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The effects of mulch on the dissipation of S-metolachlor-SMOC, foramsulfuron-FORAM, and thiencarbazone-methyl-TCM and the formation of their main degradation metabolites were studied here. The herbicides were jointly applied in preemergence of maize on two separate occasions to two agricultural soils under conventional tillage (CT) and non-tillage (NT) over two wheat-maize cycles. Herbicide concentrations were determined in topsoil samples at different times after both applications, and they were fitted to kinetic models. The half-life (DT50) values for SMOC were higher under CT management than under NT (mean values: 25.6 and 7.38 days, respectively) in both soils over the two years. The faster herbicide dissipation with mulch could be because it is partially intercepted and strongly adsorbed/retained through different potential pathways, especially biodegradation, which was supported by the detection of SMOC-ESA and SMOC-OA metabolites. The mean DT50 values for FORAM (6.15 and 6.07 days, respectively) were very close for both soils under NT and CT management over the two-year experiment. The mulch had a lesser impact than for SMOC due to the former’s higher water solubility and lower adsorption, with dissipation being controlled mainly by biodegradation and likely also by leaching. TCM recorded intermediate DT50 values (mean value 20.8 days) in both soils+CT in the two-year experiment compared to SMOC and FORAM. The mulch effect on TCM dissipation was observed only after the second application because the DT50 values were higher in soils+NT after the first application (mean value: 26.9 days) than after the second one (mean value: 5.9 days). The amount of soil surface covered by the mulch controlled the herbicide dissipation, and soil and herbicide properties determine their adsorption behaviour by both mulch and soils.

The residues of the herbicides aminopyralid and iodosulfuron-methyl-sodium are phytotoxic to rotational crops. Their behaviour therefore needs to be studied under different agronomic practises and climatic conditions. The objective of this work was to use controlled laboratory conditions to study the effect of the following: (i) the application of green compost (GC) to agricultural soil, (ii) herbicide dose, (iii) soil moisture, and (iv) soil microbial activity on the degradation rate of aminopyralid and iodosulfuron-methyl-sodium. Moreover, the formation of two iodosulfuron-methyl-sodium metabolites (metsulfuron-methyl and 2-amino-4-methyl-4-methoxy methyl-triazine) and the dissipation mechanism of labelled 14C-iodosulfuron-methyl-sodium under the same conditions were also studied. Aminopyralid and iodosulfuron-methyl showed slower degradation and half-life values (DT50) that were up to 4.6 and 1.4 times higher, respectively, in soil amended with GC, as the higher organic carbon (OC) content of this soil increased herbicide adsorption. The DT50 values were up to 2.6 and 1.9 times higher for aminopyralid and iodosulfuron-methyl sodium, respectively, in soils treated with the double herbicide dose compared to soils treated with the agronomic dose. The DT50 values for aminopyralid were up to 2.3 times higher in soils with moisture equal to 25% (H25%) of their water-holding capacity (WHC) than in soils with H50%. However, the DT50 values for iodosulfuron-methyl-sodium were slightly lower in soils with H25% than in soils with H50%, due to the formation of bound residues. A biodegradation process significantly contributes to the dissipation of both herbicides. Higher amounts of metabolite metsulfuron-methyl were formed in the GC-amended soil in all cases. The percentages of 14C extractable in soils treated with both doses of herbicide under H25% were slightly higher than in soils under higher soil moisture (H50%) over time, due to the slower degradation of 14C-(iodosulfuron-methyl+metabolites). The higher persistence of the herbicides and their metabolites when the doses were applied at a high rate in soil amended with GC and under low moisture content may have negative consequences for the rotational crop. In the case of adverse conditions leading to the persistence of herbicides in the soil during the primary crop, the intervals for crop rotation should be increased.

Intensive crop production involves a high consumption of pesticides. This is a cause of major environmental concern because the presence of pesticides in water is becoming increasingly common. Physicochemical methods based on soil modification with organic residues have been developed to enhance the immobilization and/or degradation of pesticides in agricultural soils, which may control both the diffuse and the point pollution of soils and waters. This review summarizes the influence of spent mushroom substrate (SMS) on the environmental fate of pesticides when both are simultaneously applied in agriculture. The processes of adsorption, leaching and dissipation of these compounds in SMS-amended soils were evaluated at laboratory and field scale. Relationships were established between the experimental parameters obtained and the properties of the soils, the SMS, and the pesticides in order to determine the effect that the application of SMS in agricultural soils has on the environmental impact of pesticides. Accordingly, this review highlights the use of SMS as a strategy for the prevention and/or control of soil and water contamination by pesticides to strike a balance between agricultural development and the use of these compounds.

