Khatab K. A., E. A. M. Osman and A. A. EL- Masry
A field experiment was carried out at El- Gemmeiza Agricultural Research Station, El-Gharbia Governorate during the two summer growing seasons, 2011 and 2012 located at lat. 30.47, long 31.00 and 14.80 m above the mean sea level to study the effect of nitrogen fertilizer rates, i.e., control (without N fertilizer),25, 50 and 75 kg N/fed., and foliar application of humic and fulvic acids together or individually on yield, chemical composition of rice plants and nitrate as well as nitrite content in drainage water at 60 days from transplanting as well as of soil after harvesting. High level of nitrogen fertilizer (75 kg N /fed.,) achieved significantly increases of rice yield and N, P & K content of grain and straw as well as NO2 and NO3 of grain and straw . While, the lowest significant values of such parameters were recorded by low rates(without addition of nitrogen fertilizer )followed by 25 kg N/fed.,in both growing seasons. Foliar application of humic and fulvic acids together led to significant increases of rice yield and N, P & K content of grain and straw as well as NO2 and NO3 of grain and straw, whereas, the lowest significant ones were obtained when sole foliar application of fulvic acid in both seasons. In most cases, the highest significant values of rice yield and N, P & K content of grain and straw as well as NO2 and NO3 of grain and straw were obtained when foliar application of humic and fulvic acids together under the high levels of nitrogen fertilizer was added. While, the lowest ones were recorded with sole foliar spray of fulvic acid under the low level of N in both seasons. The high level of nitrogen fertilizer achieved significantly increases of nitrate and nitrite content in drainage water at 60 days from transplanting as well as nitrate, nitrite and ammonium of soil after harvesting compared to low rates in both seasons. While, the same parameters were increased significantly by sole application of humic and /or fulvic acidc, but the lowest ones were achieved by foliar spray of both organic acids together in both seasona. On the other hand, such parameters were significantly increased by sole foliar application of humic or fulvic acids with high levels of nitrogen fertilizer. Whereas, the lowest ones were observed by foliar spray of humic and fulvic acisd together with no addition of nitrogen fertilizer in both seasons.
