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Introduction

Biostimulants for soybean are a crucial tool for improving nutrient use efficiency and increasing plant resistance to abiotic stress, such as drought and high temperatures. In Latin America, where soybean is a key crop, the adoption of biostimulants has shown promising results in terms of yield increase and agricultural sustainability.

The importance of optimizing nutrition in soybean crops lies not only in maximizing yield but also in reducing the environmental impact associated with the intensive use of synthetic fertilizers. Biostimulants offer a viable alternative to achieve these goals, especially in a context where fertilizer prices continue to rise.

Global and Regional Context

Globally, soybean is one of the most important crops, not only for oil and plant protein production but also as a key raw material in the biofuels industry. In Latin America, countries like Brazil and Argentina lead global production, together representing more than 50% of the world market. The pressure to increase yields due to rising global demand has led farmers to seek innovative solutions like biostimulants to optimize production and tackle issues such as soil degradation and climate change.

Challenges in Soybean Production

Soybean production faces various challenges, such as climate variability, water availability, and soil quality. One of the most critical issues is the dependence on synthetic fertilizers, which are not only costly but their excessive use can lead to water pollution and loss of biodiversity. In this context, biostimulants present a sustainable solution to improve soil health and resource use efficiency.

Importance of Biostimulants

Biostimulants are biological products that promote plant growth and development by enhancing nutrient use efficiency, stress tolerance, and crop quality. In the case of soybean, these products are essential for improving agricultural productivity, especially in regions with adverse climatic conditions.

Mechanisms of Action

Biostimulants act through various mechanisms, including the modulation of hormonal pathways, improvement of soil structure, and enhancement of photosynthetic efficiency. For example, compounds such as auxins, cytokinins, and gibberellins present in some biostimulants can regulate root and shoot growth, increasing the plant’s ability to absorb water and nutrients. Additionally, biostimulants can induce the expression of genes related to stress tolerance, allowing plants to better cope with adverse conditions such as salinity and drought.

Economic and Environmental Benefits

The use of biostimulants not only improves crop yields but also offers economic benefits by reducing dependence on costly chemical inputs. According to a study conducted by the International Plant Nutrition Institute, the use of biostimulants can reduce the need for nitrogen fertilizers by 20-25%, resulting in significant savings for farmers. From an environmental perspective, the reduction in the use of chemical fertilizers helps decrease nutrient leaching and greenhouse gas emissions, contributing to more sustainable agriculture. Furthermore, biostimulants, like those used in the cultivation of biostimulants in vegetables, can offer similar benefits in other crops.

Impact on Soil Health

The application of biostimulants also has a positive impact on soil health. Products containing beneficial microorganisms can increase microbial activity, improving soil structure and promoting the formation of stable aggregates. This, in turn, enhances aeration and nutrient retention, key factors for optimal root development.

Types of Biostimulants

There are several types of biostimulants used in soybean cultivation, each with a specific mechanism of action. Among the most common are seaweed extracts, humic and fulvic acids, and beneficial microorganisms such as nitrogen-fixing bacteria.

Seaweed Extracts

Seaweed extracts are a rich source of phytohormones and bioactive compounds that can enhance plant growth. They contain cytokinins, which promote cell division, and auxins, which improve cell elongation. Studies have shown that the application of seaweed extracts can increase chlorophyll content in leaves, thereby enhancing the photosynthetic capacity of soybean plants. Additionally, seaweed extracts can improve drought stress resistance by increasing water use efficiency.

Humic and Fulvic Acids

Humic and fulvic acids are key components of soil organic matter and play a crucial role in improving soil structure and nutrient availability. These compounds can chelate essential nutrients, facilitating their absorption by plant roots. Moreover, they enhance the soil’s water retention capacity, which is especially beneficial in drought-prone areas. A study published in the Soil Science Society of America Journal showed that the application of humic acids can increase root growth by 30%, thereby improving nutrient and water absorption.

Beneficial Microorganisms

Beneficial microorganisms, such as bacteria of the genus Rhizobium and Azospirillum, are essential for biological nitrogen fixation. These bacteria establish symbiosis with soybean roots, forming nodules where they convert atmospheric nitrogen into ammonia, a form of nitrogen that plants can utilize. This process not only reduces the need for nitrogen fertilizers but also improves overall soil health by increasing its organic matter content. Research has shown that soybean plants inoculated with Rhizobium can increase their yield by 10-15% compared to non-inoculated plants.

Efficiency in Nitrogen Use

Nitrogen use efficiency is a crucial aspect of biostimulation in soybean. Nitrogen-fixing bacteria, such as those of the genus Rhizobium, establish symbiosis with soybean roots, improving nitrogen availability without the need for excessive application of synthetic fertilizers.

Impact on the Nitrogen Cycle

The nitrogen cycle is an essential process in agriculture, and its proper management is fundamental for crop sustainability. Biostimulants can positively influence this cycle by promoting biological nitrogen fixation and improving the mineralization of organic matter. This not only increases nitrogen availability for plants but also reduces nitrogen loss through leaching and volatilization, processes that can contribute to environmental pollution.

Case Studies and Results

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