Nitrogen Derived by Broad Bean Grown on Heavy Texture Soil Using 15 N- Tracer Technique

A pot experiment was carried out in greenhouse to follow up nitrogen derived from fertilizer, air and soil and gained by broad bean under heavy texture soil condition. Dry matter yield of shoot and root was significantly increased with increasing addition rates of CaCO3 especially at rates of 2.5 and 5%. This holds true for shoots and roots. The highest values were12.1 and 5.5 g pot -1 which recorded at rate of 2.5% calcium carbonate comparing to control which recorded 9.1 and 3.9 g pot -1 for shoot and root, respectively. Similar trend was noticed with N and P uptake by shoot and root. Nitrogen derived from fertilizer (Ndff), from soil (Ndfs) and from air (Ndfa) by broad bean plants were markedly enhanced by increasing CaCO3 applied at different rates up to 10%. Fertilizer-N was efficiently used by plant especially when calcium carbonate added at rates of 2.5 and 7.5%, respectively.