Amino Acids in Fertilizers: A Wide Range of Applications

Fertilizers serve as an essential source of nutrients that drive plant growth, making them fundamental to modern agricultural production. Crops obtain necessary nutrients from these fertilizers, which encourage their healthy growth, leading to higher yields and enhanced quality. Amino acid fertilizer has gained significant attention in agriculture because of ongoing technological developments and increased environmental consciousness. Amino acid fertilizer demonstrates distinct benefits and multiple uses, which positions it as a critical driver for sustainable agricultural development.

Amino Acids Definition

Amino acids are the fundamental units that constitute proteins in living organisms. They are composed of an amino group (-NH₂), a carboxyl group (-COOH), and a specific side chain (R group). Based on differences in side chains, amino acids can be classified into various types, among which 20 standard amino acids serve as the primary components of proteins. These amino acids form diverse proteins through different arrangements and combinations, participating in various physiological functions of living organisms. Amino acids can be categorized according to different criteria. From a nutritional perspective, they are divided into essential and non-essential amino acids. Essential amino acids, such as lysine and tryptophan, cannot be synthesized by plants or are synthesized at a rate insufficient to meet their needs, necessitating external acquisition. In contrast, non-essential amino acids, such as glutamic acid and aspartic acid, can be synthesized by plants themselves. In the field of fertilizers, these amino acids play distinct roles, collectively supporting plant growth and development.

Fig. 1. Amino acid as fertilizer (BOC Sciences Authorized).

Amino Acid Fertilizer

Amino acid fertilizer is a new type of fertilizer that primarily consists of amino acids. It not only provides plants with abundant nutrients but also promotes plant growth and development in multiple ways. Amino acid fertilizers contain various essential amino acids for plants, such as glutamic acid, aspartic acid, and lysine. These amino acids can be directly absorbed and utilized by plants, serving as a nitrogen source and promoting protein synthesis within plants. Compared with traditional nitrogen fertilizers, the nitrogen in amino acid fertilizers exists in an organic form, making it more easily absorbed by plants with higher utilization efficiency. Additionally, amino acid fertilizers contain a certain amount of trace elements, such as zinc, iron, and manganese, which play vital roles in plant growth. These elements enhance photosynthesis, respiration, and enzyme activity, thereby improving plant stress resistance.

Amino Acids for Fertilizers

BOC Sciences, leveraging advanced biosynthesis and chemical synthesis technologies, provides high-quality amino acid raw materials to meet the diverse needs of the fertilizer industry. The amino acids we supply, such as glycine, glutamic acid, alanine, and lysine, can act as plant nutrition enhancers, boosting crop absorption of nitrogen, phosphorus, and potassium while enhancing stress resistance and improving soil microbial environments. BOC Sciences has established mature production processes and strict quality control systems to ensure product purity and stability. Additionally, we offer customized services to meet the specific needs of various crops and soil conditions.

Types of Amino Acid Fertilizers

• Amino Acid Solid Fertilizer

Amino acid solid fertilizers are typically available in powder or granular form. Their production process generally involves hydrolyzing, extracting, and drying raw materials containing amino acids, such as animal hair, feathers, and leather. These fertilizers have the advantage of easy storage and transportation, making them suitable for large-scale farmland applications. During application, they can be incorporated into the soil through broadcasting, trenching, or hole application, allowing plant roots to directly absorb the nutrients.

• Amino Acid Liquid Fertilizer

Amino acid liquid fertilizers have been rapidly developing in recent years. They have good fluidity and are easy to apply, delivering nutrients efficiently to various plant parts through irrigation systems or foliar spraying. Compared to solid fertilizers, liquid fertilizers have a higher absorption efficiency, enabling plants to quickly obtain essential nutrients, especially during critical growth periods such as flowering and fruiting. Additionally, liquid fertilizers can be combined with other liquid fertilizers or pesticides to achieve synergistic effects.

• Amino Acid Organic Fertilizer

Amino acid organic fertilizers are derived from natural organic materials such as animal manure and plant residues. These materials undergo microbial fermentation and decomposition, breaking down proteins into amino acids and other small molecules, forming an organic fertilizer rich in amino acids. Besides providing abundant amino acids, these fertilizers contain large amounts of organic matter and beneficial microorganisms, which improve soil structure, enhance aeration and water retention, and stimulate microbial activity, thereby increasing soil fertility. The use of amino acid organic fertilizers reduces dependence on chemical fertilizers, minimizes environmental pollution, and aligns with the principles of sustainable agriculture.

