Plants in arid areas often suffer from iron deficiency. In most cases, low iron-solubility due to high soil pH values is responsible for this phenomenon but not low iron concentrations of the parent material. The effectiveness of iron chelates is about five times higher than that of inorganic fertilizers, but the relative expenses compared to inorganic fertilizers are 30 to 70 times higher. Thus, commercially available organic iron fertilizers are effective to reduce iron deficiency, but on an economical basis, it is not always employable, especially in newly industrializing countries like the Iran, where iron deficiency is a big problem in the pistachio-cultivation. Therefore, the aim of our study was to optimise the effectiveness of inorganic iron fertilizers by enhancement with amply existing natural organic substances. For this purpose, hornbeam-leaves and outer rice-husks were incubated with increasing quantities of iron-sulphate and plant-available and total iron measured. Additionally, we examined, whether the iron-fertilizer-effect can be increased by addition of charcoal. Our study shows that hornbeam-leaves plus 6.4% iron-sulphate and outer rice-husks plus 5% iron-sulphate yield the best expenses-benefit-relationship. The iron-availability to plants of rotting hornbeam-leaves could be increased by factors of 14 (6.4% FeSO₄) and 24 (64% FeSO₄ plus 5% char), while the excellent iron-availability of outer rice-husks (85%) could not be further increased. With respect to both ecological and economic benefits, the best iron-organic fertilizers can be obtained using hornbeam-leaves plus 6.4% FeSO₄ and outer rice-husks plus 5% FeSO₄. In both cases an organic iron fertilizer with 0.6% plant-available iron can be obtained.