THE RESIDUAL EFFECT OF RICE N-BIOFERTILIZATION AS POTENTIAL ECONOMIC FOR MINERAL NITROGENOUS FERTILIZATION OF WHEAT CROP.

This study was conducted during winter seasons of (2009-2010) and (2010-2011) at meet louza village, mansoura province, dakahlia governorate, egypt on a silty clay soil to find out the residual effect rice n-biofertilization on the next wheat crop (triticum aestivum l. c.v. sakha 93). biofertilization 8 treatments involving inoculums of azolla (azl), azospirillum (azs), azotobacter (azt), and cyanobacreria (cyn) as well as mixtures (azl + azs), (azl + azt), (azs + azt) and (cyn + azt) which take the same location with the same layout of the experimental field for the previous crop (rice), soil n- fertilization (4 treatments of control, 12.5 %, 18.75 and 25 % of n-recommended level 75 kg n fed-1 as urea) were tasted in a split plot design with three replicates. the most important finding could be summarized as follows:  treatment of 25 % n-level led to highest increases for plant height, grain yield, chlorophyll (a) and (b) content and the highest values were (101.27cm, 1.57 mg fed-1, 13.55 mg g-1 f.w and 8.95 mg g-1 f.w) for the previous parameters, respectively. although, the highest straw yield, n, p, k, fe, mn and zn uptake by grains of (1.31 mg fed-1, 26.17, 4.27, 4.67 kg fed-1, 106.23, 47.91 and 48.33 g fed-1), were recorded at 18.75 % n-level, respectively. the highest mean value of caroteniods (2.75 mg g-1 f.w). achieved at, control treatment.  inoculation of (azl) gave maximum plant height and mn-uptake of ((98.16 cm and 47.47 g fed-1), respectively. the highest grain, straw yields, caroteniods, n, k, fe and zn uptake were due to (azs) inoculation which were (1.84, 1.40 mg fed-1, 3.48 mg g-1f.w, 27.13, 5.21 kg fed-1, 18.87 and 49.65 g fed-1) respectively, the highest p-uptake of (4.32 kg fed-1) occurred with (azt). while (azs+azt) revealed the highest values (15.05 and 10.25 mg g-1f.w) for chlorophyll (a) and (b) content, respectively.  the combination of 25 % n-level with (azl, azs, cyn, azs +azt, azs and cyn + azt) inoculations, gave superiority plant height (106.38 cm), grain yield (1.95 mg fed-1, chlorophyll (a), (b) (15.52, 13.39 mg g-1 f.w), fe and mn uptake of (137.32 and 55.49 g fed-1), respectively. the superiority average values of straw yield (1.53 mg fed-1), n and zn uptake (32.01 kg fed-1and 57.01 g fed-1), release from organic and inorganic (30.25ppm), n-uptake % (67.92%) and n-recovery % (61.66%) occurred with combination of (18.75%n-level + (azl+azs)), but 18.75 % n-level combined with (azl) and (azs) respectively gave highest p-uptake of (4.90kg fed-1) and k-uptake of (5.88 kg fed-1). the uppermost caroteniods (3.71 mg g-1f.w) occurred with the combination of (12.5% n-level + azs) and the superiority net return (3060 £.l. fed-1.) of wheat crop, was given by combination of (25 % n-level + azs).