Application of green compost as amendment in an agricultural soil: Effect on the behaviour of triasulfuron and prosulfocarb under field conditions

Abstract

Herbicides are essential in agricultural systems for maintaining crop yields, as weeds compromise grain production. Furthermore, the application of organic amendments to soil is an increasingly frequent agricultural practice for avoiding irreversible soil degradation. However, this practice could modify the behaviour of the herbicides applied, with implications for their absorption by weeds. This study evaluated the dissipation, persistence and mobility of the herbicides triasulfuron and prosulfocarb in a sandy clay loam soil unamended and amended with green compost (GC) in a field experiment using single or combined commercial formulations of both herbicides. The study was carried out in experimental plots (eight treatments × three replicates) corresponding to unamended soil and soil amended with GC, untreated and treated with the herbicide formulations Logran, Auros and Auros Plus over 100 days. The half-life (DT) of triasulfuron applied individually was 19.4 days, and increased in the GC-amended soil (46.7 days) due to its higher adsorption by this soil, although non-significant differences between DT values were found when it was applied in combination with prosulfocarb. Prosulfocarb dissipated faster than triasulfuron under all the conditions assayed, but non-significant differences were observed for the different treatments. The analysis of the herbicides at different soil depths (0-50 cm) after their application confirmed the leaching of both herbicides to deeper soil layers under all conditions, although larger amounts of residues were found in the 0-10 and 10-20 cm layers. The application of GC to the soil increased the persistence of both herbicides, and prevented the rapid leaching of triasulfuron in the soil, but the leaching of prosulfocarb was not inhibited. The influence of single or combined formulations was observed for triasulfuron, but not for prosulfocarb. The results obtained highlight the interest of obtaining field data to design rational joint applications of GC and herbicides to prevent the possible decrease in their effectiveness for weeds or the risk of water contamination.

Soil Microbial Community Changes in a Field Treatment with Chlorotoluron, Flufenacet and Diflufenican and Two Organic Amendments

“…Residual amounts of the three herbicides studied were detected at the experiment's last sampling time (Table 3), which means SMS and GC buffered the herbicides' bioavailability during their dissipation or their toxic effects on total microbial population. As indicated for the DHA changes, this may be due to the combination of certain positive properties of the organic amendments, such as the adsorption capacity of herbicides, which minimize their bioavailability, an increased input of microorganisms and improve the soil's nutrient status and physical properties [15,43,44]. In SMSor GC-amended soils, the increase in soil microbial biomass at day 0 might be due to the input of organic matter born microorganisms, but there was a decrease in soil microbial biomass from day 45 ( Figure 2).…”

“…Organic residues with a potential value are those from agricultural, industrial, and urban activities, such as the composted spent mushroom substrate (SMS) and green compost (GC) [12,13]. The OM of these residues may modify the persistence, dynamics, and environmental fate of herbicides applied to amended soils [14,15].…”

Simultaneous application of two herbicides and green compost in a field experiment: Implications on soil microbial community

“…To determine PLFAs, the samples were frozen at -80 o C and lyophilized prior to extraction and analysis. Soil characteristics were determined according to Marín-Benito et al (2018), and are included in Supplementary material (Table S2).…”

“…The physicochemical behavior of TSF and PSC herbicides, including their dissipation, mobility and persistence in a field experiment in an unamended soil and one amended with green compost (GC), has been evaluated in a previous study (Marín-Benito et al, 2018). Herbicide concentrations were determined at various times in the surface soil and at different depths up to 50 cm to evaluate the effect of the increased OC in the amended soil and the influence on the dissipation and mobility of individual Logran ® and Auros ® , or the combined commercial formulation Auros Plus ® of both compounds.…”

“…field experiment was conducted with an agricultural sandy clay loam soil (Typic Haploxerept) (Soil Survey Staff, 2010) on the Muñovela experimental farm belonging to the Institute of Natural Resources and Agrobiology of Salamanca (IRNASA-CSIC), Spain (40º55'56" N latitude and 5º52'53"W longitude). A detailed description of the experimental layout of randomized complete blocks of unamended soil (Soil) (12 plots)and soil amended with GC (Soil+GC) at the rate of 120 t ha -1 on a dry weight basis (~ 11.6 t C ha -1 ) (12 plots) and of the weather conditions is included in Supplementary material and inMarín-Benito et al (2018).…”