Defining the State of Reduction of a Paddy Soil

Summary The empirical terms ‘oxidizing conditions’, ‘healthy reducing conditions’, and ‘extreme reducing conditions’ as they are applied to paddy soils are discussed. The expression r Eh = E h + 0.180 pH is used to define these conditions more precisely, on the assumption that the presence of ferrous and ferric iron is necessary for healthy reducing conditions for rice. The concept may be useful in both well‐established and newly developing rice‐growing areas.