The increasing demand for natural rubber products has driven the expansion of rubber plantations in recent decades. Previous studies have focused on long-term effects of rubber and rubber-based agroforestry systems on surface soil properties. However, changes in deep soil properties are often overlooked.  

In a study published in Science of the Total Environment, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) examined the impact of rubber plantation expansion on deep soil properties. They filled the gap by examining changes in nitrogen (N), phosphorus (P) and metal ion levels in deep soil after long-term cultivation of rubber and rubber-based agroforestry systems. 

They found that rubber and rubber-based agroforestry systems have caused significant changes in nitrogen (N), phosphorus (P), and metal ion levels within the 0-30 cm soil layer. In mature systems, NO₃^？ and available P levels were close to zero at soil depths below 30 cm. The introduction of Flemingia macrophylla into young rubber plantations increased NH₄⁺ and NO₃^？ within the 0-90 cm soil layer and available P within the 0-10 cm soil layer.  

Long-term tillage in rubber plantations increased total P depletion within the 0-50 cm soil layer, available available iron (Fe) and manganese (Mn) within the 30-90 cm soil layer, and available available copper (Cu) and zinc (Zn) within the 0-90 cm soil layer, accompanied by a decrease in soil pH and an increase in exchangeable aluminum (Al).  

Notably, exchangeable Al levels appeared to induce aluminum toxicity. When soil pH was lower than 5.2, sharp releases of exchangeable Al occurred within the 0-90 cm soil layer of rubber plantations. 

"Our findings highlight the major challenges that future soil restoration efforts need to address to overcome these deep soil degradations” said LIU Changan of XTBG. 

 

 

Contact 

LIU Changan Ph.D 

Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China     

E-mail: liuchangan@xtbg.ac.cn  

First published: 29 June 2024