Impacts of Acacia Biochar and Irrigation Scheme on Teff Production for Dry Season in Highland of Ethiopia

Teff (Eragrostis tef) is one of the essential cereal crops grown mainly in rainy season and barely grown in dry season, but has the lowest yield compared to other cereal crops such as wheat and barley in Ethiopia. High prices and scarcity of fertilizers challenge farmers in teff production. Nitisols in tropical Ethiopia have a characteristic of low fertility and high acidity causing low crop productivity, which require application of organic amendment to bring chemical and physical soil properties at levels to achieve a good crop productivity, which could contribute to food security and sustainable agriculture. Therefore, the purpose of this study was to evaluate the effects of different application rates of acacia biochar (ACB) under two different irrigation schemes on soil nitrogen and water dynamics and teff production. Biochar application rates were 0, 5, and 20 t ha–1 (0ACB, 5ACB, and 20ACB, respectively) and irrigation schemes were 75% and 100% of water requirement (I1 and I2, respectively) by teff according to farmers’ practice. Soil pH with 20ACB at 10 cm soil depth was significantly increased in the beginning of growing season. ACB application and irrigation schemes did not significantly affect soil NH4+-N and NO3--N at both 10 and 30 cm depths throughout growing season. Soil water content limited by dry growing season in this experiment may be critical and underrated for effective amelioration of soil acidity and plant nutrient improvement by biochar application. Under both irrigation schemes, 20ABC-I1 and 20ABC-I2 presented higher teff dry biomass (22-23% and 21-30%, respectively) and plant height (9.4-9.8% and 13.2-14.7%, respectively) than those with 0ACB and 5ACB, respectively, however only under I2 irrigation scheme it was significant. This study showed that the combination of different irrigation schemes combined with biochar application had somewhat positive impacts on teff biomass production. However, limited amount of water supplied from irrigation particularly during dry season may mask such effects of biochar on crop growth by limiting interaction of biochar with soil particles compared to wet season. This combination should contribute and stimulate crop production and efficiency of water usage. However, particularly in highland of Ethiopia, to avoid grain loss by rainfall, it is recommended to start growing period early with sowing in December for dry season. Further studies with long-term biochar application and different window of sowing time are necessary for better understanding of such practices.