Understanding Plant Nutrition. What, Why and How

Like all living beings, plants need nutrition too. Better the nutrition provided, the healthier the plant will be. A healthy plant, in turn, will lead to higher yield and better nutritional content in the end product (fruits/vegetables/salad greens).

The nutritional requirements of plants can be classified into 3 categories viz Essential Nutrients, Macro Nutrients, and Micro Nutrients.

Essential Nutrients
Carbon, Hydrogen, and Oxygen are the basic constituents of life. This is true for humans and true for plants. Without these three, plants cannot survive. Plants can absorb these from the air and there is, in general, no need to provide these nutrients externally to the plants. (in specific cases / commercial application some of these nutrients are added externally, especially Carbon in the form of Carbon-di-Oxide in enclosed farms/greenhouses)

Macro Nutrients
These are the nutrients that the plants need in large quantities for efficient functioning and growth. The macronutrients required by plants are Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Sulphur (S) and Magnesium (Mg).

Micro Nutrients
Micronutrients or trace elements are the nutrients that plants need in very small quantities. These are necessary for efficient metabolism and good health. These include Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn), Boron (B), Molybdenum (Mo), Chlorine (Cl) and Nickel (Ni).

How much of these nutrients do the plants need?
To understand the nutrition process in a plant’s life-cycle, consider the analogy of humans. A human embryo grows safely inside her mother’s womb and takes the needed nutrition from her mother. There is no need of giving any external nutrition yet. Once the baby is born, she needs external nutrition, Also the nutritional requirements change with age and also with life stage of the human.

Similarly, in cases of plants, the protective casing of seed does not only protect the embryo from harsh outside conditions but also stores initial set of nutrition that can help the seed to germinate and start growing. However, once the seed has germinated, it does need external nutrition to keep growing. Also, the nutritional requirements vary according to the life stage of plants, just like it happens with humans.

How do plants get these nutrients?
Plants draw these nutrients from the growing medium which is soil in the majority of the cases. The soil, as such, does not have any nutrients of its own. It, however, acts as a storehouse of nutrients that gets added to it naturally through the atmosphere, weathering of rocks, bacterial conversion, decomposed animal waste etc or artificially by adding fertilizer, manure, and compost etc.

Can you grow plants without adding any nutrients?
Yes, you can, if you are growing in fertile soil which may have some stored nutrients. But, once the stored nutrients run out, the plant will begin to grow weak, will be unable to withstand pests and yield will decrease or become non-existent (plant will focus all its energy on surviving and not on growing like humans will do in case of a famine). Thus whether one is growing in soil or outside soil, it is imperative that external nutrition is provided to plants to ensure a healthy garden/farm. More so, in case of growing in a soil-less medium like Cocopeat, hydrotons, rice husk or water.

From where to get these nutrients?
For adding these nutrients externally, one can either depend upon Organic sources like bacteria, earthworms, fish excreta, vermicompost, manure etc or on inorganic ones like fertilizers and precision blends. Again taking the analogy of humans, one can either provide nutrition through organic means like milk, rice, etc or through inorganic supplements like baby food, Farex, Cerelac, Horlicks, Bournvita etc. or take the best of both worlds, adding a spoon of Horlicks to that milk. Which one to use? It is more a matter of individual preference, some prefer only organic, some prefer precisely measured scientific blends depending upon specific plant needs, some prefer using a mix of both. All of these should work with the plants.

Hope this article helped you understand the basics of plant nutrition and answered some of the queries you may have had. Next Tuesday we will take a closer look at the three most important Macronutrients that the plant need, viz NPK.

Happy Farming!

Gaurav is an entrepreneur whose first Start-up was focused on providing services to patients suffering from Chronic Diseases. While researching about the causes of lifestyle diseases and the ways to reduce their incidence, he chanced upon the idea of growing healthy and nutritious food using advanced farming techniques.

He founded CityGreens with a mission to enable City Dwellers to access Safe, Healthy and Fresh food.

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