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Relay‐Intercropping of Sunnhemp and Cowpea into a Smallholder Maize System in Zimbabwe
Author(s) -
Jeranyama Peter,
Hesterman Oran B.,
Waddington Stephen R.,
Harwood Richard R.
Publication year - 2000
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2000.922239x
Subject(s) - intercropping , agronomy , legume , crotalaria juncea , fertilizer , crop , vigna , field experiment , alfisol , mathematics , biology , green manure , soil water , ecology
The rising real prices of purchased inputs is driving smallholder maize ( Zea mays L.) production towards lower levels of inorganic fertilizer. Legume intercrops are a source of plant N that can be produced locally and offer a practical complement to inorganic fertilizers. Field experiments conducted on a loamy sand (Typic Kandiustalf) soil evaluated the impact of relay‐intercropping two legume crops, cowpea ( Vigna unguiculata L.) and sunnhemp ( Crotolaria juncea L.) into smallholder maize in Zimbabwe. The objectives were to quantify: (i) biomass and N yield of intercropped legumes, (ii) the impact of the legumes on companion maize yield and N uptake, and (iii) the response of a subsequent maize crop to legumes. Dry matter yield ranged from 0.6 to 4.6 Mg ha −1 for cowpea and 0.9 to 2.9 Mg ha −1 for sunnhemp, over two years. At the most, cowpea and sunnhemp produced 154 and 82 kg N ha −1 , respectively. Companion maize grain yields were not reduced when the legumes were relay‐intercropped into maize fertilized at 0 to 60 kg N ha −1 . However, maize yields were reduced 18 to 31% when maize + legume intercrops were fertilized at 120 kg N ha −1 . In the subsequent year, maize grain yields were increased by 8 to 27% following maize + legume when no fertilizer N was applied, compared with maize following maize. Legumes reduced fertilizer needs of a subsequent maize crop by 36 kg N ha −1 . Intercropped annual legumes and small amounts of inorganic fertilizer offers a strategy to meet the N needs on smallholder farms.