EFFECT OF PARTIAL AND COMPLETE REPLACEMENT OF THE FIRST UREA APPLICATION USING LOCAL GYPSUM COATING AND NANO-NITROGEN ON SORGHUM SEED EMERGENCE

Abstract

A field experiment was conducted in the experimental field of the Field Crops Department, College of Agriculture, University of Baghdad, during the spring season of 2025. Treatments were applied in a randomized complete block design (RCBD), with four replicates and three factors: the first factor seed coating (without or with gypsum), second factor suspension at Nano-nitrogen concentrations (0, 20, 40, and 60 mg L-1), third factor was the Urea replacement levels (0, 50, 100%). The results showed that the coating treatment had a significant effect on all studied traits. The local gypsum coating treatment was superior in increasing the field emergence percentage in the final count, seedling height, and dry weight, which was reflected in an increase in the seedling vigor index. Meanwhile, the uncoated treatment was superior in the first field emergence count and provided the shortest time to complete field emergence. As for the effect of nitrogen addition, Nano nitrogen showed a significant effect on all studied traits. Seed treatment at a concentration of 40 mg L-1 yielded the highest percentage of field emergence in the first and final counts. Nano nitrogen at a concentration of 60 mg L-1 yielded the shortest number of days to complete field emergence and the highest average seedling height, seedling dry weight, and seedling vigor index. Regarding the effect of partial and total replacement rates for the first batch of urea fertilizer, the results showed that total replacement yielded the highest average for the first field count, while partial replacement at a rate of 50% yielded the highest average for final count, seedling dry weight, and vigor index. We can conclude that the presence of nano nitrogen combined with a seed coating treatment with local gypsum is superior to direct seed treatment with this fertilizer. It is also noted that nano fertilizer can replace the ground application of the first batch of urea fertilizer by up to 50%.