@article{fdi:010037976,
  title = {{D}etermination of carbon and nitrogen contents in {A}lfisols, {O}xisols and {U}ltisols from {A}frica and {B}razil using {NIRS} analysis : effects of sample grinding and set heterogeneity},
  author = {{B}runet, {D}idier and {B}arthes, {B}ernard and {C}hotte, {J}ean-{L}uc and {F}eller, {C}hristian},
  editor = {},
  language = {{ENG}},
  abstract = {{N}ear infrared reflectance spectroscopy ({NIRS}) is a rapid and low-cost method that has been reported to provide accurate prediction of soil total carbon ({C}t) and nitrogen ({N}t) contents. {H}owever, methodological aspects such as sample preparation and set homogeneity have not been addressed extensively. {T}he main objective of the paper was to assess how {NIRS} determination of {C}t and {N}t was affected by sample preparation (0.2 man grinding vs. 2 mm sieving) and set heterogeneity (i.e. using the total set vs. texture or localised sets). {T}he study was performed on a range of {A}ffican and {B}razilian {A}lfisols, {O}xisols and {U}ltisols (297 samples, with 6-80% clay). {T}he total set could be divided into a coarse-textured set, including samples from {B}urkina {F}aso and {B}enin mainly, and a clayey set, including samples front {B}razil mainly. {C}alibration and validation procedures were carried out within the total set and within each of the two texture sets and the three localised sets ({B}urkina {F}aso, {B}enin, and {B}razil), {P}rediction of {C}t using first derivatives with {SNV} (standard normal variate) scatter correction, which was the most appropriate spectrum preprocessing method, was in general more accurate for ground than for sieved samples. {T}he difference was decisive when the determination was carried out on the localised clayey set, moderate on total and texture sets, and unclear on localised coarse-textured sets. {P}rediction of {N}t was less clearly affected by sample preparation, though grinding was useful for the localised clayey set and harmful for localised coarse-textured ones. {T}hus the effect of sample preparation on prediction accuracy depended on soil texture, which may explain the contradictory results reported in the literature, often referring to narrow soil ranges. {U}sing the same preprocessing method, the accuracy of {C}t prediction generally increased with set homogeneity (i.e. from total to texture sets and from texture to localised sets), providing that clayey sets were ground. {T}his agreed with deductions drawn from comparison between earlier studies carried out with either homogeneous or heterogeneous sets. {T}he effect of set homogeneity on {N}t prediction could not, however, be clearly demonstrated by this study. {I}n conclusion, the study confirmed the interest of {NIRS} for the rapid and accurate determination of {C}t and {N}t, especially when homogeneous sets including ground samples were used.},
  keywords = {near infrared reflectance spectroscopy {NIRS} ; soil ; carbon ; nitrogen ; texture ; {AFRIQUE} {SUBSAHARIENNE} ; {BRESIL}},
  booktitle = {},
  journal = {{G}eoderma},
  volume = {139},
  numero = {1-2},
  pages = {106--117},
  ISSN = {0016-7061},
  year = {2007},
  DOI = {10.1016/j.geoderma.2007.01.007},
  URL = {https://www.documentation.ird.fr/hor/fdi:010037976},
}