Urban agricultural land use and characterization of mosquito larval habitats in a medium-sized town of C?te d'Ivoire.

Urban agriculture is common across Africa and contributes to the livelihoods of urban dwellers. Some crop systems create suitable mosquito breeding sites and thus might affect malaria transmission. The purpose of this study was to identify, map, and characterize potential mosquito breeding sites in agricultural land use zones in a medium-sized town of western C?te d'Ivoire and to assess risk factors for productive Anopheles breeding sites. Two surveys were carried out; one toward the end of the rainy season and the second one during the dry season. In all identified potential mosquito breeding sites, two experienced entomologists searched for the presence of Anopheles larvae and pupae with a standardized technique. Totals of 369 and 589 sites were found in the rainy and dry seasons, respectively, mainly in vegetable gardens and irrigated rice fields. Anopheles larvae were present in 50.7% and 42.4% of the sites investigated during the rainy and dry seasons, respectively. Typical Anopheles larval habitats were characterized by the presence of algae, the absence of floating vegetation, and the co-occurrence of Culex larvae. The highest Anopheles larval productivity was observed in rice paddies, agricultural trenches between vegetable patches, and irrigation wells. An indirect link could be established between the occurrence of productive Anopheles breeding sites and agricultural land use through specific man-made habitats, in particular agricultural trenches, irrigation wells, and rice paddies. Our findings have important bearings for the epidemiology and control of urban malaria in sub-Saharan Africa.     

Risky Business: Temporal and Spatial Variation in Preindustrial Dryland Agriculture

Traditional dryland agriculture in the Pacific island was often labor-intensive and risky, yet settlement and farming in dry areas played an important role in the development of Polynesian societies. We investigate how temporal and spatial climatic fluctuations shape variation in agricultural production across dryland landscapes. We use a model that couples plant growth, climate, and soil organic matter dynamics, together with data from Kohala, Hawai'i, to understand how temperature, rainfall, nitrogen availability, and cropping activity interact to determine yield dynamics through time and space. Due to these interactions, the statistical characterization of rainfall alone is a poor characterization of agricultural yield. Using a simple linear model of human population dynamics, we show that the observed yield variation can affect long-term population growth substantially. Our approach to analyzing spatial and temporal fluctuations in food supply, and to interpreting the population consequences of these fluctuations, provides a quantitative evaluation of agricultural risk and human carrying capacity in dry regions.     

Conserving the Birds of Uganda’s Banana-Coffee Arc: Land Sparing and Land Sharing Compared

Reconciling the aims of feeding an ever more demanding human population and conserving biodiversity is a difficult challenge. Here, we explore potential solutions by assessing whether land sparing (farming for high yield, potentially enabling the protection of non-farmland habitat), land sharing (lower yielding farming with more biodiversity within farmland) or a mixed strategy would result in better bird conservation outcomes for a specified level of agricultural production. We surveyed forest and farmland study areas in southern Uganda, measuring the population density of 256 bird species and agricultural yield: food energy and gross income. Parametric non-linear functions relating density to yield were fitted. Species were identified as “winners” (total population size always at least as great with agriculture present as without it) or “losers” (total population sometimes or always reduced with agriculture present) for a range of targets for total agricultural production. For each target we determined whether each species would be predicted to have a higher total population with land sparing, land sharing or with any intermediate level of sparing at an intermediate yield. We found that most species were expected to have their highest total populations with land sparing, particularly loser species and species with small global range sizes. Hence, more species would benefit from high-yield farming if used as part of a strategy to reduce forest loss than from low-yield farming and land sharing, as has been found in Ghana and India in a previous study. We caution against advocacy for high-yield farming alone as a means to deliver land sparing if it is done without strong protection for natural habitats, other ecosystem services and social welfare. Instead, we suggest that conservationists explore how conservation and agricultural policies can be better integrated to deliver land sparing by, for example, combining land-use planning and agronomic support for small farmers.     

