Quantitative measurement of fertilizer uptake by crops.

Little justification exists for using crop yield as an indirect measure of fertilizer uptake. Most commonly, fertilizer uptake is measured by the difference in nutrient yield of a crop growing in the presence or absence of fertilizer. The method recommended, (using isotopically labelled fertilizer) dispenses with the need for control plots. Application of the isotopic method to comparative studies on the placement, timing and nature of the fertilizer, to the measurement of fertilizer uptakes in the presence or absence of plant-fertilizer interactions, to the measurement of symbiotic N fixation by legume crops and to the fertilizer uptake by tree crops is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission

The application of foliar analysis in oil palm cultivation

The chemical analysis of leaves was studied as an indication of fertilizer requirements of the oil-palm in the former Belgian Congo. Position and age of the leaf both markedly influenced chemical composition. Leaflets from the same position in leaf and plant must be compared. The age of the whole palm also had its influence; climatic influences also varied with age (generally more fluctuating in younger palms). Time of year significantly influenced leaf composition. Sampling in the rainy season was advised, between 07.00 h and 10.00 h. Analytical error should not exceed 10 %.For 20 ha bulk samples of 20 to 25 palms should be taken; they give a sampling variation of the same order as the errors in chemical analysis. Two leaflets from each side of the middle part of the youngest leaf (with fully open leaflets) were taken. Chemical composition was directly related to growth and production of oil- palms. There was an 'optimum' leaf composition. Qualitative diagnosis of deficiencies should however be based on characteristic changes in leaf composition for all the elements (N, P, S, K, Ca, Mg, Mn, B, Cu, Zn). A deficiency of a minor element may effect contents of major elements. It was possible to approach the optimum leaf concentration by fertilizing.<p/