| Abstract: | The high cost of chemical fertilizers has forced farmers to switch to intensive use of locally available manures. Two laboratory incubation experiments were carried out in Sudan to study the effects of manure (chicken, farmyard, pigeon, and goat), chemical fertilizer, and four soil types (Ustert, Fluvent, Orthid, and Psamment) on nitrogen (N) mineralization. Net N mineralization in light soils (248, 529 mg N kg?1) was significantly (P ≤ 0.02) greater than in heavy soils (44, 212 mg N kg?1). Manure pH (R 2 = 0.9, P ≤ 0.01), lignin content (R 2 = 0.74, P ≤ 0.05), lignin / total nitrogen (TN; R 2 = 0.72, P ≤ 0.05), polyphenols/TN (R 2 = 0.75, P ≤ 0.05), and TN (R 2 = 0.76, P ≤ 0.05) were found to be the best parameters to determine N mineralization from manures. These findings support earlier studies that N release from organic N of different sources depends on soil type and chemical composition of the manure. |
