Nutrient Return in Fallitter of Hevea brasisiliensis at Different Age
The account of fallitter and its content of mineral elements(N,P,K,Ca and Mg) of rubber trees(Hevea brasisiliensis) of clone PR107 at different ages from 4yr to 28yr,were determined,and the characters of falliter decomposing in different season and the effect of aging on decomposition and nutrient return of falliter were also analyzed.The main results showed that:(1)the average nutrient content,biomass and nutrient return of fall leaf were 0.841%,2357.7(4 a)～7392.3(24 a)kg/hm2,and 147.4～498.6 kg/hm2,which were 1.69,1.5～8.2,and 6.8～37 times than that of in fallbranch,respectively.During its 30 years productive period of rubber tree,the total biomass of fall leaf was almost 143 t/hm2,contributing onto mineral elements 6.01 t/hm2,and the fallbranch was 75 t/hm2,contributing onto mineral elements 1.94 /hm2.Thereinto,the total N,P,K,Ca and Mg return from fallitter were 3.17,0.14,1.13,3.04 and 0.48 t/hm2,respectively.(2)With increaseing of rubber trees' age,the biomass return of fallitter was increased accordingly.While the return for the 4-year-old tree,it was only 151.4 kg/hm2.a,that for the 24-year-old reached the highest,biggest biomass return with 431.40 kg/hm2.a at 24-year-old,.The order of mineral elements return was: NCaKMgP.(3)The return ratio of rubber tree was only 1.32%,at 4-year-stage,and became higher gradually along with age increaseing.It had the highest of 36.55% at 24-year-old stage.In general,its order was: MgCaNKP.