Analysis of Topsoil Quality Changes Across Soil Groups in Vietnam

Abstract

This study systematically investigates the changes in topsoil quality across various soil groups in Vietnam over a 13-year period, spanning from 2004 to 2017. The primary objective is to evaluate key soil quality indicators, including pH, organic matter (OM), nitrogen (N), phosphorus (P2O5), potassium (K2O), and cation exchange capacity (CEC), to assess the health, fertility, and sustainability of these soils in response to agricultural practices and environmental factors. The findings reveal significant alterations in soil parameters across the diverse soil groups studied, which include alluvial, red-yellow, acid sulfate, grey and degraded, and yellow-red humus soils. Notably, the average pH levels exhibited a decline in most soil groups, indicating a trend toward increased acidity. This decline in soil pH was accompanied by a marked reduction in nitrogen and potassium concentrations, which are critical for crop growth and productivity. For instance, alluvial and degraded soils demonstrated particularly pronounced nutrient depletion, with nitrogen levels decreasing from 0.23% to 0.19% and potassium levels from 1.23% to 1.03%. In contrast, while phosphorus levels exhibited a slight increase in some soil groups, the overall variability in nutrient content suggests that certain areas may be experiencing more severe deficiencies. Interestingly, the Yellow-Red Humus soils displayed enhanced organic matter retention, with mean OM levels increasing from 4.95% to 5.10%, highlighting their potential for improved nutrient availability and soil health. Cation exchange capacity also showed variability, with a notable decline in the grey and degraded soil group.