Semiarid Crop Production from a Hydrological Perspective: Gap between Potential and Actual Yields

Rapid population growth in the dry climate regions, arable land scarcity, and irrigation expansion limitations direct our interest to possibilities of yield increase in rainfed agriculture. Literature, however, indicates large differences between actual and potential yields, and between yields on farmers’ fields and research stations. This article focuses on the determinants of these yield gaps and the windows of opportunity for yield increase on the farmer's field together with the agricultural challenges involved. The study links the conventional approach to estimate crop water requirements and dry spell effects on biomass production to a conceptual Green Water Crop Model. This model addresses the effects on crop yields of the sequential diversions of infiltrating rainfall (rainwater partitioning into runoff, plant available soil water, and deep percolation) and of different relations between nonproductive evaporation flow and productive transpiration flow, defined together as green water flow. Also, the effects of droughts and dry spells are analyzed. The model is used to demonstrate typical situations for semiarid and dry subhumid conditions (lengths of growing period (LGP) of 90 and 179 days, respectively) for maize (Zea mays (L.)) under on-station agricultural conditions. Based on detailed water flow analysis in a 3-year on-farm case study in the Sahel on pearl millet (Pennisetum glaucum (L.) Br.), the model is used to clarify the large scope for improved yield levels, achievable through land and water management securing that runoff losses and deep percolation are reduced and nonproductive evaporation losses minimized. The analysis indicates that poor rainwater partitioning and low plant water uptake capacity alone reduces estimated on-farm grain yields to 1/10th of the potential yields. This suggests that lack of water per se not necessarily is the primary constraint to crop growth even in drought prone areas of sub-Saharan Africa. The conclusion is that even a doubling of crop yields would be agro-hydrologically possible with relatively small manipulations of rainwater partitioning in the water balance.     

Impacts of flood control schemes on inland fisheries in Bangladesh: guidelines for mitigation

Flood control, drainage and irrigation (FCDI) schemes are widespread in Bangladesh. They are built to control water levels to improve agricultural production based on high yielding varieties (HYV) of rice that cannot tolerate rapid inundation or that require irrigation, and to provide protection from extreme flood events. The benefits to the agricultural sector can be significant. At some sites in Bangladesh, farmers report up to 80% more agricultural production inside the schemes than outside. However, fish production and species richness is typically lowered by these structures. Fish yields inside a typical flood control compartment can be 50% lower than outside, with up to 25 species of fish absent or less abundant. Lower rates of recruitment of migratory whitefish species, whose lateral migrations are obstructed by the embankments, were found to be largely responsible for these differences. With a risk of more extreme flooding during the monsoon season but hotter and more arid dry season conditions predicted as a consequence of climate change, more FCDI schemes may need to be constructed to provide flood protection and to meet increasing irrigation needs. Based on fisheries monitoring and mark-recapture studies undertaken at 3 sluice gates, nine recommendations for operating sluice gates to mitigate the impacts of FCDI schemes on fish production and biodiversity are described. These recommendations aim to improve the access of migratory whitefish to modified floodplains and to improve or sustain the production of resident (non-migratory) blackfish whilst minimising agricultural sector losses. Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Predicted avian responses to bioenergy development scenarios in an intensive agricultural landscape

Conversion of native prairie to agriculture has increased food and bioenergy production but decreased wildlife habitat. However, enrollment of highly erodible cropland in conservation programs has compensated for some grassland loss. In the future, climate change and production of second-generation perennial biofuel crops could further transform agricultural landscapes and increase or decrease grassland area. Switchgrass (Panicum virgatum) is an alternative biofuel feedstock that may be economically and environmentally superior to maize (Zea mays) grain for ethanol production on marginally productive lands. Switchgrass could benefit farmers economically and increase grassland area, but there is uncertainty as to how conversions between rowcrops, switchgrass monocultures and conservation grasslands might occur and affect wildlife. To explore potential impacts on grassland birds, we developed four agricultural land-use change scenarios for an intensively cultivated landscape, each driven by potential future climatic changes and ensuing irrigation limitations, ethanol demand, commodity prices, and continuation of a conservation program. For each scenario, we calculated changes in area for landcover classes and predicted changes in grassland bird abundances. Overall, birds responded positively to the replacement of rowcrops with switchgrass and negatively to the conversion of conservation grasslands to switchgrass or rowcrops. Landscape context and interactions between climate, crop water use, and irrigation availability could influence future land-use, and subsequently, avian habitat quality and quantity. Switchgrass is likely to provide higher quality avian habitat than rowcrops but lower quality habitat than conservation grasslands, and therefore, may most benefit birds in heavily cultivated, irrigation dependent landscapes under warmer and drier conditions, where economic profitability may also encourage conversions to drought tolerant bioenergy feedstocks.     

