Agroforestry systems and soil surface management of a tropical alfisol:

Soil physical properties were measured on field runoff plots established on a tropical Alfisol in Western Nigeria. Evolution of soil physical properties was assessed over a period of 6 years beginning in 1982 (when soil was cleared off its secondary regrowth) till 1987. Changes in soil physical properties were measured for six systems including plow-till, no-till, contour hedgerows of Leucaena leucocephala established 2- and 4-m apart, and contour hedgerows of Gliricidia sepium established 2- and 4-m apart. Soil physical properties were measured once every year during the dry season following the harvest of second season crops.Over the 6-year period, there were no significant differences in relative contents of textural separates of sand, silt and clay for the surface 0–5 and 5–10 cm layers. The gravel concentration of the surface 0–5 and 5–10 cm layers, however, increased significantly due to plowing and mixing of the surface and subsoil layers. Soil bulk density of 0–5 and 5–10 cm layers, respectively, increased in all treatments from initial values of 1.02 and 1.16 g cm^–3 in 1982 to 1.43 and 1.65 g cm^–3 at the end of cropping cycle in 1986. The maximum increase in soil bulk density was observed for the no-till treatment. Accordingly, there was an increase in penetration resistance of the surface 0–5 cm layer from an average value of 25.3 kPa in 1982 to 210.7 kPa in 1986. The highest penetration resistance (353 kPa) of 5–10 cm layer was recorded for the no-till treatment. In accord with total porosity, the gravimetric soil moisture retention at zero suction was the lowest for the no-till and the highest for a Gliricidia-based system. There were significant improvements in available water capacity (AWC) of the soil by both Leucaena and Gliricidia-based systems. In comparison with the no-till system, increase in AWC by Leucaena- and Gliricidia-based systems, respectively, was 42 and 56 percent by weight for 0–5 cm depth and 12 and 58 percent by weight for 5–10 cm depth. Alterations in p^F curves by agroforestry-based systems were attributed to improvements in soil structure and structural porosity.     

Agroforestry systems and soil surface management of a tropical alfisol:

Field runoff plots, 70 x 10 m each, were established on a tropical Alifisol in southwestern Nigeria to monitor water runoff, soil erosion and nutrient loss in water runoff. The non-agroforestry control treatment (A) was established at two levels: plow-till and no-till systems of seedbed preparation. There were two agroforestry systems based on contour hedgerows of (B) Leucaena leucocephala and (C) Gliricidia sepium established at 4-m and 2-m spacings. Field plots were established in 1982 and hydrological measurements were made for uniform maize-cowpea rotation for 12 consecutive growing seasons from 1982 through 1987. Once established hedgerows of Leucaena at 2-m spacing were extremely effective in reducing water runoff and controlling erosion. Runoff, erosion and nutrient losses were generally more from maize grown in the first season than from cowpea grown in the second. Mean seasonal erosion from maize was 4.3, 0.10, 0.57, 0.10, 0.64 and 0.60 t/ha for plow-till, no-till, Leucaena-4m, Leucaena-2m, Gliricidia-2m treatments, respectively. Mean runoff in the first season from treatments listed in the order above was 17.0, 1.3, 4.9, 3.3, 4.3, and 2.4 percent of the rainfall received. There were high losses of Ca and K in water runoff from the plow-till treatment. In contrast to runoff and erosion, losses of bases in water runoff from agroforestry treatments were relatively high, high concentration of bases in runoff was probably due to nutrient recycling by the deep-rooted perennials.     

Agroforestry adoption potential in Cape Verde

In the água de Gato Watershed on the island of Santiago (Cape Verde Islands), 51 farmers were surveyed for their willingness to plant trees on their farms for various purposes. Farmer and farm demographic data were also collected to determine those characteristics associated with willingness to plant. Ninety-two percent of the farmers surveyed expressed a willingness to incorporate more trees into their farming practices, and the remainder indicated they were unsure. Linear discriminant analysis was used to relate the demographic variables to willingness groups to plant trees for fruit, fuelwood and shade. Discriminating variables were found to include farmer age, gender, marital status, family size, and farm area (owned, rented or farmed in partnership). Interactions were also observed between the various use categories. For example, farmers who were willing to plant trees for fuel were also more willing to plant trees for shade, and farmers who were willing to plant trees for fruit were unwilling to plant trees for shade. Discriminant analysis models were developed that accounted for correct classifications ranging from 63% to 88%, and averaging 75%.     

