Can selected forage species improve soil quality in subtropical smallholder farming  

Abstract

<p>Livestock is vital for food security and economy for a large part of the population in Ethiopia. The country has the highest livestock numbers in Africa, but cultivation of forage crops is still not very common. Most of the feed for the animals is derived from crop residues after harvest of arable crops, and during the dry season, the livestock roams freely and grazes on communal land. The intensive grazing causes a low return of nutrients to the soil, which leads to severe degradation of the soil quality. We are investigating how introduction of selected perennial forage species impacts microbial activity in the soil and if it potentially improves soil quality. We use four different forage species, the grasses <em>Brachiaria </em>hybrid Cayman and <em>Panicum maximum</em>, and the legumes <em>Desmodium intortum</em> and <em>Stylosanthes guianensis</em>, in a greenhouse experiment. The plants are grown in quartz sand inoculated with four degraded Ethiopian farm soils, two from the southern Sidama region and two from the northern Amhara region. The plants are grown in single stands and in two-species mixtures of <em>B. </em>hybrid Cayman<em> </em>and<em> P. maximum</em>, and <em>B. </em>hybrid Cayman<em> </em>and<em> D. intortum</em>, for 12 weeks. To assess potential plant effects on the soils, we will sample the soil at the end of the experiment and determine microbial biomass carbon, nitrogen and phosphorus, and the enzymatic activity of four enzymes involved in C, N and P acquisition. This will be compared to a time zero analysis of the soil to discern the impact the plants have on the soil microbial nutrient stoichiometry.</p>