Evaluation of Anaerobic Soil Disinfestation for Environmentally Sustainable Weed Management

In anaerobic soil disinfestation (ASD), soil amended with a carbon source undergoes anaerobic conditions accompanied by changes in microbial community composition and an increase in the concentration of organic acids, primarily acetic and butyric acids, and gases that are deleterious to plant pathogens, insects, and potentially to weeds. The purpose of this study was to explore the efficacy of ASD with different carbon sources on inactivation of propagules of a variety of weed species. Germination and viability of propagules of common lambsquarters (Chenopodium album L.), black nightshade (Solanum nigrum L.), yellow nutsedge (Cyperus esculentus L.), common pokeweed (Phytolacca decandra L.), barnyardgrass (Echinochloa crus-galli L.), dandelion (Taraxacum officinale (Weber)), and redroot pigweed (Amaranthus retroflexus L.) were tested using different rates of four carbon sources: molasses, wheat bran, mustard greens biomass, and raw chicken manure. Wheat bran was the most effective carbon source for inactivation of all weed propagules, followed by molasses and mustard greens biomass. Carbon sources were mixed with soil, which was irrigated to saturation and covered with plastic to promote anaerobic conditions for three weeks. Chicken manure inactivated all the tested species except A. retroflexus compared to the anaerobic control. Rates of carbon sources applied in soil were weakly but significantly correlated (r > 0.42 and p < 0.04) with weed seed mortality or germination inhibition (E. crus-galli) for all the tested carbon sources and weed species except for chicken manure for C. album, A. retroflexus, and S. nigrum. Laboratory tests to confirm organic acid toxicity showed that 1000 µL L−1 acetic plus 1000 µL L−1 butyric acids for at least 60 h inhibited of sprouting of C. esculentus tubers and E. crusgalli seeds, whereas 120 h or exposure was required to inhibit C. album seed germination. Anaerobic soil disinfestation effectively suppressed weed seed germination and viability when wheat bran, molasses and mustard greens biomass were used as carbon sources. This approach could be adopted for weed management in organic systems or any farming system where priority is given to environmentally sustainable practices.