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Let’s be honest, Episode 14: Amino Acid Fertilizers & Organic Food Production

Let’s be honest is a Food Circle project with the aim to open up the conversation about the challenges when being or becoming a member of the SC (Sustainability Club). This series will shine a light on the different approaches to making life more sustainable, as well as the step-backs and difficulties that arise. Being more kind and understanding, instead of critical, will hopefully help to encourage us to try, instead of giving up when facing a step-back or failure. This is made possible thanks to Sapient, the mother company of Food Circle, which every year offers internships to students from all around the world creating a uniquely multicultural environment.

Let’s celebrate the achievements and give room for honesty and struggles!

"Amino Acids have vital roles in cell life. Amino Acids are among the most important primary metabolites within plant cells."

What are we talking about?

Due to the growing need of the food and agriculture industry to develop environmentally-friendly structures and methods, healthy crop and organic farming methods and healthy food production are much faster among producers and businesses in the running agricultural sector. The use of organic product production methods has always been one of the most critical concerns of producers. More importantly, what should be the source of non-chemical substitutes such as organic fertilizers, biopesticides, etc., and how do they meet the needs of the plant. Moving from a chemical strategy to a non-chemical procedure requires tools that can meet production needs by maintaining the conditions above and, on the other hand, no change in the quality of the product.

The regulations for organic plant production are clear and detailed. The European Union (EU) regulation published in 19918 contains parts that relate directly to the composition of organic plant products. The most important aspects of this regulation include: (1) a ban on genetic engineering and genetically modified organisms (GMOs); (2) lower nitrogen levels – a maximum limit for manure application of 170 kg N ha−1 year−1; (3) a ban on synthetic pesticides; (4) a ban on synthetic mineral fertilizers; (5) a ban on growth promoters. Organic farmers must follow the above regulations if they want to pass the inspection procedure every year and receive a certification document. If all requirements are complied with, several qualitative results can be expected. The most important conclusions from scientific comparisons are given below. (Ewa Rembiałkowska 2007) [1]

The use of amino acid fertilizers of plant and animal origin as one of the effective nutrition methods in agriculture and gardens and all agricultural sector products is widespread. Amino acid-based fertilizers have been able to act as a tool and solution for the non-chemical nutrition of plants. However, the variety of products in fertilizers for better food has caused the range of amino acid fertilizers to be produced in combination with mineral elements. Fertilizers that have a purity of 100% amino acids are highly regarded by farmers and gardeners active in organic production. Institutions and organizations are responsible for certifying products authorized for organic farming, such as the OMRI and the EU, and also publish a list of these fertilizers as organic fertilizers each year to serve as a guide for organic producers.

“Does the combination of amino acid compounds has been able to meet the nutritional needs of plants in the production of organic products?”

In technical and commercial terms, amino acid fertilizers are mainly soluble liquid compounds present in the market. Also, some of these compounds are in the form of water-soluble powders, which large producers particularly consider. These powder compounds are used to produce dilute liquid fertilizers with a lower percentage of amino acids. Amino acid powders have a high rate of amino acids needed by plants. The amino acid origin of these compounds is generally obtained through animal lash, skin, hair and nails, and even animal blood. On the other hand, the source of plant compounds with higher absorption capacity plants. Although, in general, the percentage of plant amino acids is lower than animal compounds, as mentioned, the rate of absorption of these plant amino acids and their excretion through the plant is higher and more effortless.

Amino acids are the building units of proteins in all living organisms. Chelating amino acids with minerals led to a marked increase in absorption efficiency and translocation of minerals within the plant. The advantages are as follows: (1) use of small amount, (2) low cost, (3) high rate of repaying, and (4) increase in the output of crops as well as improve its quality. It may get rid of or kill bacteria and insects and decrease the residual pesticide. Chelated minerals are largely used in medicine, poultry, and the livestock industry and in agriculture as biofertilizers. (Rania H. Jacob et al 2022) [2]

According to these explanations, it can say that one of the main properties of amino acids in plants, which accelerates the internal processes of plants, is the property of increasing the absorption of elements, water, and salts. Amino acids as an activator can help plants, especially when they are under profound stress and lose their ability to grow at their maximum. Regarding the nutritional needs, it can be said that the way of consuming amino acids is significant because, for example, concerning the foliar application method, we must consider the factors that reduce the rate of amino acid absorption by the plant, such as temperature, type of sprayer, pesticide pressure spraying, complete coverage of the plant by solution, etc.

