Biophysical interactions in tropical agroforestry systems

sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Plantain production in an alley cropping system on an Ultisol in southeastern Nigeria

Plantain requires mulching for high yields and sustained productivity. Mulching is, however, labor-intensive and requires extra land for production. An experiment was conducted to determine the potential of alley cropping to supply in situ mulch for plantain production. Foliage from hedgerows of Dactyladenia barteri, Alchornea cordifolia, Senna siamea and Gmelina arborea were compared with mulch from elephant (napier) grass (Pennisetum purpureum) carried into plots that served as the no-tree control. Plantain performed best with P. purpureum mulch because this mulch shortened its fruiting cycle and gave the highest yield (17.8 t ha-1). Among the hegderow species, D. barteri mulch produced the best results because the plantain produced 85% as much bunch yield as P. purpureum mulch. However, relative yields of plantain were 77,72 and 66% for A. cordifolia, S. siamea and G. arborea, respectively. Due to differences in cycle length, cumulative yield after two years was highest in P. purpureum (35.4 t ha-1). After two years, cumulative relative yields were 51 % or less for A. cordifolia, S. siamea and G. arborea in contrast with 66% for D. barteri. D. barteri mulch reduced diurnal soil temperature fluctuations and moisture depletion as well as P. purpureum mulch. High diurnal soil temperature fluctuations, high weed infestation and superficial rooting of the hedgerow species were observed with A. cordifolia, S. siamea and G. arborea treatments which resulted in poor performance of plantain. Although P. purpureum mulch gave the best results, its use is subject to serious constraints such as the high labor requirement for cutting, transportation, application and management in addition to the extra land required for its production which cannot be justified by the higher yield. D. barteri is therefore recommended as an in-situ mulch for plantain production in this acid Ultisol

Performance of Three-Way Cross Hybrids for Agronomic Traits and Resistance to Maize Streak Virus Disease in Kenya

Maize Streak virus (MSV) disease is a major disease in many parts of Africa, and is the most important viral pathogen of maize in Kenya. A study was conducted in 2004 to evaluate the agronomic performance and maize streak virus (MSV) resistance of maize ( Zea mays L.) three-way crosses developed in Kenya. Twenty hybrids and one check were grown under normal conditions in a randomized complete block design, in two replications at Embu, 1540 masl; and Muguga, 2093 masl). In a parallel trial in Muguga, hybrids were also evaluated in two replications under artificial inoculation with MSV. The analyses of variance combined across environments showed significant differences (P<0.05) among genotypes for grain yield, days to 50% pollen shed, days to mid-silk and ear height. Genotype x environment interaction was significant (P<0.01) for grain yield and days to mid-silk, indicating some hybrids were more adapted in some environments. Grain yield for MU03-025 (10.04 t ha-1) was significantly better (P<0.05) than the check, H513 (7.53t ha-1). In the disease inoculated experiment, the best hybrids for disease resistance were MU03-012 and MU03-006 (score of 1.75), while H513 had a mean score of >3.0. The highest yielding hybrid under disease inoculation, MU03-026 showed yield gain of 5.2 t ha-1 above that of H513. The results indicate adoption of disease resistant hybrids would result in a higher maize yields in the mid-altitude areas of Kenya

Economic analysis of cutandcarry, and alley cropping systems of mulch production for plantains in southeastern Nigeria

Organic mulch is beneficial to plantain because it maintains soil fertility, prevents erosion and suppresses weeds. Mulch availability is however a major constraint. Mulching in a cut-and-carry system withPennisetum purpureum Schum. (elephant grass) was compared with mulching with the prunings ofAlchornea cordifolia (Schum. & Thonn.),Dactyladenia barteri (Hook. f. ex Oliv.)Engel. (Syn.Acioa barteri),Gmelina arborea (Roxb.) andSenna siamea (Lam.) Irwin & Barneby (Syn.Cassia siamea) in alley cropping systems. Plantain inPennisetum mulch treatment gave the highest bunch yield, but similar net revenues per hectare as theDactyladenia treatment, whileGmelina, Alchornea andSenna treatments produced the lowest incomes. But when the land required to producePennisetum mulch was included in the economic analysis, the net revenue per hectare was negative over three years of cropping. The returns to labour were also much lower for thePennisetum compared to the alley cropping systems. Among the in-situ mulch sources,Gmelina had the highest labour requirement because of the high pruning frequency. In addition, weeding inGmelina, Alchornea andSenna treatments resulted in high labour demand due to the rapid decomposition of the mulch materials leaving the soil bare for weeds to invade.Dactyladenia alley cropping was the most profitable of the five plantain production systems studied

Men who have sex with men sensitivity training reduces homoprejudice and increases knowledge among Kenyan healthcare providers in coastal Kenya

Introduction: Healthcare workers (HCWs) in Africa typically receive little or no training in the healthcare needs of men who have sex with men (MSM), limiting the effectiveness and reach of population‐based HIV control measures among this group. We assessed the effect of a web‐based, self‐directed sensitivity training on MSM for HCWs (www.marps‐africa.org), combined with facilitated group discussions on knowledge and homophobic attitudes among HCWs in four districts of coastal Kenya. Methods: We trained four district “AIDS coordinators” to provide a two‐day training to local HCWs working at antiretroviral therapy‐providing facilities in coastal Kenya. Self‐directed learning supported by group discussions focused on MSM sexual risk practices, HIV prevention and healthcare needs. Knowledge was assessed prior to training, immediately after training and three months after training. The Homophobia Scale assessed homophobic attitudes and was measured before and three months after training. Results: Seventy‐four HCWs (68% female; 74% clinical officers or nurses; 84% working in government facilities) from 49 health facilities were trained, of whom 71 (96%) completed all measures. At baseline, few HCWs reported any prior training on MSM anal sexual practices, and most HCWs had limited knowledge of MSM sexual health needs. Homophobic attitudes were most pronounced among HCWs who were male, under 30 years of age, and working in clinical roles or government facilities. Three months after training, more HCWs had adequate knowledge compared to baseline (49% vs. 13%, McNemar's test p&lt;0.001); this was most pronounced in those with clinical or administrative roles and in those from governmental health providers. Compared to baseline, homophobic attitudes had decreased significantly three months after training, particularly among HCWs with high homophobia scores at baseline, and there was some evidence of correlation between improvements in knowledge and reduction in homophobic sentiment. Conclusions: Scaling up MSM sensitivity training for African HCWs is likely to be a timely, effective and practical means to improve relevant sexual health knowledge and reduce personal homophobic sentiment among HCWs involved in HIV prevention, testing and care in sub‐Saharan Africa. </p

Increasing diversity in genomics requires investment in equitable partnerships and capacity building

Calls for diversity in genomics have motivated new global research collaborations across institutions with highly imbalanced resources. We describe practical lessons we have learned so far from designing multidisciplinary international research and capacity-building programs that prioritize equity in two intertwined programs — the NeuroGAP-Psychosis research study and GINGER training program — spanning institutions in Ethiopia, Kenya, South Africa, Uganda and the United States