Premium
Soil NO 3 ‐N Analysis in CA(OH) 2 Extracts by the Chromotropic Acid Method
Author(s) -
Haby V. A.
Publication year - 1989
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/sssaj1989.03615995005300010059x
Subject(s) - chromotropic acid , oxidizing agent , chemistry , absorbance , extraction (chemistry) , soil test , soil water , nuclear chemistry , analytical chemistry (journal) , chromatography , mineralogy , soil science , geology , biochemistry , organic chemistry , formaldehyde
Methodology and instrumentation improvements have contributed to the increased use of nitrate‐nitrogen (NO 3 ‐N) analysis of soil extracts for predicting crop N requirements. This research was conducted to determine the accuracy of the modified chromotropic acid (CTA) procedure for NO 3 ‐N in saturated Ca(OH) 2 extracts of soils. Sixty‐two soil sample extracts were analyzed for NO 3 ‐N by the CTA method modified to eliminate oxidizing agents, NO ‐ 2 , and possible interferences from CI ‐ and Fe. Results were compared with the same samples extracted and analyzed by use of the phenoldisulfonic acid method (PDSA). Comparison indicated the two methods were in close agreement (slope = 0.92 and r 2 = 0.94). The graph of CTA NO 3 ‐N concentration vs. absorbance at 410 nm followed Beer's Law. The modified CTA method, combined with Ca(OH) 2 extraction of soil NO 3 ‐N, is described in detail and presented as a standard.