Facts About Amino Acids

Amino Acids and Their Role in Plant Nutrition

Amino acids are organic compounds that serve as building blocks for proteins and play a critical role in plant growth and metabolism. When introduced to the soil, amino acids undergo various processes to become available to plants as nutrients. Here’s an explanation of how amino acids break down in soil to feed plants:

1. Decomposition by Soil Microorganisms

• Initial Breakdown: Once amino acids are applied to the soil (via organic matter, fertilisers, or biostimulants), soil microorganisms begin to decompose them. Bacteria, fungi, and other microbes use amino acids as a carbon and nitrogen source.
• Enzymatic Activity: Enzymes like proteases and peptidases break down complex proteins and peptides into individual amino acids, making them more accessible for plant uptake.

2. Mineralisation

• Conversion to Ammonium and Nitrate: During a process called mineralisation, microbes convert the nitrogen in amino acids into inorganic forms like ammonium (NH₄⁺) and nitrate (NO₃⁻). These forms are readily absorbed by plant roots.
• Step-by-Step Breakdown: Amino acids lose their amine group (NH₂) through microbial action, resulting in the release of ammonia (NH₃). This ammonia is then transformed into ammonium or nitrate in the soil.

3. Direct Uptake by Plants

• Absorption of Amino Acids: In addition to the mineralised forms of nitrogen, plants can directly absorb amino acids through their roots. Transport proteins in the root cell membranes facilitate this uptake, especially in nutrient-poor or acidic soils.
• Efficiency: Direct absorption of amino acids allows plants to conserve energy that would otherwise be spent converting nitrate or ammonium into usable forms of nitrogen.

4. Chelation of Nutrients

• Improved Nutrient Uptake: Amino acids can chelate (bind with) essential nutrients like iron, zinc, and manganese, making these micronutrients more bioavailable to plants. Chelated nutrients are more soluble and easier for plant roots to absorb.

5. Soil Health Benefits

• Microbial Stimulation: Amino acids promote the growth and activity of beneficial soil microbes, which, in turn, improve soil fertility and structure.
• Soil Organic Matter: As amino acids decompose, they contribute to the pool of soil organic matter, enhancing water retention, aeration, and nutrient-holding capacity.

6. Plant Benefits

• Energy Savings: By absorbing amino acids directly, plants bypass some of the energy-intensive steps of nitrogen assimilation.
• Growth Promotion: The nitrogen and carbon from amino acids support essential processes such as protein synthesis, enzyme function, and photosynthesis.

Summary

Amino acids break down in the soil through microbial activity and enzymatic processes, releasing nutrients like ammonium and nitrate for plant uptake. Plants can also absorb amino acids directly, gaining a quick and efficient source of nitrogen. Additionally, amino acids improve nutrient availability and stimulate microbial activity, enhancing overall soil and plant health. By understanding these processes, gardeners and farmers can harness amino acids effectively as a sustainable nutrient source.