How the nitrogen fertilization dose affects the biochemical composition and net mineralization of the artichoke residues

In Egypt, recycling of vegetable and crop residues is improving of environmental and efficiency of nitrogen use. In this study, artichoke (Cynara cardunculus L.) plants have been grown in field for nine months at three rates of nitrogen fertilization: 0 (N0), 250 (N250), 500 (N500) kg ha(-1). The aims of this study are to assess effect of nitrogen fertilization of previous treatments on the chemical composition and mineralization of the artichoke. The results showed that the artichoke residues of the treatment N500 contained higher amounts of lignin, cellulose, hemicellulose and soluble C at 100 degrees C and a lower soluble fraction Van Soest than N0 and N250 treatments. Artichoke residues contained 129.3, 89.2 and 57.4 kg N ha(-1) for N500, N250 and N0, respectively. Carbon of artichoke residues was mineralized above 60% at 50 days in the incubation experiment, and then slowly CO2 release. Net N immobilization was observed during the first days of incubation in N0 and N250 treatments. While, the N500 treatment was mineralized immediately. The study demonstrated that the net N mineralization ranged from 38.26 mg N kg(-1) dry soil for the control soil without residues to 56.30 mg N kg(-1) dry soil for the soil treated with artichoke residues N500. These results could lead to greater efficiency of N use in rotations through return of vegetable residues, and alternative methods to improve the efficiency of vegetable residues disposal.