Iron is an important micronutrient needed in small quantities by all plants. Many vital processes such as the production of chlorophyll and nitrogen fixation depends on iron. Iron deficiency is among the most widespread nutritional deficiencies.
Iron is largely sufficient in most soil; however, its availability varies with soil conditions throughout the year and on the plants themselves. Moreover, iron becomes unabsorbable when the soil is not acidic enough.
Because iron chlorosis appears mainly in crops grown on calcareous soil, it is often called lime-induced chlorosis.
Iron is considered as an immobile micro-element, meaning that signs of iron deficiency first manifest during the stage of new growth. The main symptom will be Inter-venial chlorosis of new leaves, which means that the tissue between the veins turns yellow in color, while the veins remain green.
Adding Iron: An effective iron fertilizer for correcting iron chlorosis is FeEDDHA (ethylenediamine-di-o-hydroxy-pheny lacetic acid), known as Sequestrene 138 and works best when applied to the roots via an irrigation system. Sequestered iron is available to plants without adjusting the soil’s pH, which is not the case with iron sulfate – another compound that is used to treat iron deficiency.
Avoid over-watering since it washes out nutrients more quickly.
Lowering pH: Besides adding iron, it is possible to acidify the soil. Sulfur, urea and organic matter, such as manure and compost, are known to help reduce soil pH.
Acidification using elemental sulfur is the quickest way to lower soil pH and is more effective when implemented into the soil than deposited on the ground surface. Beware that sulfur can also reduce soil pH to a dangerous level. While some plants function well in slightly acidic soil (pH 6.0-6.5), levels below 6 may cause damage to plants.
*Names marked in red are considered to be highly poisonous to beneficial insects.
*Names marked in green are considered to be organic and IPM (integrated pest management) compatible.