Submitted to: Sustainable Agriculture
Publication Type: Abstract Only
Publication Acceptance Date: August 28, 1998
Publication Date: N/A
Technical Abstract: The objective was to investigate the usefulness of NIRS in determining various constituents (total N and C, and active, biomass and mineralizable N, and pH) and parameters (soil source, depth from which sample was obtained, type of tillage used and rate of application of NH4NO3) of low organic matter soils. Samples (N = 179) were obtained from experimental plots consisting of two locations with plots under plow till and no till practices at each location with 3 rates of NH4NO3 used. For each of these, samples were taken from 5 depths for a total of 180 samples (one lost). Investigations demonstrated that NIRS could be successfully used to determine some compositional parameters of low organic matter soils particularly total C and total N). It was also apparent that for non-biological parameters, excluding pH, that NIRS is generally not very useful. For other determinations, such as biomass N and active N, results were more variable and may be useful depending on the exact needs in question. Finally, NIRS was totally useless for determining mineralizable N (21 d) in soils. In a second study, the use of NIRS as an alternative to wet chemical procedures for measuring manure nitrogen and carbon mineralization rates was investigated. Ground soil samples from studies in which manure was incubated with soil for various time periods (0 to 112 d) were scanned in the near-infrared, and calibrations for NH3, NO3-, total N (NH3 and NO3-) contents and C lost as CO2 were developed. Results indicate that NIRS might be of some benefit in limited circumstances, but that in general the accuracy is not sufficient to replace the standard wet chemical procedures used for mineralization studies.