Farmers’ Perspectives on Vital Soil-related Ecosystem Services in Intensive Swidden Farming Systems in the Peruvian Amazon

A growing dilemma is how to conserve Amazonian forest while allowing local people to secure their livelihoods. Small-scale swidden farming in Amazonia is entirely dependent on the continued provision of ecosystem services (ES) that generate the conditions for agriculture. This study identified soil-related ES needed for, and enhanced by, productive swidden systems from the farmer’s perspective. Workshops in six farming communities in northeastern Peru discussed various land uses, swidden systems that continue to be productive, and swidden systems on degraded land. The participating farmers noted changes in their production systems and described the ES (or lack thereof) in terms of soil quality, crop production quantity and quality, burning practices, forest regeneration, and farming skill. The central elements described in farmers’ own strategies for managing soil-related ES were fallow management for biomass production and crop diversity, factors identified as central to future ES management work in established agricultural areas in Amazonia.     

Commercial production of carrageenophytes in the Philippines: ensuring long-term sustainability for the industry

An abundance of marine algae along the Philippines' long, irregular coastline (36,289 km) has made it inevitable for Filipinos to exploit algae for food, feeds, medicine, or other purposes. Among the most popular of these algae are the carrageenophytes, which include four genera, six species, and 21 morphotypes/varieties/cultivars under the Family Solieriaceae. However, commercial production did not begin until 1973. The development of carrageenophyte farming for commercial purposes evolved from simple fixed-bottom monoline farming by coastal farmers, who refined the technology themselves, with the help and guidance of local and international scientists, which has led to a commercially viable industry with a maximum estimated production of 97,000–102,820 dry, metric tons in 2004. Farm gate revenues for that year were estimated at US$ 82.45–87.4 million (four croppings year^?1), whose main recipients were the local seaweed farmers. However, in 2008, production started to decline, which was brought primarily by the deteriorating quality of propagules and the perennial occurrence of “ice-ice” and harmful endophytes caused by environmental stresses due to unfavorable weather conditions, and secondarily, the peace and order problem in the major producing areas like Zamboanga, Maguindanao, Basilan, and Sulu in Mindanao and insufficient government support. This paper aims to assess the present situation and suggest how to possibly reverse the situation to its usual productive periods.     

Agricultural intensification in a Philippine frontier community: Impact on labor efficiency and farm diversity

There continues to be much debate in anthropology concerning the mechanism by which agricultural intensification takes place and its impact on labor efficiency, farm diversity, and quality of diet. A major reason for this lack of consensus is the paucity of data from case studies that focus on specific agricultural systems at the point of transition from extensive to intensive methods of cultivation. Research in a frontier community in the Philippines, where farmers are making the shift from swidden cultivation to small-scale irrigated rice production, indicates that intensification does not necessarily result in lower efficiency or a decline in dietary standards. Rather, farmers faced with growing population pressure and an unproductive short fallow swidden system have been motivated to adopt irrigation because it increases the efficiency of their labor while maintaining a reliable and diverse farming system.     

Assessing the floodwater utilization potential in a reservoir-controlled watershed: A novel method considering engineering regulations and an empirical case from China

Floodwater utilization can greatly alleviate water resource shortages. Reservoirs and their optimal operation are the most widely used measures to implement floodwater utilization. Quantitatively evaluating the floodwater utilization potential and revealing the relationship between the potential and its influencing factors are preconditions to implementing floodwater utilization; however, few studies have focused on this problem. In this study, we identified the influencing factors via the analysis of reservoir regulation and proposed a floodwater utilization potential evaluation method that considers all influencing factors. The results indicate that reservoir regulation ability, water demand, and ecological water downstream are the main influencing factors of floodwater utilization potential. The floodwater utilization potential decreases as the water demand or reservoir regulation ability increases. Moreover, water demand and reservoir regulation ability are interdependent and interactive to a certain extent. Specifically, reservoir regulation ability can affect only the floodwater utilization potential when the water demand is extremely high. Based on a time-varying operation model, we also evaluated the floodwater utilization potentials of the Longjiaoshan Reservoir (China) under different floodwater utilization statuses. The average annual floodwater utilization potential of the Longjiaoshan Reservoir watershed is 43.06 million m³ under the current floodwater utilization status, and the optimal floodwater utilization strategy is increasing the water demand under the current reservoir regulation ability. This study may contribute to the improved management of flood utilization in such reservoirs.     

