Fe, Zn, and Cu in the Organic Fraction of Soils with Different Textures Under Intense Use of Agrochemicals in Flower Cultivation

In flower production, the use of agrochemicals is common, contributing to the addition of heavy metals to the soil, and organic matter (OM) plays an important role in their solubility and dynamics. Thus, the objective was to quantify the contents of Fe, Zn, and Cu in the chemical and physical fractions of OM of soils with different textures. Two soils were selected, sandy texture (A1) and clay texture (A2), with their respective native forests (NV1 and NV2) as reference. Chemical fractionation was performed using KOH solution and, the physical fractions were separated by the particle size method. Subsequently, the determination of metals in these fractions was performed. The data were analyzed by descriptive statistics, Tukey test (p < 0.05), principal component analysis (PCA), and cluster analysis (CA). In A2, metal contents were higher when compared to NV2, while in A1 the metal contents showed no statistical difference from those found in NV1. PCA and CA indicated that A2 had the highest contents of heavy metals in the chemical and physical fractions of OM compared to A1 and the NV areas. The humin fraction (H + M) and the mineral-associated fraction (MAOM) showed a higher tendency towards adsorption of heavy metals because they were more stable in the soil and with a greater presence of acidic functional groups. The contents of the metals had more adsorption affinity in the cultivated soils, mainly of clay texture and in the different fractions of OM, so monitoring is necessary to avoid accumulation due to the application of pesticides.

Automated summary

In flower production, the use of agrochemicals leads to the addition of heavy metals in the soil, and organic matter (OM) plays a crucial role in their solubility and dynamics. This study aimed to quantify Fe, Zn, and Cu contents in the chemical and physical fractions of OM in soils with different textures. Results showed higher metal contents in A2 compared to NV2, while A1 had no significant difference compared to NV1. The study suggests the need for monitoring to prevent metal accumulation in cultivated soils, especially in clay soils.