Multi-scale trade-off analysis of cereal residue use for livestock feeding vs. soil mulching in the Mid-Zambezi Valley, Zimbabwe
Baudron, F. ; Delmotte, S. ; Corbeels, M. ; Herrera, J.M. ; Tittonell, P.A. - \ 2015
Agricultural Systems 134 (2015). - ISSN 0308-521X - p. 97 - 106.
conservation agriculture - systems - nitrogen - africa - model - knowledge - village - quality - carbon - apsim
Cereal residues represent a major resource for livestock feeding during the dry season in southern Africa. When kept on the soil surface instead of feeding them to livestock, crop residues can contribute to increasing soil fertility and maintaining crop productivity in the short- and the long-term. We explored these trade-offs for smallholder cotton–sorghum farming systems in the semi-arid Zambezi Valley, northern Zimbabwe. The analysis was done using simulation models at three scales, the plot, the farm and the territory, to simulate the effects of different sorghum residue allocations to livestock feeding vs. soil mulching, in combination with different application rates of mineral nitrogen fertilizer on crop productivity. The plot-scale simulations suggest that without N fertilization soil mulching has a positive effect on cotton yields only if small quantities of sorghum residues are used as mulch (average cotton yields of 2.24 ± 0.41 kg ha-1 with a mulch of 100 kg ha-1 vs. 1.91 ± 0.29 kg ha-1 without mulch). Greater quantities of mulch have a negative effect on cotton yield without N fertilization due to N immobilization in the soil microbial biomass. With applications of 100 kg N ha-1, quantities of mulch up to 3 t ha-1 have no negative effect on cotton yield. Results at farm-scale highlight the fundamental role of livestock as a source of traction, and the need to feed a greater proportion of sorghum residues to livestock as herd and farm sizes increase. Farmers with no livestock attained maximum crop production when 100% of their sorghum residue remained in the field, as they do not have access to cattle manure. The optimum fraction of crop residue to be retained in the fields for maximum farm crop production varied for farmers with 2 or less heads of cattle (80% retention), with 2–3 heads (60–80%), with 4 or more heads (40–60%). At the scale of the entire territory, total cotton and sorghum production increased with the density of cattle, at the expense of soil mulching with crop residues. The results of our simulations suggest that (i) the optimum level of residue retention depends on the scale at which trade-offs are analyzed; (ii) the retention of all of the crop residue as mulch appears unrealistic and undesirable in farming systems that rely on livestock for traction; and (iii) crop residue mulching could be made more attractive to farmers by paying due attention to balancing C to N ratios in the soil and by promoting small-scale mechanization to replace animal traction.
Impacts of changes in mangrove forest management practices on forest accessibility and livelihood: A case study in mangrove-shrimp farming system in Ca Mau Province, Mekong Delta, Vietnam
Ha, T.T.P. ; Dijk, J.W.M. van; Visser, L.E. - \ 2014
Land Use Policy 36 (2014). - ISSN 0264-8377 - p. 89 - 101.
land - conservation - resources - northwest - politics - village - access - policy
This paper documents how the implementation of forest tenure policy affects the decision-making of farmers in mangrove-shrimp farming systems with regard to their access to and management of mangrove forest in Ca Mau, Mekong Delta, which is the largest remaining mangrove forest in Vietnam. Policies on land allocation, land tenure and use-rights are important since they potentially promote sustainable mangrove-shrimp management. Forest management policy in Vietnam has been changed to promote equality of benefit sharing among stakeholders and devolved State forest management to the household level. However, to what extent its implementation can stimulate both mangrove conservation and livelihood improvement is still being debated. We use access and its social mechanisms to investigate how State Forest Companies (FC) and farmers can benefit from mangrove exploitation. The study was conducted from September 2008 to August 2010 using both qualitative and quantitative methods and using a participatory approach. After group discussions and in-depth interviews with a wide range of stakeholders, we interviewed 86 households in four communities using structured questionnaires. Results show the imbalance in access to finance, markets, and differences in authority between the two actors, farmers and FC. The discussion focuses on the possibilities of “win–win” outcomes, i.e. land tenure regimes promoting the devolution of sustainable forest management to farm households to balance benefits of both mangrove conservation and livelihood improvement.
