Understanding the multifunctionality of pyroligneous acid from waste biomass and the potential applications in agriculture.

Efforts have been directed to the development of environmentally friendly processes and manufacturing of green products, use of renewable energy and more sustainable agricultural practices. Pyroligneous acid (PA) is a byproduct of biomass pyrolysis that consists of a complex mixture of bioactive substances. The complexity and richness of PA composition have opened a window for PA application in agriculture and mitigation of environmental pollution. This review brings a brief historical on the use of PA and regulatory policies adopted in Brazil, China, Japan and Thailand for PA application in agriculture. The composition and stability of PAs of several origins are presented, together with a discussion of the use of PA to boost plant growth and crop productivity, remove toxic metals from soil, inhibit soil ureases, mitigate the emission of greenhouse gases, control phytopathogen proliferation and weed dissemination. A great variety of biomass types are reported as feedstock to produce PA with distinct chemically diverse and active substances at wide-ranging concentrations. PA has been shown to successfully improve farming practices in a more sustainable fashion. The disclosure of the mechanisms of action that drive the PA's effects, together with the pursue of safety and efficacy data in a case-by-case way to address toxicity and shelf stability, will be valuable to expand the use of PA worldwide for food production.