Soil fertility gradients and production constraints for coffee and banana on volcanic mountain slopes in the east African rift: a case study of Mt. Elgon

Volcanic mountains in the East African Rift (e.g. Mt. Kenya, Mt. Kilimanjaro, Mt. Elgon) are some of the most productive agricultural regions, often dominated by coffee and banana cultivation. Consequently, these regions suffer from a high and increasing population density with a declining soil fertility status imposing pressure on the available land, which in turn results in encroaching into the national forests. This study documents the soil fertility constraints along the slopes of Mt. Elgon and explores its corresponding gradients in plant nutritional status. This research links the topography of Mt. Elgon to the prevailing soil types and their current fertility status. It reveals important relations and gradients between soil fertility parameters and its corresponding environment along the slope. Soil pH, soil available P and exchangeable K, Ca and Mg are significantly decreasing with elevation. Thereby, gradients and constraints in macro- and micro-nutrient uptake by coffee and banana are revealed along the toposequence and different altitude-specific nutrient limitations are determined for both crops. K, Mn and Si uptake in both crops is decreasing with elevation along the slope, while the Mo and Ni uptake in both crops is increasing. With increasing elevation, B uptake is only decreasing in coffee and P uptake is only decreasing in banana. In addition, the antagonistic interaction between K and Mg limits the Mg uptake of both crops in the lower areas, while in the high region the Mg uptake is simply limited by low soil availability. It follows that a general fertilizer recommendation cannot be made in these regions and that the soil fertility problems along these slopes should be specifically addressed and appropriately managed according to the local requirements

Coffee-Banana Intercropping: Implementation guidance for policymakers and investors

Coffee-Banana Intercropping (VBI) addresses all 3 pillars of CSA in a multifaceted way. CBI in both Arabica nad Robusta generates 50% more revenue then either coffee or banana monocrop. Farmers' risk is reduced by practising CBI, making them more resilient to climate change impacts. Transformational changes are needed in the attitude towards CBI, to support scaling up of the practice

Characterization of cocoa production, income diversification and shade tree management along a climate gradient in Ghana

Reduced climatic suitability due to climate change in cocoa growing regions of Ghana is expected in the coming decades. This threatens farmers' livelihood and the cocoa sector. Climate change adaptation requires an improved understanding of existing cocoa production systems and farmers' coping strategies. This study characterized current cocoa production, income diversification and shade tree management along a climate gradient within the cocoa belt of Ghana. The objectives were to 1) compare existing production and income diversification between dry, mid and wet climatic regions, and 2) identify shade trees in cocoa agroforestry systems and their distribution along the climatic gradient. Our results showed that current mean cocoa yield level of 288kg ha-1yr-1 in the dry region was significantly lower than in the mid and wet regions with mean yields of 712 and 849 kg ha-1 yr-1, respectively. In the dry region, farmers diversified their income sources with non-cocoa crops and off-farm activities while farmers at the mid and wet regions mainly depended on cocoa (over 80% of annual income). Two shade systems classified as medium and low shade cocoa agroforestry systems were identified across the studied regions. The medium shade system was more abundant in the dry region and associated to adaptation to marginal climatic conditions. The low shade system showed significantly higher yield in the wet region but no difference was observed between the mid and dry regions. This study highlights the need for optimum shade level recommendation to be climatic region specific

Redesigning Delivery: Boosting Adoption of Coffee Management Practices in Uganda. The climate smart investment pathway approach and the farmer segmentation tool

Coffee is an important crop for the Ugandan economy, as it earns the country US$415 million in foreign export revenues and supports 1.7 million smallholder farmers (UCDA, 2016). Nevertheless, coffee yields have stagnated for over a decade, despite concerted efforts to improve productivity. Climate change is increasing the pressure on the sector, and the effects are already being felt. Climate smart agricultural (CSA) practices are being promoted as a means to help farmers cope with climate change. The CSA training package focuses on planning good agricultural practices in a way that the changing climate is taken into consideration. The training package for coffee consists of a large number of practices (soil and water conservation, tree management, quality of coffee, among others), and is currently provided all in one go as a complete package. This approach is cumbersome and not aligned to pertinent needs of coffee farmers, as coffee is a perennial crop and needs continuous care throughout the year. To address the need for better targeting of practices, this Info Note presents two complementary approaches: the climate smart investment pathways (CSIPs) and farmer segmentation. The CSIPs break down the full training package of CSA practices into more manageable subsets of practices. These smaller packages are aimed at being more aligned with the structural (resource endowments) and functional (entrepreneurship) characteristics of different types of farmers. CSIPs build up a sequential and incremental approach to implementing the practices. The farmer segmentation tool differentiates the coffee farmers into different groups, based on their assets and entrepreneurial characteristics. These segmentations will help advise the relevant stakeholders that support farmers on how to best engage with and train farmers in the most relevant practices (based on the CSIP) by taking their capacity and willingness to implement the practices into consideration. This Info Note will first go through the development process of the CSIPs, based on the results from a study on Robusta coffee systems in Luweero and Nakasongola. Then it will move onto the process and results of the farmer segmentation work done in the Greater Luweero region (which encompasses Luweero and Nakasongola). The implications of this work will be discussed and recommendations will be made for further work and use of these methods

