To meet the growing food demand, several African countries opt for intensification by focusing crop production on high-potential areas and by increasing the size of the production units. However, the challenges for achieving crop intensification vary with the scales considered. Capital-intensive, large-scale land-use changes can enhance regional-scale agricultural production but rarely consider variations in resource base quality and the dynamics of hydrological regimes and may no longer meet the multiple demands of diverse actors. Prevailing spatial-temporal differences in climatic, edaphic and (socio)hydrological attributes, in production unit-specific resource endowments, and in market attributes are likely to increase variabilities at the plot and household scales. The resulting risks and uncertainties on the one hand and expectations on the other present a disincentive for individual production units to participate in intensification strategies. Such considerations of the size and scale dependency of variability and its implications for future crop production will be empirically tested for lowland rice intensification in the Kilombero floodplain in Tanzania. We will follow land-use change processes over a 12-year period, covering the envisioned change towards “sustainable intensification” between 2018 and 2030.
Research Regions: Kilombero floodplain, Tanzania.
Keywords: Agronomy, Eco-Hydrology, Economics.
1. How are production variability, hydrological risks, and market opportunities related to land-use patterns (scales of variability)?
2. How do actors perceive and respond to variability, risk and uncertainty of production, hydrology and economy (social-ecological transformations)?
3. How do linkages and feedbacks between land users and the environment shape current and future agricultural land-use strategies (integrated modelling)?
Our methodology comprises a mixture of methods from natural sciences as well as social sciences. We collect primary data from soil and plant samples in our field experiments and perform statistical analyses with these data. Furthermore, we carry out household surveys, focus group discussions, choice experiments and interviews. These data are accompanied by remote sensing data and measured data from the local hydrological services. In the end, we feed these quantitative and qualitative data into economic and hydrological modeling studies, which are finally coupled in our integrated model in order to perform scenario analyses considering aspects of social sciences and natural sciences.
We observed an increasing number of conflicts between crop farmers and migratory pastoralists or sedentary agro-pastoralists, regarding access to land and water. Such conflicts present an uncertainty in the outcome of investments and hence a production risks for farmers who are increasingly reluctant to use tractor tillage operations, modern rice genotypes, or agro-chemical inputs.
Besides this “classical” conflict between farmers and herders, there is an increasing competition for land between traditional low-input rice farmers, claiming customary rights to land, and the emergence of absentee “white collar” farmers from urban centers. Such land uses entail the construction of fences that affect the passage of adjacent rainfed rice farmers as well as of migrating herders or sedentary agro-pastoralists.
In the still predominating small-scale rice production systems there is a trend towards risk alleviation by diversification rather than specialization and intensification. A recently-completed survey indicates a rather dramatic change with nearly 20% of the farmers in irrigation schemes shifting from double rice to rice-upland crop rotations, while >5% of the rainfed farmers started to practice recession cropping as one diversification strategy.
The key resource for crop production, but also a key determinant of past failures in agricultural intensification, is the high spatial and temporal variability of water resources in Kilombero. This comprises both the effects of unexpected droughts as well as severe submergence events that affect grain yields and resource-use efficiency, and clearly demonstrated the interplay as well as the interdependency between the wetland and its surrounding catchment and agricultural management.
Gebrekidan, B., Heckelei, T., Rasch, S., (2020): Characterizing farmers and farming system in Kilombero Valley floodplain, Tanzania. Sustainability vol. 12(17), pp. 7114. Link.
Höllermann, B., Näschen, K.,, Tibanyendela, N., Kwesiga, J., Evers, M. (2021): Dynamics of human-water interactions in the Kilombero Valley, Tanzania: - Insights from farmers’ aspirations and decisions in an uncertain environment. EJDR, DOI.
Kwesiga, J., Grotelüschen, C., Neuhoff, D., Senthilkumar, K., Döring, T. F., Becker, M., (2019): Site and management effects on grain yield and yield variability of rainfed lowland rice in the Kilombero floodplain of Tanzania. Agronomy, vol. 9, pp. 608. DOI.
Kwesiga, J., Grotelüschen, C., Neuhoff, D., Senthilkumar, K., Döring, T. F., Becker, M., (2020): Rice yield gaps in smallholder systems of the Kilombero floodplain in Tanzania. Agronomy, vol. 10, online. DOI.
Langensiepen, M., Jansen. M.A.K., Wingler, A., Demmig-Adams, B., Adams III, W.W., Dodd, I.C., Fotopoulus, V., Snowdon, R., Fenollosa, E., de Tullio, M.C., Buck-Sorlin, G., & Munné-Bosch, S. (2020): Linking integrative plant physiology with agronomy to sustain future plant production. Environmental and Experimental Botany, on-line. DOI.
Näschen, K., Diekkrüger, B., Evers, M., Höllermann, B., Steinbach, S., Thonfeld, F. (2019): The impact of land use/land cover change (LULCC) on water resources in a tropical catchment in Tanzania under different climate change scenarios. Sustainability, vol. 11(24), pp. 7083. DOI
Näschen, K., Diekkrüger. B., Leemhuis, C., Seregina, L.S., van der Linden, R. (2019): Impact of climate change on water resources in the Kilombero Catchment in Tanzania. Water, vol. 11(4), pp. 859. DOI
Thonfeld, F., Steinbach, S., Muro, J. Hentze, K., Games, I., Näschen, K., Kauzeni, P. F. (2020): The impact of anthropogenic land use change on the protected areas of the Kilombero catchment, Tanzania. ISPRS Journal of Photogrammetry and Remote Sensing, vol. 168, pp. 41-55. DOI.
Outlook for phase II funding
In phase 2 of the CRC, we will focus on the emerging trend of diversification, its spatial patterns and resource use efficiency (Agronomy), on water abstraction and downstream water effects originating from small multi-purpose dams (Socio-Hydrology), and market, nutrition, and risk-management implications for farm households (Agricultural Economics). The integrated model that was developed in phase 1 of the CRC will be further developed to accommodate the new trend of diversification. The project is organized into four interdisciplinary work packages (WPs) addressing
The expected outcomes are to identify emerging and likely future drivers of diversification, extend the findings to other areas with similar phenomena and conditions, and apply the integrated model to (a) project a range of likely future change scenarios, and (b) to visualize and assess the effects of emerging patterns of diversification. WPs 1 and 2 as well as WP 4 are truly interdisciplinary, while WP 3 (implications and trade-offs) is initially addressed from different disciplinary perspectives and subsequently merged in the integrated model.