Effects of Agroforestry Practices on Soil Properties in the Drylands of Eastern Kenya

Drylands, which are home to about 2 billion people face a myriad of problems among them low land productivity. Agroforestry is one of the land use practices that is perceived to be sustainable with beneficial effects on soil properties. However, the effects of agroforestry practices on soils especially in the drylands have rarely been quantified and studied in details. The study determined the effects of selected agroforestry practices on soil properties in Makueni County of Kenya where agroforestry has been promoted by various organizations. Four soil samples were collected at 0-15cm, 15-30cm, 30-45cm and 45-60cm depths in a zigzag pattern at each 10 x 10m plots established along line transects laid in woodlots established in 2007, 2010 and 2013 and their adjacent parkland and grazing land. Seven randomly selected farms were sampled. The samples were analyzed using laboratory methods for soil nutrients and physical properties. Density of tree species in these established plots were also determined using quadrat technique. Tree density was higher in woodlots followed by grazing area and parkland .Soil samples showed that Soil Organic Carbon and Total Nitrogen were significantly higher in the woodlots than in the parkland and grazing lands ((p≤0.05). Soil Organic Carbon was significantly higher in woodlots established in 2007 than those established in 2013. Phosphorus was significantly higher in cropland compared to woodlots and grazing land. Phosphorus and Potassium were significantly higher at 0-15 cm depth compared to other soil depths. Bulky density was significantly higher with a corresponding lower total porosity in grazing lands than in the woodlots and parklands. The results suggest that different agroforestry practices contribute differently to soil properties. Mixed tree woodlots contributed significantly to improving soil properties and could be considered as a strategy to sustainably restore degraded and infertile soils in the drylands

Economic Valuation of Grazing Management Practices: Discrete Choice Modeling in Pastoral Systems of Kenya

This study estimates the economic contribution of grazing management practices in pastoral systems by specifically undertaking an economic analysis of pastoralists’ preferences for grazing management practices and the economic value pastoralists place on them. The study applied the discrete choice experiment technique using a D-optimal design, a multi-attribute preference elicitation method to evaluate the economic value of grazing management options practiced in pastoral areas of Kenya. The results show that pastoral communities derive positive utility in connected systems that enable reciprocal access to resources in both wet and dry seasons. Pastoralism adapts to spatial–temporal variability of pasture and water through herd mobility; hence the positive utility derived from practices that contribute to the availability of adequate water and pasture across the seasons. These findings provide empirical evidence on the social and economic net benefits of rangeland management practices that should be enhanced to promote sustainable management of rangeland resources

Dry matter yields and hydrological properties of three perennial grasses of a semi-arid environment in east Africa

Enteropogon macrostachyus (Bush rye), Cenchrus ciliaris L. (African foxtail grass) and Eragrostis superba Peyr (Maasai love grass) are important perennial rangeland grasses in Kenya. They provide an important source of forage for domestic livestock and wild ungulates. These grasses have been used extensively to rehabilitate denuded patches in semi-arid environment of Kenya. This study investigated the dry matter yields and hydrological properties of the three grasses under simulated rainfall at three phenological stages; early growth, elongation and reproduction. Laboratory seed viability tests were also done. Hydrological properties of the three grasses were estimated using a Kamphorst rainfall simulator. Results showed that there was a significant difference (p > 0.05) in dry matter yields and soil hydrological properties at the different grass phenological stages. Generally, all the three grasses improved the soil hydrological properties with an increase in grass stubble height. C. ciliaris gave the best soil hydrological properties followed by E. macrostachyus and E. superba, respectively. E. macrostachyus recorded the highest seed viability percentage. C. ciliaris and E. superba were ranked second and third, respectively. C. ciliaris yielded the highest biomass production at the reproductive stage followed by E. superba and E. macrostachyus, respectively. (Résumé d'auteur

Adoption of water harvesting technologies among agro-pastoralists in semi-arid rangelands of South Eastern Kenya

The arid and semi-arid lands experience inherently unpredictable rainfall and frequent droughts, which are exacerbated by climate change. This consequently leads to deterioration of land resources, and eventually forage and water shortages that negatively impact livestock productivity. In Kenya, development and government agencies have been supporting on-farm adaptation strategies such as water harvesting conservation structures to cope with climate hazards that affect agricultural production and food security in agro-pastoral and pastoral systems. The various water harvesting structures that have been promoted include Zai pits for growing crops and trees, water pans and shallow wells for livestock and domestic use, as well as for irrigation. However, the impact of such interventions with regard to improvement of range productivity and therefore welfare of agro-pastoral and pastoral communities has not been felt owing to low adoption rate by households

Grass reseeding technology as a means of rehabilitating degraded lands and improving livelihoods of agro-pastoral communities in semi-arid Kenya

Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the inhabited semi-arid lands. Cenchrus ciliaris (African foxtail grass), Enteropogon macrostachyus (bush rye) and Eragrostis superba (Maasai love grass) are important perennial grasses in the Eastern African semi-arid lands. A study was conducted to establish the contribution of these indigenous grasses in improving soil hydrological properties, rehabilitation, food security and the livelihoods of agro-pastoral communities in semi-arid districts of Kenya. Soil hydrological properties were tested using a Kamphorst simulator at different stubble heights to represent three different grazing intensities (low, medium, high). Ground cover was estimated using the step-point method. A survey was also conducted across 50 agro-pastoral households to establish the multidimensional benefits of the grasses. Sediment production (as a function of run-off and infiltration capacity) was significantly different (P<0.05) at different stubble heights. Ground cover estimates of the grasses were also significantly different (P<0.05). Cenchrus ciliaris had the greatest influence in improving soil hydrological properties. Enteropogon macrostachyus and E. superba were ranked second and third, respectively. Enteropogon macrostachyus had the greatest ground cover. Cenchrus ciliaris and E. superba were ranked second and third, respectively. These results were attributed to the growth and morphological characteristics of the grasses. Generally, an increase in stubble height increased infiltration capacity and reduced run-off and sediment production. Results from the household survey showed that the grasses provide a source of income through the sale of hay, grass seeds and milk, which also achieve a balanced diet. The grasses also provide a cheap source of thatching materials and livestock feed. (Résumé d'auteur