title: In situ measurement of some soil properties in paddy soil using visible and near-infrared spectroscopy.
abstract: In situ measurements with visible and near-infrared spectroscopy (vis-NIR) provide an efficient way for acquiring soil information of paddy soils in the short time gap between the harvest and following rotation. The aim of this study was to evaluate its feasibility to predict a series of soil properties including organic matter (OM), organic carbon (OC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and pH of paddy soils in Zhejiang province, China. Firstly, the linear partial least squares regression (PLSR) was performed on the in situ spectra and the predictions were compared to those with laboratory-based recorded spectra. Then, the non-linear least-square support vector machine (LS-SVM) algorithm was carried out aiming to extract more useful information from the in situ spectra and improve predictions. Results show that in terms of OC, OM, TN, AN and pH, (i) the predictions were worse using in situ spectra compared to laboratory-based spectra with PLSR algorithm (ii) the prediction accuracy using LS-SVM (R2>0.75, RPD>1.90) was obviously improved with in situ vis-NIR spectra compared to PLSR algorithm, and comparable or even better than results generated using laboratory-based spectra with PLSR; (iii) in terms of AP and AK, poor predictions were obtained with in situ spectra (R2<0.5, RPD<1.50) either using PLSR or LS-SVM. The results highlight the use of LS-SVM for in situ vis-NIR spectroscopic estimation of soil properties of paddy soils.
authors.affiliation: Institute of Agricultural Remote Sensing and Information Technology, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Wenjun
authors.affiliation: Institute of Agricultural Remote Sensing and Information Technology, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China; Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Zhou
authors.affiliation: School of Biological, Earth and Environmental Science, The University of New South Wales, Kensington, Australia.
authors.forename: Huang
authors.initials: H
authors.lastname: Jingyi
authors.affiliation: Institute of Agricultural Remote Sensing and Information Technology, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Shuo
mesh_terms: D002244:Carbon / Q000032:analysis*; D002681:China; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D011188:Potassium / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared
chemical_list: D012987:Soil; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen; D011188:Potassium