الفهرس 
NitrogenOnly 14 pages are availabe for public view
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Abstract
Two field experiments were carried out on NPKZn fertilization at Sakha Agricultural Research Station during the seasons of 1990 and 1991 to study: - The effect of the levels of each nutrient element and time of N application on dry weight, yield and yield component of rice plants, nutrient use efficiency, uptake and recovery and also the uptake of Fe and Mn by rice plants. - The effects of a balanced fertilization containing N, P, K and Zn on yield and yield components of rice The obtained results can be summarized as follows: Nitrogen fertilization: a. Nitrogen levels: Dry matter of rice at different growth stages showed a significant increase at the smaller levels, but not at the higher levels. Moreover, dry weights slightly decreased as N levels increased over 96 kg N/ha. The grain yield of rice increased with increasing N level. The highest yield was obtained with a nitrogen level of 96 kg Nlha in the two seasons. For example, grain yield of the control (No. N added) was 5.8 1 t/ha while the grain yield was 7.75 t/ha with 96 kg N/ha in 1990 season. On the other hand the grain yield decreased to 6.41 t/ha, when 192 kg Nlha were applied.