Wood Vinegar Promotes Soil Health and the Productivity of Cowpea

Abstract

Wood vinegar (WV) is a biostimulant and a biopesticide that contains pyroligneous acid and is used as a crop growth enhancer and biocontrol agent, but insufficient information exists on WV’s effects on soil quality and cowpea production in Ghana. A field study (2 years) was conducted to determine the appropriate method of applying WV for soil health and cowpea production, and to determine the economic benefits of WV. Assessments were on nodulation, shoot biomass, yield, value–cost ratio, soil enzymes, soil respiration, microbial biomass nitrogen (MBN), permanganate-oxidizable carbon (POXC), mineralizable C, soil pH, available nitrogen and phosphorus. Results revealed soil drenching and foliar application are efficient methods of applying WV to achieve greater shoot dry matter, nodulation and grain yield of cowpea. Economically, soil drenching, followed by foliar application, generated better economic returns than the control. Adding WV to cowpea using soil drenching and foliar application improved soil health indicators. Soil enzymes and MBN were enhanced by WV applied foliarly and through soil drenching. Soil drenching with WV produced greater POXC and mineralizable C compared to the other treatments. Conclusively, WV applied foliarly and through soil drenching improved soil health, nodulation and yields of cowpea, and enhanced profitability.