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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/10074

Title: Nitrogen Mineralization in Sludge-Amended Desert Soil as Affected by Rate of Sludge, Salinity, and Wetting and Drying Cycles
Authors: A. H. M. Gomah
S. I. Al-Nahid
H. A. Amer
Issue Date: 1990
Publisher: Arid SoiI Research and Rehbilitation.
Abstract: Three incubation experiments were conducted to determine the influence of sludge rate, N addition, salinity and wetting and drying cycles on different N forms in sludge-amended calcareous silt loam soil. NH+4-N and NO-2+ NO-3-N were analysed at intervals of 1, 2, 4, 8, and 12 weeks incubation at 30 C ± 1. The rate of sludge as well as N was found to significantly affect NO-3-N accumulation. The cumulative inorganic N at the end of 12 weeks incubation was dependent on sludge rate and slightly affected by N addition. Cumulative mineralized N at 0-, 40-, 80-, and 160-t ha-1 sludge treatments were 15.4, 83.7, 105.1 and 165.0 mg kg - 1 soil, respectively. In case of sludge and N addition, these figures were 10.2, 99.6, 108.4, and 180.4 mg kg-1 soil. N-mineralization rate constant K increased from 0.214 in the control to 0.303, and 0.439 then decreased to 0.309 week-1 in soil treated with 0, 40, 80, and 160 t ha -1 sludge, respectively. Mean K values decreased with N addition and when excluding inorganic N found in soil and sludge at the start. Nitrogen mineralization potential NO values greatly increased with sludge and N addition. A salt mixture of (1:1 NaCl:CaCl2) at a concentration of 7.5 mg g-1 soil delayed nitrification in unmended soil, while 15 mg g-1 caused complete inhibition. In sludge-treated soil, retardation and complete inhibition of nitrification occurred at 7.5 and 60 mg g-1 salt mixture, respectively. Complete inhibition of ammonification occurred at salt mixture of 30 mg g-1 soil. Drying of either control or amended soil led to a marked drop in NH+4-N and NO-2+ NO-3-N content of soil. Both NH+4-N and NO-2 + NO-3-N increased during wetting cycles. Mineralization was greater after 4 cycles of wetting and drying than after the first cycle.
URI: http://hdl.handle.net/123456789/10074
Appears in Collections:College of Foods And Agricultural Science

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