Agroforestry potential in the southeastern United States: perceptions of landowners and extension professionals

The first steps in developing an agroforestry extension and training program involve compilation, synthesis, and analysis of current knowledge on existing practices. Equally important is to understand the perceptions of landowners and professionals of agroforestry as a land use option. No systematic effort has been made to assess these critical issues in the southeastern United States. Therefore, needs assessment surveys were developed following an analysis of major demographic issues that frame land use in the region and synthesis of information obtained from informal site visits and interviews with people engaged in resource and land use in the Atlantic and Gulf Coastal Plain. Surveys of extension professionals and landowners were then undertaken in the states of Alabama, Florida, and Georgia to represent the southeastern region. In addition to getting insights into the perceived benefits and concerns about agroforestry practices, the surveys indicated that the extent of alley cropping, forest farming and silvopasture practiced by landowners was less than anticipated, and that the prominence of windbreaks was overlooked by professionals. Managed riparian forest buffers or streamside management zones and windbreak technologies were the most widely used forms of agroforestry in the study area, although landowners did not recognize influence of agroforestry practices on quality or quantity of water among benefits of highest importance to them. Multistrata patio- or home gardens were also a prominent landowner-practice and acknowledged by professionals. These survey results can be useful for developing a relevant agroforestry extension and training program in the subtropical Southeast and may be of interest to agroforestry efforts in other similar settings. This revised version was published online in August 2006 with corrections to the Cover Date.     

Agroforestry systems and soil surface management of a tropical alfisol: I: Soil moisture and crop yields

Field experiments were conducted on a tropical Alfisol at Ibadan, Nigeria, to evaluate the effects on soil moisture and crop yields of three agroforestry systems. Effects of agroforestry treatments involving two perennial shrubs (Leucaena leucocephala and Gliricidia sepium), each at 2-m and 4-m row spacings, were compared with no-till and plow-till systems of seedbed preparation. Measurements were made for soil properties, runoff and erosion, nutrient losses in runoff, and crop growth and yield for a uniform maize (Zea mays) and cowpea (Vigna unguiculata) rotation. All of the six plots, each measuring 70 × 10m, were established on a natural slope of about 7%. Alterations in soil properties and effects on crop growth were evaluated for six consecutive years from 1982 through 1987.Seed germination and seedling establishment of Leucaena hedgerows were satisfactory while establishment of Gliricidia from stem cuttings was unsatisfactory. Maize germination and crop stand were normal while that of cowpea were suppressed by both Leucaena and Gliricidia. Maize growth and yield were suppressed only in the vicinity of hedgerows. Maize grain yield in agroforestry systems averaged about 10 percent lower than that of the control. In contrast with maize, agroforestry systems drastically suppressed cowpea grain yield. The average cowpea yield in agroforestry systems was 30 to 50% of the control. Regardless of the mangement system, grain yields declined over time at the rate of 340 and 96 kg ha^–1yr^–1 for maize and cowpea, respectively.Hedgerows of Leucaena and Gliricidia acted as windbreaks. Consequently, soil moisture content in the top 0–5 cm layer in agroforestry systems was generally higher than that in the control during both wet and dry seasons.     

Agroforestry policy issues and research directions in the US and less developed countries: insights and challenges from recent experience

Efforts to improve the performance of agroforestry systems, and to expand the land area and number of people able to benefit from this integrative approach to agriculture and natural resource management, are constrained throughout the world by non-supportive land use policies. A growing sense of urgency that policy change is needed to enable agroforestry to flourish has contributed during the past two years to an unprecedented level of agroforestry policy assessment and planning activity.In the US, agroforestry has emerged from academia, where it has incubated since the mid-1980s, into the professional resource management arena. A multi-organizational agroforestry evaluation process has driven national policy and program formation to the forefront of the agenda of the agroforestry community, as it seeks to influence the 1995 Farm Bill. Internationally, the Consultative Group on International Agricultural Research and collaborators fostered a sequence of policy issue identification activities as a basis for setting strategic research priorities for forestry and agroforestry.Following a brief review of forces driving agroforestry development in industrialized and less developed countries, the paper highlights recent policy assessment initiatives in each sphere. Observations on the issues driving and the priorities emerging from these processes are offered, to lend perspective to the critical challenges facing the agroforestry policy research community. An explanation for pervasive constraints and inconsistencies in policy effectiveness is then explored, from which a promising approach to research intervention is forwarded.It is argued that social scientists might influence agroforestry policy most favorably at this critical juncture, as perceptions of inter-dependence increase among different stakeholders in the policy system, by employing interventionist, actor-oriented perspectives and participatory methods to facilitate policy innovation and evaluation. The approach is consistent with participatory technology design processes that earlier helped to establish agroforestry as a prototype for sustainable development.     

Agroforestry in Nepal: research and practice

Agroforestry research and practice in Nepal is reviewed. The social and ecological complexity of the country is outlined along with some of the methodological problems. The central importance of trees for fodder and areas that they can be planted on farms are discussed. The role of adjacent forest for compost, firewood and tree seedlings is also highlighted. A system containing Nepalese Alder is outlined and assessed as an agroforestry system that is increasingly being adapted in the middle hills of eastern Nepal.     

