Effects Of Fertilization On The Soil Nutrient Conversion And Utilization Rules

In resent years, coarse tillage methods were extensively adopted, the phenomenon of unreasonable and unscientific fertilizer application was frequently happened. In the thesis, methods of field experiments and pot culture were used to study effects of different fertilizer treatments on the soil N, P and K nutrient inversion, soil supply fertilization potential, reasonable fertilization amount and crops nutrient utilization rules in the high yield soil. These were very important to provide scientific theory support for soil nutrient coversion mechanism, and explore the fertilization technology of improving fertilizer utilization efficiency and crop's production. The main results were as followed:1. The results about the effects of phosphorus on the seedling growth and P conversion in the rhziosphere soil showed that compared with the high-P level, the height, total green leaf areas, shoot and root dry weight of two maize in low P level were reduced, while the ratio of root to shoot in dry weight increased. Moreover, soil pH was reduced, the phosphatase activity increased, numbers of bacteria and available P content lessened. Compared with non-rhziosphere, pH and available P content in rhziosphere were reduced while numbers of bacteria and actinomycete increased,but no related with P levels. Plant biomass and P content were positively related with root length,root surface area and bacteria number,while had no correlation with dry weight of root. Therefore, root morphology, pH and bacteria number in rhziosphere were the main factors affected plant growth. Compared with Jidan28 cultivar,Liyu 16 had higher height, total green leaf areas, dry weight and P content. Larger root length, root surface area, ratio of root to shoot, and more bacteria number.2. The results about the effects of different N forms on the N and P conversion in the rhziosphere soil showed that compared with the N deficiency treatment, total green leaf areas, plant dry weight in the urea and NH₄⁺-N treatments were increased, while root dry weight, the ratio of root to shoot in dry weight, root length and surface area were reduced. Moreover, N, P and K content of maize were enhanced. Compared with non-rhziosphere in the same N form of soil, pH was decreased, phosphatase and urease activities were improved, but available P were reduced, contents of NH₄⁺-N and NO3—N, numbers of bacteria and actinomycete were increased. Compared with other N forms, NH₄⁺-N treatment had the highest total green leaf areas, larger dry weight and NPK nutrient content in plant and root, greater root length and surface area, lessener soil pH, stronger phosphatase and urease activity and more available nutrient content of N, P and K in soil. The field experiment also proved the similar results were as bellow. NH₄⁺-N treatment was better, urea treatment was lesser and NO₃^--N treatment was the worst. It showed that NH₄⁺-N was propitious to maize growth, nutrient activation of root, absorption and utilization of nutrient of N, P and K. 3,P in soil could meet the needs of maize-wheat as a rotation cycle, N,K was needed for every season with rational fertilization under the soil conditions of organic matter 19.2 g/kg, available N 40.4 mg/kg, available P 37.3 mg/kg, available K 141.7 mg/kg. Three crop productions of maize-wheat-maize indicated that compared with NPK treatment, the treatments of CK, PK, NK and NP decreased 29.8%, 14.9%, 11.0%, 18.5%, resepectively. Yield and it's constitute factors of NPK (1) treatment was positively better than that of NPK (2) and NPK (3) treatments. Yield of NPK (1) reached 10783.2 kg/hm². Three crop productions of maize-wheat-maize indicated that compared with NPK (2) and NPK (3) treatments, the yield of NPK (1) treatment was increased 9.0% and 23.2%, resepectively.4,With the grow of maize of different fertilization treatments, NH₄⁺-N, NO₃^--N, available P and K content were waved in each soil layer. Among the 0⁶0 cm soil depth, NH₄⁺-N and NO₃^--N content gradually decreased,while appeared rising at the depth of 60-90 cm because of N leaching losses. Available P, K content of soil straightly reduced with the soil depth in the vertical distribution.To sum up, the control technologies, such as the soil nutrient kinds and forms, crop genetic characteristics and rational fertilization, can regulate to increase crop production and nutrient using efficiency. It is also significantly important for the realization of resource sustainable.