Organo-Mineral Interactions Involved in Herbicide Sorption on Soil Amended with Peats of Different Maturity Degree

Abstract

The sorption of three herbicides (alachlor, atrazine and linuron) on samples from six peats of progressive degree of maturity (fibric, hemic or sapric types) and soil samples (dryland agricultural Calcic Luvisol amended with the peats) was determined. The extent of the sorption was examined in terms of peat maturity (up to 220 analytical descriptors of the peat material). In most cases, a sorption enhancement effect was observed in the peat–soil system compared with the sum of the sorption in peat and soil alone, i.e., a positive interaction leading to an increase in soil matrix reactive sites. The analytical characteristics of humic and bitumen peat subfractions were useful in forecasting sorption performance. This was the case for high molecular weight hydrophobic fractions, the extent of the alkyl domain in humic substances and oxygen-containing groups. Correspondence analysis illustrated how different characteristics of the peats played a distinct role in sorption in the herbicide–peat system or in the soil–peat–herbicide system. In the former system, there was a relevant bearing of parameters indicating low peat maturity, whereas in the second the sorption was mainly explained by peat colloidal properties, including the concentration and base saturation of oxygen-containing functional groups.

Soil Organic Matter Composition and pH as Factors Affecting Retention of Carbaryl, Carbofuran and Metolachlor in Soil

“…However, insecticide uptake on the loam soil material was attributed solely to montmorillonite, presumably due to the enhanced physical diffusion of the pesticide into Mt interlayers, governed by van der Waals forces [ 71 ]. It is commonly observed that the particulate organic (or organo-mineral) soil fractions form stable microaggregates where the retention of pesticides could depend more on steric factors and diffusion mechanisms than on the type and amounts of oxygen-containing functional groups [ 72 ]. Therefore, both organic (mainly CR) and inorganic (Mt) soil colloids contribute to carbofuran retention in the studied soils via hydrophobic bonding and van der Waals forces.…”

Effectiveness of Carbaryl, Carbofuran and Metolachlor Retention in Soils under the Influence of Different Colloid

“…The type of soil clay mineral becomes especially important when the soil organic carbon contents are low [13]. The extent to which clay minerals contribute to sorption depends on the nature of the pesticide, as well as the ratio of clay mineral to organic carbon fractions of the soil [14,15]. The latter is particularly important in soils abundant in organic matter, as both-mineral and organic types of colloids-might interfere with each other, modulating the number of potential sorption sites for xenobiotics.…”

Comportamento de herbicidas pré-emergentes em palhadas de diferentes plantas de cobertura

“…Por outro lado, a redução na disponibilidade destes compostos, em sistemas de cultivo contendo palhada, principalmente de aveia preta, podem contribuir com a redução dos riscos e dissipação ambiental de herbicidas. Nesse sentido, é possível pontuar os fatores que afetam a retenção de herbicidas em materiais orgânicos (por exemplo, na palhada) são (I) quantidade e tipo de palhada, (II) composição dessa palhada, (III) grau de decomposição, (IV) caráter hidrofílico e hidrofóbico dos constituintes do material, (V) o processo de decomposição e as (VI) interações das características físico-químicas do produto com o material Li et al, 2017;Dorado;Almendros, 2021).…”

“…A sorção-dessorção e a lixiviação são processos que regulam a concentração do herbicida no solo. Esses processos são influenciados por fatores físicos e químicos envolvidos na interação pesticida e material orgânico (Jensen et al, 2018;Dorado et al, 2021). Por exemplo, após a aplicação do herbicida a palhada atua como uma barreira física, sendo necessária a água da chuva ou da irrigação para carrear o herbicida para o solo (Tofoli et al, 2009).…”

“…Por exemplo, após a aplicação do herbicida a palhada atua como uma barreira física, sendo necessária a água da chuva ou da irrigação para carrear o herbicida para o solo (Tofoli et al, 2009). Fatores como as características físico-químicas do herbicida, tempo de contato do herbicida-palhada, a quantidade de chuva, o tipo e quantidade de palhada, o grau de decomposição da matéria orgânica, a composição do material, a hidrofobicidade e a aromaticidade também estão envolvidos nos mecanismos de retenção de herbicidas e poluentes em materiais orgânicos Li et al, 2017a;Ren et al, 2020;Dorado et al, 2021).…”