The role of micronutrients in crop nutrition
Micronutrients, while required in small quantities, play a crucial role in crop nutrition and overall plant health.
For both arable and livestock farmers, understanding how these nutrients impact soil fertility and crop performance is essential for achieving high quality yields.
What’s more, integrating micronutrient management with a nitrogen-based fertiliser strategy creates a powerful combination that enhances crop resilience and boosts productivity.
What are micronutrients and why do they matter?
Micronutrients include elements such as zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), boron (B), and molybdenum (Mo).
Each has a unique function in plant growth, from enzyme activation and chlorophyll production to improving disease resistance and stress tolerance.
- Zinc aids in hormone production and growth regulation
- Boron is vital for cell wall formation and pollen tube growth
- Iron supports chlorophyll synthesis, essential for photosynthesis
- Manganese plays a key role in photosynthesis and nitrogen metabolism
- Molybdenum is crucial for ensuring efficient nitrogen use
A deficiency in any of these can result in stunted growth, poor crop quality, and reduced resilience to environmental stresses. For livestock farmers, deficiencies in micronutrients in forage crops can lead to imbalances in the diet, ultimately affecting animal health and performance.
Diagnosing micronutrient deficiencies
Regular monitoring of micronutrient levels is essential to help identify potential deficiencies or imbalances, allowing for timely corrective actions.
Accurate diagnosis requires a multifaceted approach that combines soil testing, tissue testing, and field observations.
1. Soil testing
AHDB recommends conducting a thorough farm soil analysis every three to five years to assess nutrient status, including micronutrients.
Soil tests reveal the levels of essential micronutrients and highlight factors that may limit their availability, such as pH imbalances, soil compaction, or low organic matter content.
- pH and micronutrient availability: Micronutrients, like iron, manganese, and zinc become less available in high-pH (alkaline) soils, while molybdenum becomes deficient in acidic soils. Adjusting soil pH through lime or sulphur applications can improve micronutrient accessibility.
- Cation exchange capacity (CEC): Soils with low CEC may struggle to retain micronutrients, making them more prone to leaching, especially in sandy soils.
- Testing depth: Take soil samples at multiple depths, especially in min-till systems, to assess potential nutrient stratification (when nutrient distribution is uneven within the soil profile).
2. Tissue testing
Plant tissue testing offers a more immediate snapshot of nutrient uptake and plant health than soil testing alone.
It can uncover deficiencies that might be too early to appear in soil tests or are masked by other nutrient interactions.
- Timing: Conduct tissue sampling during critical growth stages, such as tillering in cereals or flowering in oilseeds, when demand for micronutrients is highest.
- Interpretation: Tissue nutrient concentrations should be compared against established critical levels for specific crops. For example:
- Zinc: Deficient levels are often <15ppm in wheat leaves.
- Manganese: Levels below 20ppm can indicate a problem in cereals.
- Follow-up actions: Tissue tests can guide immediate corrective measures, such as foliar micronutrient applications.
3. Visual inspections
Field observations provide the first line of defence in identifying micronutrient deficiencies.
Certain symptoms are characteristic of specific nutrient shortages:
- Zinc deficiency: Often causes stunted growth and interveinal chlorosis on younger leaves. In maize, white striping on leaves is a telltale sign.
- Boron deficiency: Symptoms include brittle stems, cracked tissues, and hollow or deformed fruits. It is especially problematic in oilseed rape and legumes.
- Manganese deficiency: Shows as interveinal chlorosis, particularly in young leaves of cereals. The leaves may also appear mottled.
- Molybdenum deficiency: Presents as stunted plants with distorted leaves, especially in brassicas, where ‘whiptail’ is a common symptom.
Nitrogen-based fertilisers and micronutrient uptake
Nitrogen drives vegetative growth and high yields, and pairing it with strategic micronutrient management enhances nutrient uptake and overall crop performance.
Using a nitrogen-based fertiliser such as OCI Nutramon can help bolster micronutrient availability in several ways:
- Enhanced root growth:
Nutramon provides readily available nitrogen, promoting robust root development. A healthy root system improves the plant’s ability to access micronutrients like zinc, manganese, and iron from the soil.
- Improved micronutrient solubility:
The calcium ammonium nitrate in Nutramon helps maintain a balanced pH in the root zone. This is particularly beneficial for micronutrients like manganese and zinc, which are more soluble and accessible to plants in slightly acidic conditions.
- Consistent nutrient delivery:
Nutramon ensures a steady release of nitrogen throughout the growing season, supporting continuous nutrient uptake. This consistency aligns with the micronutrient demand curve of crops, reducing the risk of temporary deficiencies during critical growth stages.
- Compatibility with micronutrient additives:
Nutramon can be applied alongside micronutrient blends or foliar sprays to address specific deficiencies, making it a versatile choice for arable and forage crops.
For example, in cereal crops, like wheat or barley, combining Nutramon with targeted foliar applications of manganese or zinc can prevent deficiencies that might limit growth or reduce yield.
Similarly, livestock farmers can use Nutramon to improve the nutrient profile of pasture and forage crops, enhancing their feed value.
By far the highest nitrogen efficiency
Nutramon’s 50/50 ratio of nitrate nitrogen and ammoniacal nitrogen guarantees fast and long-lasting nitrogen action in the crop.
This is because nitrogen losses to the soil are reduced and there are no losses to the air.
As a result, Nutramon boasts the highest nitrogen efficiency when compared with other types of nitrogen fertilisers.