Liquid Fertilizer Iron Solubility via pH Buffering

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Solution Overview

Problem

Formulating fertilizer compositions that include both slow-release nitrogen-containing fertilizers and iron is challenging, especially for turfgrass, due to the differing pH requirements of these components, which can lead to precipitation issues.

Innovation Solution

A liquid fertilizer composition that includes a slow-release nitrogen-containing fertilizer and iron chelated to an aminopolycarboxylic acid or a polycarboxylic acid, such as EDTA or DTPA, is developed to address the pH compatibility and precipitation issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If slow-release nitrogen-containing fertilizer is included in the fertilizer composition, then nitrogen release is controlled and prolonged, but iron solubility is reduced due to pH incompatibility

Engineering Contradiction:
Improvenitrogen release durationVSAvoidiron solubility
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

A pH buffer system is introduced as an intermediary component to mediate between the slow-release nitrogen fertilizer (which tends to raise pH) and the iron chelate (which requires low pH for solubility). The buffer maintains pH within the optimal range of 5.0-7.0, preventing iron precipitation while allowing slow-release nitrogen functionality. This resolves the contradiction by adding a third component that balances the conflicting chemical requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The fertilizer composition is formulated as a composite system containing multiple components: slow-release nitrogen fertilizer, iron chelate, and pH buffer agents. This composite approach allows each component to fulfill its specific function while the overall formulation maintains compatibility among all components. The composite structure enables simultaneous achievement of controlled nitrogen release and iron solubility through synergistic interaction of ingredients.

Inventive Principle:
Principle #40Composite materials

2Productivity

If iron is added to the fertilizer composition, then turfgrass greening is enhanced, but precipitation issues occur due to pH incompatibility with slow-release nitrogen fertilizer

Engineering Contradiction:
Improvegreening speedVSAvoidsolution stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The pH buffer acts as an intermediary that stabilizes the solution by maintaining pH within the optimal range for iron solubility. This prevents precipitation of iron hydroxides that would otherwise occur when slow-release nitrogen fertilizer raises the pH. The buffer ensures long-term compositional stability while preserving the greening-enhancing effects of iron.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The pH of the fertilizer composition is explicitly controlled and maintained within the parameter range of 5.0-7.0 through the addition of buffer agents. This parameter control prevents iron precipitation while allowing the iron chelate to remain soluble and bioavailable. By changing and controlling the pH parameter, both iron stability and slow-release nitrogen functionality are achieved simultaneously.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional fertilizer formulation is used, then manufacturing is simplified, but formulation difficulty increases when both slow-release nitrogen and iron are required

Engineering Contradiction:
Improveformulation simplicityVSAvoidformulation complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

By establishing specific pH parameter ranges (5.0-7.0) and incorporating standard buffer agents, the formulation process becomes more systematic and less trial-and-error based. This parameter-based approach simplifies manufacturing by providing clear guidelines for formulation, reducing the complexity that would otherwise arise from balancing conflicting chemical requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The use of a composite formulation with defined components (slow-release nitrogen fertilizer, iron chelate, and pH buffer agents) creates a standardized system that can be manufactured consistently. This composite approach, while adding components, actually simplifies the overall formulation process by providing a proven framework for compatibility, reducing the need for complex customization in each manufacturing batch.

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composition effectively provides both slow and rapid nitrogen release and maintains iron solubility, resulting in rapid greening of turfgrass within 3 days or less, as measured by the dark green color index (DGCI) value.

Implementation Method 1

iron chelated to an aminopolycarboxylic acid or a polycarboxylic acid

Methodology Applied
Scientific EffectChelation:

Data Source

PatentEP3426624B1Iron-supplemented fertilizer
Publication Date: 2025.05.07 OMS INVESTMENTS INC

AI summary

Compositions of a slow-release nitrogen-containing fertilizer and iron chelated to an aminopolycarboxylic acid or a polycarboxylic acid. The composition can be useful as a fertilizer for rapid greening of turfgrass.