Agave leaf powder enhances phosphate desorption and increases induced respiration in soils dosed with glyphosate

Due to the widespread use of glyphosate in agriculture, remediation techniques have emerged to reduce its impact on the environment. The use of agricultural by-products as soil amendments can enhance microbial proliferation in soil and subsequently reduce glyphosate persistence. Agave by-products possess constituents that can influence on the sorption of phosphorus in soil and displace glyphosate from soil surfaces, which may increase glyphosate availability and, therefore, increase the efficacy of glyphosate remediation. This work describes an initial approach to assess the potential of agave leaf powder to enhance glyphosate bioremediation. Phenolic acids, organic acids, and other constituents were evaluated from Agave attenuata leaf powder. Two experiments were performed under laboratory conditions. A batch equilibrium sorption experiment using three different New Zealand soils showed significant desorption of orthophosphate, aluminium, and iron after the addition of A. attenuata leaf powder to soil solution. Analysis of soil induced respiration showed that agave leaf powder in combination with two glyphosate doses increased the soil induced respiration ratio. Exogenous carbon associated with these treatments was positively correlated with the Carbon: Nitrogen ratio in soil solution, inferring increased microbial activity. These results suggest that Agave leaf powder has potential as a soil amendment to enhance glyphosate biodegradation. Further research is needed to clarify the effect of agave leaf powder on glyphosate biodegradation; and on the desorption of orthophosphate, aluminium, and iron from soils.