Nitrogen requirements of oil palms in Malaysia: Fifty years of experiments conducted by Guthrie
1982
Chan, K.W.
The results of sixty-seven fertiliser trials testing levels on N conducted by Guthrie Research, Chemara from 1929 to 1980 are presented in 3 phases, viz, difficult to demonstrate a yield response to nitrogen (N) fertiliser was clearing but in replants it was quickly established that N fertiliser was required for both vegetative growth and yield. Leaf N contents, like leaf potassium (K) plateaued while yield continued to increase with additional N fertiliser application. N was synergistic with K and together they enchanced the yield of oil palm. For full expression of N effect on yield in addition to a large quantity of K, phosphate (P) and kieserite (Mg) fertilisers in small amounts were rquired. Leaf N level was depressed slightly during dry conditions. Thus care must be taken in interpretation of leaf analytical values of leaves sampled under such conditions. The residual effect of N was small, and a year after its application was discontinued, yield decline was observed. Due to the rapid increase in the price of nitrogen fertilisers the efficiency of various N fertiliser sources on many soil types were also evaluated. The results point to the greater efficiency of ammonium sulphate (S/A) over urea on inland soils
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