Who believes in witches? Institutional flux in Sierra Leone
Grijspaarde, H. Van de; Voors, M.J. ; Bulte, E.H. ; Richards, P. - \ 2013
African Affairs 112 (2013)446. - ISSN 0001-9909 - p. 22 - 47.
witchcraft - accusations - poverty - village - sorcery - africa
Witchcraft has been documented across the globe. The widespread occurrence of such beliefs in modern Africa affects politics, economic development, and poverty alleviation. Anthropologists have analysed the semiotics of African witchcraft, but there is less information on distributional issues. An important question is which communities are most affected, and why? Using data from a survey of 182 villages and 2,443 household heads in the Gola Forest region of eastern Sierra Leone, we examine three manifestations of witchcraft – concerns, conflicts, and detection. We find that where patrimonial relations of agrarian production remain strong, and in settings where market forces are now well established, witchcraft is less of a concern. By contrast, witchcraft manifestations are higher in communities experiencing the competing pull of patrimonial and market norms. Witchcraft, we conclude, is a product of normative ambiguity.
HIV and orientation of subsistence and commercial home gardens in rural Ghana: Crop composition, crop diversity and food security
Akrofi, S. ; Struik, P.C. ; Price, L.L. - \ 2010
African Journal of Agricultural Research 5 (2010)18. - ISSN 1991-637X - p. 2593 - 2607.
species-diversity - homegardens - hiv/aids - village - households - africa - aids
An empirical study was conducted to explore differences and similarities in biodiversity in subsistence and commercial home gardens of HIV-positive and HIV-negative rural households in the Eastern Region of Ghana and their significance in household food security. Data were obtained through a household and home garden survey of a purposive sample of 32 HIV-positive and a random sample of 48 HIV-negative rural households and through in-depth interviews. A higher proportion of species common to all four home garden types consisted of food crops: vegetables, staples and fruits. In HIV-positive households, commercial home gardens were significantly larger, had significantly more species and individual plants, more perennial food crops and more species that were harvested all year round and evenness was lower, but there was no significant difference in species diversity compared with subsistence home gardens. Significantly, more HIV-positive and HIV-negative households with a commercial home garden consumed a staple crop cultivated in the home garden in the 24-h period prior to the survey than HIV-positive households with subsistence home gardens. Rural households with HIV that manage commercial home gardens cultivate a dual purpose home garden which supplies subsistence food and also provides cash income; such households may have better food security than households that cultivate subsistence home gardens
Observations and model estimates of diurnal water temperature dynamics in mosquito breeding sites in western Kenya
Paaijmans, K.P. ; Jacobs, A.F.G. ; Takken, W. ; Heusinkveld, B.G. ; Githeko, A.K. ; Dicke, M. ; Holtslag, A.A.M. - \ 2008
Hydrological Processes 22 (2008)24. - ISSN 0885-6087 - p. 4789 - 4801.
anopheles-gambiae diptera - aquatic stages - malaria transmission - culicidae larvae - land-cover - habitats - survival - highlands - reservoir - village
Water temperature is an important determinant of the growth and development of malaria mosquito immatures. To gain a better understanding of the daily temperature dynamics of malaria mosquito breeding sites and of the relationships between meteorological variables and water temperature, three clear water pools (diameter × depth: 0·16 × 0·04, 0·32 × 0·16 and 0·96 × 0·32 m) were created in Kenya. Continuous water temperature measurements at various depths were combined with weather data collections from a meteorological station. The water pools were homothermic, but the top water layer differed by up to about 2 °C in temperature, depending on weather conditions. Although the daily mean temperature of all water pools was similar (27·4-28·1 °C), the average recorded difference between the daily minimum and maximum temperature was 14·4 °C in the smallest versus 7·1 °C in the largest water pool. Average water temperature corresponded well with various meteorological variables. The temperature of each water pool was continuously higher than the air temperature. A model was developed that predicts the diurnal water temperature dynamics accurately, based on the estimated energy budget components of these water pools. The air-water interface appeared the most important boundary for energy exchange processes and on average 82-89% of the total energy was gained and lost at this boundary. Besides energy loss to longwave radiation, loss due to evaporation was high; the average estimated daily evaporation ranged from 4·2 mm in the smallest to 3·7 mm in the largest water pool
The effect of toposequence position on soil properties, hydrology, and yield of rainfed lowland rice in Southeast Asia
Boling, A.A. ; Tuong, T.P. ; Suganda, H. ; Konboon, Y. ; Harnpichitvitaya, D. ; Bouman, B.A.M. ; Franco, D.T. - \ 2008
Field Crops Research 106 (2008)1-2. - ISSN 0378-4290 - p. 22 - 33.
