Browsing by Subject "Agroforestry"

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Conversion of subsistence farming to sustainable agroforestry in the Midhills of Nepal : participatory action research in system development
(2015) Schick, Alina; Hoffmann, Volker
In the Midhills of Nepal, agriculture is practiced mostly as subsistence farming on often small-sized terraces. Nowadays there are often only a few trees left in cultivated areas, which leaves the soil bare for several months of the year, mostly in winter. Degeneration processes by environmental influences on bare terraces, and a deficiency of organic material lead to poor soils and consequently to a reduced harvest. A rising population leads to a fragmentation of farms by spreading estates, thus leading to ever smaller-sized cultivated land areas. These often and increasingly do not produce enough food to feed farmers and their families. The possibilities of work in other income sectors are limited. Consequently, some farmers leave their land and move to Kathmandu. To break this chain it is necessary to develop new survival strategies. One solution is to ensure that existing farms can produce enough food to feed themselves and sell to make a living. This can theoretically be achieved by alternative farming methods and the introduction of new techniques. Agroforestry with its mixed farming styles and aspects of permaculture can eventually help to ameliorate the soils and provide extra nutrition and income through a perennially mixed plant production system that also includes several cash crops. The objective of the present study is to evaluate the actual situation of farmers in the region of Kaule, Nepal, and to assess the system change from subsistence farming to agroforestry. An existing agroforestry farm established in Kaule about 15 years ago will serve as a reference. For the system change to agroforestry several hypotheses were put forward on the assumption of the stated problems. These hypotheses have been tested by several methods such as socioeconomic and ecological field surveys, in combination with qualitative social research methods like interviews, questionnaires, protocols and direct observations. The results were then ordered in case studies per household and later accumulated into comparative group observations. The system change was then contextualised to a situation-based functional theory of adoption and diffusion of innovations in social systems. This study report is the written monitoring result of the three initial project years from 2009 to 2011 in Kaule, and in some cases supplemented by additional data from earlier and later years. Data on income and expenses, work distribution within the families, soil quality and biodiversity have been selected. General descriptions of farming methods and reports on several training sessions are also included, as well as the assessment of terrace sizes and meteorological data. After comparing single household situations in the case studies with those of accumulative group observations, two different livelihood strategies were found that seemed to be sustainable for the current situation in Kaule. One strategy is where several parts of families merge together to create bigger social structures and combine their land in bigger scales to produce their livelihood. Alternatively, like the case of the agroforestry farm, the other strategy is part-time farming with enhanced cultivation methods for nutrition and income production, in addition to external work based on higher education. When agroforestry was compared to a situation-based functional approach to describe its potential for adaption and diffusion, it was found that agroforestry in its complexity is difficult to establish and places high expectations on adopters. For households that cultivate only a few plants for personal consumption, agroforestry is not suitable, although they can adopt single elements of the package. The introduction of new plants and methods into farming systems needs to be preferentially planned by marketing prospects. The potential of diffusion of the innovation depends on the necessary support. Even though agroforestry, in the form it has been promoted by the project, is relatively complex, it allows farmers to choose out of its multitude of elements which ones to adopt. The adoption of further farming methods and plants and also additional components like composting or beekeeping can be further developed over time. The potential of agroforestry to enhance soil quality and to contribute to better crop production became apparent when it was compared to other project farms. The potential of diffusion of agroforestry to other farms in the area is possible, as long as suitable local structures like demonstration farms and locally organized project structures are established and continual trainings are organized. A mixture of self-help and external support is therefore favorable.
