Effect of organic and inorganic phosphorus sources on maize yields in an acid soil in western Kenya

Maize production in western Kenya is commonly limited by P deficiencies and aluminum phytotoxicity. Due to high costs of imported fertilizers and lime, focus is now shifting to solutions that utilize local resources. We tested the effect of three inorganic P sources i.e., triple superphosphate (TSP), Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), each applied in combination with two organic materials (OMs) i.e., farmyard manure (FYM) and Tithonia diversifolia green manure (tithonia), or with urea on soil chemical properties related to soil acidity, P availability and maize yields for three consecutive seasons in western Kenya. The OMs and inorganic P sources were applied to provide 20 and 40 kg P ha-1 respectively in their combination. Where urea was used, the inorganic P sources were applied at 60 kg P ha-1. Maize did not respond to application of TSP, MPR or BPR with urea in the first two seasons. However, after three seasons, maize significantly responded to application of MPR with urea. FYM was more effective than tithonia in increasing the labile inorganic P pools but it gave lower maize yields than tithonia which was more effective in reducing the exchangeable Al. It appears that the ability of an OM to lower the exchangeable Al is more important inincreasing maize yields than its ability to increase P availability. The effectiveness of the inorganic P sources in increasing maize yields followed the order of their effectiveness in increasing available P, i.e., TSP[MPR [BPR, once Al phytotoxicity was reduced by application of tithonia but the difference between TSP and MPR was not significant. The extra maize yield obtained by the additional 40 kg P ha-1 from the inorganic P sources was, however, in most cases not substantial enough to justify their use. Economic considerations may therefore favour the use of tithonia or FYM when applied alone at 20 kg P ha-1 than when combined with any of the inorganic P sources used in this study at a total P rate of 60 kg ha-1

Nutrients limiting soybean (glycine max l) growth in acrisols and ferralsols of western Kenya

Low soybean yields in western Kenya have been attributed to low soil fertility despite much work done on nitrogen (N) and phosphorus (P) nutrition leading to suspicion of other nutrient limitations. To investigate this, a nutrient omission trial was set up in the greenhouse at the University of Eldoret-Kenya to diagnose the nutrients limiting soybean production in Acrisols from Masaba central and Butere sub-Counties, and Ferralsols from Kakamega (Shikhulu and Khwisero sub-locations) and Butula sub-Counties and to assess the effect of liming on soil pH and soybean growth. The experiment was laid out in a completely randomized design with ten treatments viz; positive control (complete), negative control (distilled water), complete with lime, complete with N, minus macronutrients P, potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S) and with, micro-nutrients boron (B), molybdenum (Mo), manganese (Mn), copper (Cu) and zinc (Zn) omitted. Visual deficiency symptoms observed included interveinal leaf yellowing in Mg omission and N addition and dark green leaves in P omission. Nutrients omission resulted in their significantly low concentration in plant tissues than the complete treatment. Significantly (P≤ 0.05) lower shoot dry weights (SDWs) than the complete treatment were obtained in different treatments; omission of K and Mg in Masaba and Shikhulu, Mg in Khwisero, K in Butere and, P, Mg and K in Butula. Nitrogen significantly improved SDWs in soils from Kakamega and Butula. Liming significantly raised soil pH by 9, 13 and 11% from 4.65, 4.91 and 4.99 in soils from Masaba, Butere and Butula respectively and soybean SDWs in soils from Butere. The results show that, poor soybean growth was due to K, Mg and P limitation and low pH in some soils. The results also signify necessity of application of small quantities of N for initial soybean use

