Temporal relationship between climate variability, Prosopis juliflora invasion and livestock numbers in the drylands of Magadi, Kenya

A study was conducted to determine the association of climate variability, Prosopis juliflora spread, and other vegetation trends with livestock population dynamics in Kajiado County, Kenya. Monthly rainfall, mean monthly temperatures, cattle, sheep and goats populations from January 2000 to December 2014, were analyzed to determine time series trends. Normalized Difference Vegetation Index (NDVI) data derived from moderate resolution imaging spectroradiometer (MODIS) 250 m satellite imageries for 2000 to 2014 were used to determine the temporal dynamics of P. juliflora invasion in the study area. Both temperature and rainfall trends showed marked variability over the period under study. The mean monthly temperatures during the long dry season increased erratically from 33°C in 2000 to 37°C in 2014. Moreover, the rainfall during the wettest season was 600 mm in 2000 and 250 mm in 2014. During the study period, divergence from the long term mean rainfall (450 mm) decreased from 585 to 403 mm. At the same time cattle population decreased, sheep and goats populations remained static. P. juliflora invasion correlated positively (r=0.2; P<0.05) with mean monthly temperature and negatively (r=-0.4; P<0.05) with rainfall and other vegetation cover in drier parts, but not in the higher altitude and wetter parts of the study area. It also correlated negatively with cattle populations (r=-0.4; P<0.05). In the 1980’s, bushlands and woodlands constituted 95 and 5% of the land cover, while in 2008, herbaceous vegetation, shrublands, and open trees together with bare areas constituted 50, 30, and 22%, respectively; out of which 70% had been taken over by Prosopis in 2014. This study demonstrated that even though the trends showed that cattle population decreased as climate variability and Prosopis invasion increased, there was no significant correlation among the attributes, over the period under study.Key words: Climate, drylands, livestock, Prosopis juliflora, variability vegetation, trends, mesquite

Sorghum production practices in an integrated crop-livestock production system in Makueni county, eastern Kenya

Productivity of sorghum has been below potential in arid and semi-arid lands of Kenya, due to poor agronomic practices and soil nutrient deficiency. Sorghum crop is fairly drought tolerant, resistant to waterlogging, and yields are reasonably better in infertile soils compared to other crops. Proper agronomic practices would significantly increase yields as well as nutrient content in grains and crop residues used as livestock feed. The objective of this study was to investigate the existing sorghum production practices and sorghum use as food and feed sources. A survey involving 90 farmers from sorghum producing areas in Makueni County was conducted. The survey focused on the varieties and fertilizers used, trends in yields, constraints to sorghum production and the present strategies used for sorghum as animal feed. Most farmers (84.4%) used uncertified seeds from own saved sources, and the commonly grown variety was Seredo (44.5%) due to resistance to bird damage. The majority (32.1%) of farmers recorded very low yield of sorghum grain, from151 to 250 kg ha-1. Most farmers (68.9%) used farmyard manure in sorghum production, while 30.9% of the farmers did not use any fertilizer. All farmers indicated that their greatest challenge in sorghum production was inadequate rainfall. Bird damage to the crop was a chronic problem to most (73.3%) farmers. The majority (58.9%) of farmers conserved sorghum residue for feed as hay. The findings show the need to provide technical information and guidance on the production practices, such as choosing best-yielding seed varieties, proper methods of pest and disease control and proper use and conservation of sorghum residue as animal feed

Effect of Tillage Practice on Soil Moisture Retention under Three Selected Cowpea Varieties

Aim: To evaluate the effect of tillage practice on soil moisture retention under three cowpea varieties. Study Design: The treatments were laid out in a randomized complete block design with a factorial arrangement and replicated three times. Place and Duration of Study: The experiment was conducted at St. Theresa farm and Nakamane irrigation scheme in Turkana county between November 2014 and January 2015. Methodology: Treatments comprised three tillage practices: conventional tillage (control), conventional tillage + mulch, and zero tillage and three cowpea varieties: M66, K80, and Kenkunde. Soil samples were collected using an auger (25 mm internal diameter) from near randomly selected 5 plants at the depth of 15 cm in all treatments at an interval of 7 days. The gravimetric moisture was determined using the FAO equation. Results: Tillage + mulch and zero tillage conserved 37.07% and 31.63% more moisture than conventional tillage at St Theresa demo farm, respectively. At Nakamane irrigation scheme, zero tillage retained more moisture content of 33.02% followed by conventional tillage + mulch at 32.24% as compared to conventional tillage. Significant interaction was realized between tillage practice and variety at Nakamane experimental site only. The main effects of variety had no effect on moisture retention. Conclusion: Tillage practice has significant effect of moisture retention in Turkana county. Any cowpea variety established has no effect on moisture retention. A broader use of tillage practices and varieties is advisable for further studies

Trees improve water storage and reduce soil evaporation in agroforestry systems on bench terraces in SW Uganda

The success of agroforestry in semi-arid areas depends on efficient use of available water and effective strategies to limit tree/crop competition and maximise productivity. On hillsides, planting improved tree fallows on the degraded upper section of bench terraces is a recommended practice to improve soil fertility while cropping continues on the lower terrace to maintain food production. This study examined the influence of tree fallows on soil water content (θ w ) and evaporation (E s ). Alnus acuminata Kunth (alnus), Calliandra calothyrsus Meissner (calliandra), Sesbania sesban L. (sesbania), a mixture of all three species, or sole crops (beans (Phaseolus vulgaris L.) or maize (Zea mays L.)) were grown on the upper terrace. The same sole crops were grown on the lower terrace. Four management regimes (unpruned, root, shoot and root + shoot pruned) were applied to the tree rows adjacent to the cropping area. Neutron probe and microlysimeter approaches were used to determine θ w and E s when the trees were c. 3.5 years old. Sesbania and alnus increased θ w by 9–18 % in the cropping area on the lower terrace but calliandra reduced θ w by 3–15 %. After heavy rain, E s comprised 29–38 % of precipitation in the tree-based treatments and 53 % under sole crops. Absolute values declined as rainfall decreased, but E s as a proportion of rainfall increased to 39–45 % in the tree-based treatments and 62 % for sole crops. Root + shoot pruning of alnus and the tree mixture increased θ w in the cropping area but had no significant effect in the other tree-based treatments. The results suggest that sesbania and alnus can be planted on smallholdings without compromising water supply to adjacent crops, whereas calliandra decreased water availability despite reducing E s . These results provide a mechanistic understanding of reported effects on crop yield in the same site