Effect of raw glycerol on plant soil system in corn and sorghum plants

Abstract

The raw glycerol obtained from the production of biodiesel contains salts and impurities that can generate negative impacts when applied to the soil, however, mixing them with solutions of nitrogen fertilizers could be a viable solution. The objective of this investigation was to evaluate the effect of glycerol on the system soil-plant, in two crops, corn (Zea mayz L.) and sorghum (Sorghum bicolor L.). The study was conducted in 2016 at the Sao Paulo State University UNESP-Jaboticabal, Brazil. The experiments were prepared in a design totally randomized in a factorial arrangement 2 x 3 with four repetitions. The studied factors were soil: Argisol (Hapludox) and Latosol (Haplustox) and fertilization (without fertilizer, urea and urea + glycerol). At 60 days of having applied the treatments, the electric conductivity (EC) and the dehydrogenase enzyme (DH) were measured in the soil and nitrogen accumulation in aboveground (NF) and the dry biomass (DM) in the plant. Raw glycerol increased EC values in both soils, while DH, NF and DM were higher in Latosol soil. The treatment urea + glycerin increased the EC, the DH and the DM, and the urea the NF. The DH and EC media values varied per treatment and in each studied soil. For application of crude glycerol to these crops, a systematic control of the EC of the soil should be carried out as well as the implementation of agricultural practices that mitigate the salinization impact.