Feed resources,livestock production and soil carbon dynamics in Teghane,Northern Highlands of Ethiopia

In the Northern Highlands of Ethiopia, integrated crop-livestock production within smallholder farms is the dominant form of agricultural production. Feed availability and quality are serious constraints to livestock production in Ethiopia in general, and in its Northern Highlands in particular. The objective of this study was to describe the relationship between feed availability and quality and live weight gain, milk and manure production and the soil C balance in Teghane, Northern Highlands of Ethiopia. The so-called JAVA model procedure, that essentially predicts metabolizable energy intake and animal production on the basis of feed quality and quantity, has been used and linked to a soil carbon balance. Forages were ranked according to their quality (on the basis of metabolizable energy intake by livestock) in descending order. Rations were formulated by stepwise including components of increasingly lower quality to calculate the trade-offs between feed quantity and quality. In the model, the soil C balance was described in relation to soil organic matter decomposition, C input from roots, grazing and/or harvesting losses, feed residues and manure. Moreover, an analysis of monetary values of live weight gain/loss, manure and draught power is included. The results of the model showed that mean daily live weight gain and milk production per TLU continuously increased with decreasing herd size, while total annual live weight gain reached a maximum (62 Mg) at the use of the 30% best feeds and a herd size of 630 TLU. Soil C balance at this level of feed use is negative and deteriorates with increasing feed use. The model estimated an optimum herd size of 926 TLU to attain the maximum combined monetary value of live weight gain, manure and draught power at 50% feed use. Actual herd size in the study area was 1506 TLU. Our results indicate that in areas where feeds of very different quality are available, maximum benefits from meat and/or milk production and soil C balance can be attained by selective utilization of the best quality feeds, through a storage and carry-over system.     

Modelling soil nutrient dynamics under alternative farm management practices in the Northern Highlands of Ethiopia

Agricultural production in the Northern Highlands of Ethiopia is low, stagnant or unsustainable. The objectives of this study were to explore long-term dynamics of soil organic carbon (C), nitrogen (N) and phosphorus (P) and the consequences for crop-available N and P to support the design of sustainable farm management practices for higher yields and improved livelihoods in the Northern Highlands of Ethiopia. Simplified soil N and P dynamics modules are described. C dynamics have been linked to the dynamics of organic N via the C:N ratio. The model has been calibrated on the basis of empirical data from the study area. The N and OC modules have been validated on the basis of an empirical data set for fields continuously cultivated for 7–53 years in smallholder farms in the Highlands of Ethiopia. The model has been applied for exploration of long-term dynamics of soil N, OC and P and crop available N and P under alternative farm management regimes. The simulation results indicate that, in terms of soil OC, the control management results in 44, 42 and 38% depletion, respectively, in Cambisols, Luvisols and Leptosols; current management practice (Alt1) results in 16% reduction in Cambisols, 32% in Luvisols, but a 22% increase in Leptosols; Alt2 (returning all non-economic organic material to the soil) results in 27% reduction in Luvisols, whereas in Cambisols and Leptosols it increases by 1 and 57%, respectively, after 50 years of cultivation. The rates of changes in soil N are similar to those in OC under current management, Alt1 and Alt2. In terms of total soil P, the control management and Alt2 result in 46 and 43% depletion in Cambisols and 53 and 52% in Luvisols over the 50 years. On the other hand, Alt1 results in build-up of total soil P in Cambisols (69% higher after 50 years), but still to depletion (8%) in Luvisols. All other management regimes are not ‘sustainable’ in terms of soil N, OC and P, and lead to ‘soil mining’. Finally, the model has been used to estimate the required organic amendments and inorganic P inputs to maintain the current status of soil OC and P, as a benchmark of management practices. To maintain the current status of soil OC, the required composted organic amendments were 5.3, 15.0 and 2.1 Mg ha⁻¹ annually for Cambisols, Luvisols and Leptosols, respectively. To maintain the current soil P-levels, required inorganic P-doses (in addition to organic P contributions from composted organic fertilizer from 5.3 (in Cambisols) and 15.0 (in Luvisols) Mg ha⁻¹ year⁻¹) were 8 kg ha⁻¹ year⁻¹ in Cambisols and 23 kg in Luvisols. The model is relatively easy to parameterize for specific situations and reproduces the most important aspects of soil nutrient dynamics. The modelling approach developed in this study can support the design of appropriate soil N, OC and P management practices that eventually should lead to higher yields and improved livelihoods.     

Genetic diversity and matrilineal genetic origin of fat-rumped sheep in Ethiopia

Ethiopia is home to a diverse gene pool of indigenous sheep populations. Therefore, a better understanding of genetic variation holds the key to future utilization through conservation. Three of these breeds, Afar, Blackhead Somali, and Hararghe Highland, are found in eastern Ethiopia where they contribute significantly to the livelihood of most pastoralist, agro-pastoralist, and smallholder farmers. These indigenous sheep are recognized on the basis of morphotype and their genetic distinction remains unknown. Here, to assess genetic variation, and matrilineal genetic origin and relationship of fat-rumed sheep found in eastern Ethiopia, 300 individuals from the three breeds were genotyped for 22 microsatellite markers and sequenced for the mitochondrial DNA displacement loop (mtDNA d-loop) region. The overall H_O and H_E were 0.57 and 0.75, respectively. Differentiation statistics revealed that a high proportion (97%) of the total genetic variation was explained by differences between individuals within populations. Genotype assignment independent of the population of origin showed K?=?2 to be the optimum number of genetic backgrounds present in the dataset. This result was further confirmed by mtDNA D-loop sequences comparison in which the matrilineal genetic origin of eastern Ethiopia sheep is from two haplotype groups (types A and B) among the five haplotypes globally observed. Taken together, our findings suggest that the sheep populations from three breeds originated from two ancestral genetic backgrounds that may have diverged prior to their introduction to Ethiopia. However, to obtain a complete picture of the evolutionary dynamics of Ethiopian indigenous sheep, more samples and populations from within and outside of the country will need to be analyzed.