NEW APPROACH TO USE FARM WASTES AS A NITROGEN FERTILIZER SOURCE: RICE STRAW

A lysimeter experiment was carried out in the year 2012 at sakha research farm kafr el-shaikh governorate. the experiment aimed to study the effect of integrated use of ammonium sulphate (as-n) and aqueous rice straw extract (rse-n) as nitrogen sources on the yield (quantity and quality) of jew,s mallow and spinach crops in addition the quality of leached drainage water. ammonium sulphate (as-n) and (rse-n) were combined in away to supply the recommended n-dose for experimental crops from both sources in (0:0) t1; (100:0) t2; (75:25) t3; (50:50) t4; (25:75) t5 and (0:100) t6 ratios arranged in a (rcb) design with three replicates. the results indicated that the highest jew,s mallow fresh yield (1583 g lysimeter-1) was recorded with (as-n 50%) + (rse-n 50%) treatment, while the highest spinach fresh yield (1405.66 g/liyzimeter) was obtained under t2 (100:0). on the other hand, the level of nitrate either in crop leaves or drainage water was greater in treatment with t2 (100:0) ratio. nitrate content (no3-n) mg kg-1 in jew,s mallow leaves reached 1.39 > 1.20 >1.16 >1.15 > 1.11 fold for treatments (100:0 as-n), (75% as-n +25% rse-n), (100% rse-n), 25% as-n +75% rse-n), and (50% as-n + 50% rse-n), respectively, compared to that under control t1 (0:0). for spinach leaves reached 4.15 > 2.57 > 2.43 > 2.09 > 1.77 fold for treatments (100:0 as-n), (75% as-n +25% rse-n), 25% as-n +75% rse-n), (100% rse-n) and (50% as-n + 50% rse-n), respectively. under all fertilizer treatments, the content of nitrate in plant leaves or drainage water were lower than the published maximum permissible level to cause humans health hazard.