Decomposition and nutrient release from litter fall in the semi-arid tropics of Sudan

In Sudan, tree plantations remain the first choice and are widely used in protecting arable lands from sand movement. Decomposition and nutrient changes from leaves of some agroforestry trees (Eucalyptus microtheca, Ficus spp., and Leucaena leucocephala) and litter fall from guava (Psidium guajava) and mango (Magnifera indica) were monitored (in a 12-week litter-bag experiment). Rate of dry-matter weight loss from guava (0.098 wk(-1)) was significantly (P < 0.01) faster than from mango residues (0.04 wk(-1)). Corresponding values for Leucaena, Eucalyptus, and Ficus were 0.0533, 0.0524, and 0.0438 wk(-1), respectively. In general, micronutrients tend to accummulate during a decomposition period. Potassium (K) was the only element found to be consistently lost by leaching very rapidly from all litters. Nitrogen (N) was released at a significantly (P < 0.03) higher rate from Leucaena (0.0558 wk(-1)) compared to Ficus (0.0399 wk(-1)) and Eucalyptus (0.0301 wk(-1)). Mobility of nutrients from the litters was in the order of K phosphorus (P) = N calcium (Ca) magnesium (Mg). It is concluded that ficus and mango leaves are suitable for improving quality of arid soils through buildup of soil organic matter and supplying easily released organic sulfur (S) (environmentally sound management practice) whereas litter from guava is suitable for temporary nutrient correction. Mixing of guava and mango residues may slow fast decomposition of the former.