On farm testing of integrated nutrient management strategies in Eastern Uganda

This paper reports on a Participatory Learning and Action Research (PLAR) process that was initiated in three villages in eastern Uganda in September 1999 to enable small-scale farmers to reverse nutrient depletion of their soils profitably by increasing their capacity to develop, adapt and use integrated natural resource management strategies. The PLAR process was also used to improve the participatory skills and tools of research and extension personnel to support this process. The farming systems of the area were characterised for socio-economic and biophysical conditions that included social organisations, wealth categories, gender, crop, soil, agro forestry and livestock production. Farmers identified soil fertility constraints, their indicators, and causes of soil fertility decline, and suggested strategies to address the problem of soil fertility decline. Soil fertility management diversity among households indicated that most farmers were not carrying out any improved soil fertility management practices, despite previous research and dissemination in the area. Following the diagnosis stage and exposure visits to other farmer groups working on integrated soil fertility projects, the farmers designed 11 experiments for on-farm testing. One hundred and twenty farmers then chose, for participatory technology development, sub-sets of these 11 experiments, based on the major agricultural constraints and the potential solutions identified and prioritised by the farmers. Quantitative and qualitative results from the testing, farmer evaluation and adaptation, training, dissemination strategies and socio-economic implications of these technologies are discussed

Assessing Responses of \u3ci\u3eBetula papyrifera\u3c/i\u3e to Climate Variability in a Remnant Population along the Niobrara River Valley in Nebraska U.S. through Dendroecological and Remote Sensing Techniques

Remnant populations of Betula papyrifera have persisted in the Great Plains after the Wisconsin Glaciation along the Niobrara River Valley, Nebraska. Population health has declined in recent years, and has been hypothesized to be due to climate change. We used dendrochronological techniques to assess the response of B. papyrifera to microclimate (1950-2014), and satellite imagery [Landsat 5 TM (1985-2011) and MODIS (2000-2014)] derived NDVI as a proxy for population health. Growing-season streamflow and precipitation were positively correlated with raw and standardized tree-ring widths and basal area increment increase. Increasing winter and spring temperatures were unfavorable for tree growth while increasing summer temperatures were favorable in the absence of drought. The strongest predictor for standardized tree-rings was the Palmer Drought Severity Index, suggesting that B. papyrifera is highly responsive to a combination of temperature and water availability. The NDVI from vegetation community was positively correlated with standardized tree-ring growth, indicating the potential of these techniques to be used as a proxy for ex-situ monitoring of B. papyrifera. These results aid in forecasting the dynamics of the species in the face of climate variability and change in both remnant populations and across its current distribution in northern latitudes of North America

Patterns of antimicrobial use in the neurosurgical ward of Kenyatta National Hospital

Background: Antibiotics in neurosurgery are used for prophylaxis and treatment of already established infection.  Guidelines state that prophylactic antibiotics should be given for up to 24 hours. For treatment of already established infections, empiric therapy with intravenous antibiotics for four to eight weeks is indicated. Studies have shown no distinction between antibiotic use for prophylaxis and treatment of established infection in neurosurgery. Objectives: To identify antibiotic use patterns and medication errors and their association with development of surgical site infections. Methods: A prospective cohort study involving adult neurosurgical patients was carried out at Kenyatta National Hospital, between April 2015 and July 2015. Patient demographic data as well as data on surgical procedures carried out, antibiotics used and medication errors was collected. Descriptive data analysis was done for all variables. To test for association between antibiotic use patterns and development of surgical site infections, the Fischer exact Chi square test was used. Results: Out of the 84 participants recruited in the study, 87.2% (n=68) used antibiotics. Ceftriaxone was the most commonly used (63.7%, n= 44), followed by metronidazole (40.4%, n=23).  Medication errors that were noted involved inappropriate choice and use of antibiotics. There was no distinction between use of antibiotics for prophylaxis and treatment of infection. There was no statistically significant association between patterns of antibiotic use and development of surgical site infection. Conclusion: Antibiotic use patterns do not affect the incidence of neurosurgical site infections. Prescribing errors of various types were prominent. An antibiotic use protocol should guide antimicrobial selection and use in neurosurgery. Key words: antibiotic, prophylaxis, medication error

Impact of neurosurgical site infections on patient expenditure at a national referral hospital in Kenya: a cost of illness study

