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Soil Nitrogen Mineralization Potential in a Fertilized Loblolly Pine Plantation
Author(s) -
Maimone R. A.,
Morris L. A.,
Fox T. R.
Publication year - 1991
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/sssaj1991.03615995005500020038x
Subject(s) - mineralization (soil science) , incubation , soil water , human fertilization , nutrient , leaching (pedology) , nitrogen , loblolly pine , zoology , agronomy , chemistry , nitrogen cycle , botany , biology , pinus <genus> , ecology , biochemistry , organic chemistry
Nitrogen deficiency is the most common nutrient deficiency in natural pine ( Pinus spp.) stands and plantations of the southern USA. This study was conducted to identify a soil test of available N that correlates well with tree growth volume response to N fertilization. We evaluated the utility of 98‐d aerobic incubation for assessing changes in soil N availability resulting from fertilization of a loblolly pine ( P. taeda L.) plantation. Results were compared with results from a 30‐d incubation and correlated with tree volume growth. Seven months after fertilization with 224 kg N ha −1 as urea, significant increases ( P > 0.0312) in N‐mineralization potential (N φ ) were found in surface (0–15 cm) soils, but not subsurface (15–50 cm) soils. The increase was also significant in subsequent incubations up to 16 mo after fertilization. A concurrent short‐term aerobic‐incubation study did not detect significant increases due to fertilization after 7 mo, illustrating the greater sensitivity of the long‐term incubation to differences in available N. No differences in N φ were attributed to P fertilization at 56 kg ha −1 , although significant increases occurred when P was included in nutrient leaching solutions in the incubated soils following CaCl 2 extraction for inorganic N. Differences in N φ occurred among seasons, with maximum mineralization occurring in spring and minimum in autumn. Nitrogen‐mineralization potential correlated with 2‐yr tree volume growth, with the best correlation at the spring sampling date ( r = 0.81, P > 0.0002). The linear relationship between volume growth and N φ was improved with the addition of tree stand stocking as a covariate ( r = 0.85). Nitrogen‐mineralization potential was also correlated with soil Kjeldahl N, organic C, and exchangeable acidity.