ABSTRACT
Soil is a very important resource in the earth’s surface, which provides a medium for the growth of plant, animals, and microbes. Furthermore, soil fertility plays a vital role in the growth of these living things and is closely linked with the production of food, fuel, feed, and fiber. Therefore,
6.1 Introduction .......................................................................................................................... 155 6.1.1 Definition of Soil Fertility ........................................................................................ 156 6.1.2 Soil Fertility and Food Production ........................................................................... 157 6.1.3 Soil Fertility and Soil Nutrients ................................................................................ 157 6.1.4 Infrared Spectroscopy in Soil Analysis .................................................................... 158
6.2 Techniques of Infrared Spectroscopy ................................................................................... 159 6.2.1 Absorption of Infrared Spectroscopy ....................................................................... 159 6.2.2 Methods of Infrared Spectroscopy ........................................................................... 159
6.2.2.1 Infrared Transmission Spectroscopy ......................................................... 159 6.2.2.2 Infrared Diffuse Reflectance Spectroscopy ............................................... 160 6.2.2.3 Infrared Attenuated Total Reflectance Spectroscopy ................................ 160 6.2.2.4 Infrared Photoacoustic Spectroscopy ........................................................ 161
6.3 Assessment of Soil Fertility by Infrared Spectroscopy ........................................................ 162 6.3.1 Infrared Spectra-Based Soil Qualitative Analysis.................................................... 162
6.3.1.1 Characterization of Soil Components ........................................................ 162 6.3.1.2 Soil Identification ....................................................................................... 165
6.3.2 Infrared Spectra-Based Soil Quantitative Analysis .................................................. 165 6.3.2.1 Soil Nutrients ............................................................................................. 165 6.3.2.2 Soil Clays ................................................................................................... 167 6.3.2.3 Soil Water ................................................................................................... 169 6.3.2.4 Soil Microbes ............................................................................................. 169
6.3.3 Mathematical Tools in the Treatment of Spectral Data ............................................ 171 6.3.3.1 Data Preprocessing .................................................................................... 171 6.3.3.2 Prediction Model ........................................................................................ 172 6.3.3.3 Model Verification ..................................................................................... 174
6.4 Soil Infrared Spectrum Information System ........................................................................ 175 6.5 Research Highlights in the Future ........................................................................................ 176
6.5.1 Construction of a Soil Infrared Spectra Library ...................................................... 176 6.5.2 Mathematic Tools in Spectral Data Mining ............................................................. 176
6.6 Conclusions ........................................................................................................................... 176 Acknowledgments .......................................................................................................................... 177 References ...................................................................................................................................... 177
assessment of soil fertility is routine work in soil management and crop production. However, laboratory analysis-based determination of soil properties is time-consuming and costly, and is often not suitable in modern agriculture. Infrared spectroscopy can be used as an alternative technique for this purpose in soil analysis, and transmission and reflectance methods are already widely used. However, the transmission method is usually used in soil qualitative analysis, while reflectance can be used in soil quantitative analysis, and most soil-related research is focused on reflectance spectroscopy. The objective of this chapter is to describe the applicability of these techniques for sitespecific management of soil fertility with specific reference to application of precision agriculture to smallholder farming in China.
