Abdul Kadir Salam, Galih Susilowati, Nanik Sriyani, Hery Novpriansyah
Heavy metal concentrations in soils may decrease over time, correlating with key soil variables such as pH, cation exchange capacity (CEC), clay, and organic carbon (organic C) content. The residual Cu and Zn were studied in tropical soils about 20 years after amendment with heavy metal containing industrial waste. Soils amended one time in 1998 with industrial waste, calcite, and cassava-leaf compost were employed as models and analysed for topsoil and subsoil Cu, Zn and several soil properties including pH, CEC, clay and organic C content in 2018. The highest Cu and Zn were detected in high heavy metal plots with the highest waste amendment, lowered by calcite and/or compost. The lower subsoil Cu and Zn were strongly affected by topsoil Cu and Zn. Single variable linear regression showed that the soil Cu and Zn had good relationships with the soil organic C and clay content. The inclusion of soil pH, CEC, clay and organic C content in multiple linear regression analysis improved their correlation coefficients, in which the correlation coefficients of Zn were higher than Cu. Long-term reaction in soils reversed the positive correlation of Cu – pH and Zn – pH in 1998 to the negative correlations in 2018. The soil Cu can be predicted with 33.8% accuracy with equation Cu = –61 – 11.6 (pH) + 0.47 (CEC) + 2.71 (Clay) + 41.7 (Org C) (R2) = –0.338 while the soil Zn with accuracy 39.2% by equation Zn = – 26.2 – 8.73 (pH) – 0.276 (CEC) +1.95 (Clay) + 24.0 (Org C) (R2). This results could be utilized to monitor the dynamic of Cu and Zn contamination in soil. Copyright © 2025 by the author(s).
Department of Soil Science, Faculty of Agriculture, University of Lampung, Bandar Lampung, 35145, Indonesia; Academic Staff, Sumatera Institute of Technology, Bandar Lampung, 35145, Indonesia; Department of Agronomy and Horticulture, Faculty of Agriculture, University of Lampung, Bandar Lampung, 35145, Indonesia