The application of bio-stimulants to improve the growth rate and quality of crops is gaining preparations that do not harm the environment and may partly supplement the action of nutrients applied. Amino acids for the production of biostimulants are obtained by chemical synthesis, from plant proteins (e.g., algae, corn, and soybean), as well as from animal proteins by chemical or enzymatic hydrolysis. Amino acids are the basic building blocks of proteins and fulfill multiple functions in the plant's structure, metabolism, and transport. Foliar nutrition is the technique of feeding plants by spraying liquid fertilizers directly to the leaves of macro and micronutrients are more effective in terms of getting maximum yield and reducing losses [15]. Potassium is of special significance because of its active role in bio-chemical functions of plants e.g. activating various enzymes, protein formation, carbohydrates and fat concentration, tolerance to drought, and resistance to frost, lodging, pests, and disease attack. (H W A Al-juthery et al. 2019) [3]

“Manufacturers generally use both plant and animal sources to originate amino acids. The number of amino acids required by the plant in the cellular process and growth is twenty-one, necessary to complete the procedures.”

Often referred to as the “building blocks of proteins”, the 20 canonical proteinogenic amino acids are ubiquitous in biological systems as the functional units in proteins. Sometimes overlooked are their varying additional roles that include serving as metabolic intermediaries, playing structural roles in bioactive natural products, acting as cosubstrates in enzymatic transformations, and as key regulators of cellular physiology. Amino acids can also serve as biological sources of both carbon and nitrogen and are found in the rhizosphere as a result of lysis or cellular efflux from plants and microbes and proteolysis of existing peptides. While both plants and microbes apparently prefer to take up nitrogen in its inorganic form, their ability to take up and use amino acids may confer a selective advantage in certain environments where organic nitrogen is abundant. Further, certain amino acids (e.g., glutamate and proline) and their betaines (e.g., glycine betaine) serve as compatible solutes necessary for osmoregulation in plants and microbes and can undergo rapid cellular flux. This ability is of particular importance in an ecological niche such as the rhizosphere, which is prone to significant variations in solute concentrations. Amino acids are also shown to alter key phenotypes related to plant root growth and microbial colonization, symbiotic interactions, and pathogenesis in the rhizosphere. (LUKE A. MOE 2013) [4]

In the science of plant nutrition, amino acids have a unique role because they can be used in most plant growth periods and are prescribed by plant nutrition experts during most plant growth periods. These amino acids are considered essential for plant growth. Most amino acid fertilizers contain all or part of these amino acids in their composition, primarily available to plants through foliar application. Some compounds are also available to roots through application in soil. Still, due to limitations that may exist concerning soil and amino acid uptake, most manufacturers prefer liquid compounds to those available for plants through foliar application. Although some combinations of amino acid fertilizers may cause damage in the form of stains on fruits and reduce the marketability of the fruit, according to the manufacturer's instructions, it can mitigate this issue in the administration of amino fertilizers.

The biosynthesis of the proteinogenic L-amino acids (L-AAs) of higher plants proceeds via well-established biochemical pathways resulting in AAs belonging to the so-called glutamate, aspartate, pyruvate, serin, and shikimate biogenetic family (Singh, 1999). In the final steps of the biosynthesis usually, an amino group is transferred by aminotransferases (transaminases) onto intermediately formed 2-oxocarboxylic acid. As these pathways are stereospecific this explains the presence and abundance of free L-AAs in plants. It was realized, however, that certain mirror images (enantiomers, or epimers if several chiral centers are concerned) of the protein L-amino acids, named DAAs, do also occur in plants. Notably, it was recognized as early as 1960 that N-acylation of D-AAs, in particular N-malonylation of D-Trp, is common in mono- and dicotyledonous plants (Zenk and Scherf, 1963; 1964). Further, D-Ala, D-Asp, and D-Glu were detected in the free and conjugated form in pea seedlings (Pisum sativum( (Ogawa et al., 1977), barley grains (Hordeum vulgare L.) and hops blossoms (Humulus lupulus L.) (Erbe and Brückner, 2000), and D Ala, as well as D-Ala-D-Ala, were found in pasture grass (Phalaris tuberosa L.) (Frahn and Illman, 1975) and wild rice (Oryza australiensis Domin) (Manabe, 1985). Conjugated D-α-amino-n butyric acid was reported to occur in nine genera of legumes (Ogawa et al., 1976). Various free D-AAs were also detected in cured tobacco leaves (Kullman et al., 1999). (H. Brückner and T. Westhauser 2002) [5]

The role of type L amino acids is much more crucial among all amino acids because this type of amino acid plays many responsibilities within the plant and leads to the regulation of intracellular processes. These processes are one of the main stages of plant and fruit growth, and stopping in these stages leads to damage to plants, such as growth retardation due to physiological factors, seasonal and temperature stresses, pests, and diseases that lead to impaired transport of plant nutrients, blockage of roots, death of vital tissues, etc. Amino acids play a decisive role in implementing these processes step by step by controlling the rhythm within the plant, so the product produced in the final stage is of high quality. Amino acids also play a vital role in fruit storage. Products and fruits treated with amino acids stay longer in healthy transport and storage, which helps reduce losses and food loss in the production cycle.