Characterisation of microclimatic indicators in coffee production systems under varying biophysical contexts and its relation to fungal coffee diseases

The comparison of performance of coffee under shaded and sun-exposed conditions has been explored in numerous studies. The beneficial effects of shading on coffee sustainability through the mitigation of microclimatic extremes have been quantified and are generally wellestablished. It has also been acknowledged that the extent to which shaded systems are advantageous depends on the biophysical context. Particularly in studies on pest and disease dynamics, this variability of shade effects across sites has resulted in contradictory assumptions. In this study, we (i) quantified microclimatic differences between three coffee production systems (coffee shaded by trees, (CT), intercropped with banana (CB), or sun exposed (CO) as a function of different environmental sites. We then (ii) related microclimatic indicators to the intensity of two fungal diseases (Coffee Leaf Rust (CLR), and Coffee Berry Disease, (CBD) of Arabica coffee. Along an altitudinal gradient from 1000 to 2200 m.a.s.l.) and in diverse production systems on the slopes of Mount Elgon, Uganda, we collected hourly data on temperature and relative humidity during the 2015/2016 season in 27 plots. Microclimatic indicators to compare included diurnal temperature range (DTR), the accumulated hours of relative humidity above 95 % (RH>95) during night, and the accumulated hours of temperatures below the dew point (Temp95 and Temp95. Our findings confirm the mitigation property of shading to microclimatic extremes. However, the widely accepted assumption of shade conserving moisture is not applicable considering the spatio-temporal context. (ii) The fact that unshaded systems at high altitudes expose better conditions for dew formation than compared to shaded systems could be a key mechanism explaining the high CBD intensity under unshaded systems and the contradictory CLR responses along the gradient of altitude and shading intensities

Institutional challenges to climate change adaptation: a case study on policy action gaps in Uganda

Article purchasedDespite the considerable progress made in the last decade towards building governance systems for climate change adaptation in Africa, implementation still limits positive responses. This study applies an iterative process of field assessments and literature reviews across multiple governance levels and spatial scales to identify constraints to effective formulation and implementation of climate change related policies and strategies in Uganda. Data was collected through sex-segregated participatory vulnerability assessments with farming communities in Rakai district, policy document reviews, and interviews with policy actors at national and district levels. Findings reveal that the key challenges to effective policy implementation are diverse and cut across the policy development and implementation cycle. Policies are mainly developed by central government agencies; other actors are insufficiently involved while local communities are excluded. There is also a communication disconnect between national, district, and community levels. Coupled with limited technical capacity and finances, political interference, and absence of functional implementation structures across these levels, climate change adaptation becomes constrained. We propose strategies that enhance linkages between levels and actors, which will improve policy formulation, implementation and ultimately adaptation by smallholders

Cocoa: Driver of Deforestation in the Democratic Republic of the Congo?

The Democratic Republic of the Congo (DRC) accounts for the largest part of the Congo Basin forest: two-thirds (some 155 million hectares) are forested and 69 percent of which is dense humid forest. With a surge in world market commodity prices for cocoa in 2008 and a steady 2-5% annual increase in global demand, incentives to expand cocoa production are significant. This study determines the role of cocoa in the RDC in terms of current deforestation, identifies actors, and estimates future expansion. Although cocoa in occurs in eight regions in the DRC, authors focused on the four major growing regions in this study, using a rough estimation to get an “order of magnitude” of cocoa as a driver of deforestation. The authors found that cocoa expansion could lead to the loss of 176-395 square kilometres of forest in the next decade, strongest in the Mambasa region and in Equatorial Province surrounding Mbandaka, Bikoro and Lukolela. However, migration of internally displaced people, production of food crops, and illegal logging are likely more severe drivers of deforestation in the Mambasa region. Deforestation caused by cocoa growing in Equatorial Province will largely depend on rejuvenation of existing fields

