种植年限对设施蔬菜土壤养分和环境的影响

为了给设施蔬菜地合理施肥提供依据,研究了不同种植年限设施蔬菜地土壤理化性质、微生物数量及酶活性变化,以露地土壤为对照(CK),采集种植1 a(年)、3 a、5 a、7 a、9 a、11 a、13 a、15 a、17 a、20 a以及20 a以上的0~20 cm设施蔬菜土壤样品,采用常规土壤理化性质检测方法测定了土壤理化性质和酶活性,采用平板计数法,分析土壤微生物数量。结果表明,设施菜地种植年限与土壤容重呈正相关,与土壤孔隙度呈负相关;设施菜地土壤pH值随种植年限的增加逐年降低,两者呈显著的负相关性;土壤EC值、土壤有机质和速效磷含量都随种植年限的增加而逐年增高,并与种植年限呈显著的正相关性;与CK相比,种植13 a的蔬菜样地土壤全氮和速效钾含量均显著地增加;连续种植20 a以上,设施蔬菜土壤含盐量比对照土壤显著地增加了486.49%。土壤细菌和放线菌数量、过氧化氢酶和碱性磷酸酶活性呈现出先增加后减少的趋势,且都在种植年限为11~13 a时达到最大;真菌数量随着种植年限的增加而增加,而土壤脲酶活性则随种植年限的增加呈下降趋势;转化酶活性随着种植年限的增加保持不变。土壤微生物数量与酶活性之间存在一定程度的相关关系,其中土壤真菌数量与土壤酶活性之间的相关性最为显著。综上所述,种植年限不同的设施菜地,土壤养分失衡,呈现酸化趋势,盐分含量逐年增加,土传真菌病害潜在发生,对设施蔬菜生产不利。

Effects of different planting ages on the nutrients and environment in vegetable greenhouse soils

In order to offer basis for reasonable application of fertilizers in protected vegetable fields,the physical and chemical properties,microorganism,and enzyme activity of soil were studied in vegetable greenhouses under different cultivation times.The open field was taken as control(CK),and the nearby greenhouses with planting ages of 1 year,3 years,5 years,7 years,9 years,11 years,13 years,15 years,17 years,20 years,and more than 20 years were chosen for the research in Qinghai.The soil samples at depth of 0-20 cm from 25 representative and different planting ages of greenhouses were collected with a S-sampling.The physical and chemical properties were analyzed using conventional chemical methods.The population of soil microorganism was measured using dilution plate counting method.The results indicated that there was a positive correlation between the planting age and soil bulk density,and negative correlation with soil porosity.Soil pH value decreased with year and showed significant negative correlation with the planting age.Soil EC value,soil organic matter,and available phosphorus contents increased with the increasing of greenhouse age and displayed significant positive correlation with the plantation age.Compared with CK,content of both the soil total nitrogen and available potassium in planting ages of 13 years were increased significantly.In the greenhouses of 20 years of planting,the salt content increased by 486.49%compared with the control.The number of soil bacteria and actinomycetes,catalase and alkaline phosphatase activity increased first and then decreased,and reached their maximum at 11-13 years of planting.With the increase of vegetable plantation age,soil fungi number was increased,while soil urease was decreased continuously and the invertase activity remained unchanged.There was a certain degree of correlation between the number of soil microorganisms and enzyme activity,among which the number of soil fungi was the most significant.In conclusion,the increase of planting ages lead to the soil nutrient imbalance,soil acidification,and significant increases in soil salt content and potential occurrence of soil-borne pathogenic fungi,which is unfavorable to the production of protected vegetable.