Distribution of soil phosphorus fractions influenced by chemical fertilizer application and frond heaping practices in an oil palm plantation in Pahang, Peninsular Malaysia

抄録

In order to contribute to developing appropriate and efficient schemes for phosphorus fertilizer, the influence of different management practices such as chemical fertilizer application and frond heaping on the distribution of soil phosphorus (P) were investigated in three oil palm fields with planting ages of 5, 10 and 18 years in Pahang, Peninsular Malaysia. Soil samples were collected from the depths of 0-3 cm, 3-10 cm and 30-40 cm at three micro sites in each field, that is, weeded circles, frond heaps and harvest paths. The distribution of soil P varied widely with different management practices; the levels of total P and Bray II P, inorganic NaHCO_3 P and NaOH P, and HCl P at 0-3 cm were higher at the weeded circle than those at the frond heap and harvest path due to continuous P fertilization through which a significant portion of the applied phosphate rocks remained undissolved and was gradually accumulated in soils. Such P accumulation tended to be more obvious in the 18 years field. Meanwhile, the levels of organic P fractions at the frond heap were similar to those at the harvest path and lower than those at the weeded circle. The levels of P at 30-40 cm were not virtually different among the micro sites.