Ecophysiological and agronomic response of Abaca (Musa textilis) to different resource conditions in Leyte Island, Philippines
(2012) Bande, Marlito M.; Sauerborn, Joachim
Abaca (Musa textilis Née) is closely related to edible bananas (Musa acuminata Colla and M. balbisiana Colla). Abaca usually thrives in the shade beneath tall trees, especially important for protecting the young plants from the sun and the older, taller plants from wind breakage. However, there is still disagreement on the need for shade trees in abaca cultivation. Hence, this study was conducted to ascertain the ecophysiological and agronomic response of abaca grown in different shade conditions, water and nutrient management systems in Leyte Island, Philippines. The objectives of the study were to: (a) explore the influence of shade and irrigation-fertilization on the morphological and physiological performance of abaca; (b) investigate the effect of reducing light intensities by 30%, 40% and 50% of full sunlight on fiber yield and fiber quality; (c) determine the optimum light requirement of abaca plants to attain the optimum yield without affecting the quality of the fiber for industrial use; (d) examine the effect of shade and irrigation-fertilization on biomass production and allocation as well as on NPK absorption and distribution among abaca organs; and (e) find out if irrigation and fertilization could offset the effect of shade on biomass production, NPK absorption and fiber yield of abaca. Field trials were established where light infiltration was reduced by 30%, 40%, and 50% of full sunlight using polypropylene shade nets. Irrigation was applied at a rate of 5 liters plant-1 application-1 day-1. The frequency of irrigation was applied two times per day at seedling stage (1-3 months after planting), three times at the early vegetative stage (4-6 MAP), four times at the late vegetative stage (7-9 MAP), and five times at flagleaf stage (10-12 MAP). On the other hand, placement application of N, P2O5, K2O using complete fertilizer was done at 14 g plant-1 in every three months for the first six months and was increased to 40 g plant-1 in every three months for the next six months after planting. The results of this study showed that plant height, cumulative leaf area, pseudostem length and base girth of abaca significantly improved when the light was further reduced to 50%. The application of NPK fertilizer and combination of irrigation-fertilization further enhanced the growth performance of abaca. Statistical analysis showed that shade, NPK fertilization and combination of irrigation-fertilization positively affected dry matter production, crop growth rate, leaf area ratio and net assimilation rate from seedling to flagleaf stage. Furthermore, biomass allocation and NPK distribution among abaca organs was significantly affected by high radiation and/or temperature at seedling and early vegetative stages, and differential leaf senescence at flagleaf stage where shade plays a considerable function. The amount of NPK absorbed by each organ was influenced by the growth made during the different stages of crop development. Meanwhile, irrigation and fertilizer application further improved biomass allocation that considerably increased NPK absorption and distribution among plant parts. With regards to agronomic response, the abaca planted under different light regimes showed that 50% shade had significantly higher fiber yield compared to those that were under other light treatments since the plants pseudostem under such treatment were longer, bigger and heavier. The combination of irrigation and fertilization could further enhance fiber yield to as much as 141% (compared to the control) but this was not enough to offset the effects of shade on the physiological performance of the plant which significantly increased fiber yield to as much as 265% (compared to the control). Statistical analysis showed that shade and irrigation-fertilizer application had no significant effect on fiber fineness and tensile strength. The superior productivity of abaca in response to shade was due to the avoidance of photoinhibition and photooxidative damage that negatively affected the abaca grown under full sunlight at seedling and early vegetative stage. Likewise, the detrimental effect of photoinhibition on the photosynthetic capacity of abaca grown in full sunlight significantly decreased biomass production and allocation among abaca organs. The amount of NPK absorbed by each organ was influenced by high radiation causing photooxidative damage at seedling stage and differential leaf senescence at flagleaf stage. This significantly affected the pattern of biomass allocation and NPK distribution among abaca plant organs. On the other hand, the application of fertilizer considerably enhanced biomass production but did not change the usual pattern of biomass and NPK distribution. The results showed that irrigation and fertilizer application cannot offset or equalize the positive effect of shade on the vegetative growth, physiological performance, and NPK absorption among plant organs.
Managing trees on arable land
(2020) Schulz, Vanessa Sarah; Graeff-Hönninger, Simone
The cultivation of several plant species on the same area of land, at the same time, is called Agroforestry (AFS). In the less developed countries and the countries of the tropics and subtropics, AFS are the main form of land management. Reasons can be found in the low degree of mechanization and the low costs of labor. AFS used to be widespread in the industrial nations, too. Over the years, however, these traditional forms have been converted into highly efficient agricultural sites. Agricultural and forest production has been separated spatially. In Germany, this was mainly due to land consolidation, which resulted in large, uniform, and easy-to-farm fields. In recent years, however, this situation has been reconsidered. The positive environmental benefits and the aspect of biodiversity protection of agroforestry systems have been recognized. There are numerous ecological, economic, and social aspects, which make agroforestry attractive again. However, a competitive situation always arises when plants are cultivated together. In addition, there are multiple forms of AFS. Special attention must be paid to the planting of the woody, perennial component, as it remains on the field for several years. Against this background, this thesis deals with the possibilities of establishing the wood component in an AFS as a short rotation strip. Combinations of different tillage and weed management practices on willow growth and yield were tested. Furthermore, the influence of shade, which is listed as one of the three main influencing factors in AFS, is discussed. Agricultural crops behave differently, on shade casts by the woody component on the understory crop, depending on their need for light. To test this, maize was used as a shade-intolerant C4 plant, which reaches its light saturation close to maximum solar irradiance. In contrast, potato was tested as a more shade-tolerant C3 plant. Observations on growth, yield and quality should provide information on their suitability for cultivation under shady conditions in AFS. Various hypotheses were developed and examined for the purpose of testing. In the following, the most central research results will be briefly outlined. When establishing a short rotation coppice with willows, an adequate