The persistence of fluopyram and tebuconazole has been studied in different crops and agricultural soils. However, the behaviour of these fungicides may be altered when they are applied as a combined formulation in organically amended vineyard soils under field conditions. The purpose of this study is to evaluate the effect of applying spent mushroom substrate (SMS) or this residue re-composted with ophite (SMS + OF) on the adsorption, dissipation, and mobility of the fungicides fluopyram and tebuconazole in vineyard soils. Triplicate 10 m2 plots per treatment were set up in two different vineyard soils in the eastern La Rioja region: silt loam (ARN1) and sandy loam (ARN2), respectively, with low organic carbon (OC) content. The organic residues SMS and SMS + OF were applied at doses of 25 and 100 Mg ha−1. The adsorption distribution coefficients (Kd) increased when SMS and SMS + OF were applied, especially at the higher dose (100 Mg ha−1). The dissipation curve of both compounds fitted a two-phase kinetic model, with a very fast initial dissipation rate, followed by slower prolonged dissipation during the second phase. The dissipation half-lives (DT50) ranged between 4.7 and 26.3 days for fluopyram and between 2.3 and 6.3 days for tebuconazole in the different soils, increasing for fluopyram in the ARN1 amended with SMS and SMS + OF. The fungicide residues at 15–30 cm depth were lower in the unamended and amended sandy loam soil (ARN2), indicating that fungicides are dissipated mainly in the topsoil. The results indicate different dissipation mechanisms for both fungicides, as the adsorption by soil OC prevented the dissipation of fluopyram but facilitated the dissipation of tebuconazole, probably due to the formation of non-extractable residues.

Organic wastes applied as composted amendments may improve the quality of degraded soils and modify the fate of pesticides. This work has set out to study the dissipation kinetics of the herbicides chlorotoluron and flufenacet during their second-year application in field experimental plots with a sandy-loam agricultural soil without amendment (S) and amended with spent mushroom substrate (S + SMS) or green compost (S + GC). The SMS and GC were applied to the soil during the previous winter’s wheat crop campaign (1 year before the second herbicide application) at rates of 140 and 85 t ha−1 (dry weight basis), respectively. The experiment involved randomized complete blocks with plots of 81 m2, including three replicates per soil treatment. Surface soils were sampled after herbicide application for 225 days, and herbicide residues in the soil samples were determined by HPLC-MS. The dissipation curves of both herbicides for the three soil treatments were better fitted to the first order multi-compartment (FOMC) kinetic model. The dissipation rates of the most hydrophobic herbicide, flufenacet, were slower than those for chlorotoluron in both unamended and amended soils. The half-life (DT50) values ranged between 20.7 to 41.1 days for chlorotoluron, and 42.9 to 75.6 days for flufenacet, and they followed the order S > S + SMS > S + GC. The DT50 values of chlorotoluron were close for S + SMS and S + GC, and the DT50 of flufenacet for S was similar to that for S + SMS. These DT50 values decreased up to four times with respect to those calculated after the first application indicating an accelerated dissipation of the herbicides after the second application especially in amended soil in comparison with unamended soil. The persistence of chlorotoluron and flufenacet in an agricultural soil was modified by the effect of the organic amendments, weather conditions, and possibly the repeated application of the compounds under real field conditions.

The protection of natural resources, particularly groundwater, is essential for the sustainability of rural environments, especially when urban centers rely on this water for consumption. The objective of this study was to evaluate the occurrence, seasonal distribution, and associated risk of pesticide residues in groundwater in a region of intensive farming in the Duero river basin (Spain). A total of 40 pesticides and 7 degradation products were analyzed at 20 sampling points over four campaigns conducted in 2018. Overall, twenty-one compounds were detected, including three insecticides, three fungicides, ten herbicides, and five degradation products. Concentrations of eight compounds (one fungicide, five herbicides, and two degradation products) exceeded the limits established by the European Union (EU) for drinking water. Herbicides were the most frequently detected pesticides and were present at the highest concentrations (up to 3.416 μg L−1) across all sampling campaigns. Metolachlor, prosulfocarb, metribuzin, and metolachlor degradation products (ethanesulfonic acid (ESA)– and oxanilic acid (OA)–metolachlor) were detected in concentrations over 1.0 µg L−1. The sum of Toxic Units (∑Tui) showed that none of samples posed a high risk. None of compounds presented a high risk for the three aquatic organismstested; only prosulfocarb for algae and Daphnia magna; pendimethalin for algae and fish; and metribuzin, chlorotoluron, and desethyl-terbuthylazine (DETbz) for algae posed high risks.