• Amino Acid Chelate Fertilizer

Amino acid chelate fertilizers utilize the chelating properties of amino acids to bind with metal ions (such as iron, zinc, and copper) or mineral elements, forming stable chelates. In these fertilizers, amino acids act as chelating agents that enhance the solubility and bioavailability of metal ions. Once inside plants, these chelates are more readily absorbed and utilized, effectively supplementing essential trace elements and preventing nutrient deficiencies. For example, amino acid chelated iron fertilizers can effectively prevent and treat iron deficiency chlorosis in plants, thereby improving photosynthetic efficiency.

Amino Acid Fertilizer for Plants

The primary components of amino acid fertilizers are free amino acids and small peptides, which plants can rapidly absorb and utilize. Amino acids not only serve as fundamental building blocks of proteins but also enhance photosynthesis, root development, nutrient uptake, and antioxidant capacity. Amino acid fertilizers can be applied via foliar spraying, soil application, or drip irrigation, showing significant effects on fruits, vegetables, grains, and cash crops. Their advantages include promoting nitrogen metabolism, improving fertilizer efficiency, and reducing environmental pollution, thereby contributing to more sustainable agriculture.

• Plant Absorption and Utilization

Plants absorb amino acid fertilizers mainly through two pathways: roots and leaves. Root absorption is the primary method by which plants obtain the nutrients from amino acid fertilizers. When amino acid fertilizer is applied to the soil, soil microorganisms further decompose the organic materials within it, releasing more amino acids and other nutrients. These substances dissolve in the soil solution and are absorbed by the plant roots through diffusion and active transport. Leaf absorption occurs through foliar spraying, where amino acid liquid fertilizer is sprayed on the surface of the plant leaves, allowing the amino acids to enter the plant through the osmosis of the epidermal cells. The amino acids that enter the plant can participate in various physiological processes, such as protein synthesis, enzyme activation, and hormone regulation, thereby promoting the growth and development of the plant.

• Promoting Plant Growth and Development

Amino acid fertilizers have multiple roles in promoting plant growth and development. First, regarding root development, amino acids can stimulate root growth and differentiation, increasing both root length and quantity, thereby enhancing the plant's ability to absorb water and nutrients. For example, glutamic acid can promote the growth of root hairs, enabling the roots to better absorb minerals from the soil. Second, in terms of stem and leaf growth, amino acids can stimulate cell division and elongation, making the plant's stems and leaves stronger. For instance, lysine can increase the level of auxin in the plant, promoting stem elongation and leaf expansion. Furthermore, amino acid fertilizers have a significant promoting effect on flowering and fruiting. They regulate the plant's nutrient distribution, directing more nutrients to the flowers and fruit, thereby improving the quantity and quality of flowers and fruit. For example, tryptophan, a precursor to auxin synthesis, can promote flower bud differentiation and fruit development when supplemented.

• Enhancing Plant Stress Resistance

In natural environments, plants often face various adverse environmental stresses such as drought, salinity, and pest damage. Amino acid fertilizers can enhance plants' resistance to stress through various mechanisms, helping plants withstand these negative environmental impacts. On one hand, amino acids can regulate the plant's internal osmotic pressure, allowing plant cells to retain a certain level of water content under stress conditions like drought, thus maintaining normal physiological functions. For example, proline is an important osmotic regulator, and its content significantly increases in plants under drought stress, enhancing drought resistance. On the other hand, amino acids can activate the plant's antioxidant system, scavenge free radicals, and reduce oxidative stress damage to plant cells. For example, glutathione is a peptide with antioxidant properties, which can eliminate reactive oxygen species in the plant, protecting cell membrane integrity and enhancing stress resistance. Additionally, amino acids can induce the production of stress-related proteins and hormones in plants, such as heat shock proteins and abscisic acid, further increasing the plant's stress resistance.