combination of soil tillage and weed management showed to be important for high yields, whereas the necessary weed management depends on the used soil tillage. Until today, there are no other recommendations for the establishment of a willow short-rotation coppice except ploughing in autumn, harrowing in spring and broad herbicide application. In the current discourse on biodiversity improvement and climate change, forms of reduced tillage (chisel plough + ley crop, no-till) with adapted herbicide-saving weed control (e.g. chemical treatment within the rows and mechanical treatment between the rows, or only mechanical weed control), were tested as alternatives that ensure successful SRC growth and, as a result, high yields while saving pesticides and fossil energy. When grown together, trees will shade the under-story agricultural crops. Some crops can deal better with this light reduction than others. Maize (Zea mays L.), as a plant with a high light saturation point, is already negatively influenced in its growth, the biomass, biogas, and methane yield, as well as the quality determining compounds (dry matter content, crude protein, crude ash) by low amounts of shade. While potatoes (Solanum tuberosum L.), known as shade-tolerant plants, can produce yields and qualities comparable to those of unshaded plants with lower levels of solar irradiance (caused by shading). It could be shown that it is possible to make a valuable contribution to biodiversity with AFS. By using adapted combinations of soil tillage and weed management systems, fossil fuels can be saved through reduced tillage. The use of chemical plant protection in the tree strips can be reduced by the sole application within the SRC strips or avoided altogether by mechanical weed control. In high-valuable timber systems there is usually no weed management necessary. Additionally, the trees strips offer a habitat and food basis for small vertebrates and some arthropods (hymenoptera, coleoptera, lepidoptera and diptera). The permanent planting of the strips reduces greenhouse gases and thus counteracts climate change. Influences of shade on crop yield and quality was only proven for plant-specific shade levels. In such AFS, the influence of shade usually only occurs in later tree ages (and crown thickness). Therefore, AFS are a valuable form of land management to reduce current environmental problems on a national and global scale, while adequate yields can be achieved at the same time.
Participatory evaluation of sustainability of farming systems in the Philippines
(2010) Vilei, Sonja; Dabbert, Stephan
Forest cover in the Philippines has been greatly reduced in the past and slightly recovered since, estimated at around 24% of land surface currently. Small-scale farmers have to survive on small landholdings (2 ha on average and mostly under 5 ha), face insecure land tenure, and the high population density leaves little scope for gaining new agricultural land. Their farming systems continue to form an important part of their livelihoods, but often their strategies are unsustainable in the long run. While the need for evaluating common farming systems and compare them with new alternatives exists, it is important to involve local stakeholders in the search for suitable sustainability indicators. In this study, the search was based on the Sustainable Rural Livelihoods Framework and therefore organised under its five types of capital assets: natural, financial, physical, human and social capital. Farmers from five study sites along the Western side of the island of Leyte were gathered in eight focus group discussions to discuss the issues of success and sustainability of their farming systems and identify and rank possible criteria for an evaluation of sustainability. Nine other stakeholders from the same sites were interviewed individually. In a second research phase, all 49 identified criteria were given to 30 farmers and 18 other stakeholders for ranking. Three groups of farmers from the municipality of Baybay were used for comparison: one group of rice and coconut farmers; a second group with (additional) exotic timber trees (usually Gmelina and Acacia mangium); a third group with (additional) indigenous timber trees (?Rainforestation Farming?). The identified indicators were tested regarding their usefulness for comparing the three groups of farmers. Rainforestation Farming, as promising alternative farming system, was analysed further regarding financial aspects and its adoptability with regard to small-scale farmers. The Sustainable Rural Livelihoods Framework was useful for identifying suitable evaluation criteria. The importance of the five capital assets groups was perceived similarly by farmers and other stakeholders, but ranking results for single criteria (i.e. soil quality, membership in organisation) differed. The same holds true when comparing results for the four study regions, where the individual ranking was carried out: significant differences existed for single, mostly financial, criteria (i.e. record-keeping, investment costs) but not for importance of the five capital asset groups. The ranking results differed quite substantially, though, between focus groups and individual farmers, indicating on the one hand the influence of group leaders. But, on the other hand, farmers had the complete list of criteria for the individual ranking, including several criteria which they had not thought of previously, but which they still regard as important. Fifteen criteria were selected as indicators for comparing the three farmers groups. Rainforestation farmers were the group scoring significantly higher on most indicators (i.e education level adults and children, land available per capita, (perceived) soil quality, number of soil conservation measures used, membership in organisation) than farmers without timber trees. Farmers having planted exotic timber trees scored closer to Rainforestation farmers. But to be able to judge if the specific farming system leads to a more sustainable livelihood, time series data would have been necessary. The data of this study allowed concluding that tree farmers planting (indigenous or exotic) timber trees are endowed with higher resources ? more land, higher income, higher education levels. Most likely they had these resources before starting their farming systems. In addition, these farmers were also more actively engaged in organisations and had more contact to extension agents, therefore enhancing their social (and human) capital. The higher score regarding (perceived) soil quality and (non-) use of pesticides these farmers groups reached are likely to be an outcome of the farming system practiced. Analysing the financial feasibility and adoptability of Rainforestation Farming, it shows that the system has the potential to be profitable, but coming with a high risk: investment costs are very high and it takes up to 13 years to regain them. Consequently, the first adopters either had unused land areas or substantial off-farm income, and the subsequent adoption rate is low. Sustainability has to be understood as a dynamic and not a static concept and the concept of sustainable land management must consequently evolve as well. This study tried to add further findings regarding the use of suitable methods for this cause, but as already mentioned above, time series data would be necessary to assess the progress of farming systems towards ?sustainability?.
