Effects Of Nitrogen And Phosphorus Addition On Rhizosphere Soil Nutrients And Enzyme Activities Of Slash Pine Plantation

Slash pine is one of the important fast-growing timber species introduced in my country in the subtropical region,however,in recent years,the decline of soil fertility and plantation degradation caused by nitrogen deposition has become more and more serious.The rhizosphere is the main part of the forest that absorbs nutrients from the soil during the growth and development of the forest,active material exchange between forest roots and soil in the rhizosphere soil area.in most cases,the nutrient status of the rhizosphere soil determines the growth and development of the forest,rhizosphere soil is of great significance to the study of soil nutrient cycling and transformation.In this experiment,the 28-year-old slash pine plantation in Wanling Forest Farm in Xuanzhou District,Xuancheng City,Anhui Province was selected as the research object,Set up 4 types of nitrogen and phosphorus addition: control(CK,N 0 kg·hm-2·a-1 + P 0 kg·hm-2·a-1),low nitrogen(LN,N 50 kg·hm-2·a-1 + P 0 kg· hm-2·a-1),high nitrogen(HN,N 100kg·hm-2·a-1 + P 0 kg·hm-2·a-1)and high nitrogen plus phosphorus(HN+P,N 100 kg·hm-2·a-1 + P 100 kg·hm-2·a-1).By analyzing the effects of different nitrogen and phosphorus addition treatments on the rhizosphere and non-rhizosphere soil nutrients,enzyme activities and fine root nutrients of Slash pine plantation,Provide theoretical support and basis for soil nutrient transformation of Slash pine plantation under the background of nitrogen deposition and application of phosphate fertilizer,as well as forest reconstruction and sustainable management.Based on the research results of this experiment,the main conclusions are as follows:(1)The C/P ratio of rhizosphere soil under the combined treatment of nitrogen and phosphorus was 109.05,40.25% lower than 182.5(CK),significant difference.The C/P ratio of non-rhizosphere soil under the combined treatment of nitrogen and phosphorus was104.71,compared with 125.57(CK),it is reduced by 16.61%.The N/P ratio of the rhizosphere soil under the combined treatment of nitrogen and phosphorus is 3.47,41.78%lower than 5.96(CK),significant difference.The N/P ratio of the non-rhizosphere soil under the combined treatment of nitrogen and phosphorus is 3.8,compared with 4.42(CK)reduced by 16.31%.The C/P ratio and N/P ratio of rhizosphere soil under nitrogen addition treatment were significantly higher than those of non-rhizosphere soil.(2)Compared with CK,the co-addition of nitrogen and phosphorus reduced the ratio of C/P and N/P of rhizosphere and non-rhizosphere soil enzymes to a certain extent.(3)The C/P ratio of the fine roots of slash pine under the combined treatment of nitrogen and phosphorus was 452.67,compared with 1065.15(CK),it is reduced by 57.5%,significant difference.The N/P ratio of the fine roots of slash pine under the treatment of coaddition of nitrogen and phosphorus is 11.82,compared with 32.24(CK),it is reduced by63.34%,significant difference.In summary,add higher concentrations of nitrogen and phosphorus,contribute to the cultivation of large-diameter slash pine timber forests in the northern subtropical regions,and alleviate soil phosphorus limits.