Deficiencies of zinc, manganese and iron are common in calcareous soils of arid and semiarid regions due to their reduced solubility alkaline conditions. However, sustainable crop production is essential for growing population. Sulfur fertilizers can increase micronutrients availability by decreasing soil pH. In order to investigate the influence of nano-chelated essential metals (Zn, Mn, Fe) and sulfur application (zero and 40 kg ha-1) an experiment was carried out in Maragheh, northwest of Iran. Phenological development, morphological and agronomic traits significantly responded to both factors. Results revealed that application of sulfur fertilizer considerably increased morphological traits such as ground cover, stem diameter, plant height and capitulum diameter. Mean comparison between nano-chelated metal showed that the highest value for seed yield and yield components (number of the capitulum per plants, seed number per capitulum and seed weight) was achieved through the application of nano-chelated Zn. The best performance was related to combined application of sulfur and nano-chelated Zn which was followed by nano-chelated Fe. Seed oil content was only affected by nano-metals, so the highest value was obtained by application of nano-chelated Zn. Overall our finding revealed that integrated application of sulfur and essential metals, especially Zn, is required to grow safflower successfully on calcareous soils. The efficiency of nano-chelated fertilizers can be noticeably increased by balanced nutrient management in semi-arid regions.
Thoughts on acidification of soils by nitrogen and sulfur fertilizers