COMPARATIVE PERFORMANCE OF SOME SLOW-RELEASE COATED NITROGEN FERTILIZERS ON LETTUCE AND CABBAGE PLANTS GROWN IN SANDY SOIL

Replacing the traditional nitrogen fertilizers with new coated fertilizers that produced using various materials in coating processes, particularly agro-industrial residues and studying their residual-effect is one of an important research approach. To prepare these alternative fertilizers, sulfur (S), gypsum (G; calcium sulfate), zeolite (Z), sugarcane filter cake/Mud (SC) and sugar beet filter cake/Mud (B) were used for coating conventional nitrogen fertilizers; urea and ammonium nitrate. Then, a field experiment was conducted at the experimental research station that belongs to the National Research Center in El-Nubaria, Beheira Governorate, during two growing seasons (2018/2019). The aim of this experiment was to evaluate the coated urea and ammonium nitrate compared with the uncoated sources in the production of green Iceberg Lettuce (Lactuca sativa var. Big-bell) followed by the cabbage crop (Brassica oleracea var. Capitata) to study the residual effect of the first application of coated fertilizers. Fresh and dry yield of lettuce and cabbage, macronutrients concentration and uptake, dry matter accumulation, yield production efficiency and crop nitrogen use efficiency were recorded. The results indicated that ammonium nitrate is the fit nitrogen form, particularly in new reclaimed areas under Egyptian conditions. Irrespective of nitrogen source, lettuce fresh yield, nitrogen use efficiency and cabbage fresh weight increased by 52.4, 67.3, 52.3, 44.6 and 94.1%, by 29.6, 28.0, 36.0, 23.7 and 59.9% and by 113.2, 96.5, 200.2, 216.6 and 264.6% for S, G, Z, SC and B compared with control (C), respectively. These general trends confirm the superiority of beet mud as a coating material and the inferiority of uncoated fertilizers. Coating both nitrogen forms with sugar beet industrial residues (B) has proven to be viable, as it gave high lettuce yield and leaves considerable residual effect on improving the soil fertility, consequently, enhancing cabbage growth.