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IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India.2002 
  
  
EVEL ASEP CATION | 11 
  
Spectral reflectance behaviour of saline and saline-sodic soils 
have been studied in detail since saline and saline-sodic soils 
are important category of soils in Mathura district. In situ 
spectral measurements of these soils have been taken using 
Ground Truth Radiometer (Model No. 041). Spectral 
behaviour have been measured in the four bands (visible and 
near IR) which are similar to IRS satellite bands of Liss I and 
II sensors — (0.45-0.52, 0.52-0.59, 0.62-0.68 and 0.77-0.86 
micronmeter). Soils within the saline-sodic category having 
different pH, EC and SAR values have been grouped into 
three classes for taking spectral measurements- highly saline 
sodic, moderately saline sodic and low saline-sodic. One 
saline soil having low pH but high soluble salt content has 
also been taken for spectral measurement. It can be seen 
from Fig. 5 and Table - 2 that the highly saline sodic soils 
have very high reflectance in all the four bands, followed by 
moderately saline soils (2 sites, 225 B and 225C) and low 
saline sodic soils. Highly saline soil (soil 246) has 
reflectance high in all the four bands as compared to 
moderate and low saline-sodic soils. This is probably due to 
high soluble salt content in this soil. From these results, it is 
evident that different types of saline and saline-sodic soils 
could be separated by radiometric measurements in the 
701 
RADIOMETRIC MEASUREMENT OF SOILS AT 10” DECADE FACTOR 
  
8 
Reflectance Factor 
8 
40 4 
30 4 
20! 
10 3 
  
  
  
0 + + 
0.45-.052 0.52-0.59 062-068 — 0.774€ 
—Anactral hand width in um. a> 
  
—U-- Highly saline-sodic (225A) 
—ér- Highiy Saline (24C) 
—t— Moderately saline-sódic (225B) 
—1— Moderately saline-sodic (225C) 
—O-— Low saline-sodic (225E) 
  
  
  
Fig. 5 : In situ radiometric measurement of salt affected 
soils 
visible and near IR bands. Saxena et al. (2000) have also 
found similar results for the soils of Indo-Gangetic plains. 
  
  
  
  
  
  
  
  
  
  
  
  
Sample Effervescence pH EC SAR 
No. with HCI dSm' 
225A Strong violent 10.50 | 02.03 94-33 
225B V. strong violent 10.32 | 01.61 81.13 
225C Weak 10.40 | 01.92 | 70.67 
225E Weak 09.83 | 00.42 | 50.78 
246H Strong 07.80 | 18.30 | 09.14 
  
Table-2 : Chemical characteristics of surface soil samples 
from sites of radiometric measureme nts 
6. CONCLUSION 
The study has clearly demonstrated the utility of satellite data 
in soil categorisation and of digital image classification in the 
mapping of small patches of degraded soils. It has also 
shown that different types of salt-affected soils (saline; 
highly, moderately and low saline —sodic soils) could be 
separated using radiometric data. The study also shows the 
utility of remote sensing technique in assessing and 
monitoring the extent of degraded soils in the semi-arid 
ecosystem, which may further help in taking long term 
control measures.