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Biology and Fertility of Soils

, Volume 26, Issue 3, pp 169–172 | Cite as

Nitrogen uptake and growth of two citrus rootstock seedlings in a sandy soil receiving different controlled-release fertilizer sources

  • H. Dou
  • A. K. Alva
ORIGINAL PAPER

Abstract

Understanding the fate of different forms of nitrogen (N) fertilizers applied to soils is an important step in enhancing N use efficiency and minimizing N losses. The growth and N uptake of two citrus rootstocks, Swingle citrumelo (SC), and Cleopatra mandarin (CM), seedlings were evaluated in a pot experiment using a Candler fine sand (hyperthermic, uncoated, Typic Quartzipsamments) without N application or with 400 mg N kg–1 applied as urea or controlled-release fertilizers (CRF; either as Meister, Osmocote, or Poly-S). Meister and Osmocote are polyolefin resin-coated urea with longevity of N release for 270 days (at 25°C). Poly-S is a polymer and sulfur-coated urea with release duration considerably shorter than that of either Meister or Osmocote. The concentrations of 2 M KCl extractable nitrate nitrogen (NO3-N) and ammonium nitrogen (NH4+-N) in the soil sampled 180 days and 300 days after planting were greater in the soil with SC than with CM rootstock seedlings. In most cases, the extractable NH4+ and NO3 concentrations were greater for the Osmocote treatment compared to the other N sources. For the SC rootstock seedlings, dry weight was greater with Meister or Poly-S compared with either Osmocote or urea. At the end of the experiment, ranking of the various N sources, with respect to total N uptake by the seedlings, was: Meister = Osmocote > Poly-S > Urea > no N for CM rootstock, and Meister = Poly-S = Osmocote > Urea > no N for SC rootstock. The study demonstrated that for a given rate of N application the total N uptake by seedlings was greater for the CRF compared to urea treatment. This suggests that various N losses were lower from the CRF source as compared to those from soluble fertilizers.

Key words Urea Coated fertilizers Ammonium nitrogen Nitrate nitrogen Nitrogen uptake 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • H. Dou
    • 1
  • A. K. Alva
    • 1
  1. 1.University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA Tel: (941) 956-1151; Fax: (941) 956-4631; e-mail: hdou@gnv.ifas.ufl.eduUS

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