Effect Of Nitrogen And Phosphorus Supply Levels On Productivity And The Soil Nutriment Feature Of Alfalfa

In arid areas northwest of Lanzhou City, Gansu Province, used " Gannong No.3" alfalfa(Medicago sativa L. cv. Gannong No.3) as material, by a randomized complete block design,simulation plot field experiments conducted to study the effect of three nitrogen levels(0,51.75and103.5kg hm-2) and three phosphorus levels (0,126and252kg hm-2) and twomowing times (3times and4times) on plant height and quality of annual and2year"Gannong No.3" alfalfa, as well as the growth of the first two years of activity, changes in soilnutrient content of alfalfa and related enzymes of nitrogen metabolism related to alfalfa.Conclusions are as follows:(1)Fertilization can significantly increased the yield of " Gannong No.3" alfalfa grownin different years, planting the first year and2-year fertilization fresh and hay yields weresignificantly higher than those without fertilization. Under the same fertilization, the yield oftwo-year alfalfa was significantly higher than the first year; nitrogen and phosphorusinteraction process the fresh and hay yield, the highest amount of fertilizer was N103.50kg hm-2+P2O5126kg hm-2when the hay production was highest. Single application of nitrogensignificant differences between the nitrogen treatment, and with the increase of nitrogensupply increases; alfalfa planted the first year compared to the first two years of significantgrowth, nitrogen application significantly increase over a single P fertilizer treatment,described in this study under the condition," Gannong No.3" then fertilizing alfalfa plantingmore effective, especially nitrogen yield more obvious, the second year is still a usefulfertilizer.(2)Nitrogen and phosphorus fertilizers can significantly improve crop crude proteincontent, lower neutral detergent fiber and acid detergent fiber content of " Gannong No.3"alfalfa each year, in the first year of each fertilization treatment mow four times higher thanmowing three times cut neutral, acid detergent fiber content lower in the second year and thefirst year of law consistent with alfalfa planting fertilizing year better, and can improve theyield and quality of good alfalfa coming year.(3)" Gannong No.3" alfalfa year in grown with irrigation, through the regulation ofnitrogen fertilizer can increase the yield of alfalfa and mow cut4times the yield wassignificantly higher than mowing3times; increased crude protein content of alfalfa, reducingthe of detergent fiber and acid detergent fiber content, mow four times had better quality;increase in plant height, promote regeneration, considered from the production point of view,the proposed " Gannong No.3" alfalfa in nitrogen and phosphorus under N103.5kg hm-2+ P2O5126kg hm-2conditions for planting then can achieve four times mowing.(4)Fertilization can significantly improve " Gannong No.3" alfalfa soil base of each cropnitrogen content and urease activity, with the increase of nitrogen increases; simultaneouslycan significantly improve the phosphorus content and alkaline phosphatase activity. Eachstubble soil nutrient content and activity are expressed as0~20cm maximum. Fertilizationhad no significant effect on soil total nitrogen, total phosphorus content." Gannong No.3"alfalfa yield (y) and soil nitrogen content (x1), urease activity (x2), phosphorus content (x3) andalkaline phosphatase activity (x4) comply with the linear regression equation y=-2976.953+53.577x1+216.824x2+58.534x3+12.145x4(R2=0.874**). Soil nitrogen content (x) andalfalfa crude protein content (y) in line y=0.203x+8.567(R2=0.472**) linear regressionrelationship with the total amount of protein in alfalfa (y) in line with a linear equation y=40.362x-567.609(R2=0.433**).(5)Nitrogen can promote the activity of alfalfa nitrogen metabolism, nitrogenassimilation are promoting all aspects of the role, thus contributing to the synthesis ofnitrogen metabolism in the direction of promoting beneficial protein synthesis, and promotenitrogen accumulation, thereby increasing protein production. When nitrogen was103.5kg hm-2, nitrogen metabolism-related enzyme activity was the highest of each crop alfalfa, andnitrogen rate (x) and total protein alfalfa (y) in line with a quadratic equation y=-0.113x2+53.632x+1681.911(R2=0.999**)." Gannong No.3" alfalfa crop nitrogen metabolism ofeach activity, soluble protein content and nitrogen accumulation was a significant positivecorrelation, indicating that nitrogen fertilizer can promote the growth of alfalfa leaf function,improve activity and nitrogen metabolism nitrogen accumulation.Comprehensive regulation of nitrogen and phosphorus in alfalfa production performance,quality, nitrogen metabolism enzyme activity and soil nutrient content related enzyme activityof " Gannong No.3" and alfalfa grassland in the study area planted alfalfa then fertilization isnecessary, first2years fertilization is still useful. Fertilization has a positive effect on theyield and quality of alfalfa nitrogen metabolism to promote activity, increased nitrogenaccumulation, and can improve soil nutrient content and activity, promote soil nutrientabsorption, utilization and transformation. Optimum fertilization of alfalfa in the area ofN103.5kg hm-2+P2O5126kg hm-2, with under irrigation conditions suitable for mowingfrequency to four times.