Experiments on correcting iron deficiency in plants

Abstract

Several approaches to correcting iron deficiency by soil application were studied. Application of chelating agents in simulated drip irrigation, application of sulfuric acid, of organic iron amendments, of crystaline iron ‐ H₂SO₄ products, and sulfur all have been subjected to experimentation. Most important results include that application via drip irrigation can greatly decrease the quantity of metal chelates needed to correct micronutrient deficiencies, FeDTPA will work on calcareous soils only if the soil is very sandy and if the soil pH is near 7, that zone acidification or zone application of iron amendments in which only part of the root system is adequately supplied with iron will provide a means of both correction of iron deficiency and preventing it for several years in perennial plants, that some H₂SO₄ to cause soil acidification will increase effectiveness of sulfur as a soil acidifier, that organic‐iron amendments placed in the root zone can provide protection to plants against iron deficiency, and that simple foliar iron sprays may be more effective than those containing other micro‐nutrients. Some of these procedures can be used to control iron deficiency in field crops. Ferric ammonium citrate poses some advantages for tree injection to correct iron deficiency in large trees. Practical control measures for line‐induced chlorosis are possible even though there was considerable past discouragement.

Key words:

• Jarosite
• chelate
• sulfur
• foliar spray
• tree injection
• organic iron wastes