Response of Maize and Wheat to Increasing Rates of Npk-fertilization

Maize and wheat are main field crops on arable lands in Croatia. According to the data of the State Bureau for Statistics (Statistical Yearbook 2011) in the five-year period (2006-2010) mean used agricultural land in the category arable land and gardens in Croatia was 867123 ha. Mean harvested areas of maize (298412 ha) and wheat (176794 ha) occupied 55% of used arable land of the country. Majority of maize and wheat growing areas are situated in the five counties of the eastern Croatia region. In general, high variation annually yields of maize and wheat in short period (for example from 4. 9 to 8.0 t ha-1 for maize and from 4.0 to 5.5 t ha-1 for wheat in the period 2006-2010) are mainly result of less or more favourable weather characteristics in the individual growing season (Josipović et al., 2005; Kovačević, 2009b; Marijanović et al., 2010). We presume that by adequate soil and crop management practice it is possible to alleviate yield variation among years. Aim of this study was testing subsequent effects of increasing rates of NPK-fertilization on maize and winter wheat yields.