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Recovery of 15N‐Labeled Fertilizer from Manured and Sludge‐Amended Soil
Author(s) -
PomaresGarcia F.,
Pratt P. F.
Publication year - 1978
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1978.03615995004200050012x
Subject(s) - fertilizer , manure , agronomy , nitrogen , tonne , mineralization (soil science) , chemistry , zoology , forage , greenhouse , environmental science , biology , organic chemistry
A greenhouse pot experiment was conducted with various rates of manure (0, 20, 40, and 60 metric tons/ha) and sludge (0, 10, 20, and 30 metric tons/ha) combined factorially with 0, 50, 100, 150, and 200 mg N/kg soil as (NH 4 ) 2 SO 4 labeled with 15 N, using barley and sudangrass as test crops. Most of the N from (NH 4 ) 2 SO 4 was recovered by the first cutting of barley forage (from 37.2 to 70.2%); the N from (NH 4 ) 2 SO 4 recovered by sudangrass, the last crop of the cropping sequence, ranged from 0.7 to 8.9%. No significant effect of both wastes and (NH 4 ) 2 SO 4 rates on the overall inorganic N fertilizer recovered by the crops was found. The difference method underestimated the (NH 4 ) 2 SO 4 ‐N recoveries by the crops under sludge treatments. The depression in the mineralization rate of sludge by the (NH 4 ) 2 SO 4 applied was proposed to account for these discrepancies. A fertilizer N balance, in which the sum of (NH 4 ) 2 SO 4 ‐N removed by the crops plus the N accumulated in the soil was subtracted from the (NH 4 ) 2 SO 4 ‐N input, was used to estimate the fertilizer N losses. These losses were 7.8, 9.1, and 13.1%, respectively, for control (unamended), manure and sludge treatments. With increasing rates of (NH 4 ) 2 SO 4 , the nitrogen “A” values defined as the N available in the soil in terms of N from (NH 4 ) 2 SO 4 , increased in the control, remained almost constant with manure, and decreased with sludge treatments.