Agronomic Viability of Landfill Leachate-derived, Humic Extract as an Agricultural Fertilizer

Abstract The objective of this study was to evaluate the agronomic viability of a humic extract (HE), obtained from landfill leachate, as an agricultural fertilizer. A sugarcane crop ( Saccharum sp., var. RB867515’) was grown in pots in a greenhouse using samples of an Argissolo Vermelho-Amarelo (Ultisol) and a Latossolo Vermelho (Oxisol). The treatments consisted of soaking sugarcane nodes with buds in either distilled water or 80% (v/v) HE solution for an hour, followed by foliar and/or soil application of 90% (v/v) HE, or mineral fertilization, or both. After 10 months of greenhouse cultivation, dry mass accumulation, nutrient and metal contents in plant dry mass, soil chemical attributes, and soil bacterial diversity were evaluated. HE promoted sugarcane growth and dry mass accumulation compared with that in control, with performance similar to that under mineral fertilization, particularly in the treatment in which the nodes with buds were soaked in distilled water and subsequently received foliar and soil applications of 90% (v/v) HE. No heavy metals (Cr, Cd, and Pb) were detected in plant tissues and in soil, and soil bacterial diversity was not affected by HE application. The data presented herein suggests preliminary evidence that HE may serve as an agricultural fertilizer under greenhouse conditions, although additional field-scale studies are required to confirm its efficacy and safety.