CIRcularity of Nutrients in Agroecosystems and co-benefits for animal and human health (CIRNA)
Permanent URI for this collectionhttps://hdl.handle.net/10568/159980
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Item type: Item , Greenhouse gas emissions and nutrient management in East African livestock systems(Presentation, 2025-11-13) Leitner, SonjaLecture on GHG emissions and nutrient cycling in mixed crop-livestock and pastoral systems in East Africa, held at the University of Hohenheim as part of the Lecture series on "Livestock Systems and DevelopmentItem type: Item , Greenhouse Gas Emissions from Manure Heaps of Dairy Cattle Fed Diets with Different Feed Qualities(Poster, 2025-10-05) Vihowanou, Gaius; Oduor, Collins; Idibu, Joachine; Garcia, Edward; Kagai, Jesse; Kiprotich, Linus; Katongole, C.B; Assouma, M.H.; Mulat, Daniel; Niu, M.; Dossa, L.H.; Lind, Vibeke; Arndt, Claudia; Leitner, SonjaItem type: Item , Greenhouse Gas Emissions from Manure of Sheep Fed on Diets Containing Calliandra and Leucaena(Poster, 2025-10-05) Idibu, Joachine; Oduor, Collins; Vihowanou, Gaius; Stanislaus, U.N.; Garcia, Edward; Lind, Vibeke; Mulat, Daniel; Gakige, Jesse Kagai; Mutian, N.; Luc, H.D.; Emmanuel, Z.; Constantine, B.K.; Arndt, Claudia; Leitner, SonjaItem type: Item , Management Practices to Increase Circularity at Farm Level by Reducing Nutrient Losses from Manure(Presentation, 2025-10-05) Leitner, Sonja; Ntinyari, Winnie; Leytem, A.; Chadwick, Dave; Salazar, Francisco; Weerden, Tony John van der; Pelster, David E.; Sommer, S.G.Item type: Item , CIRNA project inception meetings held in Uganda and Kenya(Blog Post, 2024-12-22) Wanyama, Ibrahim; Leitner, Sonja; Slater, AnnabelThis blog post summarizes the inception meetings held for the CIRNA project at national and district level in Kenya and Uganda.Item type: Item , ILRI’s work on pig manure management for improving water quality in Uganda(Presentation, 2024-08-29) Ibrahim, Wanyama; Leitner, SonjaItem type: Item , Demonstrating the potential of biochar to reduce nitrogen losses and GHG emissions from manure and improve its fertilizer quality(Poster, 2024-08-13) Keino, L.; Yuhao Zhu; Roobroeck, D.; Chebet, A.; Oduor, Collins; Njoroge, R.; Otinga, A.; Hendre, P.; Leitner, SonjaItem type: Item , Greenhouse gas emissions from cattle enclosures in semi-arid sub-Saharan Africa: The case of a rangeland in South-Central Kenya(Journal Article, 2024-06) Leitner, Sonja M.; Carbonell, Victoria; Mhindu, Rangarirayi L.; Zhu, Yuhao; Mutuo, Paul; Butterbach-Bahl, Klaus; Merbold, LutzExtensive livestock production in pastoral areas supports millions of livestock keepers in Sub-Saharan Africa (SSA). However, it is also linked to environmental externalities such as greenhouse gas (GHG) emissions. Corralling of livestock overnight in fenced enclosures (“bomas” in Kiswahili) is common to protect animals from theft and predation and is practiced across SSA. Boma manure is usually not removed and accumulates over years, making bomas GHG emission hotspots. The following study presents the first full year of CO2, CH4, and N2O emissions measurements from cattle bomas in a savanna ecosystem in Kenya, comparing active (in use) and inactive (i.e., abandoned) bomas. Active bomas were used for 1–3 months before being abandoned and cattle were moved to a new boma. GHG emissions were measured using static chambers inside three replicate bomas and along three 100 m transects from bomas into undisturbed savanna. Compared to savanna background fluxes, it was found that GHG flux rates from bomas were elevated by several orders of magnitude, with mean fluxes of 487 ± 8 mg CO2-C m−2 h−1, 325 ± 11 µg N2O-N m−2 h−1, and 3245 ± 234 µg CH4-C m−2 h−1 for active bomas, and 167 ± 52 mg CO2-C m−2 h−1, 610 ± 186 µg