Biological nitrogen fixation: An efficient source of nitrogen for sustainable agricultural production?

A fundamental shift has taken place in agricultural research and world food production. In the past, the principal driving force was to increase the yield potential of food crops and to maximize productivity. Today, the drive for productivity is increasingly combined with a desire for sustainability. For farming systems to remain productive, and to be sustainable in the long-term, it will be necessary to replenish the reserves of nutrients which are removed or lost from the soil. In the case of nitrogen (N), inputs into agricultural systems may be in the form of N-fertilizer, or be derived from atmospheric N₂ via biological N₂ fixation (BNF).Although BNF has long been a component of many farming systems throughout the world, its importance as a primary source of N for agriculture has diminished in recent decades as increasing amounts of fertilizer-N are used for the production of food and cash crops. However, international emphasis on environmentally sustainable development with the use of renewable resources is likely to focus attention on the potential role of BNF in supplying N for agriculture. This paper documents inputs of N via symbiotic N₂ fixation measured in experimental plots and in farmers' fields in tropical and temperate regions. It considers contributions of fixed N from legumes (crop, pasture, green manures and trees), Casuarina, and Azolla, and compares the relative utilization of N derived from these sources with fertilizer N.     

Conservation in tropical landscape mosaics: the case of the cacao landscape of southern Bahia, Brazil

A recent debate has contrasted two conservation strategies in agricultural landscapes; either “land sparing” farm development combining intensive production practices with forest set-asides, or “wildlife-friendly” farming with greater on-farm habitat value but lower yields. We argue that in established mosaic landscapes including old cacao production regions where natural forest has already been reduced to relatively small fragments, a combination of both strategies is needed to conserve biodiversity. After reviewing the evidence for the insufficiency of either strategy alone if applied to such landscapes, the paper focuses on the cacao production landscape of southern Bahia, Brazil, once the world’s second largest cacao producer. Here, small remaining areas of Atlantic Forest are embedded in a matrix dominated by traditional cacao agroforests, resulting in a landscape mosaic that has proven favorable to the conservation of the region’s high biodiversity. We show that current land use dynamics and public policies pose threats but also offer opportunities to conservation and describe a three-pronged landscape conservation strategy, consisting of (i) expansion of the protected areas system, (ii) promotion of productive yet biodiversity-friendly cacao farming practices, and (iii) assistance to land users to implement legally mandated on-farm reserves and voluntary private reserves. We discuss recent experiences concerning the implementation of this strategy, discuss likely future scenarios, and reflect on the applicability of the Bahian experience to biodiversity rich cacao production regions elsewhere in the tropics.     

Modelling predicts that soybean is poised to dominate crop production across Africa

The superior agronomic and human nutritional properties of grain legumes (pulses) make them an ideal foundation for future sustainable agriculture. Legume‐based farming is particularly important in Africa, where small‐scale agricultural systems dominate the food production landscape. Legumes provide an inexpensive source of protein and nutrients to African households as well as natural fertilization for the soil. Although the consumption of traditionally grown legumes has started to decline, the production of soybeans (Glycine max Merr.) is spreading fast, especially across southern Africa. Predictions of future land‐use allocation and production show that the soybean is poised to dominate future production across Africa. Land use models project an expansion of harvest area, whereas crop models project possible yield increases. Moreover, a seed change in farming strategy is underway. This is being driven largely by the combined cash crop value of products such as oils and the high nutritional benefits of soybean as an animal feed. Intensification of soybean production has the potential to reduce the dependence of Africa on soybean imports. However, a successful “soybean bonanza” across Africa necessitates an intensive research, development, extension, and policy agenda to ensure that soybean genetic improvements and production technology meet future demands for sustainable production.     

