What is it and how does it differ from soil analysis?
Foliar diagnostics is a laboratory method for determining the concentration of nutrients within plant tissues, mainly leaves. Unlike soil analysis which provides information on the availability of elements in the soil, foliar diagnostics shows us which elements were ultimately absorbed by the plant, i.e. its true nutritional status.
When is it applied and what is its value?
Leaf diagnostics is performed during the growing season, when the plant is in an active growth phase. The information it provides is useful for:
-Evaluation of the effectiveness of the fertilization program.
-Early detection of malnutrition, before symptoms appear.
-Planning corrective interventions, mainly through foliar application or fertigation.
-Improvement of quality performance, such as protein or oil content.
Practical application
In cotton, low fruit set may be related to boron or zinc deficiency. Foliar diagnostics at the beginning of flowering allows targeted correction through foliar fertilization.
In rice, low Zn values are associated with chlorosis and reduced growth.
In olive trees, B deficiency before flowering leads to reduced production. Early diagnosis allows for preventive reinforcement.
Proper sampling
For reliable results it is required:
-Select healthy plants, without severe symptoms or environmental stress.
-Harvesting leaves of a specified age, depending on the crop (e.g. 6th node in cotton, newly mature leaves in olive).
-Taking a sample at the appropriate stage of development.
-Avoid taking photos from extreme areas of the field (e.g. edges, under trees, near roads).
Other factors affecting nutrition
Soil pH: high pH limits the absorption of Zn, Mn, etc.
Water availability and irrigation conditions.
Cultivation practices: e.g. overfertilization with nitrogen can reduce K uptake.
Element interactions: e.g. excess P can reduce Zn absorption.
Conclusion
Leaf diagnostics is a precision agriculture tool and not an optional analysis. It provides a documented picture of the nutritional status, allowing the agronomist to formulate a targeted, efficient and economically optimal fertilization program. Especially in intensive crops or in fields with a history of nutritional problems, its systematic application contributes decisively to improving productivity and quality.
