The Effect Of Fertilization On Soil Fertility And Fertilizer Use Efficiency In The Montane Jujube Forest

In order to explore the effect of fertilization on soil fertility and fertilizer use efficiencyin the montane jujube forest of Loess Hilly Region, improve the fertilization systems, this teststudied on the fertilization on the soil nutrient content,enzyme activities,yield,fertilizer useefficiency under different water management(drip irrigation,straw mulch,pit scale), andevaluated the correlation between soil enzyme activities and soil fertility, the material used inthis test was the soil under successive5years fertilization and the yield. The conclusion fromthis test was:(1) The combination of NPK could increase the soil organic matter and nutrient contentsignificantly, and the effect of increased was better than the single use of N,P,K or combinedapplication of two. In the drip irrigation condition, the soil organic matter content increased1.30g/kg in the N1P3K3treatment, the increase amplitude was by35.52%. In the0⁴0cm layer, the treatment affected it significantly and decreased with deepening of soil. Thecontent of soil total nitrogen increased0.30g/kg in the N₃P₁K₃treatment, which was the mostobvious, the increase amplitude was by100.00%, the highest content of total nitrogenwas0.80g/kg which appeared in the20⁴0cm layer. The soil available nitrogen contentincreased15.57mg/kg in the N3P1K3treatment, which was the most obviously, theincrease amplitude was by133.19%. The content of soil available phosphorus andpotassium were6.40mg/kg and173.26mg/kg respectively in the N3P3K1treatment,which were the highest. The combination of NPK had the also best effect on increasing thefertilizer in the drip irrigation and straw mulch condition. The soil organic matter content wasdrip irrigation＞straw mulch＞pit scale.(2) The pH value decreased to different degree under different water management, butthere was no significant difference in the different treatment. The trend of soil acidificationcould be caused by different fertilization.(3) In the0-60cm layer the soil enzyme activity affected by successive5yearsfertilization measures significantly, in which the jujube root aggregated, the soil enzymeactivity lowered with the deepening of soil layers. The nitrogen fertilizer could increased theurease activity in the182kg/hm²⁴50kg/hm², and the urease activity increased more in treatment with nitrogen rate of182kg/hm²than the rate of450kg/hm². The soil phosphataseactivity was63.46μg/g, which was the highest level. The combination of NPK could increasethe catalase activity significantly, the other fertilization measures could not affect. There wasnot obvious difference among0²0cm,20⁴0cm,40⁶0cm layers at the catalase activity.The effect of invertase activity in the0²0cm layers was the most obviously, it increased by13.00μg/g¹46.37μg/g compared to control.(4) The correlation between soil enzyme activities and soil fertility. There weresignificant positive correlation between soil urease and phosphatase activities with thecontents of organic matter,total N,available N,available P, invertase and catalase activitieswith the contents of organic matter,total N. The result of the path analysis showed that soilorganic matter,total N were important factors of affecting activities of urease, phosphatase,invertase and catalase. The results derived from correlation analysis, path analysis andprincipal component analysis indicate that the four enzyme activities can be used to evaluatesoil fertility in the montane jujube forest of Loess Hilly Region.(5) The effect of fertilization on yield of jujube under drip irrigation condition wassignificantly greater than that of straw mulch and pit scale, the result showed that water couldimprove the fertilizer efficiency. The economic benefit of jujube was154717yuan/hm²inN1P3K3treatment under the conditions of drip irrigation, which was the highest. It increased54019yuan/hm2compared to control. The net income was90629å…ƒ/hm²in the N3treatmentunder straw mulch condition, which was the highest. The economic benefit increased27986å…ƒ/hm², the increase amplitude was by43.74%compared to control.(6) The combination of NPK could increase the nitrogen,phosphorus,potassiumagronomic efficiency significantly, while the nitrogen agronomic efficiency increased withthe fertilizer application rate reduced.