Assessing crop yield benefits from in situ rainwater harvesting through contour ridges in semi-arid Zimbabwe |
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| Institution: | 1. University of Zimbabwe, Department of Civil Engineering, Box MP 600, Harare, Zimbabwe;2. University of Witwatersrand, School of Civil and Environmental Engineering, Johannesburg, South Africa;1. CIMMYT, P.O. Box MP 163, Mount Pleasant, Harare, Zimbabwe;2. Total LandCare, P.O. Box 2440, Lilongwe, Malawi;1. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China);2. University of Chinese Academy of Sciences, Beijing 100049 (China);3. UCD School of Biosystems Engineering, Agriculture and Food Science Centre, University College Dublin, Belfield, Dublin 4 (Ireland);1. School of Ecology and Environmental Science, Yunnan University, No. 2 North Cuihu Road, Kunming 650091, PR China;2. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China;3. School of Resources and Environment Science, Wuhan University, NO. 129 Luoyu Road, Wuhan 430079, PR China;4. Key Laboratory of Geographic Information System, Ministry of Education, Wuhan University, NO. 129 Luoyu Road, Wuhan 430079, PR China;5. Institute of International Rivers and Eco-Security, Yunnan University, No. 2 North Cuihu Road, Kunming 650091, PR China;6. Yunnan Key Laboratory of International Rivers and Trans-boundary Eco–security, Yunnan University, No. 2 North Cuihu Road, Kunming 650091, PR China;1. Aksum University, College of Agriculture, P.O. Box 281, Shire Endeslasie, Ethiopia;2. Hawassa University, Wondo Genet College of Forestry and Natural Resources, P.O. Box 128, Shashemene, Ethiopia;3. International Livestock Research Institute, Box 5689, Addis Ababa, Ethiopia;4. School of Biosystems and Environmental Engineering, Hawassa University, P.O. Box 05, Hawassa, Ethiopia;5. International Water Management Institute, P.O. Box C/o ILRI 5689, Addis Ababa, Ethiopia;1. Discipline of Crop Science, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa;2. Discipline of Horticultural Science, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, Pietermaritzburg, South Africa |
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| Abstract: | Rainwater harvesting through modified contour ridges known as dead level contours has been practiced in Zimbabwe in the last two decades. Studies have shown marginal soil moisture retention benefits for using this technique while results on crop yield benefits are lacking. This paper presents results from a field study for assessing the impact of dead level contours on soil moisture and crop yield carried out from 2009 to 2011 within the Limpopo River Basin. The experiments were carried out on two study sites; one containing silt loam soil and another containing sandy soil. Three treatments constituting dead level contoured plots, non-contoured plots and plots with the traditional graded contours were used on each site. All the three treatments were planted with a maize crop and managed using conventional farming methods. Planting, weeding and fertiliser application in the three treatments were done at the same time. Crop monitoring was carried out on sub plots measuring 4 m by 4 m established in every treatment. The development of the crop was monitored until harvesting time with data on plant height, leaf moisture and crop yield being collected. An analysis of the data shows that in the site with silt loam soil more soil moisture accumulated after heavy rainfall in dead level contour plots compared to the control (no contours) and graded contour plots (P < 0.05). However the maize crop experienced an insignificantly (P > 0.05) higher yield in the dead level contoured treatment compared to the non-contoured treatment while a significantly (P < 0.05) higher yield was obtained in the dead level contoured treatment when compared with a graded contoured treatment. Different results were obtained from the site with sandy soil where there was no significant difference in soil moisture after a high rainfall event of 60 mm/day between dead level contour plots compared to the control and graded contour plots. The yield from the dead level contoured treatment and that from the graded contoured treatment were comparable and both not significantly (P > 0.05) higher than that from the non-contoured treatment. This suggests that adopting dead level contours as an in situ rainwater harvesting technique results in crop yield benefits in fields with soil type conditions that enable runoff generation but is not likely to have benefit in soils with low runoff generation. |
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| Keywords: | Rainwater harvesting Semi-arid Crop yield Zhulube Maize Soil moisture |
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