Agroforestry potential of Dacryodes edulis in the oil palm-cassava belt of southeastern Nigeria

Between June 1993 and June 1994, 112 farmers in the oil palm (Elaeis guineensis)-cassava (Manihot esclentus) belt of southeastern Nigeria were interviewed to determine the status and agroforestry potential of Dacryodes edulis. Between 50% and 100% of respondents in different states within the belt owned D. edulis trees. On average, a farmer owned 9.3 trees, the largest number being 16, by farmers in Imo State. Twenty percent of farmers in the system rated D. edulis their best farm tree. It was present in all the farm niches: homegardens (51.4%), tree crop plots (20.7%) food crop plots (11.4%), secondary forest/fallow (14.2%) and virgin forest (2.5%). The tree is planted primarily for home consumption and sale to generate cash. At the current densities, on-farm D. edulis trees generally did not decrease yield of companion crops or trees. Except for ring weeding around the stem, D. edulis trees received little or no management attention. More than 50% of the trees produced 33 to 50 kg of fruit tree⁻¹ annually. This is valued at US $0.4 to 0.8 kg⁻¹. Farmers were willing to plant more D. edulis trees provided trees with traits such as less height for easy harvesting of fruits, larger fruit, more fruits, sweeter fruits and year round production of fruits were available. Possible agroforestry technologies into which D. edulis may fit include live fences, scattered trees in food crop fields, shade trees in tree crop plots and contour bund or hedgerow planting. Research is required to determine best tree accessions, canopy management strategies, optimum tree population and improved methods on post- harvest handling of fruits. This revised version was published online in June 2006 with corrections to the Cover Date.     

Agroforestry performance on small farms in Amazonia: Findings from the Rondonia Agroforestry Pilot Project

Experiences from not only ‘success stories’ but also ‘failed’ agroforestry projects provide potentially useful lessons for future agroforestry-project designers. Experimental one-hectare agroforestry plots were established on 50 small-scale farms in the western Brazilian Amazon State of Rondonia from 1993 to 1995. Drawing from a menu of 25 different species (10 tropical hardwoods and softwoods and 15 fruits and palms), this species trial shows encouraging survival and growth performance for most species under wide ranging plot management regimes. Tropical hardwood survival rates (after 18 months) ranged from 65% for Cerejeira (Torresea acreana) to 88% for mahogany (Swietenia macrophylla). Survival rates for commercial fruit and palm species were even higher. A comparison of attributes of two sub-groups (successful and unsuccessful planters) suggests that previous experience with perennial monocultural cropping, greater social participation, land use history, and soil chemistry are positively associated with successful agroforestry species performance, while no significant differences exist between successful and unsuccessful planters in household size, area deforested, area in pasture, and land tenure security. A closer analysis of ‘failed’ agroforestry plots indicates the primary importance of social factors originating at the household-level (e.g. inadequate plot maintenance, improper planting techniques, illness, etc.). Twelve different causes of plot failure were cited, falling into three classes. Of the total number of reasons given for plot failure, household level factors represented 54% of all causes cited. Project design and implementation factors (inappropriate plot design, defective planting material, etc.) were cited 25% of the times and environmental factors (soil fertility constraints and pasture grass invasion) were cited 21% of the times. This revised version was published online in June 2006 with corrections to the Cover Date.     

Agroforestry systems in China: a survey and classification

We classified agroforestry systems in China by system type and system unit. A system type is defined as a homogenous group whose major components are closely related economically, socially, and environmentally. A system unit is defined as a basic functional unit that reveals the specific biological relationships among the major components and requires similar management strategies and techniques. Seven system types and 26 system units are recognized in China. Among them, agrosilvofishery, silvomedicinal and agrosilvomedicinal systems have values unique to Chinese. Each system type is discussed in the context of its geographical extent in China, main species components, and system units.     

Agroforestry training: global trends and needs

A major worldwide trend toward the use of agroforestry and other sustainable agricultural systems has heightened the need for training. Such training is currently underway on every continent. This paper addresses the general principles and practices of training in agroforestry focusing on who needs training, what training is required, and designing training programs. The breadth and depth of training required by the various clientele groups — villagers, politicians, technicians, and professionals — are quite different. Politicians require broad but rather shallow training in agroforestry making them aware of the physical and biological constraints, as well as the social and economic aspects of agroforestry. Villagers require applied, hands-on training but teaching principles also enables them to develop and modify their own systems. Technicians and professionals both need more in-depth and thorough training consisting of both principles and practices. Spaid's approach to training involves the 4-D program: Define, Design, Develop and Deliver. Another model for training, the critical events model, emphasizes the need for feedback and evaluation in every stage of the training program. If a series of well-defined steps is followed, valuable, efficient, effective training programs that further the understanding and practice of agroforestry can be a reality.     

