Need For Plant Nutrients ���..an insight
Need and Role of Nutrients in Plant Nutrition
Plants need water, air, light, suitable temperature, and sixteen nutrients to grow. Plants get carbon, hydrogen and oxygen from air and water. The other thirteen nutrients come from the soil. Soil nutrients are divided into two groups according to the amounts needed by plants. The Macronutrients are nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. The Micronutrients, which are needed in only trace amounts, are iron, manganese, boron, zinc, copper, molybdenum and chlorine.
These nutrients are essential for plant growth. Plants will grow normally until they run short of one nutrient. Then growth is limited by the availability of that nutrient. Occasionally two or more nutrients will run short at the same time. If the nutrients are deficient, or too abundant, then plants will be discolored or deformed.The deficiency symptoms will indicate which nutrient or nutrients are needed. However, it is much better to supply additional nutrients before deficiency symptoms appear. A soil test will tell which nutrients are low before growth is affected.
Most plants in most soils will grow better if additional nutrients are provided by fertilizing. A soil test will give a complete and accurate measure of the nutrients in the soil. A general recommendation is that all soils need more nitrogen. Shallow rooted plants, such as grass and flowers, need more phosphorus and potassium. Acid loving plants, such as rhododendrons, azaleas, camellias, junipers and pin oaks, often need more iron. Sometimes sandy soils need micronutrients, but rarely clay soils. Certain micronutrients may be deficient in certain parts of the country. Many fertilizers are available to supply additional nutrients. Some fertilizers only supply one nutrient. Many supply N, P and K only. A few fertilizers include all of the macronutrients and micronutrients. The label on the package will tell which nutrients are included as well as the sources of the nutrients. The nutrients are identical whether they come from organic or synthetic sources, but the source will affect how fast the nutrients are available to plants. Ammonia sulfate and water soluble fertilizers release most of their nitrogen in a few days and may burn plants if too much is applied. Blood meal releases its nitrogen over a period of months. Organic fertilizers and specially treated synthetic fertilizers release slowly so they last longer and won't burn. Deeper rooting trees and shrubs can be fertilized once a year, but shallow rooted plants, such as grass and flowers, will need regular fertilizing throughout the growing season.
Water can move nitrogen several inches in the soil. Phosphorus and potassium hardly move in the soil.
Soil Factors That Affect Micronutrient Availability
Physical and chemical characteristics of soil affect the availability and uptake of micronutrients