Abstract:
Peanut (Arachis hypogea cv. Shulamit) grown on very high calcium carbonate (CaCO3) content soils is showing iron (Fe) chlorosis symptoms. Supplying the plant with ammonium sulphate ((NH4)2SO4) in the presence of nitrapyrin (N-Serv) for preventing nitrification reduced Fe chlorosis. Nitrate (NO3) developed in the soil with time, even with nitrapyrin present. When ammonium (NH4) was even less than 20% of the total mineral N in the soil, no Fe-stress could be observed, suggesting that the NH4 uptake by the plant and the consequence of hydrogen (H+) efflux occurs from the root to the rhizosphere, resulting in a decrease of redox potential near the root, and solubilizing enough Fe near the root to overcome the chlorosis. © 1985, Taylor & Francis Group, LLC. All rights reserved.