Estimating yield of food crops grown by smallholder farmers: A review in the Uganda context

Precise agricultural statistics are essential for planning and evaluation of agricultural investments to improve the productivity and profitability of smallholder farming systems. However, accurately estimating crop yields is never easy and is even more of a challenge in the context of African farming systems that are characterized by smallholder farms that produce a wide range of diverse crops. With specific reference to yield estimation for food crops under smallholder farming conditions in Uganda, this paper evaluates the various methods that are available to estimate crop production and cropped area in such farming systems. A description and summary tables from a database of estimated crop yields in Uganda that was collated from a large set of field studies over past decades are also provided.agricultural statistics, crop yield, Data Collection, smallholder farming,

Channel management in the chemical industry:selecting the right option

Channel management was not until recently the chemical manufacturers’ main concern. Their main priorities were to manufacture and innovate. It was only in the nineties that the marketing imperative prevailed and that cost efficient channel management processes were put in place. Producers facing a tougher competitive environment became aware of the importance to serve well their customers through direct and indirect channels. These channels adapted themselves to the growing needs of demanding customers who are seeking high quality and competitive products and services. In this article, we will highlight the relationship between producers’ channel management and marketing strategy, selecting and managing the right market channel and finally the main challenges facing European chemical distributors

Association of cardiovascular and musculoskeletal biomarkers with clinical outcomes in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the world. In addition to premature mortality, the consequent socio-economic burden is high, causing reduced quality of life, loss of productivity, and hospital admission. Diagnosis of COPD relies on lung function tests, which are inadequate and often leave the condition undiagnosed and thus untreated. There is a growing interest in the extra-pulmonary manifestations of COPD and assessing the predictive value of cardiovascular abnormalities, musculoskeletal weakness and plasma biomarkers for acute exacerbation of COPD, hospital admission and mortality, as there is currently no individual biomarker able to reliably identify or predict these common clinical outcomes. The aim of this research was to identify and evaluate the predictive value of existing and novel biomarkers for COPD, and determine if and how these biomarkers can predict the longer-term clinical outcomes using electronic health record data. Electronic databases were systematically searched and identified 61 studies, which were synthesised, including meta-analyses to estimate pooled hazard ratios of the associations between selected biomarkers and common clinical outcomes. Data derived from the Evaluating the Role of Inflammation in Chronic Airways disease (ERICA) study were linked to electronic health record data (i.e. hospital admissions) and survival data. Predictive models for mortality and cardiovascular related hospital admission were developed using stratified multivariable Cox regression, and assessed by C-indices with 10-fold cross-validation. Negative binomial regression was used to model the event rate of acute exacerbation of COPD and determine the risk of hospitalisation due to acute exacerbation of COPD, and the associated length of stay. Data from the UK Biobank were used to explore cause-specific deaths in COPD. Sex-specific all-cause and cause-specific mortality rates were age-standardised using the 2013 European Standard Population. Hazard ratios were estimated using Cox proportional hazards regression, adjusted for age and sex. Systematic review indicated that shorter six-minute walk distance, elevated heart rate, fibrinogen, C-reactive protein, and white cell count were associated with a higher risk of mortality. Shorter six-minute walk distance and elevated fibrinogen and C-reactive protein were associated with COPD exacerbation, and shorter six-minute walk distance and higher heart rate, C-reactive protein and interleukin-6 were associated with hospitalisation. Data from the ERICA cohort indicated no significant difference between the discriminative ability of a BODE Index with six-minute walk and BODE Index with short physical performance battery when predicting mortality. For most musculoskeletal measures, poorer performance was associated with higher rate or longer duration of hospitalised acute exacerbation of COPD. Measures of arterial stiffness and carotid intima-media thickness were not associated with cardiovascular events. Measures of exercise capacity were significantly associated with cardiovascular disease and improved the discriminative ability when added to Framingham risk factors. Data from the UK Biobank indicated COPD was associated with a higher risk of all-cause mortality, and cardiovascular death. In both men and women, COPD had an associated threefold higher risk of early mortality, including a fourfold higher risk of cardiovascular-related death in women, and threefold higher risk of cardiovascular-related death in men. Epidemiological evidence indicates that musculoskeletal measures have the potential to replace the six-minute walk in the BODE Index for predicting mortality in COPD. In addition, physical capacity should be considered as an important treatable trait in reducing risk of hospitalisations for acute exacerbation of COPD. Data from the ERICA cohort does not support the use of objective measures of arterial stiffness and carotid intima-media thickness in addition to Framingham risk factors for predicting cardiovascular events within COPD. Findings in the UK Biobank indicated that COPD is associated with a higher risk of cardiovascular death but cancer and respiratory disease to be the leading causes.Collaborative award by the University of Cambridge and GlaxoSmithKline (RG79358)

Cassava and soil fertility in intensifying smallholder farming systems of East Africa

