EFFECT OF SLOW RELEASE AND READILY SOLUBLE NITROGENOUS FERTILIZERS ON THE AVAILABILITY OF SOME MACRO AND MICRO­ NUTRIENTS IN SOIL

Abstract

In Egyptian agriculture, rice crop (Otyza sa tiva L) has a great economic significance. As a food crop it contributes to more than 20 % of the total cereals consumption. The annual area cultivated with rice in Egypt has an average of one million feddans mostl y l ocated in the no1them part of the N ile Delta. Soils of these regions are characteristically sodic and/or saline, with pH around 7.8 to 8.5. Before the High Dam, there was no acquit problem conceming the application of the micro­ nutrient el ements to the field crop. This was mainly due to the N ile mud which was used to supply the soil annually with appreciabl e amounts of these elements currently, some problems conceming minor elements have been no ti ced on some crops. One of these problems is the insufficient amounts of available zinc in paddy areas. Ri ce plants are grown generall y under submerged conditions. N ih·ogen 1s removed from paddy soil by volatilizati on, l eaching, denirificati on and through crop uptake under both s ubmerging and fertilizati on management. Fe1ti li zers are sources of plant nuh·ients that can be added to soil to supplement its natural fettili ty. They are intended to suppl y plant needs directly rather than indirectly through modificati on of some soil properties such as soil pH and sh·ucture. Rice plants must have nih·ogen to f01m new cells. Photosynthesis can produce carbohydrates from C02 and H20