Analysis Of Vegetable Soil Quality Status In Solar Greenhouses In Round-Bohai Bay-Region

Round-Bohai Bay-Region is a major developing area for protected vegetable production in China. Although this area has made significant achievements, soil degradation is common in this region. However, to date few attendion has been paid to general soil quality in this region. Thus, to overall evaluate the soil quality in Round-Bohai Bay-Region, this dissertation collected solar greenhouse fruity vegetable (cucumber and tomato) soil samples with 5 different cultivation years (0,3-5,8-10,13-15 and>20) from 13 different areas in Liaoning, Beijing, Tianjin, Hebei, Shandong and Jiangsu provinces/cities, and comprehensively evaluated soil quality in the combination of water, fertilizer and pesticide inputs, soil physiochemical properties, nutrients, heavy metals and plasticizers. In addition, the major factors influencing soil quality were also analyzed. The main results were as follows:(1) Pesticides and plant growth regulator abuse was common in Round-Bohai Bay-Region, and there were 16 different plant growth regulators used in this region. The fertilizer input was significantly higher in solar greenhouse than in adjacent open vegetable fields. In solar greenhouse vegetable production systems, P input from chemical fertilizer was significantly higher in greenhouses with 13-15 and >20 cultivation years than in those with 3-5 and 8-10 cultivation years, while K input from chemical fertilizer was significantly higher in greenhouses with >20 cultivation years than those with other cultivation years.(2) Topsoil (0-30cm) pH and EC were among 5.49～8.38 and 0.08～1.51 mS/cm (variable coefficient (CV) were 9.2% and 59.2%, respectively). For most sampling sites, topsoil pH and EC were higher than those at 30-60 cm soil layer, indicating the potential acidification and salinization. Although pH and EC was significantly different among different sampling areas, they decreased (pH) or increased (EC) as the increase of cultivation years.(3) Topsoil organic matter and total N were among 2.8-40.2g/kg and 0.5-3.65g/kg (CVwere 43.5 and 52.9%, respectively), while inorganic N, available P and K were among 4.4～552.5,19.6～726.0 and 70.0～1524.0 mg/kg (CV were 86.1%,65.7% and 68.4%, respectively). Although for most sampling sites soil organic matter were in medium and lower levels, soil available P and K were in relatively high and higher levels, indicating potential soil environment and water pollution.(4) Zn and Cu were the major sources of heavy metal pollution. There were about 34.5% and 72.3% soils were polluted by Zn and Cu, respectively. Although As and Cd were not the major sources of heavy metal pollution, these two heavy metals increased with the extension of cultivation year. In addition, plasticizers were not the major factors infuluencing soil quality in Round-Bohai Bay-Region.(5) Soil microbial biomass C was in normal distribution. There was about 35.4% soils were in mehium level (150-350mg/kg), and a decreased trend was showed in lower or higher levels.The results metioned above suggests that in Round-Bohai Bay-Region, during the protected vegetable production, there were four extremely urgent practices, including supervising pesticides and growth regulators use, controlling phosphorus and potassium input, reducing copper and zinc pollution, and alleviating arsenic and cadmium accumulation.