Publication year: 2011
Source: Agriculture, Ecosystems & Environment, Available online 23 December 2011

Abdulai Jalloh, Harold Roy-Macauley, Paco Sereme

The West and Central Africa (WCA) sub region covers a total area of over 11.5 million kmwith a population of over 318 million. Most of the rural population in WCA are poor and food insecure and about 70% of the people in the region depends on agriculture, which accounts for over 35% of Gross Domestic Product (GDP) and over 40% of its export. The agroecological zones of WCA are closely related to the agro climatic zones of the region with rainfall decreasing from the southern coast in the forest region to the sub humid and semi arid Sahelian region in the north. The major agroecosystems of WCA include thesemi arid,sub humid,humid forest, andswamp. Growing populations, inappropriate agricultural practices and changing climate in the region are influencing the composition and ability of agroecosystems in providing much needed ecosystem services. Coordinating efforts to tackle these challenges and leverage opportunities for sustainable agricultural production while ensuring conservation of the diverse ecosystems in the region is therefore a major preoccupation of the West and Central African Council for Agricultural Research and Development (CORAF/WECARD).

Highlights

► Major agroecosystems in West and Central Africa are identified. ► Ecosystems are influenced by farming practices, populations and climate change. ► Agroecosystems have differential comparative advantages for sustainable productivity. ► Improved technologies and policies are required to ensure resilience and sustainability of ecosystems.

Publication year: 2011
Source: Agriculture, Ecosystems & Environment, Available online 23 December 2011

A. Tilahun, F. Kebede, C. Yamoah, H. Erens, B.B. Mujinya, ...

Maintenance of soil quality is critical to environmental sustainability. However, its input cost is becoming unaffordable to small scale farming communities in Africa. Termites are an important element in traditional land-management practices in the Sahel. In their role as regulators of soil ecosystem processes, termites perform a number of vital functions. Although the application of termite mound materials as available nutrient sources is a common practice on the African continent, little is known about the density of masses of mounds and the amounts of nutrients they contain. First, two representative sites of 2 km × 1 km were delineated and then termite mound abundance was recorded (43 and 30 in the two sites). They were used for volume and mass determinations. The study revealed an average abundance of 10 mounds haon Calcisols and 14 mounds haon Luvisols, with estimated mound soil masses of 13.5 t haand 58.9 t ha, respectively. Because termite mounds contain many pores and void spaces, a regression equation that can estimate the correct termite mound mass from mound volume and mound wall bulk density was developed. This revealed that conventional calculations of mound mass without correction for the voids overestimate the true mass by over 10%. Soil samples were collected from top and bottom parts of 6 selected mounds and in the different horizons of adjacent undisturbed soil profiles. Although insignificant differences in organic carbon and total nitrogen contents between the termite mound materials and the surface horizons of the adjacent soils were found, the termite mounds constitute a store of 27–53 kg haof total N and 186.3–306 kg haof OC. On both sites, the available P and the exchangeable Mg and K contents of termite mound soil were significantly higher than adjacent soils by 90%, 36% and 188%, respectively. Termite mounds contain a considerable store of plant nutrients and the use of mound material as a soil amendment shows great potential for improving soil chemical fertility.

Highlights

► Mound abundance ranges 10–14 hain the dryland ecosystems of Ethiopia. ► Estimated mound soil masses ranges 13.5 and 58.9 t ha. ► Termite mounds constitute 27–53 kg haof total N and 186.3–306 kg haof OC. ► Use of mound material as a soil amendment shows great potential for improving chemical soil fertility.

Publication year: 2012
Source: Agriculture, Ecosystems & Environment, Available online 16 January 2012

Lino B. Monteiro, Claire Lavigne, Benoît Ricci, Pierre Franck, Jean-François Toubon, ...

The low sustainability of pesticides calls for alternative pest control practices. Among these, the conservation of pest natural enemies is governed both by the local farming practices and by the presence of resources in the surrounding landscape. We investigated the effect of landscape composition on predation of sentinel eggs of the codling moth (Cydia pomonella), a key pest in apple orchards. Thirty egg cards of approximately 15 eggs were exposed twice in each of 12 orchards. Orchards were characterized by their area, their crop protection practices, the abundance of their codling moth population and the abundance of predatory earwigs. The landscape was characterized by the area and management of orchards host to the pest and by the characteristics of the hedgerow network in 50 m and 100 m wide buffers. On average, 12.4% and 48.3% of the egg cards were attacked by predators in June and August, respectively. Predation depended mostly on the toxicity of the crop protection programs. Predation rates were also lower in orchards surrounded by large areas of conventional orchards. No other landscape variable was significant. This indicates that the spatial distribution of pesticides around orchards impacted the within orchards natural enemies.