Available K and Total Organic C Accumulation in Soil with the Utilization Ages of the Vegetable Greenhouses in the Suburb of Shenyang

The amount of available potassium, total organic C and pH in different utilization age (0, 1, 5, 13-year) vegetable greenhouses soil was examined in Damintun Town of Shenyang. The results showed that the amount of soil available K in all utilization ages vegetable greenhouses decreased with the soil depth. For all the samples, the amount of available potassium (AK) and total organic C (TOC) in the 0-40 cm layer was higher than that in the 40-120 cm. In the 0-20 cm layer, the amount of available K in 13-year vegetable greenhouse soil is 3.4 times higher than that in the bare land, while the amount of available K in 1-year vegetable greenhouse is only 1.26 times the than the bare land. The amount of soil total organic C was the biggest in the surface soil (0-20 cm) and was in the deep soil (80-120 cm) in the 5-year and 13-year vegetable greenhouse, respectively. It implied that long-term continuous organic carbon input from chemical fertilizer and organic manure could cause total organic C translocation into deep soil layers. Soil pH in the greenhouse has little changed, which indicated that continuous addition of fertilizer has little effect on it.