Integrating biodiversity and conservation with modern agricultural landscapes

To achieve food security and meet the demands of the ever-growing human populations, farming systems have assumed unsustainable practices to produce more from a finite land area. This has been cause for concern mainly due to the often-irreversible damage done to the otherwise productive agricultural landscapes. Agro-ecology is proclaimed to be deteriorating due to eroding integrity of connected ecological mosaics and vulnerability to climate change. This has contributed to declining species diversity, loss of buffer vegetation, fragmentation of habitats, and loss of natural pollinators or predators, which eventually leads to decline in ecosystem services. Currently, a hierarchy of conservation initiatives is being considered to restore ecological integrity of agricultural landscapes. However, the challenge of identifying a suitable conservation strategy is a daunting task in view of socio-ecological factors that may constrain the choice of available strategies. One way to mitigate this situation and integrate biodiversity with agricultural landscapes is to implement offset mechanisms, which are compensatory and balancing approaches to restore the ecological health and function of an ecosystem. This needs to be tailored to the history of location specific agricultural practices, and the social, ecological and environmental conditions. The offset mechanisms can complement other initiatives through which farmers are insured against landscape-level risks such as droughts, fire and floods. For countries in the developing world with significant biodiversity and extensive agriculture, we should promote a comprehensive model of sustainable agricultural landscapes and ecosystem services, replicable at landscape to regional scales. Arguably, the model can be a potential option to sustain the integrity of biodiversity mosaic in agricultural landscapes.     

Selecting the sharpest tools to explore the food-feed-fuel debate: Sustainability assessment of family farmers producing food,feed and fuel in Brazil

Continuing interest in sustainable biofuel production is linked with sustainable farming and begs for insights from farming systems research on sustainability assessment and the role of family farms. The aims of this work were two-fold. First, to present a tools and methods selection framework supporting indicator-based sustainability assessment. Second, to apply the framework to the case of castor beans (Ricinus communis L.), family farmers and the biodiesel industry in the southeast of Brazil. The framework synthesizes existing work on sustainability assessment within the agricultural domain. Transparent selection of tools and methods is supported by sequentially accounting for the context of sustainability, dealing with space, classifying the ‘nature of research’ and the degree of integration of different facets of sustainability. The framework is demonstrated with an exploratory assessment of the potential for castor bean cultivation within the current farm type of extensive pasture and fodder crops for dairy cattle. The study accounted for the range of productivity levels within the current farm type and for different management decisions when including castor beans. Assessment was made against economic development, livelihood stability and soil fertility criteria. Selected tools and methods included farm surveys, alternative farming system design and input–output calculations. The results demonstrate the greatest opportunity for castor bean cultivation by currently low productive farms. There is a trade-off of income derived from milk production that is supported by fodder production, and income from castor beans. Decisions regarding areal extent of castor beans and supplementing animal feed, are shown to be farm-specific, and depend upon the interactions between current farm productivity and prioritisation of sustainability criteria. However, generally it is shown that castor bean cultivation should be linked to animal production so that current risk management and income levels can be supported and improved. Further, to maintain soil fertility, castor bean cultivation with nitrogen inputs is necessary. The cyclic nature of the framework supports the next contextualisation of the sustainability question. For our application, constructive future work in a next cycle could include extending to regional level and accounting for temporal variability.     

水分和腐植酸对燕麦果聚糖代谢的影响

探讨水分和腐植酸(HA)对燕麦不同器官非结构性碳水化合物(NSC)积累与分配的影响,进一步明确水分和HA对燕麦糖代谢和粒重形成的作用机制,可为旱作地区燕麦的推广种植提供理论指导和技术支撑。试验以‘蒙农大燕1号'和‘内燕5号'两个燕麦品种为材料,分别在旱作(无灌溉)和有限灌溉(拔节期和抽穗期每次灌水60 mm)两个水分条件下喷施HA与清水(CK),研究燕麦开花后不同时期NSC组分在茎、叶、穗中的动态变化以及叶片中碳代谢相关酶活性的变化。结果表明: 两个燕麦品种茎、叶、穗中的NSC组分含量均随开花后时间的延长先升高后降低,且两品种各器官中的NSC组分含量大致相同;与CK相比,在灌水条件下喷施HA后蒙农大燕1号穗部的果聚糖含量提升幅度明显大于旱作条件;喷施HA后蒙农大燕1号叶片中果聚糖外水解酶和转化酶活性分别显著提高了27.1%和30.6%,单穗粒重显著提高了55.9%,且与旱作条件下相比提高幅度更大;蒙农大燕1号籽粒千粒重和单穗粒重与叶片果聚糖含量呈显著正相关关系。综上,水分和腐植酸协同作用可以有效调节燕麦果聚糖的积累及主要代谢酶活性,从而提高千粒重和单穗粒重,促进产量形成。     

