Soil Quality And Its Effects On Vegetable Pollution In The Region Around Dongting Lake

Vegetables were necessary food in people's daily life, which can offer vitamins, mineral nutrients and celluloses to people's physiological functions and health. But the developments of modern industry, and the using of a large number of chemic fertilizers and pesticide made the quality of vegetables and the environment of vegetables bases becoming worse. The region around Dongting Lake was suitable for vegetables production in China. Systematically studying of soil quality of typical vegetables bases and their influence on vegetables quality could provide scientific foundations for rational utilization of land resource and production of free-pollutant and green vegetables, and ensure people's health. Soil quality and their influence on vegetables quality of 14 vegetables bases in 5 cities (Changsha city, etc.) in surrounding Dongting Lake hilly region were studied. The main results were as follows:1. The soil pH was between of 4.2 to 6.7 in this region. The content of soil organic matter was 29.5±0.83 g/kg in the region. The means of soil total N, P and K were 1.73±0.04 g/kg, 1.39±0.05 g/kg and 16.1±0.42 g/kg, respectively. The average contents of soil available N, P and K were 136.5±5.82 mg/kg, 93.0±7.96 mg/kg and 119.3±4.99 mg/kg, respectively. The contents of soil nutrients were higher than the natural soils, except for the contents of K. According to the grading of soil fertility, the contents of SOM, N and K were belong to or higher than gradeIII. Contents of Fe, Cu and Zn in soil were belong to grade I . Which indicates the soils were fertile and suitable for vegetables production? But we should increase organic fertilizers, and reduce P and microelement fertilizers.2. The over-limit rates of Cd, Cu and Ni in soils were 39%, 30% and 15%, respectively, and Pb, Zn, As were safe. Comprehensive evaluation shows: 65% of the soils were safe or nearly safe, 28% were low-grade polluted and 7% were medial-grade polluted. The share of Cd in comprehensive index was the highest one (51%). It was different in pollutant and degrades among soils which derived from 3 sorts of parents materials. The soils derived from Quatenary red clay was bordering warning limit, and only 15% (n=20) contents of Cd in soil over the limit. The over-limit rates of Cd, Cu and Ni were 56%, 75% and 38% of soils which derived from slate shale, and the rates were 45%, 26% and 12% in soils which derived from alluvial deposit of rivers. The both were low-grade pollution. The soils derived from Quatenary red clay were suitable for...