Tolerance of leguminous green manure species and their potential for remediating diclosulam-contaminated soil

The use of residual herbicides provides extended weed control but may negatively affect soil quality, subsequent crops, and the environment. Diclosulam, a sulfonanilide herbicide with moderate persistence and high bioavailability, presents a high potential for water contamination and carryover effects. Green manure species have emerged as promising tools for phytoremediation while simultaneously improving soil fertility. This study evaluated the morphophysiological tolerance and phytoremediation capacity of Canavalia ensiformis, Stizolobium aterrimum, and Cajanus cajan, cultivated either in monoculture or intercropped in soil contaminated with diclosulam (42 g a.i. ha−1). C. ensiformis showed no visible intoxication symptoms, whereas C. cajan and S. aterrimum exhibited maximum phytotoxicity levels of 18% and 21%, respectively. Intercropping altered physiological responses, indicating hormetic and interspecific interaction effects that enhanced plant performance in certain combinations. Leaf area, plant height, and biomass of C. ensiformis and C. cajan were maintained or increased under diclosulam exposure. In contrast, S. aterrimum showed reduced growth in monoculture but improved performance when intercropped. Diclosulam concentrations in the soil decreased by 13–18%, with the highest reduction observed in S. aterrimum monoculture (18.3%). Although remediation efficiency was moderate, the high tolerance of these species highlights their potential for use in herbicide-contaminated soils, promoting soil cover and fertility while mitigating carryover effects. This study provides the first integrated evaluation of the tolerance of widely used green manure species to diclosulam and their capacity to reduce its residues in soil. The combined assessment of plant performance, herbicide dissipation, and soil recovery offers a new perspective on the use of green manure as a remediation strategy. The findings expand current knowledge on sustainable approaches for restoring herbicide-contaminated soils.