INFLUENCE OF MINERAL NITROGEN, COMPOST AND NITROGEN FIXING BACTERIA ON TOMATO PLANTS GROWN IN SANDY SOIL

Pot trials were conducted under plastic house condition during two successive seasons of 2013/2014 and 2014/2015, at the experimental site of Central Laboratory for Agricultural Climate (CLAC), Agricultural Research Center, Giza, Egypt. The present study aims to determine the partial replacement of mineral nitrogen fertilization of tomato by nitrogen fixing bacteria with or without adding compost in sandy soil. Tomato seedlings (Lora F1Hybrid) were transplanted during the first week of October into plastic pots (30 cm diameter) filled with 10 kg of sandy soil. Three rates 25, 50 and 75% of the recommended mineral nitrogen in the nutrient solution for tomato with adding compostat 2% and nitrogen fixing bacteria (Azotobacter chroococcum and Azospirillium brasilense) at 20 ml/plant either individually or in combinationswere investigated on growth, mineral composition and yield of tomato plants compared to 100% of recommended nitrogen only (control). The plants were irrigated daily by drip irrigation and received 200 ml/plant of nutrient solution twice a weekly. The results showed that using 50 or 75% of N-mineral fertilizer + compost + nitrogen fixing bacteria gave the highest values of growth, mineral composition and yield of tomato. It is recommended that 50% of nitrogen mineral fertilizers for tomato plants could be replaced by nitrogen fixing bacteria in presence of compost, which in earn, reduce environment pollution caused by extensive application of mineral nitrogen fertilizers.