Plant Nutrition Through Soil Uptake
Excluding carbon, hydrogen, and oxygen, the essential plant nutrients primarily include both macronutrients and micronutrients, each playing specific roles in plant growth, reproduction, and metabolism.
### Macronutrients These are needed in relatively large amounts for fundamental processes:
- **Nitrogen (N)**: Crucial for leaf growth, protein synthesis, and a key part of chlorophyll and nucleic acids. It supports healthy vegetative growth and the production of vitamins, often the most demanded nutrient by plants.
- **Phosphorus (P)**: Important for root development, energy transfer (ATP), flowering, and fruiting. It also plays a role in DNA and RNA formation necessary for reproduction and metabolism.
- **Potassium (K)**: Regulates water balance, activates enzymes, and enhances disease resistance and stress tolerance. It supports robust plant health and metabolism, aiding in photosynthesis and protein synthesis indirectly.
- **Calcium (Ca)**: Provides structural integrity by stabilising cell walls and membranes. It also plays a role in signalling within the plant, affecting growth and root development.
- **Magnesium (Mg)**: Central atom in chlorophyll, essential for photosynthesis. It also activates many enzymes involved in energy metabolism and facilitates nutrient transport.
- **Sulfur (S)**: Integral part of some amino acids and vitamins, necessary for protein synthesis and enzyme function.
### Micronutrients (Trace Elements) Required in small quantities but vital for specific metabolic processes:
- **Iron (Fe)**: Essential for chlorophyll synthesis and functions in electron transport during photosynthesis and respiration.
- **Manganese (Mn)**: Activates enzymes involved in photosynthesis and nitrogen metabolism.
- **Zinc (Zn)**: Important for enzyme function, growth regulation, and synthesis of growth hormones.
- **Copper (Cu)**: Plays a role in photosynthesis, respiration, and lignin synthesis, which strengthens plant tissues.
- **Boron (B)**: Critical for cell wall formation, membrane integrity, pollen tube growth, and reproductive development.
- **Molybdenum (Mo)**: Required for nitrogen fixation and nitrate reduction, key for nitrogen metabolism.
- **Chlorine (Cl)**: Involved in osmosis, ionic balance, and photosynthesis.
These nutrients work together to support various essential physiological and biochemical functions necessary for plant growth, reproduction, and metabolism, ensuring healthy plants and productive yields.
### Foliar and Soil Applications Chelates are foliar-applied to correct zinc deficiency during the growing season but have little residual value. Zinc fertilizer can be applied to the soil or foliage, with higher rates of zinc soil application (2-5 lbs/acre) benefiting the plant for several years. Oxide forms of zinc may have limited effectiveness in the year of application but can provide a residual effect.
Deficiency symptoms of iron first appear on the younger leaves, with interveinal chlorosis being a classic symptom. In wheat and barley, the leaves may have light blotches or chlorosis between the veins. In flax, grayish-brown spots appear on the younger leaves, and the internodes appear stunted.
### Mycorrhizal Fungi Mycorrhizal fungi help plants absorb nutrients and water from the soil, leading to improved plant growth, health, and resilience to environmental stressors. They can provide protection against soil-borne diseases, improve water uptake, stimulate root growth, improve soil structure, and reduce the need for chemical fertilizers. Endomycorrhizae penetrate plant cells, while ectomycorrhizae form a sheath around plant roots.
Understanding the roles of these essential nutrients and their applications is crucial for maintaining healthy, productive plants and ensuring sustainable agriculture.
References: [1] Lin, Y., & Qiu, Q. (2014). Sulfur nutrition in plants. In Crop nutrient management (pp. 1-21). Springer, Cham. [2] Marschner, H. (2012). Mineral nutrition of higher plants (5th ed.). Academic Press. [3] Marschner, H., & Rengel, Z. (2012). Trace element nutrition of plants. Academic Press.
The essential nutrients discussed, while primarily geared towards plants, could potentially have an impact on our health-and-wellness as well, given the interconnectedness of soil health and our food chain. For instance, research in health-and-wellness and nutrition may unveil potential benefits from certain macronutrients like nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, or micronutrients like iron, manganese, zinc, copper, boron, molybdenum, and chlorine. Furthermore, science could explore the value of mycorrhizal fungi in fitness-and-exercise, as these microorganisms aid plants in absorbing essential nutrients, water, and promoting growth, resilience, and improved soil structure—factors that are equally relevant to maintaining a healthy body.
