Abstract:

Based upon the case of Qianlianghu polder in the Dongting lake region,soil nutrient contents,synthetical indexes of nutrient pool and relative coefficients among soil nutrient indexes were studied for five typical land use patterns under converting polders back into wetlands, which include forestland (Ⅰ),garden land (Ⅱ),dry land (Ⅲ),paddy land (Ⅳ) and waste land (Ⅴ).The results showed that there was an obvious regularity that soil nutrient contents were higher in 0～25 cm soil layers than in 25～50 cm soil layer.In different patterns and 0～50 cm soil layers,the contents of organic matter (OM),total nitrogen (TN),available nitrogen (AN),total phosphorus (TP),available phosphorus (AP),total potassium (TK) and available potassium (AK) were 340～3232 g/kg,223～971 g/kg,1295～11200 mg/kg,2950～6935 g/kg,415～7568 mg/kg,603～3069 g/kg and 3770～21750 mg/kg respectively.The highest contents of TN and the lowest OM occurred in pattern Ⅰ,the highest contents of OM,TK and AP were in pattern Ⅳ,and the highest AN were pattern Ⅲ.However,the contents of TN,TP,TK,AN and AP were the lowest in pattern Ⅴ.Soil nutrient pool synthetical indexes ranged from 2433 to 29593 in five land use patterns,which showed by regularities of 〖WTBX〗IⅣ（23196）＞IⅢ（19346）＞IⅡ（7090）＞IⅠ（5957）＞IⅤ〖WTBZ〗（3559）.Through Pearson coefficient analyzing,it was showed that there existed highly positive relation between OM and TP,TP and AP,TN and TK,AN and AP which relative coefficients were 0.5760,0.5961,0.6864 and 0.5701 respectively.