Fulvic acid in foliar spray is more effective than humic acid via soil in improving coffee seedlings growth

ABSTRACT

Humic (HA) and fulvic (FA) acids improve the nutrient availability and uptake by plants but some aspects of their agronomic use still need to be clarified. The effects of HA soil application and FA foliar application on the growth, Zn and B uptake by coffee seedlings were evaluated. HA was added to an Oxisol at concentrations 0, 10, 25, 50, 75 and 100 mg kg⁻¹ (C-HA), in both limed (pH 6.2) and overlimed (pH 7.2) conditions. FA (0, 0.2, 0.5 and 1 g L⁻¹ C-FA) was applied to coffee leaves in three different application modes (M): with 0.3% Zn and 0.6% B supplied via foliar (M₁), 0.6% B and 1.2% Zn supplied via foliar (M₂) and 1.2 mg kg⁻¹ B and 6 mg kg⁻¹ Zn supplied via soil (M₃). HA addition in soil significantly (p < 0.05) reduced leaf B and Zn accumulation and coffee growth in both pH conditions. In the M₁ and M₂, FA application significantly (p < 0.05) increased the shoot growth at 0.59 and 0.45 g L⁻¹ and B accumulation at 0.96 and 0.45 g L⁻¹ C-FA. Foliar application of C-FA, instead soil application of C-HA, is a suitable practice to improve coffee seedlings growth and nutrition on Oxisol.

KEYWORDS:

• Foliar spray
• humic fertilization agronomic rate
• organo-metallic complexes
• overliming

Acknowledgments

The authors thank CAPES: [Grant Number PROEX-AUXPE 593/2018] for the scholarships and financial support provided for this study. Many thanks to FAPEMIG and CNPq: [Grant Numbers 461935/2014-7 and 303899/2015-8] for funding this study and scholarship provided.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico: [Grant Number 303899/2015-8]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: [Grant Number PROEX-AUXPE 593/2018 and Finance Code 001] and Fundação de Amparo à Pesquisa do Estado de Minas Gerais: [Grant Number 461935/2014-7].