Effects of different irrigation regimes and different application frequencies of nitrogen on yield and quality of drip-irrigated silage corn under diyarbakir condition

This study investigated the effect of different irrigation regimes and nitrogen (N) fertigation frequency on drip-irrigated silage corn. Experiments were conducted in the Southeastern Anatolia Region of Turkey (Diyarbakır) in 2011 and 2012. A split-plot experimental design was applied in randomized blocks and 3 replications. The main plots contained 4 different irrigation levels. These are different ratios of evaporation from Class A Pan for 5 days interval : I1:0.50, I2:0.75, I3:1.00 ve I4:1.25. Sub-plots were designed with different frequencies of N- fertigation as follows: N1, the application of one-fifth of the total N at the sowing, two-fifths at the beginning of 6-7 leaves of plants, and two-fifth at the beginning of tasseling stage; N2, the application of one-fifth of the total N at the sowing, the application of four-fifth of the total N at equal doses every two irrigation cycles (10 days); N3, the application of one-fifth of the total N at the sowing, the application of four-fifth of the total N at equal doses each irrigation cycles (5 days). The green hay yield increased significantly depending on amount of irrigation water applied and increasing of N fertigation frequency in both experimental years. The maximum amount of irrigation water (I4(1.25):529 mm ) and N3 resulted in the maximum green hay yield (8960 kg/da). However, there were no significantly differences between I4 (529 mm) and I3 (447 mm) treatments in terms of green hay yield. Considering optimum hay yield and amount of irrigation water, 1.0 ratio of evaporation from Class A Pan for 5 days interval and the application of one-fifth of the total N at the sowing, the application of four-fifth of the total N at equal doses each irrigation cycle (5 days) might be recommended. The green hay, dry matter and total protein content of the hay for this treatment were yield 8782 kg/da, 2986 kg/da and 7.7 %, respectively. The total protein yield in dry hay was 227.2 kg/da. As a result, the study resulted in considerably water saving and the maximum silage hay yield compared to previous studies carried out in surface irrigation and conventional fertilization. Thus, application of equal doses of nitrogen for each irrigation cycle up to tasselling provide the maximum hay and protein yield.