Role of Leaf Litter on the Incorporation of Copper-Containing Pesticides into Soils Under Fruit Production: a Review

Abstract

High soil copper may result in adverse effects on natural and agricultural systems. Copper-based pesticides have long been used for control of microbial diseases on fruit tree productive systems. Although copper is relatively safe from a human health management point of view, it can be accumulated in agricultural soils, affecting soil microbiota and litter degradation. The purpose of this review was to collect the available information to critically discuss the role that litter may play in fruit tree productive systems, in terms of copper incorporation into the soil, where this element is used as a pesticide. To achieve this objective, we focused our review on (1) soil contamination by copper-based pesticides in fruit production systems, (2) soil copper behavior, (3) effects of copper contamination on soil organisms, and (4) copper-litter relation in soil. From this review, we can suggest that (1) litter is the main sink of metals coming from atmospheric fallout because it is a good complexing agent of cations, (2) litter decomposition depends on its quality and in soil microbial activity, and (3) soil and litter microbial activity is negatively affected by soil copper enrichment. Thus, under uncontrolled applications of copper-based pesticides in fruit tree productive systems, copper soil enrichment will generate a decrease in microbial activity, diminishing litter breakdown and decreasing dissolved organic carbon formation. This process will also decrease the soluble copper incorporation into the soil; however, this assumption remains unevaluated.

Micronutrients in Food Production: What Can We Learn from Natural Ecosystems?

“…Copper holds a unique role in arable agriculture because, unlike other micronutrients, it is applied both to correct deficiency and as a pesticide [25]. The use of Cu as a pesticide is one of the causes of widespread soil contamination with Cu [25,153,154], but here we focus on Cu deficiency and the role of biofertilizers for maintaining favourable soil Cu availability.…”

“…Crop deficiency in Cu can occur in soils with low Cu concentrations or low availability [9,25,156]. The low availability of Cu is often a result of leaching, but also occurs at neutral or alkaline pH levels and in soils with a high SOM content [9,25,154,156]. The biotic complexation of Cu with SOM and the abiotic adsorption of Cu onto SOM, (oxy-)hydroxides, clay fractions, and carbonates have the greatest impact on Cu availability because complexation and adsorption reduce the overall Cu solubility [9,25,154].…”

“…The low availability of Cu is often a result of leaching, but also occurs at neutral or alkaline pH levels and in soils with a high SOM content [9,25,154,156]. The biotic complexation of Cu with SOM and the abiotic adsorption of Cu onto SOM, (oxy-)hydroxides, clay fractions, and carbonates have the greatest impact on Cu availability because complexation and adsorption reduce the overall Cu solubility [9,25,154]. Approximately 20-40% of arable soils have a low Cu availability, which can be exacerbated by cultivating crops that are sensitive to Cu deficiency (e.g., cereals, vegetables, citrus trees), liming, the application of macronutrient fertilizers, and the increased availability of other micronutrients (e.g., Mn, Zn, Fe) [9,25,156].…”

Thresholds of Metal and Metalloid Toxicity In Field-Collected Anthropogenically Contaminated Soils: A Review

“…Since wood treatment with copper sulfate is a common practice around the world, we assume that historical wood treatment operations can be found in many other countries. Another possibility is to study copper toxicity in vineyards, where copper may be a major metal contaminant due to the use of copper sulfate as a fungicide (Schoffer et al 2020).…”

Increase in Phytoextraction Potential by Genome Editing and Transformation: A Review

“…Understanding the soil availability of any metal to plants is complex and multifactorial because one must consider the interactions between HMs and other soil components along with the species-specific capacity to extract metals from soils [ 5 ]. Indeed, soil metal toxicity to plants depends on a metal’s soil bioavailability, which varies according to several factors, such as the pH, presence of competitive cations, and content of soil organic matter (SOM), among others [ 6 , 7 ].…”