9, N1.2) on the biomass, root morphological parameters and nitrogen absorbing rice seedling on the conditions of potting soil column experiments were obvious. The results showed that the biomasses of shoot and root of N0.6 and N1.2 showed significant advantages compared to other treatments under the fertilizer in shallow soils of focus method and mixed method, respectively. The fertilizer in shallow soils of focus and mixed methods were beneficial to the improvement of the rice root morphology characteristics and nutrient absorption under low and high nitrogen fertilizer application, respectively. With the growth of rice root, nutrition of fertilization in shallow was in short supply in late stage. The root growth, grain yield, nutrition absorption and nitrogen use efficiency of separated layer fertilization were higher than others. It increased the number of deep root and improved the lodging resistance of rice. The trend of soil inorganic nitrogen migration was obvious with the water. Nitrogen in the soil could not be absorbed by rice root and easy to loss when fertilizer was away 10 cm from the soil surface. Therefore separated layer fertilization should kept 0~5 cm in shallow soil and 5~10 cm in deep soil.(3) Results showed that the biomass,root bleeding sap and its composition of root zone fertilization treatment(T2) was significantly higher than others at tillering stage. When rice was harvested, biomasses and nutrition absorption declined first and then rose with the increasing of fertilization site close to root zone and treatment T3 showed the highest. The treatment of fertilization site more than 8cm close to root zone was significantly lower than treatment T1. Soil available nutrition content of treatment T1 had no significant differences with others at tillering stage, and became higher the farther fertilization site close to root zone. Soil nutrition content in root zone compartment of treatment T2 was significantly higher than others. Of all the differences among treatments, the greatest one was available phosphorus, available potassium took second place, and the least one was inorganic nitrogen. Soil nutrition content in root zone compartment declined most steeply in harvest time. Soil available nutrition content in root zone compartment of fertilization site close to root zone was higher. It could promote rice yield formation and increase nutrient absorption. The nutrition migrating to rice root was limited and difficult to be absorbed, if fertilization site was more than 8cm close to root zone.