Agroecological Studies Research Articles

The simplification of traditional vineyard based agroforests in northwestern Portugal: some ecological implications

In northwestern Portugal, peasants have developed complex vineyard (Vitis vinifera) systems comprising agroforests composed of host trees, vines, annual crops and in some cases animals. Until recently these vineyards suffered very few pest problems and received relatively low pesticide loads. In the last few years, new policy and market forces have prompted the conversion of many of these systems to monoculture thereby decreasing the biodiversity inherent to traditional vineyards. Many scientists are concerned that with accelerating rates of vineyard simplification insect pest and disease problems may increase due to lack of habitat and resources for natural enemies or to a concentration of preferred host plants for specific pathogens and herbivores. During the growing seasons of 1997 and 1999 we conducted several farm surveys of traditional agroforestry and modernized, monoculture farms. We conducted field measurements to elucidate trends in insect pest and disease incidence in both types of vineyards. Our surveys revealed that monoculture vineyards exhibited lower number of species of predators and parasites and correspondingly higher densities of two grape herbivores (Lobesia botrana and Empoasca vitis) than diverse vineyard agroforests. Botrytis bunch rot seemed more prevalent in the monoculture systems, which also received increased fungicide applications when compared to the traditional vineyards. Although preliminary, our studies suggest that new vineyard designs may be more productive, but such gains occur at the expense of biodiversity and agricultural sustainability, reflected on higher pest vulnerability. Further agroecological studies are needed to account for the full ecological costs of the modernization of traditional vineyard agroforests.

Soil and water quality at different scales: proceedings of the workshop: "soil and water quality at different scales", held 7-9 August 1996, Wageningen, The Netherlands.

Preface. Part I: Keynotes. 1. Soil and water quality at different scales: concepts, challenges, conclusions and recommendations J. Bouma, et al. 2. Relevance of scale dependent approaches for integrating biophysical and socio-economic information and development of agroecological indicators J. Dumanski, et al. 3. Scale issues in agroecological research chains R.J. Wagenet. 4. Obtaining soil and land quality indicators using research chains and geostatistical methods M.R. Hoosbeek, J. Bouma. 5. Some considerations on methods for spatially aggregating and disaggregating soil information A.B. McBratney. Part II: Agroecological and Hydrological Case Studies. 6. Small scale variability in the flow of water and solutes, and implications for lysimeter studies of solute leaching L.P. Simmonds, S. Nortcliff. 7. Solute transport at the pedon and polypedon scales D.E. Radcliffe, et al. 8. Space-time upscaling of plot-based research information: frost tillage H.M. van Es, et al. 9. Mapping and interpreting soil textural layers to assess agri-chemical movement at several scales along the eastern seaboard (USA) T. Steenhuis, et al. 10. Status and trends of soil salinity at different scales: the case for the irrigated cotton growing region of eastern Australia I.O.A. Odeh, et al. 11. Investigating soil and groundwater quality at different scales in a forested catchment: the Waldstein case study G. Lischeid, et al. 12. Slope deposits and water paths in a spring catchment, Frankenwald, Bavaria, Germany K. Arno, et al. 13. Hydromorphic soils, hydrology and water quality: spatialdistribution and functional modelling at different scales P. Curmi, et al. 14. Upscaling a simple erosion model from small areas to a large region D. King, et al. 15. Research on soil fertility decline in tropical environments: integration of spatial scales J.J. Stoorvogel, E.M.A. Smaling. 16. Soil absorbing complex properties of Russian boreal soils and its dependence on the spatial scale of study area J.L. Meshalkina, et al. 17. The influence of nitrate reduction strategies on the temporal development of the nitrate pollution of soil and groundwater throughout Germany: a regionally differentiated case study F. Wendland, et al. 18. Food supply capacity study at global scale J.J.R. Groot, et al. Part III: Methods for Scale Transfer. 19. Upscaling hydraulic conductivity: theory and examples from geohydrological studies M.F.P. Bierkens, J.W.J. van der Gaast. 20. Modelling cadmium accumulation at a regional scale in the Netherlands A. Tiktak, et al. 21. The use of upscaling procedures in the application of soil acidification models at different spatial scales W. de Vries, et al. Part IV: Review Papers. 22. Modelling concepts and their relation to the scale of the problem T.M. Addiscott. 23. Prediction error through modelling concepts and uncertainty from basic data M.J.W. Jansen. 24. Uncertainty analysis in environmental modelling under a change of spatial scale G.B.M. Heuvelink. Part V: Extended Poster Abstracts -- Short Communications. 25. Regression model to predict travel time for chloride leaching through pedons using soil morphological characteristics R. Hatano.

Methodological Issues in Comparative Agro-Economic On-Farm Research Assessments of Organic Versus Conventional Farming Techniques

Organic farming is often suggested as a remedy to address farmers’ problems in developing countries. However, little is known about the comparative performance of organic versus conventional farming techniques. Publications on the potential of organic farming are often anecdotal and the research methodology used often raises doubt. Little has been published on methodologies. This paper describes methodological experiences of comparative research of organic versus conventional farming techniques in Kenya. Key characteristics of the described methodology are the comparative approach, on-farm research and the focus on a limited number of organic techniques (composting, liquid manure. double digging, storage protection and organic pest control) and their conventional equivalents (cattle manure and fertilizers, fertilizer (C.A.N.), shallow tillage, pesticides for storage protection and pest control). Criteria for selecting organic farming techniques and agro-ecological study areas are elaborated. The importance of comparable sets of farms and use of recommendation domains for their selection are explained. The experimental designs and methodology of data collection are presented. Inclusion of farmers’ perspectives in the evaluation of the different techniques is presented as a key element of the methodology. The paper concludes with an overview of the main methodological lessons learned.

Using GIS to enhance agricultural planning: The example of inter‐seasonal rainfall variability in Zimbabwe

Inter‐seasonal rainfall variability is evaluated as a potential source of much needed information for agroecological or agroclimatological classifications. For some food crop production areas, inter‐seasonal rainfall variability appears to dominate decisions in the crop‐production strategy. We constructed 31 years worth of seasonal rainfall surfaces for Zimbabwe using techniques as described by Hutchinson (1995) and his software ANUSPLIN. We evaluated these surfaces in an effort to describe the main rainfall period (October to March) for Zimbabwe in terms of rainfall variability. Our results were then put into the context of an agroecological study which produced a Natural Regions map for Zimbabwe. GIS technology enables the synthesis and integration of many more data than was possible in a pre‐computer era and robust rainfall variability surfaces contribute towards improved agroecological and agroclimatological classifications for planning (natural resource management and agricultural) purposes. GIS technology also enables a shift in the design of such agroecological or agroclimatological studies: dynamic characterization can readily produce objective specific classifications, classifications which use the wealth of data readily accessible in a GIS to produce maps and databases reflecting specific boundary conditions.

Pest-management technologies for peasants: a farming systems approach

The development of crop-management technologies for peasant agriculture must fit the socio-economic and ecological features of small farming systems. Only through research that is multidisciplinary and agroecologically orientated, is it possible to understand fully the agro-socioeconomic circumstances that determine the management criteria and levels of resource use by small farmers. Results from these agroecological studies, coupled with the farmers' practical knowledge, can serve as a starting point to develop pest-control technologies which are adapted to the farmers' resource base and local conditions. Throughout the process, technology generation must start and end in the farmers' fields.