Meristematic cell proliferation and ribosome biogenesis are decoupled in diamagnetically levitated Arabidopsis seedlings

Background: Cell growth and cell proliferation are intimately linked in the presence of Earth’s gravity, but are decoupled under the microgravity conditions present in orbiting spacecraft. New technologies to simulate microgravity conditions for long-duration experiments, with stable environmental conditions, in Earth-based laboratories are required to further our understanding of the effect of extraterrestrial conditions on the growth, development and health of living matter. Results: We studied the response of transgenic seedlings of Arabidopsis thaliana, containing either the CycB1-GUS proliferation marker or the DR5-GUS auxin-mediated growth marker, to diamagnetic levitation in the bore of a superconducting solenoid magnet. As a control, a second set of seedlings were exposed to a strong magnetic field, but not to levitation forces. A third set was exposed to a strong field and simulated hypergravity (2 g). Cell proliferation and cell growth cytological parameters were measured for each set of seedlings. Nucleolin immunodetection was used as a marker of cell growth. Collectively, the data indicate that these two fundamental cellular processes are decoupled in root meristems, as in microgravity: cell proliferation was enhanced whereas cell growth markers were depleted. These results also demonstrated delocalisation of auxin signalling in the root tip despite the fact that levitation of the seedling as a whole does not prevent the sedimentation of statoliths in the root cells. Conclusions:In our model system, we found that diamagnetic levitation led to changes that are very similar to those caused by real- [e.g. on board the International Space Station (ISS)] or mechanically-simulated microgravity [e.g. using a Random Positioning Machine (RPM)]. These changes decoupled meristematic cell proliferation from ribosome biogenesis, and altered auxin polar transport

High temperature MBE of graphene on sapphire and hexagonal boron nitride flakes on sapphire

The discovery of graphene and its remarkable electronic properties has provided scientists with a revolutionary material system for electronics and optoelectronics. Here, the authors investigate molecular beam epitaxy (MBE) as a growth method for graphene layers. The standard dual chamber GENxplor has been specially modified by Veeco to achieve growth temperatures of up to 1850 _C in ultrahigh vacuum conditions and is capable of growth on substrates of up to 3 in. in diameter. To calibrate the growth temperatures, the authors have formed graphene on the Si-face of SiC by heating wafers to temperatures up to 1400 _C and above. To demonstrate the scalability, the authors have formed graphene on SiC substrates with sizes ranging from 10 _ 10mm2 up to 3-in. in diameter. The authors have used a carbon sublimation source to grow graphene on sapphire at substrate temperatures between 1000 and 1650 _C (thermocouple temperatures). The quality of the graphene layers is significantly improved by growing on hexagonal boron nitride (h-BN) substrates. The authors observed a significant difference in the sticking coefficient of carbon on the surfaces of sapphire and h-BN flakes. Our atomic force microscopy measurements reveal the formation of an extended hexagonal moir_e pattern when our MBE layers of graphene on h-BN flakes are grown under optimum conditions. The authors attribute this moir_e pattern to the commensurate growth of crystalline graphene on h-BN

Probing neutrino masses with future galaxy redshift surveys

We perform a new study of future sensitivities of galaxy redshift surveys to the free-streaming effect caused by neutrino masses, adding the information on cosmological parameters from measurements of primary anisotropies of the cosmic microwave background (CMB). Our reference cosmological scenario has nine parameters and three different neutrino masses, with a hierarchy imposed by oscillation experiments. Within the present decade, the combination of the Sloan Digital Sky Survey (SDSS) and CMB data from the PLANCK experiment will have a 2-sigma detection threshold on the total neutrino mass close to 0.2 eV. This estimate is robust against the inclusion of extra free parameters in the reference cosmological model. On a longer term, the next generation of experiments may reach values of order sum m_nu = 0.1 eV at 2-sigma, or better if a galaxy redshift survey significantly larger than SDSS is completed. We also discuss how the small changes on the free-streaming scales in the normal and inverted hierarchy schemes are translated into the expected errors from future cosmological data.Comment: 14 pages, 7 figures. Added results with the KAOS proposal and 1 referenc