Absorption Transformation And Utilization In Phyllostachys Edulis Forests

Nitrogen is one of the limiting factors for plant growth,which is the most important active nutrition that could be consumed easily.Moso bamboo（Phyllostachys edulis）is an important ecological and economical species of bamboo to the south China,which have fast growth,but the poor return ability,leading to the moso bamboo forest soil fertility falling,nitrogen fertilizer can improve the soil nitrogen content of moso bamboo forest.Moso bamboo by nitrogen absorption,transformation and utilization,thereby affecting the power of moso bamboo growth.¹⁵N tracer technique could distinguish resources of nitrogen efficiently,barometric process separation（BaPS）is a new method of soil nitrification and denitrification rate can be determined at the same time,which was widely used in the research nitrogen absorption,transformation and utilization of crop,but reported rare of moso bamboo forest.The application of nitrogen fertilizer can improve the soil nitrogen content and then improve the moso bamboo’s productive forces.In order to explore the absorption,transformation and utilization of moso bamboo forests,experiments of moso bamboo forests in Qingshan Town,Linan City,Zhejiang Province.By using the ¹⁵N tracer markers of urea with ¹⁵N tracer technique and barometric process separation（BaPS）,there were going to find out the competition ability,absorption distribution condition,using efficiency of nitrogen fertilizer（NUE）,and the season dynamic of the effects of nitrogen fertilization on nitrification and denitrification in moso bamboo forest.This research could provide the basic data for the exploration of moso bamboo forest and provide scientific basis for moso bamboo forest’s sustainable fertilizer management,there is a significant meaningful of moso bamboo forest’s intensive management.The main conclusions were as follows:（1）The season dynamic of fertilizer nitrogen competition ability（Ndff%）of moso bamboo was different in different ages: 1 a>3 a>5 a.The Ndff% of moso bamboo leaf,branch and stem rose gradually with the passage of fertilization time.The leaf and branch’sNdff% in different ages reached the highest top in the second year of autumn after fertilization,as the stem was in winter.Through the interannual comparison of every organ of moso bamboo,we found the Ndff% of moso bamboo leaf of 5 a had the largest growth,increased 51.24%year-on-year,the Ndff% of moso bamboo stump of 1 a had the largest slippage,reduced52.07% year-on-year.The result showed that the nitrogen content in each organ of moso bamboo would change and transform during the first two years after fertilization,there was a stronger competition ability of fertilizer nitrogen on moso bamboo leaf and branch than other organs,the young moso bamboo had stronger ability than the old moso bamboo.（2）The absorption and distribution ratio of ¹⁵N in moso bamboo’s leaf,branch,stem of different ages showed: 1 a >3 a >5 a.On the individual level,the ¹⁵N absorption of leaf,branch,stem reached the highest top in the second year of autumn after fertilization,the ¹⁵N distribution ratio of leaf showed a sharp increase.On the stand level,the ¹⁵N distribution ratio of stem and leaf was significantly higher than other organs.By comprehensive comparison of the distribution ratio of ¹⁵N on the moso bamboo stand level in these two years,the distribution rates in leaf and stem were higher than the previous year,the growth of 5 a moso bamboo leaf was the largest one,increased 104.15% year-on-year,the slippage of 1 a moso bamboo stump was the largest one,reduced 76.69% year-on-year.The result showed that in the second year after the fertilizer was applied,the fertilizer ¹⁵N in bamboo’s underground part would metastasize,fertilizer nitrogen ratios of the young bamboo were slightly higher than the old bamboo.（3）The NUE improved continuously.On the stand level,the total NUE was 38.59%±3.70% in January 2016,compared with the NUE in January 2015 it increased by 3.65%.The stem of moso bamboo had the highest NUE in different organs followed by leaf.On the individual level,NUE of moso bamboo in different ages showed: 1 a >3 a >5 a,the leaf,branch,stem of NUE of moso bamboo in different ages reached the highest top in the second year of autumn after fertilization.Through the interannual comparison of each organ in moso bamboo,the NUE of moso bamboo leaf of 5 a had the largest growth,increased 115.03%year-on-year.The NUE of moso bamboo stump of 1 a had the biggest drop,reduced 78.23%year-on-year.On the moso bamboo stand level,the NUE of moso bamboo leaf of 5 a had the largest growth,increased 111.11% year-on-year,and the NUE of moso bamboo stump of 1 a had the biggest drop,reduced 75.98% year-on-year.The NUE of stem of young moso bamboo increased continuously,old moso bamboo was more inclined to accumulating nitrogen in leaf,the fertilizer nitrogen and NUE reduced continuously in the underground part of moso bamboo,in order to make the preparation of nutrient for the young moso bamboo.（4）Fertilization can improve the soil content of total nitrogen（TN）,available nitrogen,ammonium nitrogen,nitrate nitrogen microbial biomass nitrogen（MBN）content and fertilizer nitrogen,the data between different soil layers showed: 0-20cm>20-40 cm.The fertilization to0-20 cm layers performed significantly.Soil ammonium nitrogen,nitrate nitrogen and MBN content were associated with soil temperature and moisture.The ¹⁵N percentage of soil to total nitrogen（Ndff%）and ¹⁵N residual ratio in soil decreased continuously with the passage of fertilization time,and it showed that the fertilizer nitrogen was gradually being used or leached,volatilized or denitrification lossed.（5）In the period from the first spring to winter after applying fertilizer,the nitrification rates and denitrification rates in fertilized moso bamboo forest in four seasons tend to rise before reducing,and it reached the highest top in summer.In fertilized moso bamboo forest,nitrification rates and denitrification rates were respectively 27.50% and 44.60% higher than unfertilized moso bamboo forest,the minimum value was in winter and autumn,nitrification rates and denitrification rates were respectively 45.58% and 402.56% higher than unfertilized moso bamboo forest.Fertilization could promote nitrification and denitrification in moso bamboo forest.There was an significant interaction with nitrification and denitrification rates between nitrogen fertilizer and seasons.And there was a positive correlation between soil temperature,moisture and nitrification rates,denitrification rates.As a whole,soil temperature related degree was higher than that moisture.（6）The paper brings forward: applying base fertilizer in spring is beneficial for moso bamboo forest,applying base fertilizer in winter again,which was propitious to the nitrogen absorption of leaf,branch,stem of moso bamboo,and this treatment that increasing the reserveof nutrients in the underground part of moso bamboo（stump,root,rhizome）to prepare for cultivating bamboo shoots or young bamboo.In autumn,the stem of moso bamboo had the largest nitrogen absorption,distribution,and NUE,this time was appropriate to cut down the old bamboo and keep young bamboo in order to obtain higher economic benefits.Considering that the nitrogen fertilizer can promote nitrification and denitrification at the same time,so we need to control the fertilizer dosage in order to avoid the denitrifying nitrogen loss and the destruction of the ecological environment.