Organic and mineral nitrogen fertilizers in sweet maize (Zea mays L. saccharata Sturt.) production under temperate climate

The introduction of sweet maize (Zea mays L. sacharata Sturt.)into temperate climates requires additional information concerning fertilization, especially for developing organic production system.Field experiments were carried out in the Slovenian region Styria suitable for growing only early-maturity maize hybrids (FAO 100-400) with the aim of determining the effects of nitrogen applied to different nitrogen target values (70, 120, 170 and 220 kg ha -1 N) on growth, yield, photosynthetic activity and soil mineral nitrogen (N min -NO 3 -N and NH 4 -N) dynamics, as compared to the control.Nitrogen was applied as organic by-products (pumpkin cake and pig manure digestate) and mineral fertilizers (CAN 27 and ENTEC ® 26).The major points were as follows: 1) pumpkin cake had a similar effect to that of mineral fertilizers, and gave significantly higher total and marketable yields (14.476 and 11.619 t ha -1 , respectively), higher values of cob characteristics and plant mass than for pig manure digestate; 2) there were no significant differences in total and marketable yields among the target values of 120, 170 and 220 kg ha -1 N, but calculated nitrogen target value expressed as the peak of a regression curve for yield was 170 kg ha -1 N.However, the data showed that high yields of organic sweet maize can be obtained using pumpkin cake as nitrogen fertilizer based on target value 120 kg ha -1 N (rate of kg ha -1 N = 120 kg ha -1 N -soil N min till 0.9 m depth) at the time of sowing.