Effects of nitrogen fertigation on yield, quality components, water use efficiency and nitrogen use efficiency of silage maize (Zea MaysL.) as the second crop

Effects of nitrogen (N) fertigation on yield, quality parameters, water use efficiency and nitrogen use efficiency of second-crop silage maize (Zea maysL.) under Central Anatolian (Ankara) conditions of Turkey were investigated in this study. Fertigation experiments were conducted under provincial conditions of Ankara during the growing seasons of 2016 and 2017. Five different N doses (0-75-150-225-300 kg ha(-1)) were applied to experimental plots through fertigation system. Experiments were conducted in randomized blocks design with 4 replications. Class-A pan was used to measure 7-day evaporation values to be used in calculation of the amount of irrigation water to be applied in each irrigation. As the average of two years, amount of irrigation water applied throughout the growing season was measured as 480 mm and seasonal evapotranspiration was measured as 536 mm. Present total fresh yields varied between 49.8 - 104.2 ton ha(-1)in 2016 and between 50.9 - 98.5 ton ha(-1)in 2017. Present N doses applied through fertigation system had significant effects on green herbage yield, dry matter yield, dry matter ratio, plant height, first cob height, number of cobs, stem thickness, cob diameter, cob length and crude protein (p < 0.01). The relationship between the amount of N fertilizer applied and fresh yield could be expressed with the second-order equation of Y=-0.0016x(2)+0.5867x + 45.792 (R = 0.9046*, p < 0.05). It was concluded based on present findings that 186 kg ha(-1)N application through fertigation system might be sufficient for optimum economic yield (99.6 ton ha(-1)) and forage quality of silage maize as the second crop.