N2O-N m−2 h−1, and 3127 ± 1262 µg CH4-C m−2 h−1 for inactive bomas, while surrounding savanna soils only emitted 22.3 ± 18.2 mg CO2-C m−2 h−1, 2.5 ± 2.2 µg N2O-N m−2 h−1, and 0.1 ± 0.7 µg CH4-C m−2 h−1. Assuming that bomas are used for 45 days per year, annual manure emission factors were 2.43 ± 0.42%N for N2O and 0.49 ± 0.07%C for CH4, which corresponds to 2.64 ± 0.37 g CH4 kg−1 volatile solids (VS). These emission factors were similar to IPCC default values for feedlots for low-producing cattle in warm climates; however, the IPCC only considers emissions in year when bomas are in use and does not account for emissions following boma abandonment. At the farm scale, boma manure contributed little (2.2%) to total CH4 emissions, which were dominated by enteric CH4 emissions (97.6%); but bomas were a substantial source for N2O, contributing over 32% to total N2O emissions on the farm. This calls for the inclusion of active and inactive bomas in the activity data collection for national GHG inventories, as bomas are currently overlooked hotspots for GHG emissions that are not represented in the GHG budgets of African nations. To mitigate GHG emissions, manure should be removed regularly and used as fertilizer to return nutrients to the grassland, preventing nutrient mining and ensuring long-term rangeland productivity and resilience, or it might be used to grow crops and livestock feeds.Item type: Item , Simple manure management to retain plant nutrients(Extension Material, 2023-09-30) Leitner, Sonja; Kagai, Jesse; Saya, Nelson; Ngome, David; Mulat, DanielComic on better managing manure for environmental gains.Item type: Item , Characterization of pig manure management and associated environmental and health issues in central Uganda(Report, 2021-12-30) Ibrahim, Wanyama; Graham, Michael; Leitner, SonjaItem type: Item , Effect of feeding practices and manure quality on CH4 and N2O emissions from uncovered cattle manure heaps in Kenya(Journal Article, 2021-05) Leitner, Sonja; Ring, Dónal; Wanyama, George N.; Korir, Daniel; Pelster, David E.; Goopy, John P.; Butterbach-Bahl, Klaus; Merbold, LutzCountries in sub-Saharan Africa (SSA) rely on IPCC emission factors (EF) for GHG emission reporting. However, these were derived for industrialized livestock farms and do not represent conditions of smallholder farms (small, low-producing livestock breeds, poor feed quality, feed scarcity). Here, we present the first measurements of CH4 and N2O emissions from cattle-manure heaps representing feeding practices typical for smallholder farms in the highlands of East Africa: 1) cattle fed below maintenance energy requirements to represent feed scarcity, and 2) cattle fed tropical forage grasses (Napier, Rhodes, Brachiaria). Sub-maintenance feeding reduced cumulative manure N2O emissions compared to cattle receiving sufficient feed but did not change EFN2O. Sub-maintenance feeding did not affect cumulative manure CH4 emissions or EFCH4. When cattle were fed tropical forage grasses, cumulative manure N2O emissions did not differ between diets, but manure EFN2O from Brachiaria and Rhodes diets were lower than the IPCC EFN2O for solid storage (1%, 2019 Refinement of IPCC Guidelines). Manure CH4 emissions were lower in the Rhodes grass diet than when feeding Napier or Brachiaria, and manure EFCH4 from all three grasses were lower than the IPCC default (4.4 g CH4 kg−1 VS, 2019 Refinement of IPCC Guidelines). Regression analysis revealed that manure N concentration and C:N were important drivers of N2O emissions, with low N concentrations and high C:N reducing N2O emissions. Our results show that IPCC EFs overestimate excreta GHG emissions, which calls for additional measurements to develop localized EFs for smallholder livestock systems in SSA.