Improvements Of Amorpha Fruiticosa Planting To The Soil In Tibet Plateau

The two-age Amorpha fruticosa planted in the southwest of the Tibetan Plateau, Lhasa and the one-age Amorpha fruticosa planted in the north of Tibetan Plateau, Nagqu were selected to study the difference of various forms of nitrogen, total phosphorus, available phosphorus,total potassium, the contents of organic carbon and pH changes between the soil of in the crown (IC) and Out of crown (OC).The results showed as follows.Two-age Amorpha fruticosa planted in Lhasa:1) Compare to OC, Total nitrogen, ammonium and nitrate in IC were23.44%,13.95%and37.6%higher; Soil total phosphorus and available phosphorus in IC were19.57%and4.7%higher; soil organic carbon in IC was44.21%higher; soil total potassium was0.72%lower and soil pH was lower by0.09units than the OC. There were significant differences in content of soil total nitrogen, ammonium, nitrate, total phosphorus, organic carbon and soil pH between IC and OC (P<0.05).2) In vertical direction, the content of total nitrogen, ammonium, nitrate and total phosphorus reached to the maximum values in depth of10-20cm in soil. The content of organic carbon and pH reduced with increasing depth.4) Correlation analysis between soil nutrients showed that the SOC had highly significant correlation with NH4+-N, A-P and TK(p<0.01), and was significantly correlated with TP (p<0.05). The soil TN had highly significant correlation with TP. The NH4+-N had highly significant correlation with TP and A-P, and was significantly correlated with TK. The soil NO3--N had highly significant correlation with A-P, TK. The soil pH had highly significant correlation with SOC and NH4+-N, and was significantly with A-P.One-age Amorpha fruticosa planted in Nagqu:1) Compared to OC, total nitrogen, total phosphorus and total potassium in IC were11.11%,1.59%and9.3%higher; NH4+-N and NO3--N in IC were36.01%and46.55%lower; organic carbon in IC was32.36%lower; soil available phosphorus was37.13%lower and soil pH was higher by0.78units than the OC. There were highly significant differences (P<0.01) in content of soil ammonium, nitrate, available phosphorus, total potassium and pH and significant difference(P<0.05) in organic carbon between IC and OC.2) In vertical direction, the content of the total nitrogen and organic carbon reached to the maximum values in the depth of10-20cm soil, others reduced with increasing depth. The content of TK, NH4+-N and NO3--N reached to the minimum values in depth of10-20cm, the others increased with the increasing depth. The content of TP and A-P increased with the increasing depth at first, reached to the maximum values in depth of20-30cm, and then reduced with increasing depth.4) Correlation analysis between soil nutrients showed that there were highly significant positive correlation between SOC and NH4+-N, TN and TK, NH4+-N and A-P (P<0.01). NH4+-N, A-P and TK (p<0.01), and the SOC was significantly positive correlated with A-P, the TP was significantly positive correlated with pH (p<0.05). There were highly significant negative correlation between NO3--N and TP, pH, TK and NH4+-N, A-P. And NH4+-N was significantly negative correlation with pH.