Rainforestation farming on Leyte island, Philippines - aspects of soil fertility and carbon sequestration potential
(2007) Marohn, Carsten; Sauerborn, Joachim
This study aimed at investigating rainforestation systems in Leyte, Philippines, under different aspects: Characterisation of typical soils in Leyte with respect to physical, chemical and biological parameters relevant for tree growth, possible contributions of rainforestation to restoring soil fertility, performance of a recently planted rainforestation system under different microclimatic and soil conditions, potential of the rainforestation approach for projects under the umbrella of the Clean Development Mechanism (CDM). Soils in Leyte can be grouped into a volcanic and a calcareous category. The latter were formed on coralline limestone and are high in pH and Ca2+ and Mg2+. Contents of organic matter are high while concentrations of plant available PBray are low. Volcanic soils are characterised by low pH and CEC as well as extremely low PBray contents. Organic matter levels are below those of the calcareous soils but still moderate. In any analysed soil, N would not limit tree growth. Pore volume and water infiltration were propitious for all sites, which is relevant in the context of erosion. For calcareous soils, drought and reduced rootability due to clayey subsoil posed the most relevant constraints. The frequently claimed role of rainforestation in the rehabilitation of degraded soils was assessed in a paired plot approach. Chemical and biological soil parameters under 10 year old rainforestation were contrasted with adjacent fallow or Gmelina sp. Clear tendencies across all seven sampled sites were lower available Mg2+ and pH under rainforestation. Other differences were less distinct. Generally, a depletion of soil reserves e.g. in basic cations can be explained by uptake into the plants. A feed-back of these elements to the topsoil via leaf litter, however, could be observed only for available P. In conclusion, plant uptake of single elements can reach orders of magnitudethat reduce soil stocks. At the same time, generally lower pH under rainforestation may have contributed to elevated losses, especially of basic cations. A general improvement of the sampled soils in terms of chemical or biological characteristics through rainforestation could not be observed. To evaluate plant performance six timber and four fruit species, most native, were interplanted on a 1ha plot. Rainforestation, commonly understood as high-density closed canopy system was modified to a less dense 5x5m grid, interplanted with Musa textilis. The plot varied strongly on a small scale due to heterogeneous canopy closure and relief. Methodologically, the entire area was divided into 10 subplots in representative positions to be sampled. Soil physical and chemical properties, microbial activity, PAR and root length density were determined and correlated to plant survival and growth at consecutive inventories. For Musa textilis, the most sensitive species, which was used as an indicator, logistic regressions were calculated to determine the influence of all relevant parameters on survival rates. The most important predictors for survival were organic matter contents, parameters related to biological activity and leaf litter production, which resembled canopy closure and thus indirectly light intensity and soil moisture. To assess growth, multiple regressions were formulated for biomass at five inventories. Corg and NLOM were the most relevant variables determining the regressions used for biomass and growth of abaca. Assessing the potential of rainforestation for Clean Development Mechanism (CDM) measures, amounts of sequestered CO2 during 10 and 20 years, respectively, were estimated under different management options using the WaNuLCAS model. Despite all given uncertainty associated with modelling, one very obvious finding was the dominant role of soil carbon for the plot balance: Appropriate soil management, especially during land preparation (e.g. clearing vs. enrichment planting) is of paramount importance. Looking at the modelled contribution of various tree species to the carbon balance, Musa textilis had a significant influence only during the very first years; later on, the principal share of carbon was bound in the tree component. Here, exotic Gmelina arborea built up biomass more quickly than a rainforestation plot composed of native Shorea contorta and Durio zibethinus, but was then overtaken. In absolute quantities of CO2 sequestration, magnitudes matched inventory and modelled data given in various literature sources for Leyte and the Philippines. Relative to earlier inventory data from two rainforestation sites, modelled values overestimated growth.
