Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda
Cassava production in Uganda and western Kenya has been hit hard by the cassava mosaic disease (CMD) epidemic. In response, CMD resistant cassava varieties are currently released on a wide scale. The new varieties yield up to 3 times more than the local varieties. These high yield levels will put ma...
| Main Authors: | , , , , |
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| Format: | Book Chapter |
| Language: | Inglés |
| Published: |
Springer
2007
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10568/91421 |
| _version_ | 1855526769348575232 |
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| author | Fermont, A.M. Obiero, H.M. Asten, Piet J.A. van Baguma, Yona K. Okwuosa, E. |
| author_browse | Asten, Piet J.A. van Baguma, Yona K. Fermont, A.M. Obiero, H.M. Okwuosa, E. |
| author_facet | Fermont, A.M. Obiero, H.M. Asten, Piet J.A. van Baguma, Yona K. Okwuosa, E. |
| author_sort | Fermont, A.M. |
| collection | Repository of Agricultural Research Outputs (CGSpace) |
| description | Cassava production in Uganda and western Kenya has been hit hard by the cassava mosaic disease (CMD) epidemic. In response, CMD resistant cassava varieties are currently released on a wide scale. The new varieties yield up to 3 times more than the local varieties. These high yield levels will put major pressure on soil nutrient stocks. Using a local variety, an average farmer will harvest about 10 t ha-1 fresh roots, thereby removing 26 kg N, 3 kg P and 19 kg K per hectare. Using a good CMD-resistant variety, the same farmer can harvest a 30 t ha-1, thereby removing 83 kg N, 10 kg P and 47 kg K per hectare. If stems are used for planting material and/or firewood, then removal increases to 216 kg of N, 22 kg of P and 102 kg of K per ha for CMD-resistant varieties. Soils in western Kenya and Uganda are predominantly Ferrasols, Acrisols and Nitisols; old weathered soils with small nutrient stocks. Without the use of fertilizers, the rapid depletion of soil nutrient stocks seems unavoidable with the new varieties. This will eventually result in yield decline of cassava and rotational crops. The question arises if traditional cropping systems are suitable for cultivating crops with high nutrient demand. However, production levels of banana, the other important food crop in Uganda, have been sustained for over half a century in several parts of the country, despite K requirements (142 kg ha-1yr-1) of good yielding bananas (25 t ha-1yr-1) being similar to that of good-yielding cassava varieties. But, in contrast to cassava fields, traditional banana fields maintain their soil fertility through large amounts of organic inputs, on the expense of annual cropped fields and grassland. Due to the position of cassava in the farming system, it is unlikely that soil management strategies in banana can be successfully adopted by cassava farmers. However, rotating the improved cassava varieties with fertilized cash crops and introducing promiscuous leguminous inter- and relay crops in cassava fields are potential management options to improve the sustainability of the system. Nonetheless, the development of K deficits will remain a serious concern. The high yield levels of the new cassava varieties have already triggered its promotion as a cash crop. Provided that there is a good (industrial) market outlet, farmers can be motivated to use targeted organic & inorganic fertilizer to prevent soil fertility depletion. |
| format | Book Chapter |
| id | CGSpace91421 |
| institution | CGIAR Consortium |
| language | Inglés |
| publishDate | 2007 |
| publishDateRange | 2007 |
| publishDateSort | 2007 |
| publisher | Springer |
| publisherStr | Springer |
| record_format | dspace |
| spelling | CGSpace914212024-01-08T18:54:14Z Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda Fermont, A.M. Obiero, H.M. Asten, Piet J.A. van Baguma, Yona K. Okwuosa, E. cassava soil fertility nutrient removal cassava production Cassava production in Uganda and western Kenya has been hit hard by the cassava mosaic disease (CMD) epidemic. In response, CMD resistant cassava varieties are currently released on a wide scale. The new varieties yield up to 3 times more than the local varieties. These high yield levels will put major pressure on soil nutrient stocks. Using a local variety, an average farmer will harvest about 10 t ha-1 fresh roots, thereby removing 26 kg N, 3 kg P and 19 kg K per hectare. Using a good CMD-resistant variety, the same farmer can harvest a 30 t ha-1, thereby removing 83 kg N, 10 kg P and 47 kg K per hectare. If stems are used for planting material and/or firewood, then removal increases to 216 kg of N, 22 kg of P and 102 kg of K per ha for CMD-resistant varieties. Soils in western Kenya and Uganda are predominantly Ferrasols, Acrisols and Nitisols; old weathered soils with small nutrient stocks. Without the use of fertilizers, the rapid depletion of soil nutrient stocks seems unavoidable with the new varieties. This will eventually result in yield decline of cassava and rotational crops. The question arises if traditional cropping systems are suitable for cultivating crops with high nutrient demand. However, production levels of banana, the other important food crop in Uganda, have been sustained for over half a century in several parts of the country, despite K requirements (142 kg ha-1yr-1) of good yielding bananas (25 t ha-1yr-1) being similar to that of good-yielding cassava varieties. But, in contrast to cassava fields, traditional banana fields maintain their soil fertility through large amounts of organic inputs, on the expense of annual cropped fields and grassland. Due to the position of cassava in the farming system, it is unlikely that soil management strategies in banana can be successfully adopted by cassava farmers. However, rotating the improved cassava varieties with fertilized cash crops and introducing promiscuous leguminous inter- and relay crops in cassava fields are potential management options to improve the sustainability of the system. Nonetheless, the development of K deficits will remain a serious concern. The high yield levels of the new cassava varieties have already triggered its promotion as a cash crop. Provided that there is a good (industrial) market outlet, farmers can be motivated to use targeted organic & inorganic fertilizer to prevent soil fertility depletion. 2007 2018-03-07T11:25:52Z 2018-03-07T11:25:52Z Book Chapter https://hdl.handle.net/10568/91421 en Limited Access Springer Fermont, A.M., Obiero, H.M., Van Asten, P., Baguma, Y. & Okwuosa, E. (2007). Improved cassava varieties increase the risk of soil nutrient mining: an ex-ante analysis for western Kenya and Uganda. In A. Bationo, B. Waswa, J. Kihara and J. Kimetu, Advances in integrated soil fertility management in sub-Saharan Africa: challenges and opportunities (p. 511-520). Springer. |
| spellingShingle | cassava soil fertility nutrient removal cassava production Fermont, A.M. Obiero, H.M. Asten, Piet J.A. van Baguma, Yona K. Okwuosa, E. Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title | Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title_full | Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title_fullStr | Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title_full_unstemmed | Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title_short | Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda |
| title_sort | improved cassava varieties increase the risk of soil nutrient mining an exante analysis for western kenya and uganda |
| topic | cassava soil fertility nutrient removal cassava production |
| url | https://hdl.handle.net/10568/91421 |
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