Effect Of Nitrogen Application On Nutrient Content Of Soil And Soybean Plant

The research was performed in botany practice and experiment base of northeast agricultural university from April to October in 2008. Field experiments used randomized block design. Three varieties of soybean were planted, including Heinong 44, Heinong 48 and Dongnong 4400. Three levels of nitrogen treatments were designed as N0, N50, N100.Under the condition of nitrogen application of 50kg/ hm2, we designed three topdressing treatments. And we looked 25 kg/ hm2 as seed manure,dressing nitrogen fertilizer of 25 kg/ hm2 was at different periods R1, R3, R5. The research was about the effect of nitrogen fertilizer on absorption regularity of N, P, K, and the effect of fertilizer provision from soil. Nitrogen application was used to analyze the connection between soybean quality and yield formation. The results showed that:The gradation of nitrogen content of different organs manifested as seed > leaf > caudex > footstalk. The peak of nitrogen content was at seed filling stage. Nitrogen content of Heinong 48 was the highest. Nitrogen content of Heinong 44 was the lowest. Dongnong 4400 was between them. Topdressing at initial blossoming stage could increase nitrogen content of soybean Heinong 44. While, topdressing at initial pod stage could increase nitrogen content of soybean Heinong 48 and Dongnong 4400.Nitrogen topdressing could promote nitrogen accumulation of soybean stem and grain. Seedling topdressing could promote leaves to absorb nitrogen. Topdressing at initial blossoming stage could promote flower pod and new leaf to absorb nitrogen.The change of soybean phosphorus content was small at seedling stage. Phosphorus content was highest at seed filling initial stage. Phosphorus content of soybean Heinong 44 was higher than that of Heinong 48 and Dongnong 4400 at the whole growth period. At seed filling peak period , phosphorus content with N50 treatment and topdressing treatment was higher than it with N0 treatment and N100 treatment. Topdressing in initial blossoming stage could promote soybean to absorb phosphorus, improve phosphorus content, and could be propitious to the formation of the fat.Potassium content of soybean is highest on full-bloom stage and seed filling stage. Potassium content with N50 treatment was higher than it with N0 treatment and N100 treatment. The appropriate nitrogen application could increase potassium content. The seed potassium content change was consistent in the same genotype soybean.Following with soybean growth period, all of them were decreased.In the whole growth period, available nitrogen content and available phosphorus content of soil with N0 treatment and N100 treatment were the highest. Available potassium content with NR5 treatment was the lowest.The change of available potassium content in soil was little at different growth period. Available potassium content with NR3 treatment was higher than other nitrogen treatments. The change trend of soil nutrient content were contrary to it of nutrient content in plant.The appropriate nitrogen application could increase the absorption of phosphorus and potassium. The gradation of protein content of different soybean varieties manifested as NR1 treatment >N50 treatment >N100 treatment >N0 treatment. Nitrogen fertilizer was able to increase soybean yield and protein content. Nitrogen fertilizer at initial bloom stage was able to increase protein content. The protein content of Heinong48 was higher than that of Heinong44 and Dongnong4400.At the soybean early growth stage, dry matter accumulation was less. The dry matter accumulation began to increase from flowering stage. The dry matter accumulation ratio from bearing pod stage to seed filling stage was higher, and reached the peak at seed filling later stage. The change of dry matter accumulation became steady at the mature period. The gradation of dry matter accumulation and yield manifested as Heinong 48 >Dongnong 4400 >Heinong 44. The high dry matter accumulation could increase the yield. Nitrogen topdressing could accelerate dry matter to accumulate at initial bloom stage and initial pod-setting stage. Nitrogen topdressing could significantly increase the yield by increasing pods and seeds number per plant. The yield with fertilization are higher than it without fertilization. The dry matter accumulation at later stage played an important role in yield formation. Soybean yield with N50 treatment was higher than it with N0 treatment and N100 treatment. Soybean yield with N0 was lowest. Nitrogen topdressing fertilizer at initial bloom stage and initial pods stage was able to increase the yield of Heinong 44. Nitrogen fertilizer at initial pods stage and initial seed filling stage was able to increase the yield of Dongnong 4400. Condign nitrogenous fertilization can ensure soybean high quality and high yield .