Nutrient accumulations and the changes of exchangeable cation ions and their ratios in the soils under sunlight greenhouses in Guanzhong Plain of Shaanxi province were analyzed.The results showed that the contents of organic matter

nitrate

and available phosphorus and potassium in the greenhouse soils were significantly accumulated.The cation exchangeable capacity(CEC) in the greenhouse soils was also higher than that in the open fields;on the contrary

the soil pH of the greenhouse was declined.The content of exchangeable K

or Mg2 ions and the ratio of the ion to the total exchangeable ions in greenhouse soils were increased

especially for K ion.There was no significant difference in the content of exchangeable Ca2 ion between the greenhouse soil and open fields.The ratio of the exchangeable Ca2 ion to the total exchangeable ions

and the ratios of Ca/K and Mg/K in greenhouse soils were lower than that of open fields

due to the excessive application of potassium fertilizer in the greenhouses.It is suggested that to evaluate the supply of available nutrients in the greenhouse soils

not only the contents of exchangeable ions but also the ratios of these ions in soils is needed to be included.