For example, in a study on the storage of different cultivars of potatoes treated with amino acids, it was found that Potatoes of six cultivars (Solanum tuberosum L.) with red, purple, and yellow flesh were stored at 2 and 5 ◦C for 3 and 6 months, and the influence of these factors on the content of free amino acids was determined. The potato cultivar and storage time had the greatest impact on the free amino acid content. The tubers of red-fleshed (Rote Emma) and purple-fleshed (Blue Congo) potatoes contained over 28 mg/g DM of free amino acids, and the Blaue Annelise cultivar with purple flesh had over 18 mg/g DM. After 6 months, the highest increase in their content (by 36%) was recorded in tubers of the Fresco cultivar (yellow-fleshed). In the analyzed potatoes, the content of alanine, proline, serine, γ-aminobutyric acid, and α-aminoadipic acid increased, while that of asparagine, aspartic acid, and glutamine decreased. Asparagine decreased to the greatest extent in “Blaue Annelise” potatoes (by 24%) and that of glutamine in tubers of Rote Emma and Vineta by 18%. (Anna Peksa et al. 2021) [6]

Since the two types of amino acid fertilizers, powder, and liquid, are very common in plant and agricultural nutrition, many companies are also working on this type of formulation. Liquid amino acid fertilizers are very common, especially in areas where it is impossible to apply fertilizer in the soil and the surface is not smooth. In soils with high salinity, liquid amino acid fertilizers are used for foliar application. This process is done by mixing amino acid liquid fertilizer with the doses specified by the manufacturer with water. We need to integrate the liquid fertilizer with water in fixed proportions. The most crucial step is when should make the foliar application, and all parts of the tree, including the tree canopy, should be foliar. The lower and upper surfaces of the leaves should be in complete contact with the fertilizer solution so that the holes absorb this solution well.

In biology, amino acids have vital roles in cell life. Amino acids are among the most important primary metabolites within plant cells. However, they are frequently regarded as secondary metabolites, particularly in the case of proline, glycine and betaine amino acids. Many physicochemical characteristics of plant cells, tissues and organs are influenced by the presence of amino acids (Rai 2002; Marschner 2011). They are the building units of proteins, as the main component of living cells that have vital roles in many cell metabolic reactions (Kielland 1994; Rainbird et al. 1984; Jones and Darrah 1993). In addition, amino acids have various important biological functions in plant cells including detoxification of toxins and heavy metals (Hussain et al. 2018; Rizwan et al. 2017; Bashir et al. 2018), optimizing the nutrient uptake, translocation and metabolism, vitamin biosynthesis, growth biostimulation, creating higher tolerance to environmental stresses such as drought, salinity and cold conditions, as well as in the synthesis and production of aminochelate fertilizers (Jeppsen 1991; Sharma and Dietz 2006; Souri and Hatamian 2019). (Yaghoub Aghaye Noroozlo et al. 2019) [7]

Much research has been done on the effect of amino acid fertilizers on plant nutrition and the effective growth of plants and agricultural products. It can say that amino acid fertilizers, as an effective tool in organic agriculture, can lead to healthy crop production. Also, amino acids in combination with some mineral elements in the form of fertilizer can increase the percentage of mineral elements absorbed by the plant and, in this case, accumulation. There will be fewer minerals and fewer secondary poisonings. Amino acids accelerate the transfer of water and mineral by facilitating the process of absorption in plants, and by affecting cellular reactions, they cause plants to be highly productive.

Glutamine, arginine, and asparagine are the main amino acids involve in many metabolic and biochemical reactions in plants including detoxification of toxins, neutralization of the produced H+ in ammonium-fed plants, and higher tolerance to stress conditions (Cao et al. 2010; Amin et al. 2011; Marschner 2011). (Yaghoub Aghaye Noroozlo et al. 2019) [7]

Since the move to developed and sustainable agriculture and the use of non-chemical compounds instead of chemical compounds requires multiple tests in farms and gardens, it can say that amino acid fertilizers are good examples due to their increasing use in recent years. They are sustainable for agricultural development. On the other hand, one of the essential effects of using amino