Effect of Planting Years on Soil pH and Nutrient Accumulation in Greenhouse Vegetable Fields

Taking greenhouse vegetable fields in Shouguang region,Shandong Province as research objective,this study analyzed the soil physiochemical properties,including pH value,soil organic matter,contents of available phosphorous and potassium in greenhouse vegetable fields with different cropping years.The results showed that the pH value in different soil layers decreased with the increase of cropping years,and compared with the open wheat field,the soil pH value in greenhouse decreased by 0.05 to 0.69 units,especially in 0-20 cm soil layers,the decreasing amplitude was the largest.Along with the increase of cropping years,the pH value of under layer decreased obviously.In 20-40 cm soil layers,the pH value decreased from 8.67 to 7.99,after 10 years of greenhouse vegetable production.While the content of soil organic matter in 0-20 cm layers significantly increased with the increase of cropping years by 6.1%,46.4%,66.5% and 125.3%,respectively with 1-3,4-6,7-9 and ≥10 years of greenhouse vegetable production,compared with open wheat field.The soil Nmin content was significantly higher than that in wheat field,but the cropping years did not have much influence.The contents of available phosphorous and potassium in different soil layers obviously increased with the increase of cropping years.In 0-20 cm soil layers with 1-3,4-6,7-9 and ≥10 years of greenhouse vegetable production,the contents of available phosphorous were 8.9,14.8,18.1 and 18.3-fold higher than those in open wheat field;while the contents of available potassium were 2.8,3.2,3.5 and 3.5-fold,respectively,compared with open wheat field.The soil pH value declined with the increase of planting years,but compared with previous research results,the soil pH value appeared rising trend.