Investigating Heavy Metal Accumulation in Agricultural Soils and its Correlation with Crop Yield Reduction

Abstract

Heavy metal contamination of agricultural soils poses a critical global food security and public healthchallenge. This study investigates the accumulation of heavy metals—specifically lead (Pb), cadmium(Cd), chromium (Cr), nickel (Ni), and mercury (Hg)—in farm soils across three agroecological regionsand examines their correlation with crop yield reductions in staple cereals (rice, wheat, maize). Soilsamples (n=120) and corresponding crop tissues were analyzed using inductively coupled plasma massspectrometry (ICP-MS) to quantify metal concentrations. Soil physico- chemical properties (pH, organic matter, cation-exchange capacity) were measured to assess metal mobility. Crop yield data (over two growing seasons) were compared against contamination levels. Statistical analyses included Pearson correlation, principal component analysis (PCA), and multiple regression to elucidate relationships between heavy metal indices and yield outcomes. Results show that 38% of soil samples exceeded WHO/FAO permissible limits for Cd and Pb. Tissue accumulation mirrored soil trends, notably higher Cd in roots and shoots. A significant negative correlation (r = −0.67, p < 0.01) between total soil Cd concentration and grain yield was observed, with regression models predicting a 12% yield loss per mg/kg Cd increase. PCA highlighted that metal accumulation contributed 45% variance in yield reduction. Findings emphasize that soil heavy metal buildup exerts a quantifiable impact on crop productivity, mediated by soil chemistryand plant uptake dynamics. The study underscores the urgent need for soil remediation, crop rotation strategies, and heavy metal monitoring frameworks in contaminated regions. It provides a robust analytical framework to inform policymaking and sustainable agricultural practices.