ILRI LSE program outputs

Permanent URI for this collectionhttps://hdl.handle.net/10568/636

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Remotely sensed thermal decay rate: An index for vegetation monitoring
(Journal Article, 2020-06-17) Kumar, S.S.; Prihodko, L.; Lind, B.M.; Anchang, J.; Ji, W.; Ross, C.W.; Kahiu, Njoki; Velpuri, Naga Manohar; Hanan, N.P.
Vegetation buffers local diurnal land surface temperatures, however, this effect has found limited applications for remote vegetation characterization. In this work, we parameterize diurnal temperature variations as the thermal decay rate derived by using satellite daytime and nighttime land surface temperatures and modeled using Newton’s law of cooling. The relationship between the thermal decay rate and vegetation depends on many factors including vegetation type, size, water content, location, and local conditions. The theoretical relationships are elucidated, and empirical relationships are presented. Results show that the decay rate summarizes both vegetation structure and function and exhibits a high correlation with other established vegetation-related observations. As proof of concept, we interpret 15-year spatially explicit trends in the annual thermal decay rates over Africa and discuss results. Given recent increases in availability of finer spatial resolution satellite thermal measurements, the thermal decay rate may be a useful index for monitoring vegetation.
Temporal variation in confirmed diagnosis of fever-related malarial cases among children under-5 years by community health workers and in health facilities between years 2013 and 2015 in Siaya County, Kenya
(Journal Article, 2017-12) Apat, D.O.; Gachohi, John M.; Karama, M.; Kiplimo, Jusper Ronoh; Sachs, S.E.
Crowdsourcing information in the drylands
(Presentation, 2018-10-03) Jensen, Nathaniel D.
Biases in crowdsourced livestock data and its impact on modelling tick distribution in semi-arid savannas of Kenya
(Poster, 2018-10-03) Kiplimo, Jusper Ronoh; Aarts, M. Noelle C.; Boer, W. Fred de; Bommel, Severine van; Pfeifer, Catherine
A meta-analysis of soil salinization effects on nitrogen pools, cycles and fluxes in coastal ecosystems
(Journal Article, 2017-03) Minghua Zhou; Butterbach-Bahl, Klaus; Vereecken, H.; Brüggemann, N.
Salinity intrusion caused by land subsidence resulting from increasing groundwater abstraction, decreasing river sediment loads and increasing sea level because of climate change has caused widespread soil salinization in coastal ecosystems. Soil salinization may greatly alter nitrogen (N) cycling in coastal ecosystems. However, a comprehensive understanding of the effects of soil salinization on ecosystem N pools, cycling processes and fluxes is not available for coastal ecosystems. Therefore, we compiled data from 551 observations from 21 peer‐reviewed papers and conducted a meta‐analysis of experimental soil salinization effects on 19 variables related to N pools, cycling processes and fluxes in coastal ecosystems. Our results showed that the effects of soil salinization varied across different ecosystem types and salinity levels. Soil salinization increased plant N content (18%), soil NH4+ (12%) and soil total N (210%), although it decreased soil NO3− (2%) and soil microbial biomass N (74%). Increasing soil salinity stimulated soil N2O fluxes as well as hydrological NH4+ and NO2− fluxes more than threefold, although it decreased the hydrological dissolved organic nitrogen (DON) flux (59%). Soil salinization also increased the net N mineralization by 70%, although salinization effects were not observed on the net nitrification, denitrification and dissimilatory nitrate reduction to ammonium in this meta‐analysis. Overall, this meta‐analysis improves our understanding of the responses of ecosystem N cycling to soil salinization, identifies knowledge gaps and highlights the urgent need for studies on the effects of soil salinization on coastal agro‐ecosystem and microbial N immobilization. Additional increases in knowledge are critical for designing sustainable adaptation measures to the predicted intrusion of salinity intrusion so that the productivity of coastal agro‐ecosystems can be maintained or improved and the N losses and pollution of the natural environment can be minimized.
