Effect of foliar-applied humic acid-based fertilizers on potato (Solanum tuberosum L.) yield, tuber quality, and nutrient uptake efficiency, with implications for sustainable fertilization

Bagdagul Kuanyshovna Abitova, Aliya Maxotova, Elmira Yeleuova, Gulnara Tastanbekova, Gulsun Bayadilova, S.Zh. Ibadullayeva, Liza Zhussupova, B.T. Kenzhalieva

2025

Full text Open access: Gold Metadata (CSL-JSON)
DOI 10.18393/ejss.1657337
Data confidence 70 medium
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Abstract

This study investigated the effects of foliar-applied humic acid-based fertilizers on potato (Solanum tuberosum L.) yield, tuber quality, and nutrient uptake efficiency under irrigated conditions in Western Kazakhstan. A three-year field experiment (2021–2023) was conducted using the Silvana potato variety, a medium-early cultivar with high yield potential. The randomized complete block design included five treatments: (1) Control (no fertilizers), (2) Reasil Micro Hydro Mix, (3) Reasil Micro Hydro Mix + Reasil Forte Carb-Nitrogen-Humic, (4) Potassium Humate, and (5) Potassium Humate + Reasil Forte Carb-Nitrogen-Humic. All fertilizers were applied as foliar sprays at three critical growth stages: stem formation, bud appearance, and tuber formation. The humic acid-based fertilizers used in the study were produced by LLC "Life Force Group". Potassium Humate is an 80% alkaline extract of humic and fulvic acids from leonardite. Reasil Micro Hydro Mix contains various essential micronutrients, including N, Mg, B, Fe, Zn, and amino acids. Reasil Forte Carb-Nitrogen-Humic is rich in N (20%, including 18% amide-N) and also contains humic acids (6.2%), hydroxycarboxylic acids (6.2%), and amino acids (6%). Results showed that foliar humic acid application significantly increased potato yield and improved tuber quality. The highest average marketable yield (28.79 t/ha) was obtained with Potassium Humate + Reasil Forte Carb-Nitrogen-Humic, reflecting a 20% increase over the control. Starch content was also highest in this treatment (16.9%), while vitamin C content was better maintained in treated plots under stress conditions. Additionally, nitrate accumulation in tubers was reduced, improving food safety. Nutrient uptake efficiency was significantly enhanced by humic acid-based foliar treatments. The Potassium Humate + Reasil Forte Carb-Nitrogen-Humic treatment recorded the highest N, P, and K absorption levels, confirming the role of foliar humic applications in optimizing nutrient translocation. These findings demonstrate that humic acid-based foliar fertilization is an effective strategy for increasing potato productivity while reducing reliance on conventional fertilizers. These findings highlight the potential of foliar-applied humic substances as a sustainable alternative to conventional fertilization, particularly in semi-arid agricultural systems.