west-africa - northeast thailand - cropping systems - village
large proportion of rainfed lowland rice in Southeast Asia is grown in gently sloping areas along toposequences with differences in elevation of a few meters. These small differences in elevation can lead to differentiation in soil properties and hydrological conditions, which in turn may affect crop performance and yield. It may be appropriate to replace blanket crop management recommendations in rainfed areas with toposequence-specific management recommendations. However, thorough statistical analyses of the relationships between toposequence position and field and crop conditions are lacking. In this paper, we statistically analysed the effect of toposequence position on soil properties, hydrological conditions, yield, and yield increase due to weed control and/or fertilizer management in rainfed areas in four villages in Indonesia and Thailand each in 2000¿2002. Differences were substantial in field hydrology (average depth of ponded surface water and of groundwater, number of days without ponded surface water), exchangeable K, organic C, and clay content depending on toposequence position. There were also differences in other soil properties, including N, P, CEC, pH, sand, silt, bulk density, yield, and the magnitude of yield increase due to intensive weed control and/or recommended fertilizer application, but these effects were not consistent across countries, seasons, and years. The hypothesis that toposequence position would be a useful recommendation domain for weed control and fertilizer recommendations was not supported by our statistical results. The reasons why toposequence position has an inconsistent statistical effect could be (1) that the variability of the field conditions is larger among villages than among toposequence positions, and/or (2) that farmers already respond to differences in field conditions in their prevalent management practices, thus masking the effects of toposequence-specific variation on yield. Our findings suggest that despite the large toposequence effects on soil nutrient and water availability, weed and fertilizer management recommendations should be field-specific and time-specific rather than toposequence-specific
Reducing vector-borne disease by empowering farmers in integrated vector management
Berg, H. van den; Hildebrand, A. von; Ragunathan, V. ; Das, P.K. - \ 2007
Bulletin of the World Health Organization 85 (2007)7. - ISSN 0042-9686 - p. 561 - 566.
sri-lanka - field schools - rice fields - malaria - populations - irrigation - prevention - ecosystem - village - complex
PROBLEM: Irrigated agriculture exposes rural people to health risks associated with vector-borne diseases and pesticides used in agriculture and for public health protection. Most developing countries lack collaboration between the agricultural and health sectors to jointly address these problems. APPROACH: We present an evaluation of a project that uses the "farmer field school" method to teach farmers how to manage vector-borne diseases and how to improve rice yields. Teaching farmers about these two concepts together is known as "integrated pest and vector management". LOCAL SETTING: An intersectoral project targeting rice irrigation systems in Sri Lanka. RELEVANT CHANGES: Project partners developed a new curriculum for the field school that included a component on vector-borne diseases. Rice farmers in intervention villages who graduated from the field school took vector-control actions as well as improving environmental sanitation and their personal protection measures against disease transmission. They also reduced their use of agricultural pesticides, especially insecticides. LESSONS LEARNED: The intervention motivated and enabled rural people to take part in vector-management activities and to reduce several environmental health risks. There is scope for expanding the curriculum to include information on the harmful effects of pesticides on human health and to address other public health concerns. Benefits of this approach for community-based health programmes have not yet been optimally assessed. Also, the institutional basis of the integrated management approach needs to be broadened so that people from a wider range of organizations take part. A monitoring and evaluation system needs to be established to measure the performance of integrated management initiatives.
Adding a soil fertility dimension to the global farming systems approach, with cases from Africa
Smaling, E.M.A. ; Dixon, J. - \ 2006
Agriculture, Ecosystems and Environment 116 (2006)1-2. - ISSN 0167-8809 - p. 15 - 26.
primary forest - burkina-faso - land hunger - management - technologies - cultivation - dynamics - nitrogen - savanna - village
The global farming systems (GFS) approach is extended by adding a soil fertility and nutrient management dimension for Africa's forest-based, maize mixed, cereal¿root crop mixed, and agro-pastoral millet/sorghum farming systems. Use is made of sustainable livelihood concepts, translated into farmer capitals (natural, physical, financial, human, social), and the indicator-based DPSIR (driving force-pressure-state-impact-response) framework for environmental reporting. State and impact indicators show, for each GFS, levels of nutrient stocks and flows, respectively. In case of nutrient depletion, soils may (i) initially still be fertile enough to provide reasonable and stable yields, (ii) support declining yields, or (iii) support low yields at low fertility level. In the latter case, food security is generally at stake. Response indicators include the level of uptake of improved integrated nutrient management strategies at land user level, and the enforcement of new and enabling pro-agriculture and pro-environment policies. Although the extended GFS have no direct relevance for farm-level interventions, the approach can be used to frame soil fertility research priorities and policies at a regional level