Rice is cultivated in soils with a wide range solution ionic strength ranging typically from 0.02 M to 0.16 M and redox conditions ranging typically from 700 to -300 mV . The stability of metal-siderophore complexes depend on the ionic strength, decreasing stability as ionic strength increases and causing consequently a significant shift of the pH at which complex formation starts . Moreover, depending on the Eh values, metals ions such as iron and copper change their oxidation state with subsequent effects on their selective coordination by PDMA. In paddy soils, large amounts of water are added during the cultivation season and identifying the role of ion strength and redox potential is critical when attempting to understand and predict the nutrient dynamic and metal/ligand stability. These master variables affect the distribution and the selectivity of PDMA for metal ions in the soil solution. The formation and abundance of metal-PDMA complexes is finally affected by metal concentration in soil which can greatly vary depending on soil parent material, soil texture and anthropogenic activities (particularly near the soil surface). This information is essential to predict the impact of fertilization treatment on rice cultivation. In the following section the effects of ionic strength, redox conditions, metal competition and soil pH, on [Zn(PDMA)] -complex formation are discussed.