Iron chlorosis is probably the most widely occurring micronutrient problem in Nebraska. It commonly occurs in trees, shrubs, vines, field crops, flowers, grasses, and vegetables. Field crops most susceptible to iron chlorosis are sorghum, field beans, and soybeans. Corn and alfalfa are more tolerant. However, under high pH soils with excess lime, iron deficiency in corn can reduce yields. Research underway at the West Central Research and Extension Center has shown that some corn hybrids are more tolerant than others. Research results with iron sulfate have shown yield increases for both tolerant and susceptible varieties.
Iron in the Plant
Iron is a catalyst in the production of chlorophyll, the green pigment in plants. Iron-deficient plants are yellow or “chlorotic” (lack chlorophyll). The veins of the leaves are green, but the tissue between the veins is yellow.
Iron chlorosis is commonly associated with high lime soils in western Nebraska and some bottomland soils in central and eastern Nebraska. Soybeans in the Platte and Elkhorn valleys often are chlorotic, which is due, in part, to high pH, excess lime, salts, sodium, compaction, or excess soil water.
Iron in the Soil
Most Nebraska soils probably contain adequate amounts of iron for plant growth; however, other factors may restrict a plant’s absorption and/or utilization of iron. To date, a soil test for iron has not been helpful in identifying soils where chlorosis is likely to occur. Also, soil application of iron for field crop production is generally not economical. Soil management to provide adequate drainage, aeration and crop selection is probably the best method of preventing iron chlorosis. Variety selection, particularly with soybeans, can overcome problems with chlorosis in many soils. Recent field studies have identified soybean varieties tolerant to chlorosis. The article, 'Soybean,' from Nutrient Management for Agronomic Crops in Nebraska, discusses soybean varieties and other management practices.