|Authors: ||R. Pire, H. Ramirez, J. Riera, N. Gómez de T|
|Keywords: ||mineral nutrition, onion, Allium cepa|
An experiment was conducted to determine the nutrient composition and amount of N, P, K and Ca removed from the soil by an onion crop (Allium cepa L. cv.
Texas Grano 438) in a semiarid region with silty clay soils of Venezuela (9° 56’N, 700 meters a.s.l.). Replicated samples of bulb, leaves and roots were taken for nutrient analysis at 8 different growth stages in an onion field with a population of 250,000 plants/ha.
Removal of nutrients was calculated from mineral analysis and dry-weight growth data.
N and K concentrations for the whole plant were highest at early growth, P concentration at the middle of the growth period, and Ca concentration at the beginning of the life cycle.
N, P, K and Ca concentrations were lowest at harvest.
At this latter time, N and K were highest in the leaves, P in the bulb and Ca in the root.
The rate of nutrient removal was very low during early growth and increased drastically in the last 40 days of the crop due to the rapid growth of the bulb.
The final nutrient extraction was 118.6 kg/ha for N, 23.4 kg/ha for P, 110.7 kg/ha for K and 77.6 kg/ha for Ca, with a total onion yield of 28.22 tn/ha.
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