Abstract
Effects of stages of growth and intercropping of two sweet potato varieties (Hawassi-83 and Tula) (alone or with coffee or maize-haricot bean) on biomass yield and in vitro dry matter digestibility (IVDMD) of morphological fractions were assessed in Southern Ethiopia. Similar coffee plantations (age, density, soil type, topography) were selected for intercropping. Vines were planted on three plots per intercropping type at 15 days interval, and cultivated three times. Morphological fractions were collected from 1.0 m2 of land on 4th, 5th and 6th months for nutrient and partial budget analyses (revenue estimated for 100 m2 of land). Ten elders evaluated varieties at 2nd, 4th and 6th months after planting. Lowest DM (77 g/kg) was obtained from fresh Tula stem-petiole (FTSP) but highest (190 g/kg) from fresh Tula leaf (FTL) (p<0.05). Fresh Tula vine (FTV) had lowest (840 g/kg DM) organic matter and FTL (p<0.05) highest (914 g/kg DM). Crude protein content of fresh Hawassi-83 stem-petiole (FHSP) was lowest (113 g/kg DM) but that of FTL highest (269 g/kg DM). Lowest vine yield (0.27 kg/m2) was from Tula intercropped with coffee but highest (0.82 kg/m2) from maize-haricot bean intercropping followed by sole Hawassi-83 (0.56 kg/M2). Overall mean vine DM yield (333.6 g/m2) of maize-haricot bean intercropping was greater (p<0.05) than that of intercropping (174.0 g/m2) with coffee. IVDMD of fresh Hawassi-83 leaf (FHL) (78.0±0.27) and FTSP (77.0±0.10) were lowest but that of FHSP (84.3±0.59) and FTL (84.3±0.04) highest. Both Hawassi-83 and Tula vine were best produced when intercropped with maize-haricot bean, although Hawassi-83 was more profitable and preferred by respondents than Tula. Key words: Intercropping, morphological fractions, nutrients, stage of maturity, sweet potato vine.
Highlights
IntroductionThe huge livestock population is constrained by insufficient and poor quality feed
The studies of Tesfaye et al (2011) have shown that the dry matter (DM) content of unspecified sweet potato variety was 92% but neither of the DM contents of vines from the varieties in this study agreed with this value
Netsanet (2006) reported DM of unspecified variety of sweet potato vine, leaf and stem were 21.05, 21.7 and 18.67%, respectively but only the leaf part was close to the DM content of fresh Tula leaf (FTL)
Summary
The huge livestock population is constrained by insufficient and poor quality feed. Natural pastures and poor quality crop residues are the main sources of livestock feed in East Africa. Grazing lands do not fulfill the nutritional requirement of animals in dry seasons (Zinash et al, 1995). With the rapid increase in human population and high demand for food, pastures are steadily being converted to crop lands. Less productive marginal lands unsuitable for cultivation are left for grazing. Deforestation and overgrazing has substantially reduced soil fertility and productivity (Alemayehu, 1999). The limited land available for feed and fodder production and poor quality pasture demanded total dependence of livestock on crop residues and by-products (Firew, 2001). Assessing forage production options in the limited land available is of paramount importance to mitigate this constraint
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