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Soil Science Society of America Journal Abstract -

Nitrogen Mineralization from Citrus Tree Residues under Different Production Conditions


This article in SSSAJ

  1. Vol. 61 No. 4, p. 1226-1232
    Received: Jan 25, 1996

    * Corresponding author(s): aka@gnv.ifas.ufl.edu
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  1. H. Dou,
  2. A. K. Alva  and
  3. B. R. Khakural
  1. University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850



Under most citrus production conditions, dry leaves and other vegetative parts are returned to the soil under the trees. These materials and fibrous roots decompose on a regular basis. The objective here was to measure annual N contribution to citrus trees from organic residue decomposition. Mineralization of N was measured during 2 yr under citrus trees of two age groups each on Tavares fine sand (hyperthermic, uncoated Typic Quartzipsamment) and Wabasso sand (sandy, siliceous, hyperthermic Alfic Haplaquod). Mineralization of N from tree residues under the canopy accounted for 58 to 84 and 126 to 153 kg N ha−1 yr−1 for the 4- and 20-yr-old trees, respectively, on the Tavares fine sand and 39 to 64 and 121 to 126 kg N ha−1 yr−1 for the 7- and 40-yr-old trees, respectively, on the Wabasso sand. The transformation of potentially mineralizable N (i.e., total N in dry crop residue and fibrous roots under the canopy) into inorganic forms (i.e., percentage mineralization) was greater in Wabasso sand (41–86%) compared with that in Tavares fine sand (17–71%). Significant correlations (r = 0.82 [significant at P = 0.05] and 0.84 [significant at P = 0.01]) were found between measured quantities of mineralized N and potentially mineralizable N. There were also significant correlations between mineralized N and either rainfall or average temperature during each incubation interval. This study demonstrated that the quantity of net N mineralized from organic residues under the tree accounts for a significant portion of annual N requirement.

Contribution of the Citrus Research and Education Center. Florida Agric. Exp. Stn. Journal Series no. R-05007.

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