Nitrogen Distribution in Soil Profile under Sesame, Maize and Wheat Crops as Affected by Organic and Inorganic Nitrogen Fertilizers Using 15N Technique

Nitrogen remained in soil and distributed along the soil profile of virgin sandy soil after sesame, maize and wheat were examined using 15N isotope dilution concept. A field experiment was conducted on virgin sandy soil at the farm station of Soil and Water Research Department, Nuclear Research Center, Inshas, Egypt. Treatments of organic and inorganic fertilization practices were arranged in a complete randomized block design with three replications under drip irrigation system. After harvest of wheat, sesame and maize crops, nitrogen remained in soil was examined using the 15N isotope dilution concept. Results indicated that nitrogen uptake was positively affected by fertilization sole or combined treatments and significantly vary according to crop and different plant organs. Fertilizer N balance showed that the proportion remained in soil after harvest was differentiated dependable on crop and rate of application. In this regard, combined mineral-organic fertilization practice reflected significant reduction in N remained in soil after harvest. Nitrogen remained after maize was higher than those after wheat and sesame, respectively. Mineral-organic fertilization reduced the proportion of N fertilizer lost from the soil media. These losses were attributed to the tested crop and significantly vary among them. N remained in soil was distributed in depth of 0-20, 20-40 and 40-60 cm without significant difference between depths under sesame while wheat showed accumulation in 0-20 cm depth. N remained under maize showed accumulation in 0-20 cm affected by the combined application of 50% compost commercial +50% nitrogen mineral fertilizer (50%C2+50%MF).