RESEARCH ARTICLE

Journal of Oil Palm Research Vol. 16 No. 1, June 2004, p. 72-77

EVALUATING UREA FERTILIZER FORMULATIONS FOR OIL PALM SEEDLINGS USING THE N ISOTOPE DILUTION TECHNIQUE

ABDUL RAHMAN Bah* ; ZAHARAH Abd Rahman*

ABSTRACT

High N volatilization severely limits the use of urea in oil palm cultivation. Urea-based compound formulations incorporating K, Ca and/or Mg have the potential for enhancing urea-N utilization, but information on their efficacy is scanty. Compound and bulk blended urea-based NPK and a bulk blend of gypsum urea were evaluated for oil palm at the main nursery stage on an ultisol (Rengam series). The normal recommended N rate and half of it were used for the urea NPK fertilizers, and only the normal rate for the gypsum urea blend. Nitrogen uptake and utilization from the fertilizers were quantified by the 15N isotope dilution technique. Dry matter yield was not significantly different between the fertilizer treatments irrespective of the rates applied. Percent N utilization was markedly greater at half the normal rate of application (60% versus 33%-38%). Much higher N concentration, uptake and N utilization efficiency (%NUE) were obtained with gypsum urea, probably because the Ca2+added by this material minimized the volatilization of urea-N. Thus, gypsum urea has greater potential than the compound and bulk blended urea-based NPK fertilizers as a source of N for oil palm seedlings

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* Department of Land Management,
Universiti Putra Malaysia,
43400 UPM, Serdang,
Selangor, Malaysia.
E-mail: bahabdulr@yahoo.com