Legumes, such as clover and lucerne, are especially sensitive to trace element imbalances. One of the most effective tools for understanding your legumes trace element status is herbage testing. Soil testing indicates what nutrients are potentially available, but it cannot show what the plant is taking up. Soil testing for trace elements is unreliable, except for Boron (B), and therefore, typically not included in a standard soil test. Elements, such as Molybdenum (Mo), Copper (Cu), B, Zinc (Zn), and Manganese (Mn), are needed in very small quantities but have a major impact on legume performance, Nitrogen (N) fixation, and overall pasture productivity.
Trace imbalances
Trace element deficiencies often limit legume growth long before visible symptoms appear. Herbage testing provides a direct measure of what nutrients the plant is actually absorbing at the time of sampling. Because clover develops deficiencies before grasses, clover-only testing is an excellent early indicator of nutrient problems, allowing farmers to detect hidden deficiencies before they affect production. Regular herbage testing helps refine fertiliser programmes to maintain the right balance of macro
and micronutrients for optimal legume performance.
Why it matters
Clover plays a vital role in supplying N to mixed pastures through biological fixation. Mo is essential for the rhizobia bacteria that fix N in root nodules. When Mo is low, nodules become pale and inactive, reducing N supply to both the legume and companion grasses. Similarly, Cu and B deficiencies restricts growth, flowering, and persistence — reducing feed quality and dry matter yield.
When herbage tests reveal trace element deficiencies, foliar fertiliser provides a fast and effective corrective option. Foliar products deliver nutrients directly through the leaf, bypassing soil limitations such as cold, dry, or high/low-pH conditions restricting root uptake.
Elements like Mo, Mn, or Zn respond particularly well to foliar application, giving an immediate boost to plant health while longer-term soil-based strategies take effect.
TECH TIPS
- If crops are showing signs of a nutrient deficiency, get the herbage tested. Depending on the deficiency, this can be corrected with a solid or foliar fertiliser.
- If water is limiting (drought) and plants are not growing, then N fertiliser will be of little benefit until the soil re-wets.
- If weather conditions are suitable, early summer N helps build covers going into the dry part of the summer.
Foliar nutrition should complement, not replace, a well-balanced soil fertiliser plan. Used alongside regular herbage testing of clover and lucerne — farmers get a precise, responsive way to sustain N fixation, improve trace element management, and keep legume and pasture systems performing at their best.
