ABSTRACT: In a field study in the region of Meknes, Morocco, two experiments were conducted. The first was carried out to investigate wheat's response to nitrogen supply (0.80 and 140 kg N/ha) and to soil incorporation of sunflower residues (0 and 5t/ha). The second field experiment was carried out to study wheat response to soil incorporation by increasing sunflower residues rates (0,5 and 10 t residues/ha). In the first experiment, nitrogen fertilization and residue incorporation only slightly affected wheat yield. This was related to drought which could have reduced wheat nitrogen needs and decreased the importance of immobilization. The results of the second experiment showed that wheat yield was depressed as a result of residue incorporation into soil but was not affected by increasing residues rate. It was concluded from this study that residues incorporation into soil can immobilize soil nitrogen and depresses wheat production. This effect is more important in humid conditions.
Keywords: Immobilization, nitrogen fertilization, residues incorporation, soil, sunflower residues
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