摘要
以正茬土壤和连作2～5年桔梗田土壤为研究对象，采用大田试验研究桔梗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。结果表明，随连作年限增加，土壤有机质含量变化不显著，土壤速效氮含量逐年增加，速效钾含量逐年下降，速效磷含量呈先升后降趋势，土壤镁、铁含量呈下降趋势，锰含量呈上升趋势，连作3～4年土壤锌和钙含量显著高于正茬土壤，而第2年、第5年显著低于正茬土壤。不同连作年限土壤铜含量变化不显著。土壤微量元素与土壤物理、化学和生物学指标呈显著相关。土壤pH、孔隙度随连作年限增加呈下降趋势，而土壤容重呈上升趋势，毛管持水量变化没有规律性。土壤脲酶活性逐年降低，连作5年比正茬土壤降低43．69％，磷酸酶和过氧化氢酶活性均呈先降后升趋势，过氧化物酶（除连作5年外）和多酚氧化酶活性呈先升后降趋势，但均高于正茬土壤。桔梗连作改变了土壤微生物区系，细菌急剧减少，连作5年比正茬土壤降低81．07％，真菌迅速增多，连作5年比正茬土壤增加587．57％，放线菌变化没有规律性。细菌／真菌比值在连作第3年比正茬土壤降低90．27％。脲酶活性与真菌数量、土壤速效氮含量分别呈极显著、显著负相关，与细菌数量、速效磷含量、pH分别呈极显著、显著正相关，可用脲酶活性表示土壤肥力和生物学性状变化。综合桔梗连作土壤理化性状和生物学性状变化，桔梗连作导致土壤氮磷钾比例失衡、酸化明显、物理性状变劣，破坏土壤微生物区系，土壤质量变劣。
Choosing the soils which cropped Platycodon grandiflorus for 1~5 years as testing material, field experiment was conducted to investigate the effects of continuous cropping of P. grandiflorm on soil physi- cal-chemical properties, soil microflora and soil enzyme activities. Results showed that with increasing con- tinuous cropping years, available nitrogen raised gradually, while available potassium decreased, and availa- ble phosphorus raised first and then decreased, no significant change was observed on soil organic matter. The contents of Mg and Fe increased with increasing successive cropping of P. grandiflorus, but Mn con- tent increased, no significant difference was found in Cu content. The contents of Zn and Ca increased from 3 to 4 year and decreased in 2th and 5th year. There were significant relationship between soil microelement content and soil physical-chemical and biological indictors. As for soil physical properties, soil pH and soil porosity decreased with increasing continuous cropping but soil bulk density increased, the effect of continu- ous cropping on capillary water capacity was irregular. The activity of urase gradually decreased, it decreased by 43.69% under successive cropping 5 years. Activities of catalase and phosphatase decreased from 2 to 3 continuous cropping years, while those enzyme activities increased from 4 to 5 years. However, peroxidase activity and polyphenol oxidase activity showed a reverse tendency. Soil bacteria number remarkably de- creased with increasing continuous cropping years, it decreased by 81.07~/00 compared to rotation cropping. In contrast, the number of fungi rose sharply, it increased by 587. 570/00 compared to that in rotation cropping, no regular tendency was observed in actinomycetes. With the increase of continuous cropping years, the ratio of bacteria and fungi decreased, it decreased by 90. 27% for successively cropping 3 years. Correlation be-tween urase activity and fungi number, soil available nitrogen was significant negative at 0.01 % and 0.05% level, while the correlation between urase activity and bacteria number, soil available phosphorus content, soil pH was significant positive, urase activity could use as a predictor index for the changes of soil fertility and biological properties. Considering physical-chemical properties and biological properties under continuous cropping of P. grandifZourm, soil pH decreased, soil N, P and K contents imbalanced, the balance of soil microflora was destroyed and soil quality declined.
出处
《水土保持学报》
CSCD
北大核心
2013年第6期177-181,共5页
Journal of Soil and Water Conservation
关键词
桔梗
连作
土壤理化特性
土壤微生物
土壤酶活性
Platycodon grandiflorus
continuous cropping
soil physical-chemical property
soil microor- ganism
soil enzyme activity
