Effect Of Fertilization On Larix Principis-rupprechtii Mayr Woodland Soil Fertility Degradation

Larix principis-rupprechtii Mayr has been attach importance to production because of rapidgrowth, straight trunk, excellent material, easy propagation, high rate of surivival. Originallyintroduction revealed better growth condition, however the growth potential decreasedsiginificantly in recent years since1958which Shaanxi province had introduced and plantedLarix principis-rupprechtii Mayr. in Qinling and Huanglong forest area. This study selectedsample sites from wild forest in nantanmiaopu forest station of Taibai Bureau and Huoditangforest station of Norwest Agriculture and Forest University, studying the wood of soil nutritioncontent, soil enzyme activities, and soil microbe quantity in different growth years of Larixprincipis-rupprechtii Mayr, aiming to reveal the forms and period of recession of Larixprincipis-rupprechtii Mayr. In this study, there are5different forest ages gradient, including5years old,10years old,20years old,30years old and40years old Larix principis-rupprechtiiMayr, respectively. The conclusion of this study is below:With the growth years of Larix principis-rupprechtii Mayr. age increasing, there appears thetrendy of soil acidification, especially in the deeper soil layers. Soil organic matters, ammoniumnitrogen and available phosphorus was decreased from5years old to20years old, but increasedfrom20years old to40years old. This varied index which can be used to demonstrated thevariation of soil nutrition revealed significantly recession of Larix principis-rupprechtii Mayr. at20years old.With the growth years increasing, soil catalase activities, phosphatase activities, ureaseactivities and invertase activities was declined first and then increased, the lowest contentoccurred in20years old, the decline of phosphatase years old from5years old to20years oldwas not significant, however soil catalase activities, urease activities and invertase activitieswere significantly rise after a significant decreased. Soil enzyme activities as indicators of soilnutrition revealed20years old woodland is a most obvious recession age.With increasing age of Larix principis-rupprechtii Mayr., soil microbial (bacteria,actinomycetes and fungi) quantity was significantly decreased from5years old to20years old,but increased from20years old to40years old has this change actinomycetes most significant. In soil, the activity of microorganism is important to matter recycling and energy flow, and itsactivity level can be as a target which reflect the strength of soil nutrients, thus affecting thegrowth of Larix principis-rupprechtii Mayr. Woodland soil fertility also showed a decline in themost significant at20years old from the perspective of microbial.In conclusion,20years old Larix principis-rupprechtii Mayr. woodland fertility is the mostsignificantly soil degradation, therefore we selected20years old Larix principis-rupprechtiiMayr. as the object of study, which "fertilization on North Larch woodland soil degradation,"soil nutrients, soil enzyme activities, soil microbial activity and soil fertility as a number of themeasure of targets, aims to explore whether mitigation Larix principis-rupprechtii Mayr.woodland soil fertility degradation can play a role in fertilization. The main conclusions are asfollows.Different fertilizer treatments made the Larix principis-rupprechtii Mayr. soil acidificationin different degrees, Soil pH level returned to the original level gradually with the time whenfertilizer was applied, which indicated fertilizer treatment on Larix principis-rupprechtii Mayr.was temporary.Soil nutrition was increased in different degree with different treatments of fertilization.Nitrogen and phosphate fertilization treatment could increase the content of soil organic matter,ammonium nitrogen and nitrate nitrogen, fertilization effectively relief the situation of soilnutrition inefficient.Different fertilizer treatments increased soil phosphatase and invertase activities, butexcessive application of nitrogen fertilizer reduce soil phosphatase and invertase activity;catalase was insensitive to fertilization. Soil enzyme was one of the major indicator of soilfertility, the fertilization effectively improve soil fertility Larix principis-rupprechtii Mayr fromthe angle of soil enzyme activity;Fertilizer treatment increased soil bacteria, soil actinomycetes, soil fungi quantity indifferent degree, but excessive application of nitrogen fertilizer reduce soil fungi quantity.In conclusion, the reasonable measures of fertilizations can effectively relieve soil fertilitydegradation of20years old Larix principis-rupprechtii Mayr.