The Investigation of slag effects as an iron fertilizer on corn growth and nutrients uptake

Nowadays some industrial by-products are used for amending and increase in some nutrients of soils. One of these by-products is steelmaking slag that has calcareous property. In this study, the possibility of using this compound as an iron fertilizer in calcareous soils and its effects on maize growth has been investigated. Applied slag contains 16.8% iron oxides, 52.8% calcium oxide and also some amounts of P, Si and Mn oxides. At first phase, for an incubation experiment, three calcareous soils from 0-30 cm depths in Isfahan province were sampled. Treatments include 0, 2, 4, 8 and 16 % (w/w) of slag/kg soil. Several treatments consisting of elemental sulphur and organic matter (alfalfa powder) with and without slag were also examined. The slag was thoroughly mixed with 500g soil in plastic pots. Soils moisture content was adjusted about field capacity and changes in pH, EC and AB-DTPA-extractable Fe were determined at 1, 10, 30 and 60 days. Results showed that soil pH increased with increase in slag rates. Slag application increased available Fe; the increases were proportional to the amount of slag used. At the second phase, regarding Isfahan soils map with the view of iron critical concentration, two regions were sampled. Treatments include 0, 0.5 and 1% slag (w/w)/kg soil, 1% slag with 2% Organic matter (alfalfa powder) and Fe-EDDHA (5 mg Fe/kg). Corn variety single cross 647 was planted as the test plant. After 50 days, plant dry matter and Fe, Mn, P, Zn and K uptake by plant were measured. Results showed that slag increased Fe uptake by plant and disappeared iron chlorosis. Uptakes of P, Mn and K by plant were increased. The effect of slag on disappearing iron chlorosis and iron uptake by plant was higher than Fe-EDDHA application. Regarding the derived results, converter slag can be used as an iron fertilizer.