Search Results (4)

Straw from no-till cropping systems, in addition to increasing the soil organic matter content, may also impede the movement of applied herbicides into the soil and, thus, alter the behavior and fate of these compounds in the environment. Rain or irrigation before or after an herbicide treatment can either help or hinder its movement through the straw, influencing weed control. Our objective was to develop a system for herbicide application and rain simulation, enabling the evaluation of the movement of various herbicides either in dry or wet straw under different rainfall volumes (25, 50, 75, and 100 mm). The amount of the applied herbicides that moved through the straw were collected and measured using a liquid chromatograph with a tandem mass spectrometry system (LC-MS/MS). Measurements obtained with the developed system showed a high herbicide treatment uniformity across all replications. The movement of the active ingredients through the straw showed variability that was a function of the applied herbicide, ranging from 17% to 99%. In wet straw, the collected herbicide remained constant from 50 to 100 mm of simulated rainfall. For the wet straw, the decreasing percentages of the herbicide movement through straw to the soil were sulfentrazone (99%), atrazine and diuron (91% each), hexazinone (84%), fomesafen (80.4%), indaziflam (79%), glyphosate (63%), haloxyfop-p-methyl (45%), and S-metolachlor (27%). On the dry straw, the decreasing percentages of the herbicide movement were fomesafen (88%), sulfentrazone (74%), atrazine (69.4%), hexazinone (69%), diuron (68.4%), glyphosate (48%), indaziflam (34.4%), S-metolachlor (22%), and haloxyfop-p-methyl (18%). Overall, herbicide movement was higher in wet straw (with a previous 25 mm simulated rainfall layer) than in dry straw. Some herbicides, like haloxyfop-p-methyl and indaziflam, exhibited over 50% higher movement in wet straw than dry straw after 100 mm of simulated rain. The developed system can be adapted for various uses, serving as a valuable tool to evaluate the behavior of hazardous substances in different agricultural and environmental scenarios. Full article

The leaching of herbicides into the soil is essential to control germinating seeds and parts of vegetative weeds. However, herbicide transportation to deeper soil layers can result in groundwater contamination and, consequently, environmental issues. In this research, our objective was to investigate differences in herbicide leaching between commercial formulations and analytical standards using three different soils. Leaching experiments were carried out for diuron, hexazinone, and sulfometuron-methyl herbicides isolated and in binary and ternary mixtures. The herbicide residue quantification was performed by ultra-high-performance liquid chromatography coupled to a mass spectrometer (LC-MS/MS). Diuron had less mobility in soils and was retained in the most superficial layers. Hexazinone and sulfometuron-methyl were more mobile and leached into deeper layers. The leaching process was more intense for hexazinone and sulfometuron-methyl. The additives present in the commercial formulation favored the leaching in soils of diuron, hexazinone, and sulfometuron-methyl herbicides isolated and mixture compared to the analytical standard. This fact highlights the importance of considering these effects for the positioning of herbicides in the field to increase the efficiency of weed control and minimize the potential for environmental contamination. Full article

Sugarcane cultivation uses many chemical inputs to ensure good yields, which puts local water resources under pressure. Grey water footprint (GWF) is a widely used indicator of the volume needed to assimilate a pollutant load in a water body. However, the GWF relies on leaching runoff fractions, which are empirically determined. We hypothesize that these fractions might not represent the true magnitude of the Brazilian sugarcane environment and that management practices can further reduce this fraction loaded into the environment. In two field trials, we measure the herbicides and nitrate loaded into the environment through in situ measurements, determine their loss fractions, compare them with some empirical models, calculate the GWF, and estimate the potential for nitrate pollution attenuation with the adoption of split and incorporated nitrogen application. Both hypotheses are confirmed. For nitrate, our results suggest that the leaching runoff fraction used in most GWF studies is overestimated by about two times, impacting the GWF estimation for the Brazilian sugarcane environment. However, the same conclusion was not possible for herbicides due to the low diversity of the analyzed molecules. In addition, the fertilizer management application reduced the nitrate load on the environment, which the GWF did not necessarily detect. Full article

Tomatoes are often grown in proximity to other crops such as grain, which can increase their susceptibility to herbicide drift and subsequent crop. Therefore, the objective of this study was to evaluate the effect of simulated herbicide drift on tomato plants. Treatments were established in a 10 × 3 + 1 factorial scheme using a completely randomized design with four replications. The first factor consisted of ten herbicides, while the second was composed by three subdoses (1/4, 1/16, and 1/32) along with an additional treatment without herbicide application. The herbicides 2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, and isoxaflutole caused injury levels greater than 20% or reductions in plant biomass greater than 30% at the lowest subdose. Increasing the subdose resulted in a corresponding increase in injury level and a reduction in biomass. Tomato exposed to hexazinone, diuron, nicosulfuron, and diquat at a subdose of 1/64 exhibited low injury levels and biomass reductions. However, at other subdoses, these herbicides caused significant plant damage. Among the herbicides tested, the auxinic herbicides, particularly dicamba, presented a higher risk for the tomato crop. The documentation and description of the visual symptoms caused by each herbicide applied to tomatoes will aid producers to identify drift problems in the field. Full article