Soil degradation is among the most important issues that threaten the sustainability of the world’s agriculture, and its effects can be seen in all continents including America and Africa. The first objective of research in Chapters 3 (Ohio) and 4 (Tanzania) was to evaluate the effect of various forage cover crop species under varying levels of fertilizer treatment on forage production (yield) and stand density. The second objective was to determine the effect of the same vegetation and fertilizer treatments on water infiltration and soil penetration resistance (SPR). The third objective was to evaluate various seed characteristics on germination and yield in the laboratory and greenhouse in an attempt to understand factors affecting establishment success in the field studies. Both Exp. 1 (Ohio), 2 and 3 (Tanzania) used a split plot design with two factors, namely, species and fertilizer where Exp. 1 had species at four levels plus an unsown control as the main plot factor, and fertilizer at two levels (+N and +P) plus the unfertilized control as the sub-plot factor. Exp. 2 and 3 (Tanzania) had species at four levels and the subplot factor was fertilizer at three levels. The main-plot vegetation treatments for Exp. 1 were Cenchrus ciliaris (buffel grass) that was dominated by weeds, Brachiaria deflexa (brachiaria), Glycine max (soybean ), Eragrostis teff (teff), and the control (bare soil). The main plot vegetation treatments for Exp. 2 included, C. ciliaris, Chloris gayana, Stylosanthes scabra, and the unplanted control while Exp. 3 mainplot vegetation treatments included E. teff, Vigna inguiculata, Sorghum vulgare and the unplanted control. Fertilizer treatments applied to Exp. 2 and 3 were DAP (diammonium phosphate, 46% P2 O and 18% N) at the rate of 30, 20, and 0 kg/ha. In all experiments there were four replications as a randomized complete block design making 60 experimental units in Exp. 1, and 48 experimental units for Exp. 2 and 3. The measurements were similar in all experiments and included, baseline chemical status, soil penetration resistance (SPR) by penetrometer, seedling emergence, water infiltration using the Mariotte bottle technique, yield, plant density, plant cover and soil moisture. In Exp. 1 there were significant effects (P<0.05) between species for yield, species population density, penetration resistance, and water infiltration. However, there were no significant effects of fertilizer, or the fertilizer by species interaction (P>0.05). Water infiltration was negatively correlated with SPR . In Exp. 2 and 3, species treatments were significantly different for yield, SPR at some depths, water infiltration, population density, emergence, and cover (P<0.05). Fertilizer treatments were significantly different in yield, water infiltration and SPR for both experiments (P<0.05). However, fertilizer had no significant effects on emergence, cover, population density, and soil moisture. There was a species by fertilizer interaction effect (P<0.05) in yield and soil penetration resistance in both experiments. Therefore improved soil physical characteristics through biomass production and soil organic matter can reduce vegetation and soil degradation and enhance the overall sustainability of the soil quality.