The effect of incorporating palm residues at replanting on phosphate dynamics in an inland soil in Malaysia

The effects of adding approximately 200 mg P kg-1 soil in three different palm residue treatments (pulverized, shredded and partially-burned) at replanting on P fractions were investigated in a field experiment at Kluang, Johor, two and three years after oil palm replanting. The three treatments led to about two- to four-fold increases in the organic P pool over the control. This indicates the importance of biological activity, stimulated by incorporation of palm residues, in the distribution of P fractions. Organic P and microbial P are thought to be the main soil P fractions involved in P cycling in the soil when added through palm residues. The results also suggest that when palm residues were incorporated, the amount of P adsorbed was reduced by 40% to 50% after two years and by 45% to 50%, three years after replanting. Decreasing P sorption together with increasing P desorption in the soil is one important aspect for improving plant P uptake efficiency. Amending the soil with palm residues may supply a greater percentage of residual P to oil palm. Therefore, with incorporation of palm residues, P fertilization probably can be reduced for the two years following replanting