Department of Soil Science and Agricultural Chemistry, College of Horticulture, Kerala Agricultural University, Thrissur, Kerala, 680656.
*Corresponding author: (E-mail: dvknrao@rubberboard.org.in
†Present Address: Agronomy/Soils Division, Rubber Research Institute of India, Kottayam, Kerala, 686 009.
An experiment was conducted with 14 soils from different fields grown with young Hevea plants. Majority of the soils were Ultisols characterised by low activity kaolinitic clay. A modified centrifugal filter was fabricated and the soil solution was extracted. Both the solution and exchange phases of the soils were analysed for pH, EC, Ca, Mg, K, Na, Mn and Al. Significant correlations were found among divalent (Ca vs Mg and Mn) and monovalent cations (Na and K) in the soil solution. The factor analysis of solution data revealed that ionic strength was influenced by (i) pH and divalent cations, (ii) monovalent cations, and (iii) trivalent aluminium. All these three factors could explain the variability to the extent of 83.3 per cent. The multiple regression including interaction terms indicated that soluble Ca, Mg and Mn were significantly related to EC. Only solution Ca could be regressed significantly to interaction term (exchangeable Ca and EC). Solution Mg and Mn were regressed to their exchangeable form as well as solution EC.
Soil solution, Ultisols, Hevea
