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This study discusses the results of a 5-year Agroecology Research and Advocacy project at three Tanzanian field sites in different agroecological zones. We investigated four common agroecological practices: compost application, mulching, intercropping, and biological pest control either alone or in combination. Two custom-built ICT tools – AgroEco Research (AER) and AgroEco Analysis (AEA) application – supported the field research. AER and AEA integration allowed secure data storage and real-time automated visualization and statistical analyses without programming. At no field station did legume intercropping or biological pest control increase cassava yields. The Chambezi field station had the highest yields even under untreated control conditions and only here, soil fertility amendments further increased root weights. Intercropping with cowpea legumes, alone or in combination with other practices, had no significant effect on cassava plant size or survival at the Mumbaka and Vianzi field sites and even negatively affected one or both parameters. Organic pest control had no effect on any target variable, except for plant size at Chambezi. Therefore, labor-intensive and expensive pest control practices may not be worth the investment at least when virus-resistant cassava varieties like Kiroba are used. [ABSTRACT FROM AUTHOR]

Agroecology has become increasingly popular but locally optimized agroecological production methods and information and communication technology (ICT) support tools are limited. This study was conducted at three different geographic locations across Tanzania; we co-developed an integrated participatory field research methodology consisting of two components, each supported by a specifically developed, complementary ICT tool, with maize and cassava as the two focal crops, to examine soil fertility and conservation (compost and mulching), increased biodiversity through intercropping (legumes), and organic pest control measures. Two specifically developed ICT tools, the AgroEco Research application (AER) and AgroEco Analysis application (AEA) were used for data gathering & storage and visualization & statistical analysis, respectively. Further, farmer-managed satellite experiments were performed to further test the research premises and validate their outcomes in the "real world" of smallholder farmers, which was supported by a smartphone application called "Ugunduzi" – enabling farmers to collect, store, and evaluate data generated at different stages of their research. Farmers were free to choose any type, number, and combination of the agroecological practices tested in the field research. This study serves as a methodology reference for a number of companion publications reporting on the findings of this project. [ABSTRACT FROM AUTHOR]

Sub‐Saharan Africa (SSA) must undertake proper cropland intensification for higher crop yields while minimizing climate impacts. Unfortunately, no studies have simultaneously quantified greenhouse gas (GHG; CO2, CH4, and N2O) emissions and soil organic carbon (SOC) change in SSA croplands, leaving it a blind spot in the accounting of global warming potential (GWP). Here, based on 2‐year field monitoring of soil emissions of CO2, CH4, and N2O, as well as SOC changes in two contrasting soil types (sandy vs. clayey), we provided the first, full accounting of GWP for maize systems in response to cropland intensifications (increasing nitrogen rates and in combination with crop residue return) in SSA. To corroborate our field observations on SOC change (i.e., 2‐year, a short duration), we implemented a process‐oriented model parameterized with field data to simulate SOC dynamic over time. We further tested the generality of our findings by including a literature synthesis of SOC change across maize‐based systems in SSA. We found that nitrogen application reduced SOC loss, likely through increased biomass yield and consequently belowground carbon allocation. Residue return switched the direction of SOC change from loss to gain; such a benefit (SOC sequestration) was not compromised by CH4 emissions (negligible) nor outweighed by the amplified N2O emissions, and contributed to negative net GWP. Overall, we show encouraging results that, combining residue and fertilizer‐nitrogen input allowed for sequestering 82–284 kg of CO2‐eq per Mg of maize grain produced across two soils. All analyses pointed to an advantage of sandy over clayey soils in achieving higher SOC sequestration targets, and thus call for a re‐evaluation on the potential of sandy soils in SOC sequestration across SSA croplands. Our findings carry important implications for developing viable intensification practices for SSA croplands in mitigating climate change while securing food production. [ABSTRACT FROM AUTHOR]

Crop residue management strategies must be adapted for improving carbon (C) balance and soil C stock in agroecosystems in sub‐Saharan Africa with consideration of the crop residue availability and site‐specific soil characteristics. We conducted field experiments to determine the effects of crop residue application method (incorporation/mulching) and quality (maize/cowpea) and N fertilizer application on the soil respiration rate and soil C stock in the surface soil layer (0–15 cm) in maize croplands with contrasting soil textures (clay/sandy) over 2 years from 2012 to 2014 in Tanzania. At the clay site, the incorporation of maize residues showed a 38% increase in CO2 flux compared to mulching, whereas, at the sandy site, mulching showed a 16% increase compared to the incorporation. At the sandy site, mulching practice retained soil moisture content and apparently enhanced the decomposition of the original soil organic C in the surface layer. It is, therefore, suggested that mulching practice may accelerate a long‐term depletion of soil C stock at the sandy site. The cowpea residue incorporation led to rapid decomposition because of its high biodegradability at both sites. The N fertilizer application stimulated the decomposition of labile soil organic matter. The soil C stock in the surface layer did not significantly change after the 2‐year experiment, irrespective of crop residue treatment and soil type. In conclusion, adequate crop residue management in terms of suppressing CO2 flux during a cropping season depends on soil type, but the long‐term effect on soil C stock is unclear. [ABSTRACT FROM AUTHOR]

Water erosion is one of the main concerns driving land degradation in mountainous areas throughout the world, and its characteristics change widely with soil and climate conditions in different locations. To investigate the effects of soil and rainfall properties on surface runoff and soil loss, we installed runoff plots (width 0·8 m × slope length 2·4 m) enclosed by corrugated iron sheets, and evaluated water budgets for rainfall, surface runoff and soil moisture for every rainfall event over a rainy season at four sites (designated NY, TA, SO and MA) in the Uluguru Mountains of Tanzania. Two of the sites, NY and TA, were located in mountainous areas and had steep slopes and higher rainfall amounts, while the two foothill sites, SO and MA, were flatter and with coarser textures. Runoff amount was related to rainfall amount, but also to infiltration capacity. Runoff amounts in mountainous areas were higher than in foothill sites while runoff ratio was low at sites with high permeability in the surface layer, TA and MA. Sediment concentrations and soil loss were basically enhanced by high rainfall amount and intensity at mountainous sites. Soil texture also controlled the erodibility of soils; MA had twice the soil loss of SO owing to sandy soil despite similar rainfall amounts at MA and SO. Our results show that the high rainfall amounts in the mountainous areas and high susceptibility of sandy soils to erosion enhanced soil loss by water erosion in this study. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]