University of Debrecen
University of the Free State
Purpose The aim of this study was to prove that the Fe-containing by-products (compost, sewage and lime sludge) have potential infuence on the correction of Fe defciency in sunfower and maize. Methods The physiological parameters used were the dry matter (DM), the relative chlorophyll content, and the content of photosynthesis pigments (chlorophyll a, chlorophyll b and carotenoids). Results The results showed that sewage sludge was efective even when applied at low concentration (2 g L−1) for both sunfower and maize plants. In maize, however, chlorophyll a was the only pigment induced after sewage sludge treatments in contrast to sunfower, which could be the reason for lower DM in maize. Compost could only be efective when applied at higher concentrations (4 g L−1) for sunfower because of its low-Fe content, further showing that maize plants require more Fe. Despite its high-Fe content, lime sludge could not be efective in alleviating Fe defciency for both sunfower and maize plants because of its high pH, which makes Fe unavailable for uptake by the plants. Conclusions Although the investigated by-products can be hazardous depending on their origin, their use as micro-element fertilizer can be a very economical way of utilization in the agricultural felds, which may limit the use of high quantities of expensive Fe-containing fertilizers. Among the three waste products, sewage sludge application proved to have a great potential of correcting Fe defciency by inducing accumulation of the photosynthesis pigments, leading to high photosynthesis and eventually high DM.