白术连作根际土壤的理化性质及微生物区系变化

对不同种植年限白术(Atractylodes macrocephala Koidz.)根际土壤的部分理化指标、酶活性和微生物区系进行了测定和比较。结果表明:随白术种植年限的增加(0、1和2 a),根际土壤pH值显著下降(P<0.05),根际土壤中有机质和全氮含量呈先升高后降低趋势,速效钾含量则逐渐升高,而有效磷含量和C/N比小幅波动,总体上不同种植年限根际土壤的这些指标差异不显著;根际土壤中有效铁、有效铝和交换性锰含量显著或极显著(P<0.01)增加,且较对照(未种植白术的土壤)分别增加了127.51%、18.38%和106.83%,但有效铅含量变化幅度较小;2年生白术根际土壤中过氧化氢酶、脲酶和蛋白酶活性显著低于对照;2年生白术根际土壤中细菌和放线菌数量及微生物总量较1年生白术根际土壤显著下降,真菌数量则显著上升。结果显示:土壤酸化严重、金属离子大量积累、主要酶活性失调以及微生物区系改变可能是白术连作障碍的潜在原因。

Changes of physicochemical property and microflora in rhizosphere soil of continuous cropping of Atractylodes macrocephala

Some physicochemical indexes, enzyme activity and microflora in rhizosphere soil planted with Atractylodes macrocephala Koidz. for different years were determined and compared. The rsults show that with increasing of planting year （0, 1 and 2 a ） of A. macrocephala, pH value in rhizosphere soil decreases significantly （ P〈0.05 ）, contents of organic matter and total N in rhizosphere soil appear the trend of first increasing and then decreasing, available K content increases gradually, while available P content and C/N ratio fluctuate slightly. Generally, these indexes in rhizosphere soil planted for different years have no significant difference. And contents of available Fe, available A1 and exchangeable Mn in rhizosphere soil increase significantly or extremely significantly （P〈0.01）, and increase by 127.51%, 18.38% and 106.83% compared with the control （soil unplanted with A. macrocephala）, respectively, but change range of available Pb content is a little. The activities of catalase, urease and protease in rhizosphere soil planted with A. macrocephala for two years decrease significantly than those of the control. The numbers of bacteria, actinomycetes and total number of microorganism in rhizosphere soil planted with A. macrocephala for two years decrease significantly but the number of fungi increases significantly than those in rhizosphere soil planted with A. macrocephala for one year. It is suggested that serious acidification, massive metal ions accumulation, main enzymes inactivation, and microflora alteration of soil may be the potential cause of continuous cropping obstacle of A. macrocephala.