Regional simulation of maize production in tropical savanna fallow systems as affected by fallow availability
Upscaling of crop models from the field scale to the national or global scale is being used as a widespread method to make large-scale assessments of global change impacts on crop yields and agricultural production. In spite of the fact that soil fertility restoration and crop performance in many developing countries with low-input agriculture rely strongly on fallow duration and management, there are only few approaches which take into account the effect of fallowing on crop yields at the regional scale. The objectives of this study were to evaluate the sensitivity of maize yield simulations with the Environmental Policy Integrated Climate (EPIC) model to fallow availability at the field and regional scale and (2) to present a novel approach to derive a model-based estimate of the average fallow availability within a typical catchment of the sub-humid savanna zone of West Africa. Therefore, the EPIC model has been validated at the field scale and then incorporated into a spatial database covering a typical catchment within the sub-humid savanna zone of West Africa with 121 sub-basins. Maize-fallow rotations have been simulated within 2556 quasi-homogenous spatial units and then aggregated to the 10 districts within the catchment assuming three different scenarios of fallow availability: 100% of the bush-grass savanna area is available and used in fallow-crop rotations (FU100), 50% of the bush-grass savanna area is available and used in fallow-crop rotations (FU50) and 25% of the bush-grass savanna area is available and used in fallow-crop rotations (FU25). A new aggregation procedure has been developed which is based on changes in the frequency of fallow-cropland classes within the sub-basins to render the simulation results in the spatial database sensitive to changes in fallow availability. Comparison of the average simulated grain yield with the mean yield over the catchment shows that the simulations overestimate maize yields by 62%, 44% and 15% for scenario FU100, FU50 and FU25, respectively. The best agreement between simulated and observed crop yields at the district scale was found when using the assumption that 25% of the savanna is available as fallow land under the present cropping patterns, which corresponds to a fallow-cropland ratio of 0.9. Comparison with farm surveys shows that the combination of remote sensing and dynamic crop modelling with yield observations provides realistic estimates of effective fallow use at the regional scale.
If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.
As the access to this document is restricted, you may want to look for a different version under "Related research" (further below) or search for a different version of it.
References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
- Gassman, Philip W. & Wu, JunJie & Mitchell, Paul D. & Babcock, Bruce A. & Hurley, Terrance M. & Chung, S. W., 1998. "Impact of U.S. Agricultural Policy on Regional Nitrogen Losses [Poster Papers]," Staff General Research Papers Archive 1186, Iowa State University, Department of Economics.
- Bernardos, J. N. & Viglizzo, E. F. & Jouvet, V. & Lertora, F. A. & Pordomingo, A. J. & Cid, F. D., 2001. "The use of EPIC model to study the agroecological change during 93 years of farming transformation in the Argentine pampas," Agricultural Systems, Elsevier, vol. 69(3), pages 215-234, September.
- Philip W. Gassman & Jimmy R. Williams & Verel W. Benson & R. CÃ©sar Izaurralde & Larry M. Hauck & C. Allan Jones & Jay D. Atwood & James Kiniry & Joan D. Flowers, 2005. "Historical Development and Applications of the EPIC and APEX Models," Center for Agricultural and Rural Development (CARD) Publications 05-wp397, Center for Agricultural and Rural Development (CARD) at Iowa State University.
- Hartkamp, A. D. & White, J. W. & Rossing, W. A. H. & van Ittersum, M. K. & Bakker, E. J. & Rabbinge, R., 2004. "Regional application of a cropping systems simulation model: crop residue retention in maize production systems of Jalisco, Mexico," Agricultural Systems, Elsevier, vol. 82(2), pages 117-138, November.
- Liu, Junguo & Williams, Jimmy R. & Zehnder, Alexander J.B. & Yang, Hong, 2007. "GEPIC - modelling wheat yield and crop water productivity with high resolution on a global scale," Agricultural Systems, Elsevier, vol. 94(2), pages 478-493, May.
- Manlay, Raphael J. & Ickowicz, Alexandre & Masse, Dominique & Floret, Christian & Richard, Didier & Feller, Christian, 2004. "Spatial carbon, nitrogen and phosphorus budget of a village in the West African savanna--I. Element pools and structure of a mixed-farming system," Agricultural Systems, Elsevier, vol. 79(1), pages 55-81, January.
When requesting a correction, please mention this item's handle: RePEc:eee:agisys:v:103:y:2010:i:9:p:656-665. See general information about how to correct material in RePEc.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Shamier, Wendy)
If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.
If references are entirely missing, you can add them using this form.
If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.
If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.
Please note that corrections may take a couple of weeks to filter through the various RePEc services.