Volume 49 Number 3

Unveiling novel insights into potassium extractability in rubber-growing soils: A comparative analysis using single extraction and a sequential extraction process

Chakkrit Poonpakdee^a,*, Arirat Chumekha^a, Jumpen Onthong^a, Khwunta Khawmee^a, Yao-Tung Lin^b

 
ABSTRACT:     Potassium (K) is a limiting element for rubber trees grown in southern Thailand. The availability of soil K depends on the K fractionation. The aims of this study were to explore K fractionation distribution, to assess the correlation between K fractionation and soil properties, and to compare K fractionation received by single extraction (SE) and a sequential extraction process (SEP). Coarse, medium, and fine soils were collected (0?30 cm) from rubber plantations for K fractionation analysis. The results showed that soil K was high in fine > medium > coarse soil textural categories. K fractionation using SEP was increased in residue K > exchangeable K > K bound to Fe-Mn oxide > K bound to organic matter > K bound to carbonate, whereas K fractionation using SE was increased in mineral K > fixed-K > exchangeable K > water soluble K. Available K received by SE and SEP was positively correlated with organic matter, cation exchange capacity, and clay content. It was lower than the optimal soil K level for rubber plantations. The combination of potash and organic fertiliser to support K for plant uptake is essential in this region. Soil K fractionation received by SE and SEP was highly correlated. Therefore, SEP may be a viable alternative for K fractionation analysis in rubber-growing soil. Rubber soil K management by increasing the solubility of mineral K or residual K combined with SEP monitoring soil K fractionation would be useful for sustaining crop yield and soil K fertility.

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* Corresponding author, E-mail: chakkrit.p@psu.ac.th

Received 1 Jun 2024, Accepted 23 Nov 2024