Premium
Variability of the Illinois Soil Nitrogen Test across Time and Sampling Depth
Author(s) -
Wall David P.,
Weisz Randy,
Crozier Carl R.,
Heiniger Ronnie W.,
White Jeffrey G.
Publication year - 2010
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/sssaj2009.0253
Subject(s) - fertilizer , environmental science , soil test , sampling (signal processing) , tillage , hydrology (agriculture) , nitrogen , soil water , agronomy , soil science , geology , chemistry , biology , geotechnical engineering , organic chemistry , filter (signal processing) , computer science , computer vision
There is potential for using the Illinois soil nitrogen test (ISNT) to improve N fertilizer recommendations for crops in the southeastern United States. The ISNT has been previously calibrated to predict N rates for corn ( Zea mays L.) in North Carolina. This study evaluated the effects of sampling time, sampling depth, crop rotation, and fertilizer application on soil ISNT‐N during a 2‐yr period in the humid Coastal Plain and Piedmont regions of North Carolina. Ten sites were repeatedly sampled at 0‐ to 10‐, 10‐ to 20‐, and 20‐ to 30‐cm depths in fall, mid‐winter, and spring between October 2006 and May 2007. Illinois soil nitrogen test N, KCl‐extractable soil NO 3 –N and NH 4 –N, and soil organic matter (SOM) derived by loss‐on‐ignition (LOI) were evaluated at each sampling. Temporal changes in these soil parameters were evaluated for various crop rotations and N fertilizer applications. Soil ISNT‐N decreased with depth and showed significant variation with time at all three depths at all sites. Soil ISNT‐N was influenced by crop rotation and tillage but was not significantly affected by N fertilizer applications. Considering all sites together, ISNT‐N was well correlated with LOI; however, ISNT‐N was not correlated with LOI across time within sites. This suggests that the ISNT measured a fraction of SOM that behaved somewhat independently with time.