Dr Gebreyohannes Girmay1, Mr Masakazu Yamada2, Mr Tesfay Berihu1, Mr Kazuhisa Koda2
1Mekelle Univeristy, Mekelle, Ethiopia, 2Japan International Research Center for Agricultural Sciences, Rural Development Division, Ibaraki 305-8686 , Japan
Ethiopian highland agriculture is dominated by crop production on small holder farms. Farmers in Tigray are abandoning cereal-legume crop rotation due to very low legumes’ yield. Continuing use of mineral fertilizers often fail to sustain cereal crops’ yield due to declining soil productivity and drought. A field experiment was conducted since 2014 to appraise legumes for green manure, and to evaluate wheat productivity for continuous 3 years (2015-2017) after one-time incorporation of green manure on degraded soil. Six leguminous species (Vicia faba, with recorded dry matter yield of 19.7t/ha and Vicia villosa, 12t/ha; Dolicos lablab, 10t/ha and Vigna unguiculata, 6.7t/ha; Lupinus angustifolius, 8.3t/ha and Lupinus albus, 6.7t/ha) were incorporated in 2014. There was no mineral fertilizer use and no crop residue left after each harvest. The results indicated wheat yield on average increased from 0.74t/ha on absolute control to 3.2t/ha in 2015 and 2016 but declined to 1t/ha in 2017 on Vicia species incorporated plots. Wheat yield increased to 2.7t/ha in 2015, 3.1t/ha in 2016 but declined to 1.4t/ha in 2017 on Dolicos lablab and Vigna unguiculata incorporated plots. Wheat yield increased to 1.6t/ha in 2015, 3.1t/ha and then declined to 1.3t/ha in 2017 on Lupinus species incorporated plots. It was observed that Vicia faba (also food crop), Vicia villosa, Dolicos lablab and Lupinus angustifolius in that order are good candidate green manure legumes for conservation agriculture. Wheat grown on Vicia species incorporated plots responded faster than on plots incorporated with Vigna unguiculata, Dolicos lablab and Lupinus species. On average, wheat yield significantly increased more than two-fold over the absolute control for three consecutive years once legume green manure is incorporated. Leguminous green manure obviates mineral fertilizer use in farming systems, sustains crop productivity leading to improved rural livelihoods in the Ethiopian and sub-Sahara African highlands.
Keywords: Wheat production, leguminous species, crop rotation, green manure, Ethiopia
Gebreyohannes Girmay has his expertise in soil fertility management systems focusing on exploring techniques for improving soil quality and health. He teaches and advices post graduate students in the soil science, dryland ecology and resource management, dryland agronomy, sustainable watershed management, and dryland agroforestry and land restoration programmes in Mekelle University, Ethiopia. His current research activities focus on integrated soil fertility management, carbon sequestration in soils, reservoir conservation and sediment use, and land evaluation for irrigation.