Importance of Micronutrients in Agriculture
Micronutrients are essential plant nutrients that are required in very small quantities for plant growth and development. Though required in small amounts, micronutrients play a vital role in numerous plant metabolic processes and deficiency of even one micronutrient can impact crop yield and quality.
Micronutrients Defined
Agricultural Micronutrients, also known as trace elements, are chemical elements required by plants and animals in very small amounts. These include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). Micronutrients facilitate various enzyme reactions in plants and help them carry out normal physiological functions and metabolic processes critical for plant health and growth. While macronutrients like nitrogen, phosphorus, and potassium are required in relatively larger quantities, micronutrients are needed by plants in amounts ranging from parts per million to parts per billion.
Role of Micronutrients
Though required in minute amounts, micronutrients play crucial roles in plant growth:
- Chlorine is involved in photosynthesis, transpiration and activities of various enzymes.
- Boron is essential for cell wall synthesis, sugar translocation, and reproductive processes. It aids in flowering, fruiting and seed development.
- Iron aids chlorophyll synthesis for photosynthesis and is involved in nitrogen fixation by leguminous plants.
- Copper acts as cofactor for many redox enzymes and helps in respiration and photosynthesis.
- Zinc is necessary for auxin production and DNA synthesis. It helps in stem elongation, root development and seed production.
- Manganese helps in photosynthesis, nitrogen fixation, carbohydrate and fatty acid production.
- Molybdenum acts as cofactor for nitrogenase enzyme involved in nitrogen fixation by legumes.
Thus, inadequate supply of even a single micronutrient can negatively impact plant growth and development leading to decreased yields.
Micronutrient Deficiencies
Micronutrients are commonly deficient in agricultural soils due to various reasons like exhaustive cropping, imbalance use of fertilizers focusing only on NPK, soil erosion and leaching. Some of the prominent deficiencies observed include:
- Zinc deficiency is widespread affecting crops like rice, wheat, maize etc. leading to poor grain filling.
- Iron deficiency called chlorosis is seen in alkaline soils affecting horticultural crops like citrus and ornamentals.
- Boron deficiency occurs in coarse textured sandy soils reducing yields of fruits, vegetables, oilseeds and cereals.
- Copper deficiency results in grey speck disease of sugarcane and reduces tomato yields.
- Manganese deficiency is observed in acidic upland soils reducing paddy yields.
Left uncorrected, these deficiencies can reduce crop yields by as much as 50% highlighting the importance of micronutrient management.
Micronutrient Management
Various strategies are followed to ensure adequate availability of micronutrients to crops:
Foliar Fertilization
- Direct application of micronutrient fertilizers as sprays corrects existing deficiencies quickly without waiting for absorption from soils. Elements like zinc and magnesium are commonly applied through foliage.
Soil Application
- Basal application of micronutrient fertilizers before sowing ensures sustained availability through the cropping season. Elements like boron and manganese are usually applied to soil.
Seed Treatment
- Coating seeds with micronutrient fertilizers ensures seedling establishment by providing micronutrients during early growth stages when plants are most susceptible to deficiencies.
Integrated Nutrient Management
- Balanced use of organic manures, biofertilizers along with reduced chemical fertilizers helps maintain micronutrient levels in soils without disturbing the soil biological and chemical properties.
planting micronutrient-responsive crop varieties
- Adopting new high yielding crop cultivars which respond better to applied micronutrients brings yield gains.
Thus, following an integrated approach addressing both soil and foliar needs is most effective for correcting micronutrient deficiencies and realizing higher agricultural productivity. Periodic soil testing helps monitor micronutrient status and decide fertilization needs.
Increasing fertilizer use targeting macronutrients alone has led to emerging micronutrient deficiency issues. Micronutrients are just as important for plant metabolic processes and deficiency of even one element impacts crop yields. An integrated soil-plant tissue test based micronutrient management helps tackle the hidden hunger and sustain agricultural production. Widespread micronutrient deficiency correction holds immense potential to boost global food security.
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