Humic and fulvic acid derived from slaughterhouse waste compost as biostimulants in Marandu grass

Abstract

Humic and fulvic acids promote the growth and development of different cash crops through biostimulation. However, when extracted from alternative sources, their effects on forage crops are unknown. Thus, the present study aimed to assess the effect of foliar spraying humic and fulvic acids derived from composted slaughterhouse waste compost on the morphophysiology and forage yield of Urochloa brizantha cv Marandu grass. The experiment used a randomized block design in a (2 × 2) + 1 factorial scheme, with five replicates. The first factor was humic and fulvic acids, and the second two doses (1 and 2 L ha-1), in addition to a control treatment. Humic acids increased shoot fresh mass and forage yield by 10 and 20%, respectively, in relation to the control. Fulvic acids obtained lower results for these variables than their humic counterparts in these variables, differing from the control only for forage yield. Similar responses were observed for the CO2 assimilation rate, transpiration, chlorophyll index, and photosynthetic forage surface. Both the univariate and multivariate statistical approaches confirmed that foliar spraying at 1 L ha-1 produced superior results in Marandu grass than those obtained at 2 L ha-1, regardless of the source. Humic and fulvic acids derived from slaughterhouse waste compost have biostimulant effects on Marandu grass. Humic acids exhibit greater biostimulation than fulvic acids in morphophysiological and forage yield, except for leaf area and specific leaf area.