Catenary Variation of Soil Properties under Oil Palm Plantation in South Western Nigeria

This study characterizes variations in soil properties in a catena under a 30-year oil palm (Elaeis guineesis) plantation established on sedimentary soil in south-western Nigeria. A 300 metre transect was delimited in an oil palm plantation adjoining a tributary of Ossiomo River at Okhuo, near Benin, Nigeria. The transect was divided into upper, middle and lower slope segments. Each segment was further subdivided into ten 10 by 10 metres quadrats, making a total of 30 quadrats. Five soil samples were randomly collected from 0-20cm layer of each quadrat and analysed for particle size composition, organic carbon, macronutrients and micronutrients.Exchangeable calcium and cation exchange capacity were significantly higher in the middle slope segment of the catena due to the combined influence of soil organic matter and clay which were also higher in the middle slope than in the upper and lower slopes. Soil pH was highest in the upper slope and declined down slope.There were no significant variations in the levels of extractable manganese, copper and zinc between the upper, middle and lower slopes but extractable iron was significantly higher in the lower slope due to the occurrence of more moist and acidic soils in the lower slope. Topographic position and ground slope are the main factors accounting for variations in soil properties along the catena. There is the need to manage parts of oil palm plantation on different topographic positions differently, taking cognizance of variations in soil properties along the catena, in order to ensure long term sustainability.Key words: Oil palm, catena, soil, macronutrients, micronutrients, Nigeri

Effects of Charcoal Production on Soil in Kiln Sites in Ibarapa Area, South Western Nigeria

In Nigeria, charcoal is a major source of energy, especially among the urban poor. However, the effects of charcoal production on the environment, especially the soil, have not been adequately documented. This study examines the effects of charcoal production in kiln sites on soil properties in the derived savanna zone of Ibarapa region, south-western Nigeria. Soils in ten kiln sites were sampled at depths of 0-10cm and 10-20cm and their characteristics were compared with those of the corresponding layers of soil in ten adjoining derived savanna sites which were used as the control. Unlike in previous studies reported for West Africa, charcoal production in the kiln sites did not result in a significant reduction in soil organic matter levels, presumably because the humid climate of the derived savanna zone, hindered a substantial rise in soil temperatures during biomass burning. Similarly, there were no significant increases in the levels of exchangeable cations in both soil layers, except for soil exchangeable sodium. There was a rise in kiln site soil pH and available phosphorus mainly due to the effects of soil heating. Biomass burning in the kiln sites did not result in significant increases in the levels of the soil micronutrients - extractable iron, copper, zinc and manganese in both the 0-10cm and 10-20cm soil layers and it had no severe deleterious effects on soil chemical status.Keywords: Charcoal production, kiln sites, macronutrients, micronutrients, Nigeri

How effective are on-farm conservation land management strategies for preserving ecosystem services in developing countries? A systematic map protocol

Background An extensive body of literature in the field of agro-ecology claims to show the positive effects that maintenance of ecosystem services can have on sustainably meeting future food demand, by making farms more productive and resilient, and contributing to better nutrition and livelihoods of farmers. In Africa alone, some research has estimated a two-fold yield increase if food producers capitalize on new and existing knowledge from science and technology. Site-specific strategies adopted with the aim of improving ecosystem services may incorporate principles of multifunctional agriculture, sustainable intensification and conservation agriculture. However, a coherent synthesis and review of the evidence of these claims is largely absent, and the quality of much of this literature is questionable. Moreover, inconsistent effects have commonly been reported, while empirical evidence to support assumed improvements is largely lacking. Objectives This systematic map is stimulated by an interest to (1) collate evidence on the effectiveness of on-farm conservation land management for preserving and enhancing ecosystem services in agricultural landscapes, by drawing together the currently fragmented and multidisciplinary literature base, and (2) geographically map what indicators have been used to assess on-farm conservation land management. For both questions, we will focus on 74 low-income and developing countries, where much of the world’s agricultural expansion is occurring, yet 80% of arable land is already used and croplands are yielding well below their potential. Methods/Design To this end, reviewers will systematically search bibliographic databases for peer-reviewed research from Web of Science, SCOPUS, AGRICOLA, AGRIS databases and CAB abstracts, and grey literature from Google Scholar, and 22 subject-specific or institutional websites. Boolean search operators will be used to create search strings where applicable. Ecosystem services included in the study are pollination services; pest-, carbon-, soil-, and water-regulation; nutrient cycling; medicinal and aromatic plants; fuel wood and cultural services. Outputs of the systematic map will include a database, technical report and an online interactive map, searchable by topic. The results of this map are expected to provide clarity about synergistic outcomes of conservation land management, which will help support local decision-making