Abstract

Effects of organic inputs (OIs) on maize grain yield and chemical properties of Ultisols were assessed at Msekera and Misamfu Agricultural Research Stations in the medium and high rainfall regions respectively of Zambia. The OIs included biomasses of the leguminous species Cajanus cajan, Tephrosia vogelii, and Crotalaria juncea, in-situ composted native grasses and shrubs called fundikila, modified fundikila using Mucuna pruriens, and composted cattle manure, with chemical fertilizer as a control. After two crop growing seasons, cattle manure significantly increased soil pH, while modified fundikila significantly increased levels of soil organic matter. At Msekera, OIs increased levels of total N by 300%. At Misamfu, fundikila and Cajanas cajan increased total N by 35%. The OIs did not significantly increase available P and K at both sites. In the first season at Msekera, OIs had a higher mean maize yield (6075±368 kg/ha) than chemical fertilizer (3567±715 kg/ha). Maize yields for OIs in the second season did not differ significantly from those of the first season. At Misamfu the leguminous OIs Cajanas cajan and Tephrosia vogelii, had a lower combined mean maize yield (5405±242 kg/ha) than chemical fertilizer (7426±430 kg/ha) in the first season. A 70% decline in maize yield occurred on plots with leguminous OIs in the second season compared to the first season. Leguminous OIs generally performed better at Msekera than at Misamfu. At both sites, the traditional OIs, cow manure at Msekera, and fundikila at Misamfu had higher maize yields than leguminous OIs. We concluded that effects of OIs on soil chemical properties and maize yield vary with soil and climatic conditions and that these need to be considered when selecting OIs for use by farmers.

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