Effects of Different Fertilization Patterns on Available Cadmium and Copper in Acidic Soil and Its Impact on Cd and Cu Accumulation in Head Lettuce

• Yuwen YANG, 
• Qiuhui CHEN, 
• Yunguan XI, 
• Mingqing LIU, 
• Li GAO, 
• Taoming YANG, 
• Liping HE