Afield experiment was conducted at the Experimental Farm, Department of Field Crop, College of Agriculture, University of Baghdad during 2009 and 2010 Seasons to study the response of Cotton cultivars to mineral and organic fertilizers mixed in different rates or lonely. RCBD in split plots arrangement with three replications was used, main plots includedfertilizers treatments, control treatment (without fertilization), 100% mineral fertilizer as recommendation, 100% organic fertilizer (poultry manure) at rate of 10 ton.ha1-, 75% mineral fertilizer of recommendation + 25% organic, 50% mineral fertilization of recommended + 50% organic and 25% mineral fertilizer of recommendation + 75% organic. While subplot included four cultivars of cotton (Mersomi-1, Coker 310, Ashaur and Lachata.
The results showed that Mersomi-1 was superior in plant height (122.8, 126.7 cm), boll weight (4.4, 4.3 gm) for boll seasons, while coker variety was superior in number of sympodial (13.8, 12.6), boll number (28.1, 27.6) so gave highest seed cotton yield about 4.225 and 4.331 ton.ha1- for both seasons. Mineral and organic fertilization caused significant increases in most growth characters and yield compared with control treatment (without fertilizers). The treatment 50% mineral of the recommended + 50% organic increased seed cotton yield about 32.11% and 30.84% compared with mineral fertilizers only and 52.66% and 44.62% for organic fertilizers onlyfor both seasons as a results for-its superior in sympodial numbers (17.5 and 16.2) and boll numbers (37.5 and 35.5) resp. There was significant interaction between cultivars and fertilization treatments in all characters except monopodial numbers. Cokers 310 cv. In the treatment of50% mineral + 50% organic gave highest seed cotton yield about 6.239 and 6.320 ton.ha1- for both seasons resp.We can concluded that organic fertilizers may replace some of mineral fertilizers to improve growth and increasing the yieldof cotton