Due to the changing climatic conditions, irrigation is becoming increasingly important in Hungary. However,from an economic and environmental point of view,the application of different water use technologies in agriculture should be considered. The main goal of our research is to develop irrigation methods aimed at sustainable and reasonable water utilization. Two varieties of forage sorghum (Gigant, Szarvasi titán) were used in our study at the Lysimeter Station (Szarvas, Hungary) of the National Agricultural Research and Innovation Centre, Research Institute of Irrigation and Water Management (NAIK ÖVKI) in 2015. Irrigation interval in the lysimeter experiment was 7 days as an average during the growing season. Five treatments (non-irrigated control (Ø); surface water (the Körös river (K)) and fish farm effluent (H) with the irrigation rates of 15 (K15, H15) and 30 mm (K30, H30) per weeks) were applied in lysimeter. The intensive African catfish farm uses confined ground water what is characterized by high concentration of sodium (222–314 mg l-1) and high total salt content, but also by an elevated rate of nutrients (N: 32–33 mg l-1, P: 2–3 mg l-1, K: 6–11 mg l-1). During the study of cultivation technology, the height of the plants and the relative chlorophyll content were measured once a week. The dry matter content of the examined plant parts was weighted after heading and harvesting, while the mineral content was analysed only after the harvest. The biomass production of the sorghum varieties was found genotype dependent. Yield-increasing effect of the irrigation with wastewater from the intensive fish farm was proved as it increased both fresh and dry crop production significantly. Furthermore a large yield difference caused by irrigation treatments was observed, that might be the effect of the extremely hot and dry wheather during the production season in 2015. We found that irrigation with waste-water at the rate of 30 mm had a significant increasing effect on biomass production of both varietes compared to the surface water irrigated or to the non-irrigated control treatments. The average biomass weight of the Gigant variety was 6210–8303 g m-2, which means 72 t ha-1 of green fodder. The Na uptake of plants was closely monitored, since a significant amount of Na was released to the field with the irrigation water. Based on our results, the leaves and stems of sorghum accumulated less Na than it was measured in roots. The average Na content of the root samples was 846 mg kg-1 dry matter, which was double that of the control samples. Consequently, the Na content of the root residues and the chemical composition of the sewage irrigation water justify the subsequent monitoring ofthe parameters indicating soil salinisation and, if necessary the application of soil improvers.

Keywords: sewage irrigation, phenology, mineral content, biomass product, lysimeter