Original Articles

Rapid simultaneous rating of soil texture, organic matter, total nitrogen and nitrogen mineralization potential by near infra-red reflectance

Published in: South African Journal of Plant and Soil
Volume 6, issue 1, 1989 , pages: 59–63
DOI: 10.1080/02571862.1989.10634481
Author(s): J.H. Meyer, Republic of South Africa

Abstract

A rapid non-destructive technique for the determination of various soil properties by near infra-red spectrophotometry is described. Over 100 soils, of which the organic matter content, total nitrogen (N) content, N-mineralizing potential and particle size distribution were known, were used as a basis for programming three instruments (Technicon InfraAlyzers models 300, 400 and 450). In general the results of subsequent analyses indicated that the larger 450 and 400 models were more reliable than the smaller 300 instrument. The reliability of all three instruments decreased when determining clay, organic matter, total N, sand and silt (in this order). Standard errors of prediction in the range 0,3 to 7,0% for organic matter and 0,03 to 0,60% for total N were 0,46 and 0,011 % respectively. Coded soil samples from 21 N trials showed also that the infra-red spectrophotometry technique holds promise for rating the N-mineralizing potential of soil according to a four-point scale that was recently developed for sugarcane. The main advantage of the infrared method compared with conventional methods is that it is rapid. Less than 30 seconds is required to produce a complete rating.

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