The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85 % of the herbicide applied still persisted in the sterile soil, 73 % in the pine-amended one and 63 % in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loam soil, in the absence of amendments, the herbicide was found to be quite persistent ( t 1/2  > 95 days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24 days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction.

Spent mushroom substrate (SMS) is the organic residue generated during mushroom cultivation, and it is being produced in ever-greater quantities around the world. Different applications for this residue have been proposed for its valorization, but its application as a soil amendment could be one of the most sustainable. SMS improves soil quality by increasing its organic matter (OM), thereby enhancing the sustainability of agricultural systems. The objective of this work was to evaluate the effect of the application of two doses of SMS on the chemical, biochemical, and microbiological characteristics of two degraded vineyard soils in La Rioja (Spain) with different textures, as a new regenerative agricultural practice. The variations in organic carbon (OC), micro- and macronutrients, soil microbial biomass (BIO), respiration (RES), dehydrogenase activity (DHA), and the profile of phospholipid fatty acids (PLFAs) extracted from the soils were evaluated over two years. An initial increase in soil OC content was recorded in both soils, although the content that remained over time differed for each site. In general, SMS enhanced DHA, RES, and BIO in the soils, but the effect varied, possibly being conditioned by the availability of OC for soil microorganisms. In general, changes in the soils’ microbial structure after SMS application were not very significant over the two-year experimental period.

The management of large volumes of organic residues generated in different livestock, urban, agricultural and industrial activities is a topic of environmental and social interest. The high organic matter content of these residues means that their application as soil organic amendments in agriculture is considered one of the more sustainable options, as it could solve the problem of the accumulation of uncontrolled wastes while improving soil quality and avoiding its irreversible degradation. However, the behavior of pesticides applied to increase crop yields could be modified in the presence of these amendments in the soil. This review article addresses how the adsorption–desorption, dissipation and leaching of pesticides in soils is affected by different organic residues usually applied as organic amendments. Based on the results reported from laboratory studies, the influence on these processes has been evaluated of multiple factors related to organic residues (e.g., origin, nature, composition, rates, and incubation time of the amended soils), pesticides (e.g., with different use, structure, characteristics, and application method), and soils with different physicochemical properties. Future perspectives on this topic are also included for highlighting the need to extend these laboratory studies to field and modelling scale to better assess and predict pesticide fate in amended soil scenarios.

The capacity of spent mushroom substrate (SMS) as a sorbent of fungicides was evaluated for its possible use in regulating pesticide mobility in the environment. The sorption studies involved four different SMS types in terms of nature and treatment and eight fungicides selected as representative compounds from different chemical groups. Nonlinear sorption isotherms were observed for all SMS–fungicide combinations. The highest sorption was obtained by composted SMS from Agaricus bisporus cultivation. A significant negative and positive correlation was obtained between the Koc sorption constants and the polarity index values of sorbents and the Kow of fungicides, respectively. The statistic R2 revealed that more than 77% of the variability in the Koc could be explained considering these properties jointly. The other properties of both the sorbent (total carbon, dissolved organic carbon, or pH) and the sorbate (water solubility) were nonsignificant. The hysteresis values for cyprodinil (log Kow = 4) were for all the sorbents much higher (>3) than for other fungicides. This was consistent with the remaining sorption after desorption considered as an indicator of the sorption efficiency of SMS for fungicides. Changes in the absorption bands of fungicides sorbed by SMS observed by FTIR permitted establishing the interaction mechanism of fungicides with SMS. The findings of this work provide evidence for the potential capacity of SMS as a sorbent of fungicides and the low desorption observed especially for some fungicides, although they suggest that more stabilized or humified organic substrates should be produced to enhance their efficiency in environmental applications.