Effects Of N And P Additions On C And N Pools Of Rhizosphere And Non-rhizosphere Soils In A Subtropical Evergreen Broad-leaved Forest

Rhizosphere through rhizosphere activities affects plant growth and soil environment,which is transferring water and nutrient with roots,making nutrients contents of rhizosphere soil and non-rhizosphere soil different from each other.It is quite different that the addition of nitrogen and phosphorus change the availability of soil nutrients.Roots nutrients,plant growth and rhizosphere activities will be further affected,causing the feature of rhizosphere and non-rhizosphere carbon and nitrogen pool through rhizosphere activity.The feature of carbon and nitrogen pools in rhizosphere and non-rhizosphere soils and the differences between them will also change.In order to study the effects of fertilization on rhizosphere and non-rhizosphere C and N pool in evergreen broad-leaves forest,four treatments were conducted at the following levels:CK(0 kg N/hm~2/yr),N(100 kg N/hm~2/yr),P(50 kg P/hm~2/yr)and NP(100 kg N/hm~2/yr+ 50 kg P/hm~2/yr).We did 1 year seasonal soil sampling to analyze C and N pool of rhizosphere and non-rhizosphere to different fertilization.Results are following:(1)Effects on soil C pool of rhizosphere and non-rhizosphere soil to nitrogen and phosphorus additionIn different treatments,SOC,DOC and LOC contents were significantly larger than those in non-rhizosphere soil,but LOC/SOC was lower than that in non-rhizosphere soil.In the rhizosphere soil,the DOC contents and LOC/SOC decreased significantly in the +N treatment,but the DOC contents significantly increased in +P and +NP treatments.In the non-rhizosphere soils,+P treatment significantly increased SOC,DOC and LOC contents significantly but reduced the LOC/SOC.The +NP treatment significantly increased the SOC and LOC contents.The differences of LOC/SOC between rhizosphere and non-rhizosphere soil significantly increased in +NP treatment.The differences between non-rhizosphere SOC significantly decreased.(2)Effects on soil N pool of rhizosphere and non-rhizosphere soil to nitrogen and phosphorus additionIn different treatments,the contents of rhizosphere nitrogen in different seasons was generally higher than that in non-rhizosphere soil.In the rhizosphere soil,the contents of NH4+ increased significantly in +N treatment,and the contents of TN increased significantly in +P and +NP treatments,and the contents of NH4+ and NO3-increased significantly in +NP treatment as well.In the non-rhizosphere soils,the contents of NH4+ decreased significantly in the +N treatment,while the contents of NO3-significantly increased in +N treatment,and the contents of TN and NO3-increased significantly in +NP treatment.The differences of NH4+ between the rhizosphere and non-rhizosphere soil significantly increased in +N and +P treatments,while differences of TN,NH4+ and TSN concents between rhizosphere and non-rhizosphere soils significantly decreased in the +NP treatment.In general,P addition had a greater effect on the carbon pool than N addition,whereas N addition had greater effect on nitrogen pool than P addition.