Studies on the sensitive limiting factors of soil fertility for continuous cropping fruits and vegetables in greenhouse.

【Objective】Soil fertility was measured in order to study the mechanisation,clarify the most sensitive limiting factors of soil nutrients and provide reference for continuous cropping in greenhouse.【Method】To evaluate these influences,we analyzed the rhizosphere and non-rhizosphere soil of strawberry and tomatoes rotation(RST),2 years continuous strawberry cropping(CS2),3 years continuous strawberry cropping(CS3),4 years continuous tomatoes cropping(CT4) and 10 years continuous tomato cropping(CT10),respectively.【Result】The result showed that all the soil samples in our study were alkali at the beginning,but finally were seriously acidified.Compared with rotation cropping,the nitrate nitrogen con-tent of rhizosphere and non-rhizosphere soils in continuous cropping increased by 10.3%-30.0% and 2.4%-23.2%,organic matter declined by 4.4%-8.8% and 2.8%-7.4%,and extractable P declined by 5.5%-24.4% and 8.7%-25.5%,respectively.These led to some trace element deficiency(such as Zn2+ and Fe2+)in soil,which was essential for plant growth after a long period of continuous cropping.The extractable Zn2+,Mn2+ and Fe2+ in CT10,appeared to be seriously deficient,while the extractable Zn2+ content in rhizosphere and non-rhizophere soils of CS2 respectively decreased by 36.8% and 35.2%comparing with RST.The decline of extractable Mn2+ was not so significant in CT4 and CS2.It had a significant correlation between trace elements and soil orgnic matter,but not significant with soil nitrate and extractable P.The activity activtitys of catalase,urease and cellulase in non-rhizosphere soil of CS2 and CS3 was higher than that of rhizosphere soil,while saccharase in CS2,CS3 and CT4 showed a contrary trend.【Conclusion】 The deficiency of soil extractable Zn2+ and Fe2+ is the most sensitive limiting factor of soil fertility.