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| Titel |
Modelling field scale water partitioning using on-site observations in sub-Saharan rainfed agriculture |
| VerfasserIn |
H. Makurira, H. H. G. Savenije, S. Uhlenbrook |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 4 ; Nr. 14, no. 4 (2010-04-06), S.627-638 |
| Datensatznummer |
250012265
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| Publikation (Nr.) |
 copernicus.org/hess-14-627-2010.pdf |
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| Zusammenfassung |
| Smallholder rainfed farming systems generally realise sub-optimal crop
yields which are largely attributed to dry spell occurrences during crop
growth stages. However, through the introduction of appropriate farming
practices, it is possible to substantially increase yield levels even with
little and highly variable rainfall. The presented results follow research
conducted in the Makanya catchment in northern Tanzania where gross rainfall
amounts to less than 400 mm/season which is insufficient to support staple
food crops (e.g. maize). The yields from farming system innovations (SIs),
which are basically alternative cultivation techniques, are compared against
traditional farming practices. The SIs tested in this research are runoff
harvesting used in combination with in-field trenches and soil bunds (fanya juus).
These SIs aim to reduce soil and nutrient loss from the field and, more
importantly, promote in-field infiltration and water retention. Water
balance components have been observed in order to study water partitioning
processes for the "with" and "without" SI scenarios. Based on rainfall,
soil evaporation, transpiration, runoff and soil moisture measurements, a
water balance model has been developed to simulate soil moisture variations
over the growing season. Simulation results show that, during
the field trials, the average productive transpiration flow ranged between
1.1–1.4 mm d−1 in the trial plots compared to 0.7–1.0 mm d−1 under
traditional tillage practice. Productive transpiration processes accounted
for 23–29% while losses to deep percolation accounted for 33–48% of
the available water. The field system has been successfully modelled using
the spreadsheet-based water balance 1-D model. Conclusions from the research
are that the SIs that were tested are effective in enhancing soil moisture
retention at field scale and that diversions allow crop growth moisture
conditions to be attained with early rains. From the partitioning analysis,
it is also concluded that there is more scope for efficient utilisation of
the diverted runoff water if storage structures could be installed to
minimise runoff and deep percolation and, hence, regulate water flow to the
root zone when required. |
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