Soil fertility management is a key issue for sustaining agricultural production in dry lands. Organic resources are important for nutrient avail-ability and maintenance of soil organic matter. Sustaining fertility of arid soils necessitates in-creasing inputs of organic residues. Two experi-ments with water hyacinth were carried out to monitor (in the first; field study with litter bags) decomposition and changes in N, P, K, Ca and Mg as influenced by method of application where, in the second (greenhouse study) short-term effect on some properties of a sandy soil and early estab-lishment of fodder sorghum (Sorghum bicolor). Results of the first experiment showed that resi-dues incorporated in the top 0-30cm soil depth had significantly (P≤0.01) increased loss of dry matter weight compared to surface application. Decom-position rate constants of surface and sub-surface application were 0.029% week-1 and 0.041% week-1, respectively. Potassium was the fastest nutrient released with 50% loss attained after the 2nd and 6th week from incorporation and surface application, respectively. Nitrogen, P, Ca, and Mg releases from water hyacinth incorporated in the sub-soil were significantly (P≤ range from 0.0001 to 0.008) high compared to surface application. Nutrients loss was in the order of K =Mg > P > N > Ca. However, results of the second experi-ment showed that incorporation of water hyacinth residues significantly (P ≤ 0.001) decreased pH (by about 27%) and hydraulic conductivity (by 40-46%). Also, cation exchange capacity and organic C were significantly increased by about 23 and 100%, respectively. The study concluded that ap-plication of water hyacinth could be one of the good alternatives for improving quality of arid soils.