The sewage sludge is a waste but it has many favourable properties in respect of agricultural use, therefore it can be used in crop production for nutrient supply after composting. The sewage sludge compost may be suitable for nutrient supply of sandy soil in the Nyírség region which has low macro- and micro-nutrients and organic matter content.

In the University of Debrecen CAS Research Institute of Nyíregyháza a field experiment was started in 2003 for examining the regular (in every 3rd years) sewage sludge compost application for agricultural purposes. It makes possible to measure the effect of the applied sewage sludge compost (called Nyírkomposzt) on the chemical, physical and microbiological properties of sandy soil, its potentially toxic element content and the yield of crops.

The applied compost contains the following (in m/m% dw.): 40% of sewage sludge, 25% of straw, 30% of rhyolite, 5% of bentonite. The doses applied in five replications were used at the rates of 0, 9, 18, 27 t ha-1. The years of the re-treatments were 2006, 2009 and 2012. In the experiment, pea (Pisum sativum L.), triticale (x Triticosecale Wittmack) and maize (Zea mays L.) test plants followed each other in a crop rotation. In this article we present the effect of compost treatment on the yield of pea, triticale and maize during the period from 2007 to 2013. The elements content of the compost used meets the requirements of the regulations. We found different plant responses to the compost application. Triticale had higher yield in the second year after the treatment. The yields of maize increased in the sewage sludge compost treatments but they were strongly affected by weather conditions while the yield of green pea was not affected by sewage sludge compost application. Therefore, our results should be taken into account before compost application and planning the crop rotation.

Keywords: composted sewage sludge, nutrient supply, crop yield, long-term experiment