Influences of Chemical and Spraying Organic Fertilizers (Humic acid) on Consumptive Use, Growth and Yield of Onion (Allium Cepa L.)

This field study is conducted during the growing season of 2012-2013 in the experimental farm- Department of Horticulture/ College of Agriculture- University of Baghdad to investigate the influences of chemical and spraying organic fertilizers on the growth, yield and consumptive use of Onion (Allium cepa L.). The experimental treatments included in this study as follows: chemical fertilizers (non-fertilizer, 50% recommended fertilizers and 100% recommended fertilizers) and spraying organic fertilizers (Humic Acid) (non-spraying, two, four and six foliar sprays) with concentration 1.5 ml.L-1. The experimental design used is Randomized Complete Block Design in three replicates and 36 experimental unit. The experimental total includes: plant length, number of leaves/plant, leaf area, dry weight of vegetative, concentration of nitrate in the bulb, the yield component and consumptive use.<br /> The experimental results show that there is a significant difference between the chemical and the spraying organic fertilizer as compared with the control treatment. Treatment with 100% recommended fertilizers + treatment spraying organic fertilizer with 6 foliar gave the highest of value of plant height, number of leaves. plant1-, leaf area, dry weight of vegetative 70.8 cm, 18.7 leaf. plant-1, 21.43 dcm2 and 9.92 gm as compared with the control treatment which gives 46.3 cm, 10.8 leaf.plant-1, 8.44 dcm2 and 2.89 gm, respectively. Treatment 100% recommended fertilizers also gives the highest concentration of nitrate 1.18 g.mg-1 compared with 50 % recommended fertilizers 0.76 g.mg-1 and 0.57 g.mg-1 with non-chemical fertilizers. The spraying organic fertilizers gives the lowest concentration of nitrate in bulb 1.06, 0.91, 0.73 and 0.65 g.mg-1 in the treatment without foliar, two, four and six sprays, respectively. The results show the heights value of length and diameter bulb and total yield in spraying organic fertilizers (6 time foliar) 9.23 cm, 8.52 cm, and 22.93 T.ha-1, while the treatment with 100% recommended fertilizers + treatment spraying (6 time foliar with organic fertilizers) give the highest value for this characteristic 10.81cm, 10.21 cm and 30.4 T.ha-1, respectively. The actual evapotranspiration (ETa) values of complete irrigation are 470-495 mm for chemical fertilizers and spraying organic fertilizers. The water use efficiency in spraying organic fertilizers (6 times foliar) is increased 23.08, 9.09 and 2.12 as compared with non-foliar, two, four and six sprays, respectively.