Abstract
Assessing and mapping spatial distribution variability of soil reaction (alkalinity and acidity denoted as soil pH) and electrical conductivity (EC) in cultivated areas is crucial for degradation monitoring, precision soil fertility management, and sustainable crop production. The distribution of soil reaction and EC is affected by several factors together with elevation (E), temperature and rainfall. We assessed spatial distribution variability of soil reaction and EC in cultivated areas of 29 states of India, and evaluated the relationship of soil pH and EC with E, average annual maximum temperature (AAMT), and average annual rainfall (AAR). Altogether, 237,496 georeferenced and representative surface (depth of 0 to15 cm depth) soil samples were collected, and processed. Subsequently, processed soil samples were analyzed for soil pH and EC. Soil pH varied from 2.80 to 10.2 (mean ± SD 6.98 ± 1.16) with coefficient of variation of 16.64%. Whereas, EC values ranged from 0.01 to 7.75 dS m−1 (mean ± SD 0.31 ± 0.30 dS m−1) with CV of 96.30%. Soil pH was negatively and significantly correlated with E, AAMT, and AAR. Whereas, soil EC was positively and significantly correlated with E, and negatively and significantly correlated with AAMT, and AAR. The semivariogram analysis resulted in exponential best-fitted model both for soil pH and EC with the lowest MSE and RMSE values. Soil pH (nugget / sill ratio 0.35) and EC (nugget / sill ratio 0.57) had moderate spatial dependence. The interpolation maps, developed by ordinary kriging technique, revealed diverse distribution shapes for soil pH and EC in different states, and agro-ecological regions of India. About 9.7, 18.8, and 31.2% area had soil pH of > 4.5 to ≤ 5.5, > 5.5 to ≤ 6.5, and > 6.5 to ≤ 7.5, respectively. Whereas, 34.6 and 5.6% area had pH value of > 7.5 to ≤ 8.5, and > 8.5, respectively. About 93.1 and 6.7% study area had soil EC value of ≤ 0.50, and > 0.50 to ≤ 1.00 dS m−1, respectively. The generated soil pH and EC maps could be used as reference for local and regional scale policy making, and adoption of suitable soil-crop management strategies for effective soil acidity and salinity management in the study area in order to achieve improved soil health, land degradation neutrality, and sustainable crop production.
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Acknowledgements
The authors thank Indian Council of Agricultural Research, Department of Agricultural Research and Education, Ministry of Agriculture and Farmers Welfare, Government of India, New Delhi for extending financial support for this study. The authors thank Director, Indian Council of Agricultural Research-Indian Institute of Soil Science, Bhopal, Madhya Pradesh, India for proving required support to undertake the study. All authors thank scientists of different cooperating centers of All India Coordinated Project on Micro- and Secondary Nutrients and Pollutant Elements in Soils and Plants for collecting and analysis of soil samples. The authors thank Dr. G. P. Obi Reddy, ICAR-NBSSLUP, Nagpur, India for providing additional soil pH data pertaining to state of Arunachal Pradesh, and Dr. Vikas Sharma, SKUAST, Jammu, India for providing additional soil pH data pertaining to state of undivided Jammu and Kashmir.
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The research work was financially supported by Department of Agricultural Education and Research, Indian Council of Agricultural Research, Govt. of India, New Delhi funded the research.
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Behera, S.K., Shukla, A.K., Mishra, R. et al. Understanding spatial distribution variability of surface soil reaction and electrical conductivity in cultivated soils of India as influenced by some environmental factors. Sci Rep (2026). https://doi.org/10.1038/s41598-026-52844-6
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DOI: https://doi.org/10.1038/s41598-026-52844-6
