Q. Please explain how the presence of different nutrients affect plant growth.
Plants, as well as all living things, need nutrients and minerals to thrive. These chemical elements are needed for growth, metabolic functioning, and completion of its life cycle.
Plants take in Carbon (C) and Oxygen (O2) in the air from their leaves. All other nutrients are found in the soil and are taken up for use in the roots. Macronutrients are consumed in large quantities: nitrogen (N), phosphorus (P), potassium (K), calcium (C), sulfur (S) and magnesium (Mg). Smaller amounts of micronutrients (or trace minerals) are needed: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni).
Most soil conditions will provide plants adequate nutrition. Testing is available to see what nutrients are in the soil and if the PH is correct, which is necessary for the plant to absorb the nutrients. Nutrient deficiency requiring fertilizing and/or soil amending has many causes. Growing certain crops or plants might deplete the soil. In agriculture, crops are rotated from year to year with increasing soil fertility in mind. Some plants, like roses, are considered "heavy feeders" and need frequent fertilization. A problem that a plant exhibits can often be diagnosed as having a deficiency of a certain element. For instance, iron chlorosis, a deficiency in iron, may be one reason why a plant's leaves turn yellow or brown between the veins.
Replenishing nutrients in the soil can be done by adding organic material such as compost, dehydrated manure, compost tea or fish emulsion. Traditionally, most "all-in-one" chemical fertilizers have an "NPK" rating (Nitrogen-Phosphorus-Potassium) and can be purchased in liquid or granule form. In addition to other properties, Nitrogen helps plant foliage to grow strong. Phosphorous helps roots and flowers grow and develop. Potassium (Potash) is important for overall plant health. The plant needs will determine the ratio of each nutrient needed.
HOWEVER - too much of some nutrients, such as phosphorus, can jeopardize the quality of neighboring water bodies from run-off or leaching into the ground when not absorbed by plants. This can contribute to livestock and aquatic animal death, increase the difficulty of water purification, as well as affect recreational use of the water. Many states have banned the use of certain nutrients. Phosphorus has been banned in NY under certain circumstances since 2012. Check with your local extension service for specific information about your state.
Growers of hydroponic plants, grown in water, have found ways for their plants to receive all the necessary nutrients usually found in the soil.
Hope that answers your question.
Courtesy of NYBG Plant Information