Effect Of Long-term Fertilization On Nitrogen Fixation Ability Of Soybean

As important grain crops and oil plants in China, soybean is the highest nutritional value invarieties of beans. But because of the impact of foreign imports of soybeans, soybean pricescontinued to fall and soybean planting area decreased year by year. Therefore, there is in urgentneed of some effective measures of boosting output of soybean to obtain cost-effective, meetingthe needs of the people. In order to study the effects of different fertilization methods underlong-term fertilization on growth and nitrogen fixation in soybean, four fertilization ways isselected, named different amounts of nitrogen fertilizer, phosphate fertilizer, balanced fertilization,different organic and inorganic fertilizer,which is based on the long-term experiment in HailunAgricultural Ecology Station of Chinese Academy of Science. The followings are experimentalresult:(1) Long-term application of N fertilizer significantly increased the plant height andchlorophyll content, promoted the dry matter accumulation. Plant height, chlorophyll content andbiomass of plants was the maximum under N3P2K treatment owing to the different levels ofnitrogen, which inhibited the formation and growth of soybean rhizobia, reduced the number ofnodules and nodule dry weight, decreased nitrogenase activity. With the compared to low nitrogen,other treatments got the weak of nitrogenase activity of nodules. We can improve the yield ofsoybean, increase pod number per plant and grain number in the way of increasing the amount ofnitrogen fertilizer. But compared with N1P2K, N2P2K, N3P2K decreased slightly the yielddecreased by6.8%,1.1%, respectively.(2) Application of P fertilizer on soybean won little influence in soybean plant height andchlorophyll content, and it was not significant difference between different quantity of phosphatefertilizer. Applying different quantity of phosphate fertilizer on soybean had an effect on plant drymatter accumulation mainly in flowering and podding stage. N1P3K and N1P2K treatmentcompared with N1P1K treatment reached p<0.05difference significant level, but has little effecton soybean growth early. With the increase of the quantity of phosphorus, nodule number andnodule dry weight would increase. N1P2K treatment of nitrogenase activity was the strongest whatcompared with CK and N1P3K, an increase of74%and1.5%. Yield of soybean were significantlyinfluenced by phosphorus fertilizer, so phosphorus fertilizer can significantly increase the podnumber per plant, seed number per plant and grain weight, and get high yield. Compared with CK, N1P3K treatment increased the yield by27.3%, at the same time between different amount ofphosphate fertilizer reached significant difference level.(3) Long-term balanced fertilizer to promote the growth of soybean. NPK had the highersoybean plant height, maximum chlorophyll content and plant biomass. Balanced fertilizationinhibited the ability of soybean nodule nitrogen fixation, what were significantly lower than thosein CK treatment that nodule number, dry weight of nodules and nitrogenase activity. Pods per plantand grains of NK treatment were higher than other treatments, PK treatment received a higher seedweight. Soybean yield was the highest in the conditions of balanced fertilization than those withCK treatment, the yield increased39.4%.(4) It is application of organic and inorganic fertilizer that increase soybean plant height andchlorophyll content, and promote the soybean plant dry matter accumulation. Different types oforganic fertilizer had same effect on the growth of soybean, but increasing organic fertilizer haslittle effect on soybean plant height, chlorophyll content and plant biomass. A small amount oforganic fertilizer can promote soybean nodule formation and a large amount of organic fertilizer onsoybean root nodule azotification has the obvious inhibitory action. Organic and inorganicfertilizer can improve the yield of soybean, as follows: With the increase in the number of organicfertilizer, yield components factor was a growing trend. Compared with CK, the yield of highamount of straw increased61.3%, the high amount of pig manure treatment increased49.8%.Though the data analysis, the treatment of balanced fertilization can significantly increasesoybean yields, but there is a certain inhibition of soybean root nodule nitrogen fixation capacity;Application of organic fertilizer can further increase production on the basis of balancedfertilization, and can alleviate the suppression of balanced fertilization on of soybean nodulesbiological nitrogen fixation. Therefore, within the study area, mixing balanced fertilization andorganic manure is the best fertilizer of planting soybeans.