Journal of Agriculture and Environment for International Development

Formerly Rivista di Agricoltura Subtropicale e Tropicale

Volume 98 Number 1/2 January/July 2004	Index: L. De Filicaia , C. Zanchi Evaluation of soil erosion in the watershed of the Sbaïhya river (Tunisia) Language: English Abstract: The research was carried out in the Sbaihya watershed as it is representative of a large area of central Tunisia for what concerns human pressure, climatic, soil, morphological, and land uses conditions. The gully erosion is dominant, originating a badland landscape, but also sheet and rill erosion are very diffuse, even if less spectacular. These latter are favoured mainly by the tillage and cultivation up and down slope, overgrazing, reduced fallow duration, and crops that leave the soil unprotected during the rainy season. In these fragile ecosystems the increase of the soil loss rate causes a progressive soil degradation that leads to a decrease of the soil fertility and crop productivity. The main objectives of the research are: -To measure the soil loss and runoff on the most representative situations of land uses and canopy cover -To verify, in this environment, the reliability of the physically based erosion model-WEPP- for predicting soil loss. -To render the farmer consciousness of the importance of vegetation cover, and conservative cropping systems for maintain, in the time, the soil fertility and to achieve the sustainability of their agricultural activities. The research has been carried out on five plots of 21.1 m long (USLE standard plot) with different degree of vegetation canopy, and cropping systems. Three plots were prepared in forested area with different degree of canopy cover 0%, 33%, and 73%). The two standard agricultural plots were placed on a versant with the 12% slope with the following different treatments: - One plot tilled up and down slope and cultivated with wheat; - One plot cultivated with consociation of olive trees and wheat. Moreover the soil loss and runoff measured were utilized for to validate the WEPP (Water Erosion Prediction Project) model in this semiarid Mediterranean environment. As the Sbaïhya watershed is also strongly affected by the gully erosion, the dimensions of a gully section were monitored for measuring its enlargement rate.   O. I. Oladele, Jun-Ichi Sakagami Agricultural research and extension indices as determinants of agricultural growth in Nigeria: 1981-2002 Language: English Abstract: This paper examines the determinants of agricultural growth in Nigeria from the research and extension indices over the period of 1981 to 2002. A Principal Component Analysis extraction method was used to isolate the variables from a list of 22 indices that have been previously used in assessing the performance of agricultural research and extension. Five components identified are funds allocated to extension services: Share of agriculture in the national budget; Agricultural active population; Land use area for arable and permanent crops, and Expenditure per person of the agricultural population. The result of the multiple regression analysis shows that the double log function is the best fit for the regression equation. The function has the least standard error of the parameter estimate, and high coefficients of determination. All the five variables are significant at 5% and only 4 at 10%. The overall findings shows that the trend on funding on extension, pattern land use and the instability of agricultural budget will suggest that transitory agricultural growth is a potential problem in Nigeria.   M. Isabirye, B. Isabirye, M.K. Magunda, J. Deckers, J. Poesen Impact of Land Use-systems on soil invertebrate macrofauna communities in the Lake Victoria fringe Language: English Abstract: LU – systems are very dynamic along the fringes of Lake Victoria. Sustainability is of utmost importance and therefore calls for the need to put in place mechanisms to assess and monitor land qualities of major LU – systems. This study investigates the impact of the different ecosystems on abundance and diversity of soil invertebrate macrofauna. Taxonomic diversity and abundance of macrofauna in the various LU-systems (maize, coffee, banana, pasture and a native forest) was assessed. Annual LU-systems are associated with lowest macrofauna population and diversity and generally have low soil fertility status. Since they are becoming dominant LU - systems in the area, monitoring of biota is called for a proxy for system sustainability. This survey demonstrates the role of soil macrofauna as indicator of disturbance LU-systems. Soil invertebrate macrofauna species give the best picture of sustainability when counts are implemented during the start of the dry season when population dynamics is at a climax.   P. Casini, W. Pastén Green manuring and mulching in a three-crop sequence in the Bolivian Amazon Language: English Abstract: Three successive crops (maize – common beans – rice) were cultivated in the same plots in the Amazon basin in Bolivia between 1996 and 1998. A split-plot design was used. The presence/absence of mulch (80% Panicum maximum plus 20% Brachiaria decumbens) was considered as the main plots and the manure sources (control – Mucuna pruriens var. utilis – Pueraria phaseoloides – mineral fertilizer) as subplots. Top cuttings of kudzu and mucuna were incorporated with a hoe to a depth of 10 cm before every planting. Grass mulch significantly decreased weed number until 28-35 days after emergence (DAE) compared to the bare plots. Weed reduction was 48, 45 and 50% for maize, beans and rice, respectively. The effects of legume incorporation and chemical fertilizer application on yields were different for each crop. In maize, the mucuna and kudzu top cuttings produced yields of 50 and 68%, respectively of that obtained with mineral fertilizer (3.4 t ha-1). The incorporation of kudzu in common beans produced yields significantly higher than the control, but 45-50% of the grain obtained in comparison to chemical input. Only mineral fertilizer application significantly increased grain production compared to the control (by 45%). It can be concluded from this study that: 1. grass mulch decreases weed population and reduces competition. 