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.

Background: Land degradation and unsustainable management practices have resulted in soil organic carbon and nutrient depletion, hydrological instability, reduced primary productivity, and low biological diversity. In response to these problems, communities in the Central Rift Valley area of Ethiopia have started to establish exclosures about three decades ago. This study has investigated the variations in selected soil properties (soil textural fractions, bulk density, soil moisture content, pH (H 2 O) and soil organic carbon content) under two land use types: open grazing land and exclosures in the Central Rift Valley of Ethiopia. Results:Results showed that soil organic carbon varied significantly with land use types (p = 0.040), soil depths (p = 0.010) and the interaction effect (p = 0.039). The soil moisture content showed significant variation (p < 0.0001) only with soil depth.

SUMMARYLow soil pH and associated soil infertility problems are considered to be amongst the major challenges to barley production in the highlands of Ethiopia. In response to this, an experiment was conducted at low soil pH (< 5 H2O) site on the effects of different levels of lime and phosphorus (P) fertilizer on soil pH, exchangeable aluminium (Al3+), grain yield and yield components of barley during 2010 and 2011 cropping seasons. The experiment comprised factorial combinations of five lime rates (0, 0.55, 1.1, 1.65 and 2.2 t ha−1) and four P rates (0, 10, 20 and 30 kg ha−1) in a randomized complete block design in three replications. The amount of lime that was applied at each level was calculated on the basis of Al3+. Results of soil analysis after 2 years of liming showed that liming significantly (P < 0.05) increased soil pH, and markedly reduced exchangeable Al3+. Liming at the rate of 0.55, 1.1, 1.65 and 2.2 t ha−1 decreased Al3+ by 0.88, 1.11, 1.20 and 1.19 mill equivalents per 100 g of soil, and increased soil pH by 0.48, 0.71, 0.85 and 1.1 units, respectively. Amongst the liming treatments, liming at the rate of 1.65 and 2.2 t ha−1 gave significantly (P < 0.05) the highest grain yield and yield components of barley. However, grain yield obtained by applications of 1.65 and 2.2 t ha−1 lime was statistically comparable. By additions of 10, 20 and 30 kg P ha−1, grain yield of barley increased by about 29, 55 and 66% as compared to control (without P). During 2010, however, the combined applications 1.65 t ha−1 lime and 30 kg P ha−1 gave 133% more grain yields of barley relative to control (without P and lime). Therefore, sustainable barley production on acid soils in the central highlands of Ethiopia should entail combined applications of both lime and P fertilizer.

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