• Contact Us
    • Send Feedback
    • Login
    View Item 
    •   Home
    • Books and Book Chapters
    • Books and Book Chapters
    • View Item
    •   Home
    • Books and Book Chapters
    • Books and Book Chapters
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    Whole Repository
    CollectionsIssue DateRegionCountryHubAffiliationAuthorsTitlesSubject
    This Sub-collection
    Issue DateRegionCountryHubAffiliationAuthorsTitlesSubject

    My Account

    Login

    Welcome to the International Institute of Tropical Agriculture Research Repository

    What would you like to view today?

    Improved cassava varieties increase the risk of soil nutrient mining: an exante analysis for western Kenya and Uganda

    Thumbnail
    Date
    2007
    Author
    Fermont, A.M.
    Obiero, H.M.
    Asten, Piet J.A. van
    Baguma, Yona K.
    Okwuosa, E.
    Type
    Book Chapter
    Metadata
    Show full item record
    Abstract/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.
    http://dx.doi.org/10.1007/978-1-4020-5760-1_48
    Multi standard citation
    Permanent link to this item
    https://hdl.handle.net/20.500.12478/3098
    Digital Object Identifier (DOI)
    http://dx.doi.org/10.1007/978-1-4020-5760-1_48
    IITA Subjects
    Cassava; Soil Fertility; Plant Diseases; Plant Production
    Agrovoc Terms
    Cassava; Soil Fertility; Nutrient Removal; Cassava Production
    Regions
    Africa; East Africa
    Countries
    Kenya; Uganda
    Collections
    • Books and Book Chapters953
    copyright © 2019  IITASpace. All rights reserved.
    IITA | Open Access Repository