The interaction of herbicides in the nitrogen cycle and their consequences on soil health and agricultural production are essential topics in agronomic research. In this systematic review article, we have synthesized recent studies on this subject. The results revealed that the indiscriminate use of herbicides can have negative effects on vital processes in the nitrogen cycle, such as reduced enzymatic activity and microbial respiration. Moreover, herbicides alter the soil microbial composition, affecting nitrogen cycling-related activities. Symbiotic nitrogen fixation is also impaired, resulting in a reduction in the population of nitrogen-fixing bacteria and a decrease in the availability of this nutrient in the soil. These effects compromise soil fertility and the release of nitrogen to plants. Therefore, sustainable agricultural practices must be adopted, considering nitrogen cycling efficiency and the preservation of soil and natural resources. This understanding is crucial for guiding appropriate management strategies aimed at minimizing the negative effects of herbicides on the nitrogen cycle and ensuring soil health and agricultural productivity.

Herbicides applied in PRE-emergence enables sustainable weed control. The objective of this study was to evaluate the control of gallant soldier (Galinsoga parviflora) with the residual herbicides oxyfluorfen, flumioxazin, and linuron in soils cultivated with garlic from two regions of Brazil: Rio Paranaíba-MG (Oxisol) and Curitibanos-SC (Ultisol). The efficiency of the herbicides was evaluated at the following doses: oxyfluorfen (0, 3, 6, 12, 24, 48, 96, 192, 384, and 768 g a.i. ha⁻¹), flumioxazin (0, 2, 4, 6, 8, 15, 30, 40, 60, and 120 g a.i. ha⁻¹), and linuron (0, 30, 40, 50, 100, 200, 400, 800, 1600, and 2430 g a.i. ha⁻¹). The degree of damage on the 7th, 14th, and 21st day after emergence (DAE) and dry matter on the 21st day after emergence (DAE) were determined to evaluate the control (C₈₀) and the growth reduction (GR₈₀) of 80% of the plant, respectively, compared to the treatment without herbicide. Three herbicides were effective at the control of G. parviflora, with the C₈₀ at 21 DAE on Ultisol being 81.82, 4.59, and 141.26 g a.i. ha⁻¹, and a GR₈₀ of 61, 8.3, and 151.3 g a.i. ha⁻¹ for oxyfluorfen, flumioxazin, and linuron, respectively. On the other hand, on Oxisol (lower clay content and soil organic matter), the doses were lower, with the C₈₀ at 21 DAE at 20.85, 3.50, and 118 g a.i. ha⁻¹, and a GR₈₀ of 54, 4.03, and 101.23 g a.i. ha⁻¹, respectively. This weed showed higher control under flumioxazin compared to the other herbicides in both soils. The use of low doses of residual herbicides contributes to sustainable weed control in garlic growing in the field.

Goosegrass (Eleusine indica) is a major weed in Brazilian soybean, corn, and cotton systems, infesting over 60% of grain-producing areas and potentially reducing yields by more than 50%. Its competitiveness is due to its rapid emergence, fast tillering, C4 metabolism, and adaptability to various environmental conditions. A critical challenge relates to its widespread resistance to multiple herbicide modes of action, notably glyphosate and acetyl-CoA carboxylate (ACCase) inhibitors. Resistance mechanisms include 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) target-site mutations, gene amplification, reduced translocation, glyphosate detoxification, and mainly ACCase target-site mutations. This literature review summarizes the current knowledge on herbicide resistance in goosegrass and its management in Brazil, with an emphasis on integrating chemical and non-chemical strategies. Mechanical and physical controls are effective in early or local infestations but must be combined with chemical methods for lasting control. Herbicides applied post-emergence of weeds, especially systemic ACCase inhibitors and glyphosate, remain important tools, although widespread resistance limits their effectiveness. Sequential applications and mixtures with contact herbicides such as glufosinate and protoporphyrinogen oxidase (PPO) inhibitors can improve control. Pre-emergence herbicides are effective when used before or immediately after planting, with adequate soil moisture being essential for their activation and effectiveness. Given the complexity of resistance mechanisms, chemical control alone is not enough. Integrated weed management programs, combining diverse herbicides, sequential treatments, and local resistance monitoring, are essential for sustainable goosegrass management.

The aim of this study was to evaluate the role of rock powder in the phytoremediation of Inceptisol (sandy loam) and Oxisol (clay) contaminated with diuron. Canavalia ensiformis plants were grown in pots containing 7.5 kg of both soils, with doses of 0, 4, and 8 t ha⁻¹ of rock powder. Diuron was applied in doses ranging from 875 to 3500 g of a.i. ha⁻¹. The injury level was assessed at 42 days after emergence (DAE), and the morphological characteristics were assessed at 120 DAE. After phytoremediation, the soil was analyzed using High Performance Liquid Chromatography (HPLC) and by bioassay with cucumber (Cucumis sativus) to detect diuron. In Oxisol, no injury was observed, and the rock powder (4 t ha⁻¹) benefited the growth of C. ensiformis regardless of the dose of diuron. In Inceptisol, the greatest reduction in growth occurred with 3500 g a.i. ha⁻¹ of diuron and 8 t ha⁻¹ of rock powder. Diuron was detected after 120 days in Inceptisol with 2625 g a.i. ha⁻¹ without rock powder and 3500 g a.i. ha⁻¹ with and without rock powder. The cucumber bioindicator in Inceptisol showed an increase in the level of injury as the dose of diuron increased. The rock powder favored the growth of C. ensiformis and was able to phytoremediate high concentrations of diuron, which supports the safe use of this herbicide for weed control, minimizing environmental impacts.

The objective of this work was to verify the correlations between carbon isotopic composition and traits of superior rice genotypes. Twenty genotypes were analyzed for morphology, micromorphology, anatomy, physiological performance, and carbon fingerprint. The plots consisted of 500 L plastic boxes sowed with rice, to allow of a plant density of 300 plants per square meter. Plant anatomy and physiological performance were evaluated using a microscope and an infrared gas analyzer, respectively. There is a correlation between rice water use efficiency (r = 0.45) and carboxylation efficiency (r = 0.39).

The objective of this study was to assess the competitive ability of canola (Brassicanapus var. oleifera) hybrids in competition with black oat (Avena strigosa) in a subtropical environment. The experiments were conducted in a greenhouse where canola hybrids ‘Hyola 61,’ ‘Hyola 76,’ ‘Hyola 433,’ and ‘Hyola 571’ were tested individually for their competitive performance with black oat. The plant proportion between black oat and the canola hybrid was changed (100%:0%; 75%:25%; 50%:50%; 25%:75%; and 0%:100%) while keeping the total population of plants constant (20 plants plot‑1). Photosynthesis rate (μmol m-2 s-1), internal CO2 concentration (μmol mol-1), and transpiration rate (mol H2O m-2 s-1) were assessed using an infrared gas analyzer 55 days after emergence. Leaf area (m2 m-2) and dry matter (g m-2) were also assessed on the same day. The data set was analyzed by the replacement series method for competition studies. There was evidence of intense competition between canola and black oat, independent of plant proportion. The competitive ability of canola was distinct among hybrids; Hyola 571 performed better than the others in the competition against black oat. Choosing the most competitive hybrid, such as Hyola 571, helps maintain high canola grain yield levels in areas infested with black oat. Highlights: There is difference in competition among canola hybrids against black oat; Hyola 571 performed better in the competition; Preference should be given for most competitive canola genotypes against weeds, and weed control should be carried out early in the critical period of interference; Aggressiveness is the most preponderant parameter in determining canola genotypes with superior ability in competition against weeds.