2. in the absence mineral fertlizers, the incorporation of kudzu in maize and beans significantly increases crop yields when compared to control. 3. the different effects of organic additives within a crop can be directly attributed to specific changes in the physical-chemical characteristics of soil induced by organic incorporation and grass mulch; 4. the potential use of incorporated green manure and the mulching practice may be significant for small farms.   B. Conaire, O. Asemota, A. Isenmila Pattern of seedling root development among some oil palm genotypes Language: English Abstract: Comparative root development was monitored in 11 oil palm progenies. From the observed mean dry weights of different vegetative parts, the genotypes could be grouped into 5. One group generally produced higher dry matter than the others. Significant differences between the crosses, in root dry matter and root length were observed. Differences in rooting patterns could confer advantages on the lines with more profound roots in conditions of limiting moisture.   G. Rambaldi, A.C. Manila Innovative Tools for Mastering Space in Collaborative Natural Resource Management Language: English Abstract: The paper focuses on the evolution of community-based mapping techniques increasingly being associated with Geographic Information Technologies (GIT), and specifically on methods used for enabling marginalised communities to depict their knowledge of the territory in the form geo-referenced and scaled data and to visualize it in two and/or three dimensions. The paper focuses in particular on a method known as Participatory 3-D Modelling (P3DM), which has been used in the Thailand, the Philippines, and Vietnam in the contexts of collaborative natural resource management and lately in protected area management. P3DM captures local knowledge and combines it with more traditional spatial information, such as contour intervals to produce – through a participatory process - functional stand-alone relief models. The process has proved to generate a high level of awareness of the distribution and use of resources over relatively vast areas and on the functioning of linked ecosystems. It was found that 3-D models provide stakeholders with an efficient, user-friendly and relatively accurate spatial learning, research, planning and management tool, the information from which can be extracted and further elaborated in a GIS environment. The synergies resulting from the combinations of P3DM and GIT make data depicted on relief models widely exchangeable through maps and digital datasets. These formats add veracity and authority to community knowledge and make the power that comes from recording and controlling space available also to those sectors of society, which have traditionally been disenfranchised by maps. Mastering space at grassroots level has been instrumental to improving the capacity of communities in interacting with national and international institutions and to play a proactive role in inducing change and/or innovation in terms of resource allocation and management. The evolution of the P3DM method and its recent integration with Geographic Information Systems (GIS) and Global Positioning Systems (GPS) is discussed taking into account the presence or absence of enabling environments. P3D models are currently being used in Southeast Asia for (i) conducting community-based research on distribution of and access to resources in protected areas and critical watersheds; (ii) developing resource use, ancestral domain and protected area management plans; (iii) negotiating boundary delineation and zoning; (iv) raising environmental awareness; (v) facilitating conflict resolutions and (vi) addressing resource tenure issues.   L. Mulazzani, L. Omodei Zorini Evaluación de factibilidad socio-economica de un proyecto de recuperación ambiental (lomas de Atiquipa, Perú) Language: Spanish Resumen: Las lomas costeras del Perú constituyen un ecosistema único para su vegetación y para su manera particular de mantenerse a través del agua contenida en las neblinas. Estas islas de vegetación en el medio del desierto hospedaron comunidades humanas ya en época prehispánica, pero en los siglos han sufrido un proceso de degradación debido a la disminución de las precipitaciones y al sobrepastoreo ocurrido con la introducción del ganado vacuno y caprino. El Instituto Regional de Ciencias Ambientales (IRECA) de Arequipa ha preparado un proyecto para la lucha contra la desertificación y la conservación de la biodiversidad en las lomas de Atiquipa, las lomas mejor conservadas del Perú. Esta investigación se propone de avaluar los efectos socio-economicos (factibilidad) del proyecto sobre la población local. Para hacerlo se adopta una metodología que recalca los principios del Planning Balance Sheet. A través del estudio de los sistema agrarios con entrevistas familiares y encuentros participativos, la población ha sido subdividida en diferentes categorías sociales y económicas. Los efectos del proyecto han sido estudiados para cada una de las categorías. De la investigación resulta que en largo plazo las actividades de reforestación traeran ventajas para la economía agro-forestal del Distrito. Durante la implementación del proyecto los ganaderos sufriran por la disminución de los pastos disponibles, mientras que los efectos sobre la mayorìa de la población, la que es sin tierra, serán marginales.
Further information: Istituto Agronomico per l'Oltremare,  rivtrop@iao.florence.it