Madhavan, D.Baldock, J.Read, Z.Murphy, S.Cunningham, S.Perring, M.Herrmann, T.Lewis, T.Cavagnaro, T.England, J.Paul, K.Weston, C.Baker, T.2017-05-102017-05-102017Journal of Environmental Management, 2017; 193:290-2990301-47971095-8630http://hdl.handle.net/2440/105029Available online 21 February 2017Reforestation of agricultural lands with mixed-species environmental plantings can effectively sequester C. While accurate and efficient methods for predicting soil organic C content and composition have recently been developed for soils under agricultural land uses, such methods under forested land uses are currently lacking. This study aimed to develop a method using infrared spectroscopy for accurately predicting total organic C (TOC) and its fractions (particulate, POC; humus, HOC; and resistant, ROC organic C) in soils under environmental plantings. Soils were collected from 117 paired agricultural-reforestation sites across Australia. TOC fractions were determined in a subset of 38 reforested soils using physical fractionation by automated wet-sieving and 13C nuclear magnetic resonance (NMR) spectroscopy. Mid- and near-infrared spectra (MNIRS, 6000–450 cm−1) were acquired from finely-ground soils from environmental plantings and agricultural land. Satisfactory prediction models based on MNIRS and partial least squares regression (PLSR) were developed for TOC and its fractions. Leave-one-out cross-validations of MNIRS-PLSR models indicated accurate predictions (R2 > 0.90, negligible bias, ratio of performance to deviation > 3) and fraction-specific functional group contributions to beta coefficients in the models. TOC and its fractions were predicted using the cross-validated models and soil spectra for 3109 reforested and agricultural soils. The reliability of predictions determined using k-nearest neighbour score distance indicated that >80% of predictions were within the satisfactory inlier limit. The study demonstrated the utility of infrared spectroscopy (MNIRS-PLSR) to rapidly and economically determine TOC and its fractions and thereby accurately describe the effects of land use change such as reforestation on agricultural soils.en© 2017 Elsevier Ltd. All rights reserved.C sequestration; biodiverse environmental plantings; mid-infrared spectroscopy; near-infrared spectroscopy; NMR spectroscopy; partial least squares regressionJournal article003006501410.1016/j.jenvman.2017.02.0130003976871000292-s2.0-85013290745289962Cavagnaro, T. [0000-0002-9922-5677]