Study On Soil Characteristics Of Cultivated Land With Different Fertility In Guangdong Province

Soil fertility is the main function and essential attribute of soil.The study on soil fertility characteristics can strengthen the understanding of the cultivated land quality, and has important significance to the national food security and agricultural sustainable development. Topsoil samples(0~20cm) were collected from cultivated land with different fertility in Zhangjiang, Nanxiong and Zhongshan of Guangdong province, the main soil chemical and biological indicators were determined, and soil fertility characteristics were studied in this paper. The main results were as follows:(1)The soil bulk density in cultivated land with higher fertility in Zhanjiang was1.01~1.09 g·cm-3,and 1.06~1.20 g·cm-3with lower fertility. The soil bulk density in cultivated land with higher fertility in Nanxiong was 1.4~1.52 g·cm-3and 1.37~1.42 g·cm-3with lower fertility. The soil bulk density in cultivated land with higher fertility in Zhongshan was 1.2~1.38 g·cm-3,and 1.57~1.58 g·cm-3with lower fertility. The bulk densities of soils with higher fertility were lower or significantly lower than those of soil with lower fertility.(2)The soil p H in cultivated land with higher fertility in Zhanjiang was 4.43~4.54,and 4.22~4.31 with lower fertility, the soil was strongly acidic. The soil p H in cultivated land with higher fertility in Nanxiong was 7.8~8.01, and 6.55~7.87 with lower fertility, the soils were alkaline or neutral. The soil p H in cultivated land with higher fertility in Zhongshan was 4.24~4.35, and 6.02~6.1 with lower fertility, the soils were strongly acidic or acidic.(3)The soil organic matter(SOM), easily oxidized organic carbon and active organic carbon in soil with higher fertility were lower or significantly lower than those in soil with lower fertility. The SOM in Zhanjiang and Zhongshan soil were first-class or second-class level, The SOM in Nanxiong soil was three-class level. There existed significantlypositive correlation between SOM and total N and alkali-hydrolyzale N.(4)The total N, alkaline hydrolysis N and total P in soil s with higher fertilitywere lower or significantly lower than those in soil with lower fertility. The total N of Zhanjiang and Nanxiong soil were three-class level. The total N of Zhongshan soils with higher fertility was first-class level, but second –class level with lower fertility soil. The alkali-hydrolyzale N in soils of Zhanjiang was second-class level, in soils of Nanxiong with higher fertility was second-class level, and three class level in soil with lower fertility. The alkali-hydrolyzale N in soils of Zhongshan with higher fertility was first-class level, and second-class level in low fertility soil. The total P in Zhanjiang soil was first-class level; the total P in Nanxiong soils with higher fertility was first-class level, and second-class level with lower fertility; the total P in Zhongshan soils with higher fertility was three-class level,and second-class level in soils with lower fertility.(5) The catalase, invertase and urease in soil with higher fertility was lower or significantly lower than those in soil with lower fertility. The significantly positive correlation existed between catalase and soil organic matter, alkali-hydrolyzale N, between phosphatase and soil organic matter, between catalase and phosphatase, between invertase and urease.