Soil moisture dynamics in integrated crop - livestock - forestry systems in the Cerrado Biome in Central - West Brazil
(2021) Glatzle, Sarah; Asch, Folkard
The Cerrado biome in Brazil covers about 200 million ha and is a global biodiversity hotspot. Over the last decades, the Cerrado biome underwent and is still undergoing an excessive expansion in agriculture. Deforestation and replacement of the natural Savannah vegetation by cropland and pasture contributes to serious environmental problems, including soil degradation and altered water cycles. The integrated crop-livestock-forestry (ICLF) system is currently promoted as a measure for sustainable intensification. It improves the use of cultivated areas, recovers previously degraded land, and could be a strategy for adapting agriculture to climate change. Despite being considered a key indicator of how integrated systems affect ecological processes, soil moisture (SM) dynamics in literature have not been consistently analyzed, and continuous observation of seasonal SM dynamics are mostly unaddressed. Since SM of complex ecosystems is influenced by numerous factors, several additional parameters need to be considered to create a comprehensive understanding of the interlinked processes, such as radiation, rainfall, and biomass. The objective of this cumulative PhD thesis was to investigate SM dynamics and aboveground grass biomass under different land use systems in the Cerrado biome of Central West Brazil. In the first study, photosynthetically active radiation (PAR) received at grass canopy level, SM, AGBM between the tree rows, and seasons in a mature ICLF system were investigated. Across the seasons, a distinct gradient was observed with SM being lower close to the tree rows than in the space between them. During winter, SM in the topsoil decreased to critical values, and dropped to the permanent wilting point next to the tree rows. During spring and summer, incident PAR was lower close to the trees than at the center point, while during autumn and winter, when PAR is generally lower, it was more evenly distributed between the tree rows. Aboveground grass biomass (AGBM) showed a distinct distribution within the ICLF system with maximum values in the center and about 50% of the biomass close to the tree rows. The results suggest that, restrictions in AGBM accumulation shifted among seasons between water limitations in winter and light limitations during summer. In the second study, the seasonal and spatial variability of SM of Cerrado soils under four different land use systems was investigated under consideration of soil physical characteristics and grass biomass. In rainy and dry season, SM in the upper 100 cm of the soil was highest in the integrated crop-livestock (ICL) system, followed by the continuous pasture (COP), and lowest in the land use systems including trees, ICLF and Cerrado. Whereas in COP and in ICL, water was mainly taken up from the upper 30 cm, in ICLF, the strongest soil moisture depletion was observed between a soil depth of 40 and 100 cm. Although in the Cerrado SM in the topsoil was lower than in the other land use types, water was conserved below 60 cm depth. Both integrated systems improved soil properties, such as bulk density and soil organic carbon compared to COP, and increased biomass productivity was observed, demonstrating the benefits of the integrated systems over the traditional grazing system. The results suggest that ICLF systems show increased evapotranspiration compared to conventional pasture and other integrated systems without trees. In the third study, the effects of the presence of eucalyptus trees on the seasonal pasture and animal performance in ICLF systems 8 years after establishment were investigated. Forage morphology, production, and nutritive value plus performance of Nellore heifers in two ICLF systems with varying in trees density, were evaluated and compared with a grass-only pasture. In both ICLF systems, the forage nutritive values were improved compared with a grass-only pasture. Nevertheless, grass biomass and accumulation rate were higher in the grass-only pasture. By the 8th year, the ICLF systems were unable to support both forage and animal production equivalent to a grass-only pasture, due to the high impact of the Eucalyptus trees on radiation received at the grass canopy and on soil moisture. Improved soil characteristics and forage nutritive values compared to grass-only pastures, and the potential restoration of natural ecosystem functions regarding water recycling into the atmosphere, demonstrated the benefits of ICLF systems and highlight their potential to contribute to sustainable agricultural intensification. However, high water consumption by trees poses a risk to grass productivity during the dry season and thus, the system may consequently not be used for grazing all year round. Therefore, research on management options mitigating the impact of drought on grass productivity is needed. As the impact of the trees on the system is highly dependent on their age, these studies should consider the entire life cycle of the system.