Nitrate leaching and soil nitrous oxide emissions diminish with time in a hybrid poplar short‐rotation coppice in southern Germany
(Journal Article, 2017-03) Díaz Pinés, Eugenio; Molina Herrera, S.; Dannenmann, Michael; Braun, J.; Haas, E.; Willibald, G.; Arias Navarro, Cristina; Grote, R.; Wolf, B.; Saiz, Gustavo; Aust, C.; Schnitzler, J.P.; Butterbach-Bahl, Klaus
Hybrid poplar short‐rotation coppices (SRC) provide feedstocks for bioenergy production and can be established on lands that are suboptimal for food production. The environmental consequences of deploying this production system on marginal agricultural land need to be evaluated, including the investigation of common management practices i.e., fertilization and irrigation. In this work, we evaluated (1) the soil‐atmosphere exchange of carbon dioxide, methane, and nitrous oxide (N2O); (2) the changes in soil organic carbon (SOC) stocks; (3) the gross ammonification and nitrification rates; and (4) the nitrate leaching as affected by the establishment of a hybrid poplar SRC on a marginal agricultural land in southern Germany. Our study covered one 3‐year rotation period and 2 years after the first coppicing. We combined field and laboratory experiments with modeling. The soil N2O emissions decreased from 2.2 kg N2O‐N ha−1 a−1 in the year of SRC establishment to 1.1–1.4 kg N2O‐N ha−1 a−1 after 4 years. Likewise, nitrate leaching reduced from 13 to 1.5–8 kg N ha−1 a−1. Tree coppicing induced a brief pulse of soil N2O flux and marginal effects on gross N turnover rates. Overall, the N losses diminished within 4 years by 80% without fertilization (irrespective of irrigation) and by 40% when 40–50 kg N ha−1 a−1 were applied. Enhanced N losses due to fertilization and the minor effect of fertilization and irrigation on tree growth discourage its use during the first rotation period after SRC establishment. A SOC accrual rate of 0.4 Mg C ha−1 a−1 (uppermost 25 cm, P = 0.2) was observed 5 years after the SRC establishment. Overall, our data suggest that SRC cultivation on marginal agricultural land in the region is a promising option for increasing the share of renewable energy sources due to its net positive environmental effects.
Land use alters dominant water sources and flow paths in tropical montane catchments in East Africa
(Preprint, 2018) Jacobs, S.R.; Timbe, E.; Weeser, B.; Rufino, Mariana C.; Butterbach-Bahl, Klaus; Breuer, Lutz
Conversion of natural forest to other land uses could lead to significant changes in catchment hydrology, but the nature of these changes has been insufficiently investigated in tropical montane catchments, especially in Africa. To address this knowledge gap, we identified stream water sources and flow paths in three tropical montane sub-catchments (27–36 km2) with different land use (natural forest, smallholder agriculture and commercial tea plantations) within a 1 021 km2 catchment in the Mau Forest Complex, Kenya. Weekly samples were collected from stream water, precipitation and soil water for 75 weeks and analysed for stable water isotopes (δ2H and δ18O) for mean transit time estimation, whereas trace element samples from stream water and potential end members were collected over a period of 55 weeks for end member mixing analysis. Stream water mean transit time was similar (~ 4 years) in the three sub-catchments, and ranged from 3.2–3.3 weeks in forest soils and 4.5–7.9 weeks in pasture soils at 15 cm depth to 10.4–10.8 weeks in pasture soils at 50 cm depth. The contribution of springs and wetlands to stream discharge increased from 18, 1 and 48 % during low flow to 22, 51 and 65 % during high flow in the natural forest, smallholder agriculture and tea plantation sub-catchments, respectively. The dominant stream water source in the tea plantation sub-catchment was spring water (56 %), while precipitation was dominant in the smallholder agriculture (59 %) and natural forest (45 %) sub-catchments. These results confirm that catchment hydrology is strongly influenced by land use, which could have serious consequences for water-related ecosystem services, such as provision of clean water.
Soil organic carbon changes following degradation and conversion to cypress and tea plantations in a tropical mountain forest in Kenya
(Journal Article, 2018-01) Chiti, T.; Díaz Pinés, Eugenio; Butterbach-Bahl, Klaus; Marzaioli, F.; Valentini, R.
Aims This study investigates, in a montane forest in Kenya, the changes in amount and stability of soil organic carbon (SOC) as a consequence of: a) forest degradation, by comparing primary and degraded forests; b) the replacement of degraded forests with cypress and tea plantations, by considering sites installed at different time in the past. Methods The SOC concentrations and stocks were determined in different layers to 1 m depth, and the SOC turnover time (TT) derived by measuring the 14C concentration in the layers within the 0–30 cm depth. Results A significant SOC decline was evident in the 0–5 and 5–15 cm layers of degraded forest while, on the long term, both plantations induced a significant SOC increase in the 0–30 cm depth. The longer TT’s and lower SOC concentrations in the upper layers of degraded rather than primary forests imply an impact of forest degradation on the decomposition of the fast cycling SOC. Similarly, the shorter TT with increasing plantations age implies differences in SOC stabilization mechanisms between plantations and forests. Conclusions Cypress and tea plantations established on degraded forests stimulate a long term SOC accrual but at the same time decrease the stability of the SOC pool.
