Study on soil magnesium in the Tieguanyin tea plantations of Fujian Province

The contents and availability of Mg in surface soils and Mg contents of the corresponding tea leaves of 150 Tieguanying tea plantations in Anxi, Huaan and Yongchun Counties of Fujian Province were investigated. The supplying capacity of soil Mg and its relationships with soil conditions were discussed. The mean total Mg content of the soil samples is 1.77 g/kg. The total Mg contents of the soils derived from metamorphic rocks are higher than those derived from granites. There are positive correlations between the total soil Mg and the contents of organic matter and 0.02-0.002 mm soil particles, respectively. The correlation between total soil Mg and content of 2-0.02 mm particle is negative. The average exchangeable Mg is only 9.63 mg/kg which indicates a widespread Mg deficiency in the tea plantation soils. The exchangeable Mg is significantly correlated with soil pH, organic matter content and total soil Mg. The availability degree of Mg (the ratio of exchangeable to total Mg) is significantly and negatively correlated with 0.002 mm particles. The mean concentration of Mg in tea leaves is 1.78 g/kg, and there is a significant and positive correlation between Mg content in tea leaves and soil exchangeable Mg.