Does agricultural efficiency contribute to slowdown of deforestation in the Brazilian Legal Amazon?

Historically, agricultural production in the Amazon has been painted as the most environmentally impacting activity. In this study, we investigated the relationship between the increase in agricultural efficiency and the slowdown of deforestation rates in the past decade, correlating these data with municipalities’ agricultural specialization. With the data from the 2006 and 2017 Brazilian Agricultural Census we classified municipalities according to its vegetal or animal specialization and estimated a production frontier using the Stochastic Frontier Analysis (SFA), considering a set of production factors and technological variables. Our results demonstrated that most part of municipalities have no specialization or are based in cattle ranching activities, and the overall agricultural efficiency in the Amazon municipalities grew from 69.5% in 2006 to 74.1% in 2017. The new institutional path in the 21st century contributed to slow deforestation in agricultural activities through an increase in productivity (yield/ha) in the last decade, mainly for vegetal production. Cattle ranching also increased output and efficiency, but it remains the most environmental impacting activity. However, several municipalities could not develop their agricultural production value relative to the most productive areas, suggesting that some factors —technological and productive— that could lead to output increase are not being efficiently allocated, which results in concentrating deforestation in inefficient systems and limiting the effectiveness of current policies. Technological diffusion, especially for small farmers, and private support in environmental issues could contribute to slowdown deforestation without loss of agricultural output.     

Persistent negative effects of pesticides on biodiversity and biological control potential on European farmland

During the last 50 years, agricultural intensification has caused many wild plant and animal species to go extinct regionally or nationally and has profoundly changed the functioning of agro-ecosystems. Agricultural intensification has many components, such as loss of landscape elements, enlarged farm and field sizes and larger inputs of fertilizer and pesticides. However, very little is known about the relative contribution of these variables to the large-scale negative effects on biodiversity. In this study, we disentangled the impacts of various components of agricultural intensification on species diversity of wild plants, carabids and ground-nesting farmland birds and on the biological control of aphids.In a Europe-wide study in eight West and East European countries, we found important negative effects of agricultural intensification on wild plant, carabid and bird species diversity and on the potential for biological pest control, as estimated from the number of aphids taken by predators. Of the 13 components of intensification we measured, use of insecticides and fungicides had consistent negative effects on biodiversity. Insecticides also reduced the biological control potential. Organic farming and other agri-environment schemes aiming to mitigate the negative effects of intensive farming on biodiversity did increase the diversity of wild plant and carabid species, but – contrary to our expectations – not the diversity of breeding birds.We conclude that despite decades of European policy to ban harmful pesticides, the negative effects of pesticides on wild plant and animal species persist, at the same time reducing the opportunities for biological pest control. If biodiversity is to be restored in Europe and opportunities are to be created for crop production utilizing biodiversity-based ecosystem services such as biological pest control, there must be a Europe-wide shift towards farming with minimal use of pesticides over large areas.     

土壤微生物:可持续农业和环境发展的新维度

可持续农业在当今世界至关重要,因为它有潜力满足我们的农业需求,而这是传统农业无法做到的。这种类型的农业采用一种特殊的耕作技术,既能充分利用环境资源,又能保证不造成任何危害。因此,该技术对环境友好,保证了农产品的安全和健康。微生物种群对推动农业生态系统稳定和生产力的基本过程起着重要作用。若干调查旨在增进对土壤微生物群落的多样性、动态和重要性及其在农业生产力中的有益合作。综述了部分土壤微生物及其对可持续农业生产的重要性。