Study on soil magnesium in the Tieguanyin tea plantations of Fujian Province Evaluation on the environmental quality about lead, cadmium, arsenic, chromium, mercury, copper and fluorine in the soils of Tieguanyin tea plantation in Fujian Province Soil nitrogen status in Tieguanyin tea plantation of Fujian Province Investigation and analysis of soil molybdenum in the Tieguanyin tea plantations of Fujian Province