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 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 (K_d) 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.

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 (∑Tu_i) 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.