Adsorption–desorption behavior of benzobicyclon hydrolysate in different agricultural soils in China

Tang

et al. 2021

Preprint

Self Cite

Abstract. Benzobicyclon is a triketone pro-herbicide that needs to be hydrolyzed to form an active compound benzobicyclon hydrolysate (BH). This study aimed to investigate the migration behavior of BH in different types of agricultural soil and the associated influencing factors. Soil thin-layer chromatography and column leaching tests were used to study the migration behavior of BH in these soils. Based on the mobility retention factor (Rf = 0.34–0.90), the mobility of BH in thin soil layers was ranked in the order Lixisols > Anthrosols > Ferralsols > Phaeozems. The Rf value of BH was linearly positively correlated with soil sand content and pH, and negatively correlated with other physical and chemical properties of soil. BH was difficult to leach in Phaeozems, less difficult to leach in Ferralsols, and easy to leach in Anthrosols and Lixisols. Increasing the BH dosage and rainfall amount or adding humic acid and anionic (dodecyl benzene sulfonic acid) or nonionic (Tween-80) surfactant blocked BH migration in soil columns. In contrast, increasing the leaching solution pH and adding cationic surfactant (cetyl trimethyl ammonium bromide) promoted BH migration in soil columns.BH application has a low risk of groundwater pollution in Phaeozems and Ferralsols, but poses a potential threat to groundwater in Anthrosols and Lixisols.

Section: Migration Characteristics Of Bh In Thin Soil Layerssupporting

confidence: 87%

Migration behavior of benzobicyclon hydrolysate and associated influencing factors in different agricultural soils

Rao

Tang

et al. 2021

Preprint

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“…Notably, the soil with the highest fumigant adsorption capacity was also possibly that with the highest OM abundance and CEC. For example, strong linear and positive correlations have been found between the adsorption-desorption of benzobicyclon hydrolysate and the soil clay content, OC content, OM content, and CEC, while moderate linear and negative correlations were observed between those processes and the soil pH (Rao et al, 2020). The KOC value is typically used to indicate the EPM sorption capacity of a soil (Fao, 2000;Xiang, 2019) (see Table 2).…”

Section: Adsorption-desorption Isothermsmentioning

confidence: 99%

“…Nevertheless, the effects of soil properties on the adsorption-desorption, degradation, and leaching behaviors of EPM have rarely been reported. A number of researchers have reported that the soil matrix is a highly complicated system, in which environmental processes (e.g., the sorption-desorption and leaching of herbicides) are affected by multiple factors, including the soil organic matter (OM) content, pH, cation exchange capacity (CEC), microbial or chemical degradation, chemical type, environmental conditions (e.g., temperature, humidity, and rainfall), and texture (Alonso et al, 2011;Rao et al, 2020;Xie et al, 2020;Zhou et al, 2019a). Nevertheless, soil organic or inorganic colloids and pH (pH < pKa neutral state and pH > pKa negative charge) can influence soil-herbicide interactions.…”

Section: Introductionmentioning

confidence: 99%

Environmental behaviors of (E)-Pyriminobac-methyl in agricultural soils

Jia

et al. 2021

Preprint

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Abstract. (E)-Pyriminobac-methyl (EPM), a pyrimidine benzoic acid esters herbicide, has a high potential as weedicide; nevertheless, its environmental behaviors are still not well understood. In this study, we systematically investigated for the first time the adsorption–desorption, degradation, and leaching behaviors of EPM in agricultural soils from five exemplar sites in China (characterized by different physicochemical properties) through laboratory simulation experiments. The EPM adsorption–desorption results were well fitted by the Freundlich model (R2 > 0.9999). In the analyzed soils, the Freundlich adsorption (i.e., Kf-ads) and desorption (i.e., Kf-des) coefficients of EPM varied between 0.85–32.22 mg1−1/n L1/n kg−1 and between 0.78–5.02 mg1−1/n L1/n kg−1, respectively. Moreover, the degradation of EPM reflected first-order kinetics: its half-life ranged between 37.46–66.00 d depending on the environmental conditions, and abiotic degradation was predominant in the degradation of this compound. The mobility of EPM in the five soils varied from immobile to highly mobile. The groundwater ubiquity score ranged between 0.9765–2.7160, indicating that EPM posed threat to groundwater quality. Overall, the results of this study demonstrate the easy degradability of EPM, as well as its high adsorption affinity and low mobility in soils with abundant organic matter content and high cation exchange capacity. Under such conditions, there is a relatively low contamination risk for groundwater systems in relation to this compound. At the same time, due to its slow degradation, EPM has a low adsorption affinity and tends to be highly mobile in soils poor in organic matter content and with low cation exchange capacity. Under such conditions, there is a relatively high contamination risk for groundwater systems in relation to this compound. Overall, our findings provide a solid basis for predicting the environmental impacts of EPM.

“…However, recent extensive and nonselective use of herbicides has led to weed resistance, thereby reducing the efficiency of weed management (Magnoli et al., 2020). More importantly, accumulation of herbicide residues is also threatening the food safety and environmental quality of farmland ecosystems, posing a threat to human health (Lamichhane et al., 2017; Rao et al., 2020; Yuan et al., 2020). Implementation of appropriate weed management with reduced herbicide use has therefore become important issues in sustainable agricultural management.…”

Section: Introductionmentioning

confidence: 99%

Effects of Monochoria vaginalis density on yield losses, economic thresholds, and gross returns in paddy rice (Oryza sativa L.)

Luo

et al. 2021

Crop Science

Self Cite

Monochoria vaginalis (Burm. f.) Kunth is an annual weed commonly found in paddy fields. Understanding the effects of M. vaginalis on the yield and economics of paddy rice (Oryza sativa L.) is essential for integrated weed management. Here, a field experiment was conducted over two consecutive years (2017–2018) to determine the effects of different densities of M. vaginalis (0, 1, 4, 8, 12, 16, 20, and 24 plants m–2) on yield losses, economic thresholds, and gross returns in paddy rice. The results showed that a higher density of M. vaginalis exhibited greater inhibitory effects on plant height, tiller number per plant, and adjusted gross returns in both early and late rice. The inhibitory effects on spike number per plant, filled grains per panicle, and 1,000‐kernel weight were also significant, although lesser than those observed on the other yield traits. The economic threshold of M. vaginalis under manual weeding varied from 2.80 to 4.44 plants m–2, whereas the threshold levels under herbicide application ranged between 0.71 and 1.03 plants m–2 in the 2 yr. Averaged across all other factors, the adjusted gross returns decreased by 45.0% with increasing M. vaginalis density from 0 to 24 plants m–2. Taking into account the economic thresholds and gross returns, irrational use of herbicides should be prevented for weed management in paddy fields. This study provides useful data for reducing the use of chemical herbicides, saving the costs of weed management practices, and protecting the environment of farmland ecosystems.