Around 1900 temperate and semidesert grassland productivity declined, soil erosion incrensed, and drought destabllixed the live stock industry in the northern and southern hemispheres. As government leaders throughout the world began to recognize the importwee of grassiaad productivity nnd soil conservation, a massive experiment began to evolve. Government and private hrdividurls collected seed from every continent, and planted seed at experimental stations and ranches in their respective countries. Hundreds of individuals who conducted thousands of seeding trials observed that buffelgrass (Cenekrur c&u& L.), weeping lovegrass [Erugrostts curv& (Schrad.) Neesl, kleingrass (Pun&urn coiivatwn L.), and Lehmann lovegrass (Eragrostts l&mum&no Nees) plants from seed coiiected in Africa were easier to establish and persisted longer than other grasses. Uetween 1930 and 1986 scientists in many countries evaluated the estabiishment and persistence of these grasses, but no attempt was made to syntbesixe the data base and determine the effects of climate and soil on piant estab-Ushment and persistence. Our objective was to: (1) determine the climatic and edapbic characteristics of areas where the seed of each grass was collected in Africa, and where each grass has been successfuliy established in both hemispheres, and (2) identify characteristics which infiuence long-term persistence. Where buffelgrass predominates and spreads, summer rainfall varies from 150 to 550 mm, winter rainfall is less than 400 mm, mean miminum winter temperatures rarely fall below 50 C, and soil texture is loamy. Weeping lovegrass can be established and plants persist when spring, summer, and fail rainfall varies from 400 to 1,000 mm on deep sandy soil end mean minimum winter temperrtures rarely fall below -50 C. The invesion of adjacent nonplanted sites occurs only in Africa where growing season reinfall infrequently cycles between 750 and 1,000 mm and soils remahr wet in mid-summer. Kleingrass can be established where mean maximum daily summer temperatures are above 300 C, mean minimum daily winter temperatures rarely fall below 00 C, summer growing season rainfall vuies from 400 to 999 mm, and soils are clayey or silty. Kleingrass, like weeping lovegrass, spreads to nonplanted sites only in Africa where a mid-summer drought does not occur. Lehmann lovegrass predominates and spreads only in southern Africa, southeastern Arizona, and northern Mexico when summer r&fail in 30 to 40 days exceeds 150 mm, and soil textures are sandy or sandy loam.

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A field experiment was conducted to assess the effect of the combined use of farmyard manure and inorganic fertilizer on the growth and yield of sorghum and on soil chemical properties in a semi-arid area in northeastern Ethiopia. Twelve treatments comprising factorial combinations of four levels of farmyard manure (0, 5, 10, and 15 t ha −1 ) and three levels of inorganic fertilizers (0%, 50%, and 100% of the recommended rate) were compared in a randomized complete block design with three replications over a period of six years. The results revealed significant improvements in the growth and yield of sorghum due to the main and interaction effects of farmyard manure and inorganic fertilizer application. The combined application of farmyard manure and inorganic fertilizers increased post-anthesis dry-matter production by 147%-390% and grain yield by 14%-36%. The main effects of farmyard manure and inorganic fertilizers increased stover yield by 8%-21% and 14%-21%, respectively. Farmyard manure application increased total nitrogen (N) uptake by 21%-36%, grain protein yield by 8%-11%, and grain protein concentration by 20%-29%. Application of farmyard manure along with 50% of the recommended inorganic fertilizer rate resulted in a grain yield equivalent to, or greater than that for 100% of the recommended inorganic fertilizer rate, thus effecting a 50% savings of inorganic N and phosphorus (P) fertilizer. Application of 5, 10, and 15 t farmyard manure ha −1 along with 100% of the recommended fertilizer rate and 5, 10, and 15 t farmyard manure ha −1 along with 50% of the recommended fertilizer rate can be recommended for farmers who can and cannot afford to buy inorganic fertilizers, respectively.

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Sub-Saharan Africa contains soils that have been cropped for generations. Consequently, their inherent fertility has been severely depleted. In such soils, net negative balances of nutrients are a common problem. The current soil nutrient depletion rates are contributing towards decreasing crop yields. The search for sustainable soil fertility replenishment techniques is, therefore, an urgent need. A key resource in this respect is animal manure. Such manure can increase and maintain soil fertility by providing N, P, K, S, Ca, Mg, Na and other trace elements such as Fe, Mn, Cu, Zn. It also improves the pH of acid soils and calcareous soils, increases soil organic matter content and cation exchange capacity, improves soil aggregate stability, soil macro-structure, infiltration, water holding capacity and erosion resistance. However, animal manure cannot meet crop nutrient demand over large areas, because of the limited quantities available and the relatively low nutrient content W. Bayu is affiliated with the