Iron deficiency chlorosis is a major nutritional problem affecting cultivated plants in calcareous soils characterized by yellowing of young leaves. In sensitive plants, severe Fe deficiency results in high economic losses, particularly in perennial crops. Efficient Fe chlorosis control involves the use of expensive Fe-chelates, being its use restricted to high profitable crops. The application of Fe salts (ferrous sulphate) to soil is cheaper, but not so efficient controlling this problem due of its rapid oxidation, and foliar application has a low residual effect. Vivianite (ferrous phosphate) has been revealed as an economic and effective method to control Fe chlorosis, even valid for not so profitable crops such as olive trees. Organic matter has a significant role in metal dynamics in soils (complexation) which may accounts for changes in nutrient and pollutant availability for plants. Iron-humates can increase Fe availability for plants. The main objective of this research is to study the effect of an organic residue of sugar industry (vinasse) to increase the effect to iron salts (ferrous sulphate and vivianite) controlling iron chlorosis. A completely randomized experiment was performed using calcareous sand as growing media and involving two factors: dialyzed sugar-beet vinasse and Fe source. Dialyzed sugar-beet vinasse were applied at 0, 0.1, 0.4, and 1 g of organic C kg-1 growing media. Iron sources were: No Fe, Fe chelate (EDDHA-Fe, applied in nutrient solution, 10 micromolar), FeSO4•7H2O and vivianite at a rate equivalent to 0.36 g Fe kg-1 growing media. After three weeks of growing, vivianite and EDDHA-Fe yielded the higher dry matter production in aerial part. On average, no significant differences between growing media without Fe application and with ferrous sulphate were observed in dry matter production. The higher chlorophyll content after three weeks estimated by using a chlorophyll metter (SPAD) corresponded to EDDHA-Fe, being vivianite significantly more effective increasing chlorophyll content than ferrous sulphate. Organic matter applied as vinasse had a significant effect increasing dry matter in aerial part and SPAD readings after one and two weeks of growing. No significant differences for different vinasse rates were observed for SPAD readings at three weeks. Vinasse significantly increased the effect of ferrous sulphate increasing SPAD readings. No significant differences in SPAD readings after three weeks between EDDHA-Fe application and the combination of vivianite and vinasse at a rate of 0.4 g C kg-1 were observed. It can be concluded that the application of organic matter as vinasse can be effective increasing the effect of ferrous salts to control Fe chlorosis. Reasons for this effect can be ascribed not only to Fe complexation but also to a decrease in the crystallinity of Fe oxides formed from salts applied.