SOIL SALINITY DYNAMICS AND CARBON SEQUESTRATION POTENTIAL UNDER CLIMATE CHANGE IN IRRIGATED AGROECOSYSTEMS OF PAKISTAN’S INDUS BASIN: A GEOSPATIAL AND BIOGEOCHEMICAL ASSESSMENT

Abstract

Soil salinity is a major constraint to agricultural productivity and carbon sequestration in irrigated agroecosystems of Pakistan’s Indus Basin. This study assessed soil salinity dynamics and carbon sequestration potential under changing climatic conditions using an integrated geospatial and biogeochemical approach. A total of 300 soil samples were collected from five agro-ecological zones at 0–30 cm and 30–60 cm depths and analyzed for electrical conductivity (EC), pH, soil organic carbon (SOC), total nitrogen, and bulk density. Geospatial mapping using Landsat 8 imagery and statistical analyses (correlation and regression) were conducted to identify key determinants of salinity and carbon stocks. Results revealed that downstream and delta regions exhibited the highest salinity (EC up to 18.5 dS/m) and lowest SOC (0.5–1.0%), while upstream and reclaimed areas had lower EC and higher SOC. Soil salinity was significantly influenced by temperature, evapotranspiration, and groundwater salinity, and negatively affected SOC (r = -0.68, p < 0.01). Spatial analysis highlighted salinity hotspots and areas suitable for targeted soil reclamation and carbon-enhancing management. The findings underscore the importance of climate-informed soil management and organic amendments to mitigate salinity, enhance carbon sequestration, and sustain agricultural productivity under climate change.