Adsorption, complexation, and phytoavailability of copper as influenced by organic manure

Abstract

Copper (Cu) is bound strongly to clay minerals and organic matter in soils, and forms both insoluble and soluble organic complexes with organic carbon. In this experiment, the effect of five manure composts (biosolid, farmyard manure, spent mushroom, pig manure, and poultry manure) on the adsorption and complexation of Cu in a mineral soil (Manawatu sandy soil, Palmerston North, New Zealand) low in organic matter content was examined. The effect of biosolid on the uptake of Cu from the soil, treated with various levels of Cu (0-400 mg/kg soil), was examined by using mustard (Brassica juncea L.) plants. The redistribution of the added Cu in soil was evaluated by a chemical fractionation scheme. Addition of manure compost increased the adsorption and complexation of Cu by the soil. At the same level of total organic carbon addition, a significant difference was found in the extent of Cu adsorption among the manure-amended soils. However, less difference was found in the amount of Cu complexed among the manure-amended soils. A significant inverse relationship was found between the extent of Cu adsorption and the dissolved organic carbon (DOC) in the manure-amended samples, indicating that DOC formed soluble complexes with Cu. Increasing addition of Cu increased Cu concentration in plants, resulting in decreased plant growth at high levels of Cu (i.e., phytotoxicity). Addition of biosolid was found to be effective in reducing the phytotoxicity of Cu at high levels of Cu addition. Significant relationships were found between dry matter yield and total Cu or free Cu2+ concentration in soil solution. Addition of biosolid decreased the concentration of the soluble and exchangeable Cu fraction but increased the concentration of the organic-bound Cu fraction in soil.

Influence of nitrogen form on the phytoextraction of cadmium by a newly discovered hyperaccumulator Carpobrotus rossii

“…In general, organic amendments such as animal manures contain a high proportion of humidified organic matter, which forms strong complexes with Cd, resulting in Cd immobilization and decreased Cd bioavailability in the soil (Putwattana et al 2010). Additionally, manures often contain high contents of dissolved organic matter which forms soluble organic-metal complexes (Bolan et al 2003a;Vaca-Paulin et al 2006) that reduce metal availability to plants (Bolan et al 2003b). Soluble organic-Cd complexes are also likely to have contributed to the lower phytoextraction by the manure treatment.…”

Changes in copper content and distribution in young, old and abandoned vineyard acid soils due to land use changes

“…The most useful finding of this work is the role played by soil organic matter in Cu retention as judged from the prevalence of the Cu OM fraction in all soils, but especially in old and abandoned vineyards. Copper binding to soil organic matter reduces the potential adverse effects of accumulated Cu on microbial or plant toxicity as shown by Bolan et al (2003a). Low concentrations of Cu bound to exchangeable sites in young vineyards also diminish its potential bioavailability since this is the most labile Cu fraction of all.…”

Contribution of on-farm and industrial composts to soil pH and enrichment in available nutrients and metals

“…High molecular weight organic substances like lignin were reported to immobilize Zn and other micronutrients (Tisdale et al 1993). On the other hand, complexation involving dissolved organic matter, which was found in larger amounts early in the composting process , is the most important driving force along with pH for heavy metal solubilization (Japenga et al 1992;Bolan et al 2003).…”