The judgement of the water supply of crop populations largely depends on the chosen index number and the related reference period. The precipitation sums of different length periods and a water supply index were compared on the basis of their correlations with the yield obtained on different nutrient treatment levels and under irrigated or non-irrigated conditions in a multifactoral long-term field experiment on maize established in Debrecen-Látókép. The nutrient dose that can be utilised the best under the given circumstances and the dependence of the water utilisation from the nutrient level were determined. Considering that the primary element of economical production is the increase of production to a marginal efficiency level of production inputs and the maximisation of yield safety, specific recommendations were provided in relation to the most effective nutrient level and its associated irrigation water need.

Keywords: maize, water supply, water utilisation, nutrient utilisation