Land Use, Land Use History, and Soil Type Affect Soil Greenhouse Gas Fluxes From Agricultural Landscapes of the East African Highlands
(Journal Article, 2018-03) Wanyama, Ibrahim; Rufino, Mariana C.; Pelster, David E.; Wanyama, George N.; Atzberger, Clement; Asten, Piet J.A. van; Verchot, Louis V.; Butterbach-Bahl, Klaus
This study aims to explain effects of soil textural class, topography, land use, and land use history on soil greenhouse gas (GHG) fluxes in the Lake Victoria region. We measured GHG fluxes from intact soil cores collected in Rakai, Uganda, an area characterized by low‐input smallholder (<2 ha) farming systems, typical for the East African highlands. The soil cores were air dried and rewetted to water holding capacities (WHCs) of 30, 55, and 80%. Soil CO2, CH4, and N2O fluxes were measured for 48 h following rewetting. Cumulative N2O fluxes were highest from soils under perennial crops and the lowest from soils under annual crops (P < 0.001 for all WHC). At WHC of 55% or 80%, the sandy clay loam soils had lower N2O fluxes than the clay soils (P < 0.001 and P = 0.041, respectively). Cumulative soil CO2 fluxes were highest from eucalyptus plantations and lowest from annual crops across multiple WHC (P = 0.014 at 30% WHC and P < 0.001 at both 55 and 80% WHC). Methane fluxes were below detectable limits, a shortcoming for using soil cores from the top soil. This study reveals that land use and soil type have strong effects on GHG fluxes from agricultural land in the study area. Field monitoring of fluxes is needed to confirm whether these findings are consistent with what happens in situ.
Tagasaste (Chamaecytisus palmensis) leaf supplementation to enhance nutrient intake and production performance of sheep in the Ethiopian highlands
(Journal Article, 2017-10) Mengesha, M.; Bezabih, Melkamu; Mekonnen, Kindu; Adie, Aberra; Duncan, Alan J.; Thorne, Peter J.; Tolera, Adugna
The objective of this study was to determine the effect of supplementing increasing levels of dried tagasaste (Chamaecytisus palmensis) leaf on the nutrition and performance of sheep fed a basal diet of barley straw. The study had four treatments, which involved supplementation of dried tagasaste leaf at 100, 200, 300, and 400 g/day. Twenty-four yearling Menz sheep (weight 17 ± 0.83 kg) were assigned to one of the four treatments in a randomized complete block design. The experiment comprised a feeding trial lasting for 90 days, a digestibility trial, and carcass evaluation using all animals. Samples of the feed consumed, refused, and feces were analyzed for nutrients. Intake and digestibility of dry matter (DM) and nutrients increased linearly (P < 0.001) as tagasaste supplementation increased from 100 to 400 g/day. Similarly, average daily body weight gain increased linearly (P < 0.001) from 20 to 73 g/day, feed conversion efficiency from 0.04 to 0.10, and dressing percentage from 40 to 48%, as the supplementation increased from 100 to 400 g/day. Proportion of tagasaste leaf in the diet increased from 20 to 50%, while the ratio of neutral detergent fiber (NDF) to crude protein (CP) decreased from 7.9 to 5.3, as the level of supplementation increased. It was thus concluded that supplementation of dried tagasaste leaf up to 50% of the diet DM, resulting in a NDF:CP ratio of 5.3, produces no deleterious effects on the performance of sheep, and inclusion to this level can be applied for superior growth performance and carcass yield in sheep fed crop residue-based diets.
Improving small ruminant productivity and livelihoods through feed and health interventions: Evidence from northern Ghana
(Brief, 2016-11-30) Ayantunde, Augustine A.
Using the CLEANED approach to assess the environmental impacts of livestock production
(Brief, 2016-12) Notenbaert, An Maria Omer; Lannerstad, Mats; Barron, Jennie; Paul, Birthe K.; Ran, Ylva; Morris, Joanne; Fraval, Simon; Mugatha, Simon M.; Herrero, Mario
Using the CLEANED approach to assess environmental impacts in the dairy value chain in Tanga, Tanzania
(Brief, 2016-12) Notenbaert, An Maria Omer; Morris, Joanne; Pfeifer, Catherine; Paul, Birthe K.; Birnholz, Celine A.; Fraval, Simon; Lannerstad, Mats; Herrero, Mario; Omore, Amos O.
The CLEANED R simulation tool to assess the environmental impacts of livestock production
(Brief, 2016-12) Pfeifer, Catherine; Morris, Joanne; Lannerstad, Mats
Site characterization and systems analysis in Central Mekong
(Book Chapter, 2016-11-15) Staal, Steven J.; Njiru, Nelly M.; Thinh Nguyen; Kihoro, Esther; Karimov, A.A.; Teufel, Nils; Wijk, Mark T. van; Ritzema, Randall S.
