Micronutrients including iron, manganese, zinc and copper serve critical functions in plant growth and development. Deficiencies in any of these can hinder growth and yields. In high pH soils, these nutrients readily become unavailable to plant roots due to chemical reactions that cause precipitation and binding to soil particles. Chelated micronutrient fertilizers provide the solution.
What Are Chelated Micronutrients and How Do They Work?
Chelated micronutrients have the minerals encased within organic chelating agents such as EDTA or EDDHA. These agents bind to and hold the micronutrient ions in a stable structure, preventing them from being bound up as insoluble hydroxides and oxides in alkaline soils. The plant-available chelated form remains soluble and mobile in the soil solution longer.
The key benefit of chelation is it allows micronutrients to remain soluble, plant-accessible, and actively mobile within the plant for longer periods. This efficient delivery system prevents deficiencies and maintains optimal nutrition. Chelated micronutrients represent an important tool for crops grown in unideal conditions where availability would otherwise be reduced. The chelating agents boost nutrient uptake and utilization.
Specific Benefits of Chelated Micronutrient Fertilizers
- Increased Micronutrient Absorption: Chelates have higher solubility and mobility for greater plant uptake and translocation to deficient areas.
- Improved Correction of Deficiencies: EDTA-chelated manganese foliar sprays can correct manganese deficiency in under 3 weeks based on University of Florida research.
- Higher Yield Potential: Field studies show chelated zinc increased corn yields by 16 bushels per acre compared to unchelated zinc applications.
- Lower Input Rates: Chelated micronutrients have up to 5-6 times higher efficiency, allowing lower application rates.
The key differences between EDTA, EDDHA, DTPA, and IDHA
EDTA (ethylene diamine tetraacetic acid)
- Most widely used and cost-effective chelate
- Works well in moderately alkaline soils up to pH 7.5
- Not stable in soils above pH 7.7
- Used for iron, zinc, copper, manganese, etc.
- Suitable for foliar and soil application
EDDHA (ethylene diamine-N,N′-bis)
- Most stable chelate, especially o,o-EDDHA
- Effective in soils with pH above 8.0
- Used for iron uptake in alkaline soils
- Prevents and corrects iron chlorosis
- Mainly used in soil applications
DTPA (diethylenetriaminepentaacetic acid)
- Moderately stable chelate
- Most useful in soils with pH between 7.5-8.0
- Often used for zinc, iron and manganese
- Lower cost alternative to EDDHA in marginal soils
IDHA (isopropylidenediamine diacetic acid)
- Newer chelate gaining use
- Stability between EDTA and EDDHA
- Used for iron, manganese or zinc uptake
- Promising for high pH soils and foliar use
- Being tested as alternative to EDDHA
- Biodegradable
In summary, EDTA works for moderately alkaline soils, EDDHA is the premium chelate for high pH conditions, DTPA offers an intermediate option, and IDHA is an emerging next-generation chelate still under development.
Get More from Your Fertilizer with Chelated Micronutrients
While nitrogen, phosphorus and potassium are considered macronutrients needed in relatively large amounts, micronutrients such as iron, manganese, zinc, copper and boron are required in much lower concentrations by plants. However, deficiencies in these essential micronutrients can significantly reduce yields and crop quality.
The issue is that micronutrients become unavailable to plant root uptake in alkaline soils, leading to deficiencies. This is where chelated micronutrient fertilizers make a big difference. Because the chelated micronutrients stay dissolved in the soil solution longer, plants have increased opportunity for absorption through roots and leaves. Chelates also facilitate mobility within the plant, leading to more efficient distribution and use of the nutrients.
By preventing micronutrient deficiencies, chelated fertilizers optimize plant nutrition and unlock the genetic potential of crops. Adequate micronutrient nutrition results in improved plant vigor, increased yields, better fruit quality, and higher profitability per acre. Chelated micronutrient fertilizers deliver an excellent return on investment for all growers, especially those dealing with alkaline soils. When it comes to plant nutrition, chelated micronutrients are a key tool for maximizing productivity.