Amino Acid Fertilizer Benefits

• Promotes Nutrient Absorption: Amino acids can form organic-mineral complexes, significantly improving the efficiency of nutrient uptake by plants. For example, in AMINO® ULTRA fertilizer, which is based on GCAA technology, glycine forms complexes with trace nutrients, allowing nutrient molecules to reach the appropriate cellular sites more quickly and efficiently.
• Enhances Nutrient Transport: Certain amino acids act as natural chelating agents, facilitating the absorption of essential nutrients such as minerals, nitrogen, phosphorus, and potassium. They also promote the activity of enzymes responsible for breaking down nutrients into simpler forms that plant roots can absorb.
• Stimulates Growth: Amino acids are key intermediates in numerous metabolic processes, supporting the synthesis of proteins, enzymes, and plant hormones. They actively participate in protein synthesis, cell division, stem and root elongation, and the regulation of plant tissue formation. Additionally, amino acids play a role in activating plant growth hormones such as auxins and cytokinins.
• Improves Flowering and Fruit Setting: The application of amino acid fertilizers enhances optimal flowering by influencing multiple crucial physiological and biochemical processes. As precursors for floral hormone synthesis, amino acids regulate the formation and development of floral organs, leading to more vigorous flowering and increased flower quantity and quality.
• Enhances Stress Resistance: Amino acids help regulate and protect crops under adverse conditions. They contribute to osmotic balance and cellular homeostasis, increasing plant tolerance to environmental stresses such as drought, cold, extreme heat, and diseases. For instance, proline helps regulate osmotic pressure, protecting plants from drought and high salinity stress.
• Reduces Chemical Stress: When used in combination with plant protection products, amino acids can mitigate the stress caused by their application. They also accelerate tissue repair and stimulate the plant's natural immune mechanisms.
• Promotes Soil Microbial Activity: Amino acids serve as an excellent energy source for soil microbes. Amino acid-trace nutrient complexes are efficiently utilized by plants without generating harmful chemical residues in the environment.
• Increases Fertilizer Utilization Efficiency: By enhancing nutrient absorption and reducing nutrient loss, amino acid fertilizers improve overall fertilizer efficiency. This means that less fertilizer is required to achieve the same or even better results, thereby minimizing the environmental impact of fertilization.
• Versatile Application Methods: Amino acid fertilizers can be applied in multiple ways, including foliar spraying, soil application, and irrigation systems. Foliar spraying is particularly efficient, as it delivers nutrients rapidly and effectively to the plant.
• Suitable for Various Crops: Amino acid fertilizers are applicable to a wide range of crops, including fruits, vegetables, grains, and ornamental plants. They can be customized to meet the specific needs of different crops and growth stages.

How to Make Amino Acid Fertilizer?

Amino acid fertilizer is a highly efficient biostimulant that promotes plant growth, enhances crop resistance to stress, and improves soil fertility. It is primarily produced by hydrolyzing animal or plant proteins or through microbial fermentation to obtain an amino acid-rich solution, which is then purified and formulated for use in either liquid or solid form in agricultural production. Depending on the production process, amino acid fertilizers are mainly manufactured using acid hydrolysis, enzymatic hydrolysis, or microbial fermentation, each with distinct characteristics and applications.

• Acid Hydrolysis

The acid hydrolysis method is a traditional approach to producing amino acid fertilizers, suitable for protein-rich raw materials such as animal hair, feather meal, fish meal, soybean meal, and bone meal. This method uses hydrochloric acid or sulfuric acid to hydrolyze proteins under high temperature and pressure, breaking them down into free amino acids or short peptides. Subsequently, impurities are removed through neutralization, decolorization, and filtration, and the pH is adjusted to meet plant absorption needs. Acid hydrolysis efficiently degrades proteins, yielding a high amino acid content at a low cost, making it suitable for large-scale production. However, certain beneficial amino acids (such as tryptophan and cysteine) are prone to degradation under strong acid conditions, affecting the nutrient composition of the fertilizer. Additionally, impurities generated during acid hydrolysis require further purification.

• Enzymatic Hydrolysis

Enzymatic hydrolysis is a rapidly developing biotechnological method that utilizes proteases to catalyze protein hydrolysis under mild conditions, breaking them down into amino acids and short peptides. This method is suitable for protein-rich raw materials such as soybean meal, fish meal, and animal by-products. The resulting amino acid solution retains more nutritional components and biological activity and can be directly used as a liquid fertilizer or further concentrated and spray-dried into powder form. The mild enzymatic process preserves amino acid integrity, enhances fertilizer activity, and reduces pollution associated with acid hydrolysis. However, the effectiveness of enzymatic hydrolysis depends on the type and quantity of enzymes used, making production costs relatively higher.

• Microbial Fermentation

The microbial fermentation method utilizes specific microorganisms (such as lactic acid bacteria, Bacillus subtilis, and yeast) to metabolize organic matter in nutrient-rich media, releasing amino acids. This method is widely used in organic agriculture and can utilize agricultural residues, livestock manure, and food processing waste as raw materials. Microbial fermentation does not require added acids or enzymes, making it environmentally friendly while enhancing soil microbial activity and improving soil structure. However, fermentation takes longer, and the resulting amino acid concentration is relatively low, requiring optimization of microbial strains and fermentation conditions to improve production efficiency.

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