Investigating the Effect of Organic Biostimulants and Different Levels of Chemical Fertilizers on the Growth, Yield Components and Yield of Faba Bean (Vicia faba L.)

Document Type : Original Article

Authors

Masoumeh Naeemi

Ziba Avarseji

Leila Ahangar

Department of Plant Production, Faculty of Agriculture and Natural Resources, Gonbad Kavous University, Gonbad Kavous, Iran

10.22067/ijpr.2025.91464.1102

Abstract

Introduction
Faba bean (Vicia faba L.) is a strategic legume crop widely cultivated for its high protein content, contribution to human and animal nutrition, and its capacity to biologically fix atmospheric nitrogen, thereby enhancing soil fertility and reducing the need for synthetic nitrogen fertilizers. Despite these advantages, faba bean productivity in many semi-arid regions remains suboptimal, largely due to inefficient nutrient management practices and an overreliance on chemical fertilizers. Excessive use of mineral fertilizers not only increases production costs but also contributes to soil degradation and environmental pollution. Consequently, there is growing interest in sustainable nutrient management strategies that integrate chemical fertilizers with organic inputs and biostimulants to improve crop performance while minimizing environmental impacts. Organic biostimulants, such as humic substances and plant-derived extracts—are increasingly valued for improving soil properties, stimulating root growth, enhancing nutrient availability, and regulating key physiological and biochemical processes in plants. Humic acid, a major component of soil organic matter, plays a crucial role in improving soil structure, cation exchange capacity, and nutrient uptake efficiency. Similarly, Equilibrate Vegetative Organic (EVEO), a plant-based biostimulant, contains naturally occurring growth-promoting compounds that can enhance photosynthetic activity, metabolic efficiency, and overall plant vigor. However, information on the combined effects of these biostimulants with reduced or recommended rates of NPK fertilizers on faba bean growth and yield under semi-arid conditions remains limited.
 
Materials and Methods
The present study was conducted to evaluate the effects of humic acid and EVEO, applied alone or in combination with different levels of NPK fertilizers, on growth characteristics, yield components, biological yield, harvest index, and green pod yield of faba bean. The experiment was carried out during the 2018–2019 growing season at the research farm of Gonbad Kavous University, northern Iran, under semi-arid climatic conditions. The experimental design was a randomized complete block design (RCBD) with three replications and nine nutritional treatments, including: (1) control (no fertilizer), (2) 100% recommended NPK, (3) 100% NPK + humic acid, (4) 100% NPK + EVEO, (5) 50% NPK + humic acid, (6) 50% NPK + EVEO, (7) humic acid alone, (8) EVEO alone, and (9) combined application of humic acid and EVEO without mineral fertilizer. Standard agronomic practices were applied uniformly throughout the growing period.
 
Results and Discussion
The results demonstrated that nutrient management treatments significantly affected most growth parameters, yield components, and total biomass production of faba bean. In contrast, the harvest index was not significantly influenced by the applied treatments, indicating that yield enhancement was mainly driven by increased biomass accumulation rather than changes in biomass allocation. Treatments combining organic biostimulants with mineral fertilizers consistently produced superior results compared with the control and sole mineral fertilizer treatments. Notably, the application of humic acid or EVEO in combination with 50% of the recommended NPK rate resulted in yields comparable to or higher than those obtained with the full NPK rate, highlighting the capacity of these biostimulants to improve nutrient use efficiency. The observed improvements in growth and yield attributes can be attributed to the synergistic interaction between organic biostimulants and mineral fertilizers. Humic acid likely enhanced root growth and nutrient uptake through improvements in soil structure and nutrient availability, while EVEO may have stimulated key physiological processes via its bioactive constituents. These complementary mechanisms promoted improved vegetative growth, reproductive development, and yield formation. Importantly, the ability to maintain or enhance yield with reduced mineral fertilizer inputs underscores the potential of biostimulants to support more sustainable and resource-efficient cropping systems.
 
Conclusions
The findings of this study demonstrate that integrating organic biostimulants such as humic acid and EVEO with mineral fertilizers is an effective and environmentally sustainable strategy for improving the growth, yield, and productivity of faba bean under semi-arid conditions. This integrated nutrient management approach reduces dependence on synthetic fertilizers while maintaining high crop performance, thereby contributing to more sustainable agricultural practices. The results provide valuable insights for faba bean cultivation in northern Iran and other regions with similar agro-ecological conditions and support the broader adoption of combined organic–inorganic fertilization strategies in sustainable crop production systems.
 
Acknowledgements
I am very grateful to the vice-chancellor for education and research of Gonbad Kavos University for the financial support of this research.

Keywords

Green pod

Grain yield

Humic acid

Organic fertilizer

Subjects

• Agronomy

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Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)

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