Study Of Agroforestry Systems Effects On The Soil And Benefit Of Different Peacan Stands In Northern Anhui

Because of the high economic value,ornamental and ecological benefits Pecan is one of the main plantingtree species in Anhui forestry construction.Due to the sparse planting density,more than 90% of them are agroforestry systems.In order to probethe long-term effects of the agroforestry systems on pecan,this research compared the changes of soil elements and physical characteristics of the different understory plants that were compared.In thispaper,four kinds of typical agroforestry systems such as pecan-oil Peony(PPeo),pecan-chrysanthemum(PC),pecan-peanut(PPea)and pecan pure forest(P)were studied.The author compared the soil physical properties,pH value and the content of K?Ca?Mg and some trace elements of different agriforest ecosystems.The main results showed that:(1)There was significant difference between soil physical properties between the agroforestry systems and pecan pure forest(p<0.05).Because of the increase of underground fine roots,the soil bulk density and soil porosity can be significantly reduced,which can increase the formation of soil aggregate structure and the ability of water conservation.(2)Agroforestry systems are better than pure forest to improve soil pH value.There was a significant difference in pH between the three agroforestry systems and pecan pure forest(p<0.05).The soil pH value was reduced from the weakly acidic to neutral.Those soilwith lower pH could bemore suitable for the growth of pecan and lots other species in the future.(3)Under the same condition of non fertilizer,the content of trace elements in the soil of the agroforestry systems was significantly reduced(p<0.05).The composite content of trace elements in forest soil Cu,Fe,Mn,Zn were decreased by 39.15%,21.14% 27.91%and 45.47% to the pure forest;K,Ca,Mg were the most reduced by 45.64%,75.33%,48.12%.(4)The results of the internal difference test of different agroforestry systems showed that the content of soil element of PPeo system was significantly different from that of PC and PPea systems(p<0.05).PPeo system in addition to Cu,Fe,Ca,the content of each element is lower than the PC and PPea system,where Mn,Zn were lower 21.82%,respectively,K,Mg were lower than 43.27%.(5)Compared the three kinds of agroforestry systems,PPeo system was the best economic benefit with annual 5150 yuan/mu,followed by PPea,PC systems' benefit are4875?3185 yuan per year.