Enhancing Plant Nutrition: Chelated Iron Micronutrients for Agricultural Sustainability

Importance of Iron in Agriculture

Iron is an essential micronutrient required by plants for healthy growth and development. It plays a vital role in important biological processes like photosynthesis, nitrogen fixation and oxygen transport within the plant system. However, iron deficiency often occurs in soils due to various factors like high pH, waterlogging, presence of lime etc which affects its availability to crops. This leads to iron chlorosis in plants characterized by yellowing of leaves even when other nutrients are sufficient. It is one of the most widespread nutritional disorders faced by farmers worldwide causing significant losses. Application of chelated iron helps overcome this issue and ensures optimum iron uptake by crops.

Chelated Iron - An Effective Solution

Chelated iron is a type of iron that is bound to organic acids or amines which keeps it soluble and available to plants. The metal ion is trapped inside a cage formed by the chelating agent which protects it from reactions with soil or water and favors its absorption by roots. Common chelating ligands used are ethylenediaminetetraacetic acid (EDTA), lignosulphonates, hydroxamates etc. This chelated form of iron is readily taken up through root permeation as it isn't affected by soil pH, phosphate or lime content unlike inorganic iron salts. It remains stable in the soil for extended periods and doesn't precipitate, allowing sustained iron supply to crops.

Forms of Chelated Iron products

Chelated iron products are available in both dry and liquid formulations catering to varied application needs:

- Chelated iron Agricultural Micronutrient such as iron EDDHA, iron EDTA etc are water soluble powders easy to blend with NPK fertilizers for uniform spreading in fields. They have extended shelf life and suit foliar as well as soil applications.

- Liquid chelated iron concentrates including iron lignosulphonate, iron HEDTA solutions are diluted with water before spraying. They dry rapidly on leaf surfaces and penetrate rapidly into plants. Various analysis percentages ranging from 6-15% iron content are commercially available.

- Micro granules containing chelated iron provide controlled release over months with each irrigation/rainfall. They uniformly cover large acreage and don't require frequent applications.

- Seed treatment with liquid chelated iron ensures iron nutrition from early seedling establishment stage itself. This boosts germination and yields better plant stands.

Effective Routes of Application

Foliar spray: Chelated iron spray effectively corrects iron deficiency in plants when applied as foliage fertilizer. Being readily absorbed through leaves, it produces quick greening effect within 1-2 weeks. Multiple thin cover sprays are recommended with an interval of 10-15 days.

Soil application: Broadcasting dry chelated iron products or drenching liquid formulations in soil supplements root zone iron reserves . This sustains crop nutrition throughout the growth cycle. Being non-phytotoxic, high doses can be safely applied.

Seed treatment: Soaking seeds in diluted chelated iron solution before sowing furnishes iron to nascent seedlings from first leaf stages itself. This aids healthy crop establishment.

Fertigation: Fertilizing crops with chelated iron through drip or sprinkler irrigation ensures continuous iron supply with each watering. Frequent light doses are more effective than heavy applications.

Foliar Spray - The Best Method

While all application methods are effective, foliar spray with chelated iron emerges as the method of choice for quick visibility and high absorption rates. Being a direct mode, it bypasses intricate soil factors hindering iron availability. Even highly calcareous soils respond well to foliar nutrition. The iron penetrates directly into leaf cells within hours of application. This is crucial in correcting visible iron chlorosis on standing crops in minimum time. Multiple thin cover sprays sustain the greening effect until harvest. Its widespread use by farmers across the world underlines efficacy as the premier iron application technique.

Role in Boosting Crop Yields

By overcoming iron deficiency, chelated iron significantly improves crop productivity and quality. Iron plays a vital role in chlorophyll synthesis controlling photosynthesis rates. Its adequate supply results in:

- Darker green healthy foliage
- Increased leaf area for maximal photosynthesis
- Enhanced tillering and plant growth
- Better flowering and pod/grain formation
- Heavier crops with superior grains
- Alleviation of iron chlorosis symptoms

Application on major field crops like cereals, pulses, vegetables, fruits, plantations have demonstrated 10-15% higher yields besides reduced morbidity. With expanding cultivation of high yielding varieties globally, use of chelated micronutrients will keep rising to support intensive cropping systems sustainably.

Effective Iron Nutrition Management

An ideal iron nutrition program should include:

- Soil testing to ascertain deficiencies and optimum fertilizer needs
- Application of chelated iron before onset of deficiency symptoms
- Foliar sprays during active growth periods for quick effects
- Seed/soil treatment for early nutrition of crops
- Tank mixing with major NPK fertilizers for uniform spreading
- Regular monitoring and additional foliar sprays if required
- Maintenance of ideal soil pH range by liming/gypsum application
- Crop rotation and inclusion of legumes to maintain soil iron levels