Agroforestry practices in Nigeria

The problems of too much pressure on land for the production of food and wood for the increasing population have made it mandatory to look into the various ways of maximising the uses of agricultural land in different parts of the world. Under this high demand for land, the system of shifting cultivation which has been practised from time immemorial can no longer support the needs of farmers in Nigeria. As a result of this, the different agroforestry practices have received increased attention. The experiences obtained with shifting cultivation, homestead gardens, taungya, alley-farming and scattered farm tree methods including shelterbelt planting in the country are reviewed in this paper and some research findings on these practices are highlighted.     

Agroforestry and portfolio theory

Portfolio theory is used to analyse the risk of hypothetical agroforestry systems. It is shown that the relationship of the returns of the components of an agroforestry system, expressed in terms of the covariance or correlation of returns, is of vital importance in correctly defining risk. Agroforestry systems can be classified as efficient or inefficient. Inefficient systems are such that an alternative system exists which has a greater return for the same level of risk. Thus, inefficient systems do not represent rational choices for agroforestry systems. Finally, the conclusion is reached that it is impossible to design a best system, but rather a set of efficient systems of differing risk and return can be defined. This set of efficient systems is referred to as the efficient frontier.     

Agroforestry and organic agriculture

Current conventional agriculture is considered unsustainable and inadequate to address great societal challenges such as climate change, environmental pollution, food security, dependence on fossil energy as well as the decline of natural resources and biodiversity. Many of these problems are related to agricultural specialization (i.e. monoculture) and the consequent simplification of the agroecosystem. In this respect, efforts aimed at improving individual agronomic techniques and at increasing the use-efficiency of external inputs (e.g. synthetic inputs, fossil fuels), without modifying the structure and functions of the whole system, appear to be insufficient to achieve sustainability in most conventional and intensive farming systems. Current organic farming systems adopting the so-called input substitution approach remain intensive and highly specialized and not necessarily able to significantly improve their sustainability. This would require system diversification and redesign of the agroecosystem to increase the spatial and temporal diversification of all its components and promote positive ecological relationships between them. Agroforestry is an agricultural approach based on the diversification of the agroecosystem production components (woody perennials, such as trees or shrubs, plus crops and/or livestock) and on the intensification of the agroecological relationships between these components. As such, it has transformative potential, providing an opportunity for increasing the sustainability of organic farming. In this article we review how the adoption of agroforestry practices could contribute to increasing sustainability in organic farming, and discuss the challenges and opportunities of this adoption.

     

Agroforestry and the environment

Agroforestry is a traditional land use system that may contribute to the solution of environmental problems in agriculture. Agroforestry is the practice of deliberately integrating woody vegetation (trees or shrubs) with crops and/or animal systems to benefit from the resulting ecological and economic interactions. Recent research indicates that a wider adoption of agroforestry principles and practices is a key means by which the global agri-food sector might achieve more sustainable methods of food and fiber production by producing both economic benefits for farmers and environmental benefits for society. Agroforestry provides numerous provisioning, regulating, cultural and supporting ecosystem services and environmental benefits while promoting eco-intensification based on a more efficient use of the resources. Nevertheless, there is only little published recent information on the contribution of agroforestry to the environment in general and on climate change, carbon sequestration and forest fires in particular. In this special issue a number of articles are included that provide a kaleidoscope of the environmental benefits that agroforestry provides to the environment.

     

农林复合经营系统及其实践

在阐述农林复合经营系统概念的基础上，将该系统划分为６个类型即农林复合型，林农复合型，林牧复合型，农林渔复合型，林特复合型，地域性农林复合型，并作概要描述，对国内外农要复合经营系统的实践也作了典型介绍，这些典型的共同特点是根据生态学和经济学原理，利用物种在时空上合理布局，保持组合的动态平衡，提高经济效益。     

Agroforestry research in India: a brief review

India's long tradition of agroforestry has been influenced by numerous religious, social, and economic factors. Several indigenous agroforestry systems, based on peoples' needs and site-specific characteristics, have developed over the years. Agroforestry research was initiated in the country about two decades ago; since then, considerable progress has been achieved. The interactions between and among the tree, crop, grass, and animal components have been studied, and several agroforestry technologies have been developed and tried on farmers' lands. Agroforestry research is now conducted under the auspices of the All India Coordinated Agroforestry Research Project of the Indian Council of Agricultural Research at 31 centers distributed over India's tropical and temperate regions. In addition to research, the program includes agroforestry training of farmers, technicians, and scientists at 28 centers throughout the country. Expectations from agroforestry are high in India in both rural and urban areas; these expectations include production benefits that are in harmony with the ecology, environment, traditions, and heritage of the country.