Atrazine and Metolachlor Sorption to Switchgrass Residues

Abstract

Herbicide retention by residue mulch in vegetative filter strips could be an effective attenuation mechanism for removing herbicides from runoff. Adsorption studies were conducted to quantify the amount of atrazine and metolachlor that can be adsorbed and removed from runoff by thatch or fresh switchgrass residue. Adsorption of C 14 -atrazine and metolachlor on thatch or fresh switchgrass residue was conducted by using concentrations of 2.5, 7.5, 13.2, and 26.4 mmol L 21 and a 24-h equilibration period. Adsorption coefficients (K d ) decreased in the order, atrazine sorption on fresh switchgrass residue (81.1 L 21 kg 21 ), metolachlor sorption on fresh residue (32.9 L 21 kg 21 ), atrazine sorption on thatch residue (21.4 L 21 kg 21 ), and metolachlor sorption on thatch switchgrass residue (15.1 L 21 kg 21 ). On a volumetric basis (K dvol ), only atrazine showed a significantly greater K d-vol value on fresh residue than on the thatch residue. Absorption through cut ends of the residues (especially the fresh residue) may have produced adsorption capacities that would not be observed under field conditions. Fresh or thatch switchgrass residue in vegetative filter strips can help abate atrazine and metolachlor by intercepting and sorbing some of the herbicides.

Switchgrass for bioethanol and other value-added applications: A review

“…These reductions were attributed to slower runoff velocities and increase in soil retention. Mersie et al (2006) reported significant levels of sorption of atrazine and metachlor to switchgrass residues that accumulate over time on filter strips. Entry and Watrud (1998) tested the ability of Alamo switchgrass to remediate soil contaminated by cesium-137 and strontium-90.…”

Using satellite vegetation and compound topographic indices to map highly erodible cropland buffers for cellulosic biofuel crop developments in eastern Nebraska, USA

“…Growing perennial grasses such as switchgrass and prairie cordgrass for biofuel in riparian zones, stream waterway buffers, and highly erodible cropland areas has been proposed and investigated (Dominguez-Faus et al, 2009;Mersie et al, 2006;Powers et al, 2010;Sanderson, 2008;Sanderson et al, 2001;Tufekcioglu et al, 2003;Koh et al, 2009; http://nac.unl.edu/buffers/guidelines/4 opportunities/6.html; http://www.globalbioenergy.org/uploads/ media/0702 FAO -Water quality and environmental dimensions in biofuel production.pdf; https://bioenergy.ornl.gov/papers/ misc/switgrs.html). Cultivating perennial grass in these high reliefs, intensive agriculture areas can improve local environment conditions and ecosystem services (Dominguez-Faus et al, 2009;Powers et al, 2010;Sanderson et al, 2001;Tufekcioglu et al, 2003).…”

S-metolachlor efficacy on the control of Brachiaria decumbens, Digitaria horizontalis, and Panicum maximum in mechanically green harvested sugarcane

“…When retained by the crop residue, herbicide losses are likely to occur due to photo degradation, volatilization, and its adsorption by plant residues. The adsorption by plant residues is dependent on their degree of decomposition and age (Mersie et al, 2006). Studies with metolachlor have reported its possible retention by plant residues and thus reduced efficacy (Oliveira et al, 2001;Teasdale et al, 2003;Fontes et al, 2004).…”