الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
SUMMARY
The present study was conducted to study the effect of sources and rates of nitrogen in soil as related to the nitrification inhibitors for the optimum growth and yield of corn. Field experiment were carried out at the Experimental Station, Faculty of agriculture, Saba Basha, Alexandria University during 2004 (Summer season). The experiment design used was split-split plot with three replications. Five nitrogen rates (0, 30, 60, 90 and 120 kg/fed) were applied to the main plots, five nitrogen sources (Ammonium nitrate (AN), calcium nitrate (CN), Ammonium sulphate (AS), Urea (U) and Ammonium nitrate plus urea AN + U) were assigned to the subplots and two nitrification inhibitors (furdan (F) and sodium azide (S) were assigned randomly to the sub-sub plot.
Three corn plant samples were taken to determine leaf area index (LAI) crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR). The chlorophyll content was determined at 60 days from sowing. The plant height and dry weight/plant were determined at 75 days from sowing. At maturity the weight of grain yield was measured. Nitrogen, phosphorus and potassium contents in leaves and stems were determined. Ammonium and nitrate nitrogen forms in soil were determined. The obtained results could be summarized as follows:
Effect of nitrogen rate
1. LAI, NAR and CGR were significantly increased by increasing N application but RGR was decreased.
2. The highest value of plant height, dry weight/plant and grain yield ton/fed were produced with 120 kg N/fed, while chlorophyll content was produced with 90 kg N/fed.
3. Increasing nitrogen rates up to 120 kg/fed significantly increased N, P and K contents in plant corn stem and leaves during the three growth stages except total nitrogen content in plant corn stem at first stage.
4. Ammonium form concentration in soil was increased with increasing nitrogen rates from 0 to 120 kg N/fed. The highest values of ammonium concentration in soil was obtained using 120 N/fed at 75 days from sowing.
5. Nitrate nitrogen form in soil was increased with increasing nitrogen application rates. The highest values of nitrate nitrogen form in soil were obtained using 120 kg N/fed.