Background In Southwest Ethiopia, various plant species are coexisting in wild and cultivated forms. This provides an ideal setting for studying folk biosystematics of neglected species. One of such species is the Dioscorea species, in which we studied to assess the commonly applied folk wisdom of identifying, naming, and classifying yams by Sheko and Bench farmers. Methods This study was conducted in Bench-Maji and Sheka Zones using 272 farmers. Data on the lists of local names and system of folk taxonomy; the inherent logic, etymons, and consistency of names; and the folk descriptors and other criteria involved in taxonomy were collected. Data were collected by establishing participatory research appraisal tools, i.e., informant interviews and researcher direct observation. Results The result suggests that there exists a well-developed folk taxonomic system in Sheko and Bench. This is evident in the recognition of four distinct folk ranks: sub-variety, variety, supra-variety, and folk generic. Taxa assigned to each ranks have distinct features that mark them as members of a separate categories. Farmers over-differentiate 58 individual taxa at the intraspecific levels. Of these, 37 represented varietal taxa while the rest are sub-varietal taxa. Structurally, over 78% of the varieties are labeled with unitary names while all the sub-varieties consisted of binomial names. Farmers used a total of 26 characters and 74 character states for identifying the different taxa. More than 84% of these refer to aspects of plant characteristics. Tuber characters played a key role in the local identification of varietal and sub-varietal taxa while contexts and gender played a key role in the recognition of supra-variety groups. Conclusions This study documented a great wealth of knowledge on indigenous biosystematics of yams, constitutes an essential step towards setting development priorities aimed at in situ conservation. The study clearly demonstrated the value of folk biosystematics for assessing the actual extent and spatial dynamics of yam diversity in traditional farming.

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Potassium dynamics of soils is constituted by constantly changing relationship between soil K forms, and this relation is affected by some soil physical and chemical properties. Most Sidama (south Ethiopia) farmers grow enset crops which have high K requirements. The soils were collected from Awassa-Zuriya and Dale districts; 'Woinadega' (warm subtropical climate) and Hula district 'Dega' (wet, cool temperate climate). Overview of K dynamics in soils via Quantity-Intensity (Q/I) curves was used to evaluate the dynamics of K in fifteen soil samples representing the enset farming systems of Sidama. All of the Hula district soils and half of the Dale district soils had low percent K saturation. There were significant correlations between some soil properties and Q/I parameters and among equilibrium solution parameters and Q/I parameters. Variations among the mean quantity (±∆K) values of the soils were not significant. The Dale and Hula district soils had higher K intensity than the Awassa-Zuriya district soils; where the Hula (Adola kura kebele) soil had the highest value. Therefore, the Dale and Hula district soils will require frequent and split K applications since they have lower capacity to maintain long-term supply of K. On the other hand, Awassa-Zuriya district soils had high K quantity than the Dale and Hula district soils. This shows that the Awassa-Zuriya district soils have a higher potential to supply K for a longer period of time from the exchangeable pool. However, the AwassaZuriya district soils require less frequent and higher K fertilization to saturate the exchangeable pool to meet immediate potassium requirement of crops. The low equilibrium activity ratio of potassium and low potassium replenishing capacity of nearly all of the soils studied also indicated the need for K application.