Limestone mining coproducts enhance soil pH and micronutrient availability in tropical sugarcane systems

This study evaluated the effects of contrasting limestone coproducts used as Ca–Mg–S sources, combined with different potassium (K) fertilizer sources, on soil chemical attributes, micronutrient dynamics, and plant performance in a sugarcane system. A split-plot field experiment was conducted during plant cane and ratoon cycles, with soil sampling at two depths (0–20 and 20–40 cm) to determine pH and extractable Cu, Fe, Mn, and Zn, as well as leaf micronutrient accumulation and stalk yield. Limestone coproducts significantly increased soil pH relative to the control, with maximum increases of up to 30%, particularly under rhythmite-based and combined limestone–rhythmite treatments. These amendments reduced extractable Mn concentrations by up to 60% in the surface layer. Linear mixed-effects models showed significant main effects of crop cycle and soil depth on Fe and Zn contents (p < 0.01), while cycle × depth interactions were not significant. Potassium source selection had no consistent effect on soil chemical attributes. Leaf micronutrient accumulation and stalk yield were not affected by limestone coproducts or K sources, with stalk yield ranging from approximately 88 to 128 Mg ha −1 across crop cycles. Multivariate analyses revealed strong separation among treatments based on soil chemical attributes, driven mainly by soil pH and Fe–Mn availability, whereas plant variables showed limited differentiation. Overall, limestone mining coproducts acted as effective multinutrient amendments, improving soil chemical conditions without inducing short-term changes in plant nutritional status or yield, supporting their use as sustainable tools for long-term soil fertility management in sugarcane systems.