Pyroligneous Acids as Herbicide: Three-Years Field Trials Against Digitaria sanguinalis, Cyperus rotundus, Capsella bursapastoris and Amaranthus lividus

Food quality and food safety issues has drawn wide public concern, and thereby organic agriculture has experienced rapid growth worldwide. In the production of organic crops, weeds control is the biggest problem. The comprehensive utilization of agricultural and forestry residues is an attractive option. Biochar as potential agricultural application benefits, has attracted wide attention. However, this will lead to a large overproduction of the by-product pyroligneous acids (PAs) involved in bamboo/wood/straw vinegar. Therefore, research needs to be done to improve the vinegar weed control effect, reduce the use-cost and accordingly to expand the application scope of PAs. Three tests of new herbicide discovery were conducted to evaluate the weeding effect of 4 PAs and acetic acids (AA) using greenhouse tests and field trials using Digitaria sanguinalis (L.), Cyperus rotundus (L.), Capsella bursa-pastoris (Linn.) Medic. and Amaranthus lividus L. Field trial showed that a good herbicidal effect of PAs on four weeds. Broadleaf weeds were more sensitive than narrowleaf weeds. Biomass tar had strong herbicidal synergistic effect of AA. PAs with the sum content of the AA and tar (>6%) have the potential for development as a bioherbicide in organic agriculture and non-crop land areas.