Keywords: Cost-benefits, Crop management, Farming systems, Fertilizer, Food security, Generalizations, Income, Labour, Land pressure, Niche, Rainfall, Sub-Saharan Africa, System analysis, Yield gap. Cassava is an important crop in Africa. This thesis focuses on cassava production in the mid altitude zone of East Africa, an area characterized by high population densities, bimodal rainfall patterns and relatively poor soils. The overall aim was to better understand the roles and production constraints of cassava in order to explore opportunities to improve the productivity and sustainability of intensifying cassava-based smallholder farming systems in East Africa. Increasing land pressure has changed agricultural landscapes from traditional millet-, cotton-, sugarcane- or banana-based systems with an important fallow component to continuously, cultivated cassava-based systems. Cassava cultivation on cropped fields increased from 1-11 to 16-55% in three to four decades as farmers believe that cassava improves soil fertility for the subsequent crop and increasingly target cassava to low fertility soils when land pressure increases. The substantial increase in cassava cultivation has allowed farmers to postpone intensification of crop management, but it seems that the elasticity of the traditionally low-input systems is coming to an end as production of the two most important crops (cassava and maize) is limited by nutrients. Farmers in areas of high land pressure have started to adopt fertilizer and manure and to improve crop management. Contrary to existing generalizations, cassava is not a food security crop for poorer farmers in East Africa, but an important food and cash crop for farmers from all wealth classes. Average farm income was not less than in other farming systems in the region, while average food security was higher (>10 months year-1) than in maize-based systems. Cassava is also not predominantly grown as an intercrop, as is often thought, nor is it grown without inputs, because farmers commonly use hired labour and improved genotypes. In addition, its labour requirements are higher than commonly assumed (287 man days ha-1), due to large requirements for weed control. Existing generalizations concerning cassava are therefore either false or half truths and a continued belief in them will hamper the effectiveness of policy and development efforts aimed at improving cassava production. Efforts to increase cassava production in cassava-based farming systems will, for example, improve its scope for commercialization, but will not significantly enhance food security. Average farmer yields for cassava (7-12 t ha-1) are far below attainable yields on farm (30-50 t ha-1). Still, on-farm yields are highly variable. Largest yields were obtained on farms with high labour availability, fertile soils, good weed management and timely (not too early) harvesting. An improved technology package more than doubled average yields in farmer fields, whereby the largest yield increase for a single technology was observed with 100-22-83 kg ha-1 N-P-K fertilizer. Multivariate analysis identified soil fertility, rainfall and weed management as the most important production constraints, while biotic factors were less important. Many fields were affected by multiple and interacting production constraints. Fertilizer responses were governed by the same, interacting factors influencing unfertilized cassava production. Genotype and biotic factors did not influence fertilizer response. Closing the considerable yield gap between actual and attainable cassava yields at farm level, can not be achieved by integrated pest management and breeding alone. Instead, research and development organizations should focus on addressing the whole range of interacting production constraints through the development and evaluation of integrated management packages. Improving cassava production will be more difficult for poorer than for wealthier farmers, as the first have less social and financial capital and less fertile soils and are therefore more likely to face multiple production constraints. The positive impact of cassava on soil fertility perceived by farmers is supported by model simulations and nutrient balances that indicate that cassava may improve SOC contents of low fertility soils compared with maize and contribute to higher N recycling through crop residues. Adoption of higher yielding genotypes and improved production practices will improve yields and increase nutrient removal rates, but may simultaneously have a positive effect on SOC contents and nutrient recycling rates. Improving cassava stem management after harvesting seems an interesting option to improve sustainability of the system. This thesis concludes that there is an urgent need to invest in agronomy and ISFM research and to reform existing research for developments programmes with a strong emphasis on breeding and IPM into integrated programmes that are able to address the multiple production constraints of cassava and thereby significantly contribute to improving the livelihoods of smallholder cassava farmers. <br/

Towards understanding factors that govern fertilizer response in casave: lessons from East Africa

Information on fertilizer response in cassava in Africa is scarce. We conducted a series of on-farm and on-station trials in two consecutive years to quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda and to evaluate factors governing the responses. Average unfertilized yields ranged from 4.2 to 25.7 t ha-1 between sites and years. Mineral fertilizer use increased yields significantly, but response to fertilizer was highly variable (-0.2 to 15.3 t ha-1). Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005. Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age. Relative N and K yields were positively correlated to SOC and exchangeable K, while response to fertilizer decreased on more fertile soils. Still, fertilizer response varied widely on low fertility soils (e.g. on soils wit

A novel bioreactor for immobilized phototrophs

A novel configuration of photobioreactor is described in which filaments of alginate containing immobilized cells of a leaky mutant of Dunaliella parva are wound round a central light well which is located within a glass outer chamber so that a liquid medium is caused to flow in the annular space between the outside chamber and the alginate filaments. Glycerol production by D. parva was maintained for 700 h and the highest concentration of glycerol attained was approx. 12 mg l-1

Public stated preferences and predicted uptake for genome-based colorectal cancer screening

Background Emerging developments in nanomedicine allow the development of genome-based technologies for non-invasive and individualised screening for diseases such as colorectal cancer. The main objective of this study was to measure user preferences for colorectal cancer screening using a nanopill. Methods A discrete choice experiment was used to estimate the preferences for five competing diagnostic techniques including the nanopill and iFOBT. Alternative screening scenarios were described using five attributes namely: preparation involved, sensitivity, specificity, complication rate and testing frequency. Fourteen random and two fixed choice tasks, each consisting of three alternatives, were offered to 2225 individuals. Data were analysed using the McFadden conditional logit model. Results Thirteen hundred and fifty-six respondents completed the questionnaire. The most important attributes (and preferred levels) were the screening technique (nanopill), sensitivity (100%) and preparation (no preparation). Stated screening uptake for the nanopill was 79%, compared to 76% for iFOBT. In the case of screening with the nanopill, the percentage of people preferring not to be screened would be reduced from 19.2% (iFOBT) to 16.7%. Conclusions Although the expected benefits of nanotechnology based colorectal cancer screening are improved screening uptake, assuming more accurate test results and less preparation involved, the relative preference of the nanopill is only slightly higher than the iFOBT. Estimating user preferences during the development of diagnostic technologies could be used to identify relative performance, including perceived benefits and harms compared to competitors allowing for significant changes to be made throughout the process of developmen