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Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia
Thesis (PhD)--University of Pretoria, 2009.
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University of Pretoria
2013
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| _version_ | 1867613517473906688 |
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| access_status_str | Open Access |
| author2 | Steyn, Joachim Marthinus |
| author_browse | Steyn, Joachim Marthinus |
| author_facet | Steyn, Joachim Marthinus |
| collection | Thesis |
| dc_rights_str_mv | © University of Pretoria 2008 |
| description | Thesis (PhD)--University of Pretoria, 2009. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/24932 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:24.530Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/24932 Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia Steyn, Joachim Marthinus Annandale, John George geremewe@yahoo.com Geremew, Eticha Birdo Furrow irrigation Irrigation scheduling Leaf area index Neutron probe Onion bulb yield Potato tubers Soil water balance model Traditional irrigation Water stress Dry matter partitioning Canopy cover UCTD Thesis (PhD)--University of Pretoria, 2009. Traditional irrigation was practiced in Ethiopia since time immemorial. Despite this, water productivity in the sector remained low. A survey on the Godino irrigation scheme revealed that farmers used the same amount of water and intervals, regardless of crop species and growth stage. In an effort to improve the water productivity, two traditional irrigation scheduling methods were compared with two scientific methods, using furrow irrigation. The growth performance and tuber yield of potato (cv. Awash) revealed that irrigation scheduling using a neutron probe significantly outperformed the traditional methods, followed by the SWB model Irrigation Calendar. Since the NP method involves high initial cost and skills, the use of the SWB Calendar is suggested as replacement for the traditional methods. SWB is a generic crop growth model that requires parameters specific to each crop, to be determined experimentally before it could be used for irrigation scheduling. It also accurately describes deficit irrigation strategies where water supply is limited. Field trials to evaluate four potato cultivars for growth performance and assimilate partitioning, and onions' critical growth stages to water stress were conducted. Crop-specific parameters were also generated. Potato and onion crops are widely grown at the Godino scheme where water scarcity is a major constraint. These crop-specific parameters were used to calibrate and evaluate SWB model simulations. Results revealed that SWB model simulations for Top dry matter (TDM), Harvestable dry matter (HDM), Leaf area index (LAI), soil water deficit (SWD) and Fractional interception (FI) fitted well with measured data, with a high degree of statistical accuracy. The response of onions to water stress showed that bulb development (70-110 DATP) and bulb maturity (110-145) stages were most critical to water stress, which resulted in a significant reduction in onion growth and bulb yields. SWB also showed that onion yield was most sensitive to water stress during these two stages. An irrigation calendar, using the SWB model, was developed for five different schemes in Ethiopia, using long-term weather data and crop-specific parameters for potatoes and onions. The calendars revealed that water depth varied, depending on climate, crop type and growth stage. Plant Production and Soil Science unrestricted 2013-09-06T18:52:41Z 2009-06-02 2013-09-06T18:52:41Z 2009-04-23 2009-06-02 2009-05-24 Thesis Geremew, EB 2008, Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia , PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/24932 > D625/ag http://hdl.handle.net/2263/24932 http://upetd.up.ac.za/thesis/available/etd-05242009-121531/ © University of Pretoria 2008 application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Furrow irrigation Irrigation scheduling Leaf area index Neutron probe Onion bulb yield Potato tubers Soil water balance model Traditional irrigation Water stress Dry matter partitioning Canopy cover UCTD Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title | Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title_full | Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title_fullStr | Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title_full_unstemmed | Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title_short | Modelling the soil water balance to improve irrigation management of traditional irrigation schemes in Ethiopia |
| title_sort | modelling the soil water balance to improve irrigation management of traditional irrigation schemes in ethiopia |
| topic | Furrow irrigation Irrigation scheduling Leaf area index Neutron probe Onion bulb yield Potato tubers Soil water balance model Traditional irrigation Water stress Dry matter partitioning Canopy cover UCTD |
| url | http://hdl.handle.net/2263/24932 http://upetd.up.ac.za/thesis/available/etd-05242009-121531/ |