非洲菊连作对土壤理化性状与生物性状的影响

 【目的】研究非洲菊连作土壤物理化学性状、土壤微生物区系和土壤酶活性动态变化。【方法】以未种植过非洲菊的土壤作对照，测定连作非洲菊1、3、5和7年土壤的理化性质、酶和微生物活性的变化。【结果】随着连作年限的增加，土壤pH和容重下降，连作1、3、5和7年的土壤总含盐量分别比对照增加4.00%、72.80%、24.00%和88.00%。土壤有机质和速效氮含量随着连作年限的增加而上升，土壤速效磷和速效钾含量呈下降趋势。土壤脲酶和蔗糖酶活性呈先升后降的趋势，连作1年和3年土壤酶活性降低，连作5年以后又升高，土壤过氧化氢酶和中性磷酸酶活性呈下降趋势，连作1、3、5、7年土壤蛋白酶活性分别比对照增加9.09%、50.00%、63.64%、93.18%。土壤真菌数量随着连作时间延长而增加，连作7年的土壤真菌数与对照相比增加了192.04%，细菌数量呈下降趋势，其它微生物类群的数量呈先升后降的趋势。【结论】非洲菊连作后土壤pH降低，土壤总含盐量逐渐增加，有次生盐渍化的趋势，土壤中氮、磷、钾比例失调。连作5—7年，土壤真菌数量上升，细菌和放线菌数量和土壤酶活性下降，连作障碍明显。

Effects of Continuous Cropping System on the Soil Physical-Chemical Properties and Biological Properties of Gerbera jamesonii

【Objective】The objective of the experiment is to study the effect of Gerbera jamesonii continuous cropping on soil physical-chemical and biological characters. 【Method】 Using conventional methods, an experiment was conducted to investigate the changes of Gerbera jamesonii continuous cropping on soil physical-chemical properties , soil microbial and enzyme activities.【Result】Results showed that compared with control, soil salt content was increased by 4.00%, 72.80%, 24.00% and 88.00%, respectively, under 1-7 years continuous cropping, while soil pH and bulk density began to decline. With the increasing of continuous cropping years, soil organic matter content and available N content was remarkably raised, but the soil available P and available K content was decreased. The activities of urase and sucrase increased in 1-3 years continuous cropping, while those enzyme activities decreased in 5-7 years, the soil catalase and phosphatase activity decreased with the continuous cropping year increasing, while the protease activity increased by 9.09%, 50.00%, 63.64%, 93.18%, respectively, under 1-7 years continuous cropping, compared with control. With the time of continuous cropping increasing, soil fungi number increased gradually, the number of 7 years continuous cropping increased by 192.04%, the number of bacteria decreased, but the number of other microorganisms increased in 1-3 years continuous cropping and decreased in 5-7 years. 【Conclusion】 Under continuous cropping, soil pH and bulk density decreased, soil salt content increased, while soil N, P, K proportion was imbalanced. The quantities of bacteria and actinomycetes and the enzyme activities of soil decreased under 5-7 years continuous cropping, but soil fungi number increased, the obstacles of continuous cropping were obvious.