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A rapid method for estimating nitrate‐nitrogen concentration in field soils
Author(s) -
Hunt John,
Ng Wai Y.,
Barnes Anthony,
Greenwood Duncan J.
Publication year - 1979
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740300402
Subject(s) - soil water , range (aeronautics) , nitrate , statistics , nitrogen , mathematics , core (optical fiber) , soil test , soil science , field (mathematics) , reagent , systematic error , observational error , approximation error , substitution method , environmental science , biological system , chemistry , computer science , materials science , telecommunications , organic chemistry , biology , pure mathematics , composite material
A rapid method is described to enable farmers to measure the NO 3 ‐N levels in a field simply and cheaply. It involves taking soil cores from the field, kneading them with water in polythene bags, adding the resulting suspensions to test strips of reagent impregnated paper and estimating the intensity of colour that develops. A formula to relate the errors incurred at each step to the overall error of the method was derived. These components of error were estimated and their substitution into the formula enabled the overall errors in using the method to assess nitrate concentrations in different fields to be calculated. The largest component of error was the variation in NO 3 ‐N from core to core within a field. The median value over a range of sites was 57%. For a soil with this value the overall standard error in estimating NO 3 ‐N concentration was 22% which is similar to that found with the methods of soil analysis currently used for advisory purposes. The increased number of determinations in the rapid method compensated for larger errors in each individual measurement so that the overall error in estimation by rapid and standard methods were both dominated by core to core variability. Measurements of NO 3 ‐N concentration in each of 18 different fields by the rapid method were in reasonably good agreement with those made entirely independently by a laboratory procedure.