Magnesium Fertilizers

All plants need magnesium (Mg). Essential for chlorophyll production, magnesium enables plants to harness the sun’s energy through photosynthesis, fueling their growth and development. Beyond this, it plays a crucial role in nutrient uptake, energy transfer, and stress tolerance, influencing everything from yield to resilience. In the context of modern agriculture, where maximizing efficiency and crop performance is paramount, understanding and optimizing magnesium levels can lead to remarkable improvements in both crop quality and quantity. Under optimum growing conditions, plants absorb magnesium from the soil. But magnesium availability can be hampered due to leaching, especially in sandy soils, or because of environmental conditions such as wet, cold, or an acidic root environment. An imbalance of nutrients in the soil, including high levels of potassium, calcium, or ammonia, can also restrict magnesium uptake by plants. Let’s explore why magnesium is so crucial for plant health, how it impacts crop productivity, and best practices for ensuring your plants receive this essential nutrient.

Central to Chlorophyll Production: Magnesium is a key component of chlorophyll, the green pigment in plants that enables photosynthesis by capturing sunlight and converting it into energy. As the central atom in the chlorophyll molecule, magnesium makes up about 6.7% of each chlorophyll molecule. Beyond its role in photosynthesis, magnesium is vital for activating enzymes involved in respiration, photosynthesis, and nucleic acid synthesis, all of which are essential for plant growth and development.
Facilitates Energy Transfer: It plays a crucial role in the transfer of energy within the plant, which is vital for growth and development.
Enhances Nutrient Uptake: Magnesium aids in the efficient uptake of other essential nutrients, ensuring balanced nutrition for optimal plant health. It aids in phosphate metabolism, serving as a carrier of phosphate compounds throughout the plant.
Supports Translocation: It helps in the transportation of sugars from the plant’s source (leaves) to the sink (roots and fruits), impacting crop yield and quality. Magnesium facilitates the translocation of carbohydrates (sugars and starches), enhances the production of oils and fats, and is necessary for cell division and growth.
Boosts Stress Tolerance: Magnesium contributes to a plant’s resilience against environmental stresses, improving overall plant health and productivity.
Prevents Deficiency Issues: Adequate magnesium levels are crucial, as deficiencies can severely impair plant health, reducing both yield and quality.

Application Methods and Timing

Soil Applications: Most magnesium fertilizers are incorporated into the soil before planting to ensure they are available to the crop as it grows. Polysulphate is recommended as an alternative or complementary solution to dolomitic lime, magnesium sulfate and magnesium oxide. As a gradually releasing, natural source of sulfate-based sulfur, magnesium, calcium and low-chloride potassium, Polysulphate can reduce potential loss of Mg to leaching, while increasing Mg uptake. Soil applications are usually done several weeks to months prior to planting to allow the magnesium to become available in the soil.
- Explore how Polysulphate can improve nutrient use efficiency when compared potassium magnesium sulfate (SOPM) as a magnesium source.
Foliar and Fertigation Applications: Magnesium can be applied directly to plant leaves or integrated into irrigation applications during the growing season. Foliar sprays are often used for quick correction of magnesium deficiencies, especially when visual symptoms appear or soil tests indicate a shortfall. Nova Magnific 11-0-0+9.3Mg, Nova MagPhos 0-55-18+4.21Mg, Nova FLOW (5-10-20 +9Mg) and Agrolution pHLow High K 15-11-31 +Mg +micros are reliable, water-soluble solutions rich in magnesium ideal for foliar or fertigation applications.
Integrated Approaches: In many cases, a combination of soil amendments, fertigation and foliar applications may be used to ensure both immediate and long-term magnesium needs are met.

Proper timing and application method depend on factors such as the specific crop, soil conditions, and the severity of magnesium deficiency. Regular soil and tissue testing help determine the most effective magnesium fertilization strategy for optimal crop performance.

Magnesium-deficient plants show interveinal chlorosis (dark green veins with yellow areas between them) on their older leaves. These yellowed or chlorotic leaves develop spotted areas of dead tissue and the leaf edges curl. Since magnesium is mobile in the plant, the lower or older leaves are always affected first. Learn more about Magnesium (Mg) deficiency.