Humic Substances for the Productio1n of Liquid Fertilizer

Objective: This study sought to determine the best stabilizers for the HS extract and to evaluate the resulting extract in the semi-hydroponic cultivation of lettuce. Method: Experiment I and II was conducted in a completely randomized design (CRD) with 6 treatments and 4 replications. The treatments were: T1: Humic substances extract (extract without additives); T2: Algae extract 5% + calcium lignosulfonate 5% + 0.3% guar gum; T3: Algae extract 5% + calcium lignosulfonate 5% + pyroligneous acid 5% + 0.3% guar gum; T4: Algae extract 3% + calcium lignosulfonate 3% + 0.3% guar gum; T5: Algae extract 3% + calcium lignosulfonate 3% + pyroligneous acid 3% + 0.3% guar gum; T6: Control salts. A slab was used with the dimensions of 0.30 m x 1.5 m and with 5 plants per slab, using 30 slabs. The treatments were: T1: Salts; T2: Salts 25% x liquid fertilizer; T3: Salts 50% x liquid fertilizer; T4: Salts 75% x liquid fertilizer; T5: Salts 100% x liquid fertilizer; T6: Dose x liquid fertilizer. Results and Discussion: The response variables were: spectroscopy in the visible ultraviolet region (UV/Vis); NDVI; SPAD; EC; green and dry mass of the shoot, and leaf tissue analysis. In the conditions in which the experiment was conducted, it can be concluded that in Experiment I, Treatment 5 (Algae extract 3% + calcium lignosulfonate 3% + pyroligneous acid 3% + 0.3% guar gum) has the most suitable stabilizers for the HS extract, and that in Experiment II, Treatment 1 (salts) provided the best results. Implications of the research: In line with the environmental theme, the study presents and discusses relevant initiatives in society associating agribusiness and sustainable development.