Suppression of nitrous oxide production by the herbicides glyphosate and propanil in soils supplied with organic matter

Abstract

Abstract Laboratory experiments were conducted to investigate the impact of two herbicides, a commercial formulation of glyphosate (Roundup) and propanil (DCPA), on nitrous oxide (N2O) production and soil respiration in two different soils (Tyatkone and Miura) amended with rice straw and chitin. The N2O production rates were very small in both control soils (maximum activity during a whole incubation period was 0.1 µg N kg−1 of soil), but increased with the application of chitin (59 and 152 µg N kg−1) and rice straw (26.6 and 6.2 µg N kg−1) in Tyatkone and Miura soils, respectively. Throughout the 6-week incubation, the application of glyphosate and propanil suppressed cumulative N2O production in both types of organic matter amended soils. In the rice straw amended Tyatkone soil, the application of glyphosate and propanil decreased N2O production by 92 and 89%, respectively, and it decreased N2O production by 20 and 79%, respectively, in the chitin amended Tyatkone soil. In the Miura soil amended with rice straw, the application of glyphosate and propanil decreased N2O production by 50 and 65%, respectively, while it decreased N2O production by 49 and 48%, respectively, in the soil amended with chitin. There were no significant differences in cumulative CO2 evolution between the treatments. It might be suggested that the herbicides used in this study had no severely adverse effects on the overall soil microbial community. Collectively, glyphosate and propanil application can be used as a mitigation strategy to reduce N2O production from agricultural soils with organic amendment.