by Understanding Micronutrients
Micronutrients, also known as trace elements, are chemical elements required in small quantities for proper plant growth. In comparison to macronutrients like nitrogen, phosphorus, and potassium, plants need micronutrients in minute amounts. However, they are equally important for various metabolic activities in plants. The micronutrients essential for plant growth include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn). Deficiency or toxicity of these micronutrients can negatively impact crop yield and quality.
Role of Micronutrients
Each Micronutrients Fertilizers plays a vital physiological role in plant growth. For example, boron is important for sugar translocation, flowering, and seed production. Chlorine aids in osmoregulation and photosynthesis. Copper acts as a cofactor for various enzymes involved in photosynthesis, respiration, and iron mobilization. Iron is a component of chlorophyll and various oxidation-reduction enzymes. Manganese participates in photosynthesis and activation of several enzymes. Molybdenum acts as a cofactor for nitrogen fixation and nitrate assimilation. Nickel supports ureide metabolism in legumes. Zinc plays a role in various enzymatic reactions and protein synthesis. Therefore, maintaining adequate micronutrient levels in soil is necessary for optimum crop productivity.
Micronutrient Deficiency Issues
The deficiency of micronutrients is a widespread problem affecting crop yield worldwide. Some key reasons for micronutrient deficiencies include exhaustive cropping, imbalance in soil pH, high phosphorus application, intensive leaching due to rains, and nutrient antagonism. Marginal soil properties like high or low pH could induce deficiencies by affecting micronutrient availability. For instance, zinc deficiency is common in alkali soils due to reduced solubility and uptake at high pH levels. Similarly, copper fixation occurs in acidic soils. Excessive use of nitrogen and phosphorus fertilizers also affects micronutrient availability.
Practices to Address Deficiencies
Various agronomic practices can be employed to address micronutrient deficiencies in crops. Soil application of micronutrient fertilizers is a direct way to improve their availability. Foliar sprays of water-soluble fertilizers are useful for quick corrections. Integrated nutrient management through organic and inorganic sources supplies micronutrients in a balanced manner. Liming acidic soils raises pH to optimal levels for micronutrient availability. Application of ammonium-based nitrogen fertilizers enhances zinc solubility compared to nitrates. Crop rotation with legumes helps restore depleted micronutrients in soil. Selection of genotypes tolerant to deficiencies also minimizes yield losses. Guidelines provided by soil testing help determine the kind and quantity of micronutrients required.
Micronutrient Fertilizer Formulations
To overcome deficiencies, fertilizer companies offer different formulations of micronutrients suitable for soil and foliar applications. Some common examples include:
– Borax or sodium borate supplies boron. It is typically applied at 5-10 kg/ha.
– Zinc sulphate or zinc oxide are commonly used zinc sources. The dosage ranges from 25-50 kg/ha depending on soil zinc status.
– Copper sulphate is a widely adopted copper fertilizer applied at rates of 5-25 kg/ha.
– Manganese sulphate and manganese oxide serve as sources of manganese in fertilizers, applied at 10-20 kg/ha.
– Sodium molybdate supplies molybdenum at 0.5-1 kg/ha.
– Chelated micronutrients like EDTA complexes of zinc and copper facilitate efficient plant uptake.
These fertilizers are broadcasted before sowing or applied as foliar sprays for fast recovery from deficiencies during the crop growth period. Choice depends on solubility, crop requirement, and extent of deficiency.
Case Studies of Micronutrient Responses
Research from various regions demonstrates significant crop yield increases in response to micronutrient application.
In India, application of zinc sulphate @ 25 kg/ha increased rice yields by 12-15% in deficient soils of Bihar. Similarly, 15 kg copper/ha raised wheat yields by 13-18% in deficient soils of Uttar Pradesh.
Studies in Indonesia reported 6-8% higher oil palm fresh fruit bunch yields due to foliar spray of magnesium sulphate and manganese sulphate.
Research from Pakistan found 11-22% and 9-16% increases in maize grain and fodder yields respectively due to foliar application of zinc sulphate.
These case studies substantiate the effectiveness of different micronutrient fertilizers in resolving deficiencies and boosting crop production worldwide. Close monitoring of soil health and nutrient requirements aids in making prudent fertilizer recommendations.
Micronutrients assume great significance as yield-boosting inputs especially on soils deficient in these elements. Judicious application of appropriate fertilizer formulations guides sustainable intensification of crop production globally.