The systems addressed in this chapter and in the CGIAR Research Program on Integrated Systems for the Humid Tropics (Humidtropics) broadly include natural systems comprising biophysical, resource and climate realities; social systems made up of people, societies and their institutions; and, what some term as artificial systems built on elements of the first two (Checkland 1981). Agricultural systems, for example, modify natural systems for productive use, add infrastructure to provide markets, and modify human institutions to organize labour and services to enable the agricultural system to function. Regardless of how systems are categorized, they can be simplistically deconstructed into components and the interactions between them. In this chapter we characterize some of the Central Mekong systems, and also address some of the system dynamics, at two basic levels of resolution. Section 2 addresses regional agricultural systems consisting of one or more districts within a country, and includes variations in natural and social systems in addition to agricultural systems. Five regional cases that reflect the diversity across the Central Mekong Action Area are examined and compared. The authors focus on systems at the community or local landscape level, particularly the individual farm household component, and the variation between households within the landscape. Variables include household agricultural practices, household resources, capacity, and links to markets and institutions. Section 3 looks at diversity in the variables among farm households and the implications for livelihoods and well-being. Section 4 examines food security levels arising from specific farm household strategies and performance, how the two are related, and the implications for potential farm interventions. We conclude by comparing the types of systems examined, the differences in types of tools needed, and the differences in questions asked and learning generated. Throughout this chapter, authors refer to data from reports and articles that interested readers can find in Annex I.
A review of efforts to integrate nutrition in systems research
(Book Chapter, 2016-11-15) Raneri, Jessica Evelyn; Ritzema, Randall S.; Le Thi Nga; Ray-yu Yang; Groot, Jeroen C.J.; Kae, C.; Bolliger, Adrian M.; Chau Thi Minh Long; Hammond, James; Wijk, Mark T. van; Kennedy, G.
Hearing voices: Reconciling scale and gender in agricultural research
(Video, 2016-11-21) Lannerstad, Mats
Mats Lannerstad is currently working on two major projects that incoroprate gender. One is funded by the Bill and Melinda Gates Foundation; it assesses the environmental imapcts of development projects. The researchers ask local stakeholders to contribute in various stages of the process, analysis and recommendations. They now consider gender issues in this work. A second grant, from the UK Department for International Development is looking at gender equity and dynamics. The research team is also trying to develop a framework that captures social equity and gender dimensions at the landscape level. Interview with Mats Lannerstad (ILRI) for the book "A different kettle of fish? Gender integration in livestock and fish research". http://hdl.handle.net/10568/76684
Agricultural productivity and nutrition: The role of women
(Video, 2016-11-21) Wijk, Mark T. van
It is often assumed that increasing agricultural productivity leads to a better diet. But in fact the relationship is more complex, and gender has an important role in mediating it. There are only a few harmonized datasets available, so the research team built its own tool and used it around the world in different systems. There was a sharp contrast between Africa and Asia. In East Africa, greater market orientation does not lead to better diets because money is spent in lots of ways other than nutrition. In Asia, women have much more control over agriculture and cash, which means that an increase in productivity does improve diets. In Africa, to improve diets it is better to work on crop diversification. Interview with Mark van Wijk (ILRI) for the book "A different kettle of fish? Gender integration in livestock and fish research". http://hdl.handle.net/10568/76684
Conceptual framework for analysing science-policy interactions for improved climate policy
(Report, 2016-05-30) Robinson, L.; Crane, Todd A.
Connaissance locale des pratiques de la transhumance dans la zone soudano-sahélienne du Mali
(Journal Article, 2016) Umutoni, Clarisse; Ayantunde, Augustine A.; Sawadogo, G.J.
Les études sur la transhumance ont souvent ciblé les pasteurs – notamment peuls – des zones sahéliennes. Pour en donner une autre perspective, la présente étude a été centrée sur les pratiques de la transhumance dans la zone soudano-sahélienne du Mali en intégrant la perception des agriculteurs et des pasteurs sédentaires concernés par la transhumance dans les zones d’accueil. Les scénarios envisageables pour le futur des systèmes pastoraux ont aussi été analysés. Les données ont été collectées à travers des groupes de discussion et des enquêtes individuelles. Les résultats ont montré que la transhumance n’était plus le seul fait des populations pastorales peules mais concernait diverses ethnies. Plus de 70 % des agriculteurs, des pasteurs sédentaires et des pasteurs transhumants interviewés dans les deux sites de l’étude ont rapporté que les avantages de la transhumance pour les communautés d’accueil en termes de dépôt de fumier dans les champs des cultures décroissaient. Quand bien même la majorité des répondants ont rapporté une augmentation des pratiques de la transhumance au cours des trente dernières années, ils prévoyaient leur diminution dans les années à venir. L’augmentation de la compétition autour des ressources pastorales entre les membres des communautés d’accueil et les pasteurs transhumants dans le sud du Mali crée une situation d’impasse et des frustrations se manifestant par une méfiance mutuelle.

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