Remote sensing is the process of acquiring and interpreting spectral measurement at distant location to collect information about earth’s surface features. The electromagnetic radiation (EMR) moves in the form of an advancing interaction between the electrical field and the magnetic field at right angle to each other. Sensors receive from a distance, the EMR reflected/emitted by earthly features. A pictorial representation of any feature is called the image of that feature. The image of a whole area is instantaneously acquired in the remote sensing framing system. In the case of the remote sensing scanning system, EMR reflected from a very small area reaches the detector, which is then amplified, recorded on magnetic tape and later played back to produce the image. Aerial photography is photographing earth’s surface features from air/spacecraft.
Earthly features reflect the EMR incident upon them to the scan mirror which deflects it to the spectrometer that splits up the incoming EMR spectrum into blue, green, red and infrared wavelength bands. Remotely sensed data are to be classified into categories of soil classification for remembering their properties in a systematic manner, knowing their best utilization and predicting their response to management practices. Soil survey is the process of systematically examining soils in their natural landscape, classifying them into well defined mapping unit describing them, demarcating their boundaries on the base map and predicting their behaviour under specific management practices. Soil erosion survey aims to assess the erosion hazard.
Remote sensing emerged as a powerful tool to collect useful information about natural resources. Geomorphology, geology, soils, crops, forest, and water resources are some of the fields in which up-to-date, accurate, and rapid survey greatly facilitates collection of useful information about them. Application of remote sensing techniques in the assessment of land, soil, water, forest, and crop resources is perhaps the most essential for any country, particularly in underdeveloped country like India.
This book Remote Sensing and Assessment of Soil Resources comprehensively covers various aspects of the application of remote sensing in the study of soil sources. It deals with the basics of remote sensing and photogrammetry. It explains how basic remote sensing and photogrammetry are useful in understanding the assessment of crops and soil resources. This book is of immense help to geographers and soil surveyors besides the students and teachers of Agriculture and Bio-science and the researchers in these fields.
A.K. Kolay, M.Sc. (Agriculture), Ph.D., is a retired professor from the School of Agricultural Science & Rural Development, North Eastern Hill University, Shillong. Earlier he served at the Soil Conservation Department of the Government of Himachal Pradesh and also at the National Bureau of Soil Survey and Land Use Planning, New Delhi. He has authored many books which include Manures and Fertilizers; Water and Crop Growth and Soil Genesis, Classification Survey and Evaluation.