Background: Neurosurgical site infections result in prolonged hospitalisation and increased treatment costs. Cost of illness studies are important in computing the total costs of treatment of disease, as they quantify the burden of disease in terms of direct costs, productivity losses and intangible costs. Neurosurgical site infections do not occur at a high rate in most clinical settings. Their economic impact has been assumed to be minimal, and most studies have not exclusively studied their economic impact. Objective: To assess the economic burden of treatment of surgical site infections among trauma patients admitted at the neurosurgical ward of Kenyatta National Hospital. Methods: A prospective cost of illness study was conducted between April 2015 and June 2015 as part of a larger prospective cohort study. The patient perspective was adopted. The time horizon was the hospitalization period of the patients, which was a median of ten days. No discounting was done because the study was done within a year. A micro costing approach was used to compute direct costs on medication, laboratory and radiologic tests, cost of surgical procedures and nursing care, and direct non-medical costs incurred by patients for the average 10 day hospitalisation period. Productivity losses were also computed. Results: The total median cost of treating patients with neurosurgical site infections was higher, at USD 203.95 than that of patients without infection at USD 141.20. The median cost on antibiotics was USD 18.70 while that of non- antibiotic drugs was USD 33.03. The total median cost on laboratory and radiologic tests was USD 20 and USD 55 respectively. The key cost drivers were expenditures on meropenem, phenytoin, urea, electrolyte and creatinine tests and CT scans. With regards to costs of services, care-giver costs accounted for the highest median expenditure, followed by costs of surgery and nursing care. Conclusion: Neurosurgical site infections increase hospitalisation duration and costs. Prevention of these will reduce patient expenditure. Key words: cost of illness, neurosurgical site infection, productivity losse

Phosphorus Sorption and Lime Requirements of Maize Growing Acid Soils of Kenya

In Kenya, maize (Zea mays L.) is mainly grown on acid soils in high rainfall areas. These soils are known for low available phosphorus (P), partly due to its sorption by aluminium (Al) and iron oxides. The study determined soil P sorption, lime requirements and the effects of lime on soil pH, Al levels and available P on the main maize growing acids soils in the highlands east and west of Rift Valley (RV), Kenya. Burnt lime containing 21% calcium oxide was used. The soils were strongly to extremely acid (pH 4.85-4.07), had high exchangeable Al3+ (> 2 cmol Al kg-1) and Al saturation (> 20% Al), which most maize germplasm grown in Kenya are sensitive to. The base cations, cation exchange capacity and available P (< 10 mg P kg-1 bicarbonate extractable P) were low, except at one site in the highlands east of RV indicative with history of high fertilizer applications. Highlands east of RV soils had higher P sorption (343-402 mg P kg-1) than the west (107-258 mg P kg-1), probably because of their high Al3+ ions and also the energies of bonding between the soil colloids and phosphate ions. Highlands east of RV also had higher lime requirements (11.4-21.9 tons lime ha-1) than the west (5.3-9.8 tons lime ha-1). Due to differences in soil acidity, Al levels and P sorption capacities within and between highlands east and west of RV, blanket P fertilizer and lime recommendations may not serve all soils equally well. Keywords: acid soils, phosphorus sorption, lime requirement

Systematic Review, Meta-Analysis and Grading of Evidence on the Effectiveness of Antimicrobial Prophylaxis for Neurosurgical Site Infections

Background: Antimicrobial prophylaxis is crucial for neurosurgical procedures, even though they are clean procedures. Observational studies have shown the effectiveness of different antibiotics in preventing neurosurgical site infections, but there remains paucity of systematic reviews and meta-analyses which have assessed their effectiveness in East Africa. Objectives: To generate and appraise the quality of evidence that would inform antimicrobial prophylaxis in neurosurgery. Methodology: A systematic review and meta-analysis was conducted between October 2014 and December 2015. Studies that involved the administration of systemic antibiotics for prophylaxis, use of antibiotic impregnated shunt catheters among adult patients aged over 18 years were included and subjected to abstract, title and full text screening. A meta-analysis was carried out using RevMan (Review Manager) version 5 software. The quality of evidence was evaluated using the GRADE system. Results: One systematic review of randomized controlled trials (n=17) and 11 randomised controlled trials were included in the study. From the first meta-analysis, use of systemic antibiotics demonstrated an overall protective effect of 52% from development of surgical site infections [OR 0.48 (95% CI 0.30, 0.79)]. In the second meta-analysis, the use of antibiotic impregnated shunt catheters was associated with a higher risk of mortality compared to use of the standard shunt [(OR 1.47(95% CI 0.82, 2.62)]. Following evaluation of quality of evidence, in the antibiotics versus placebo arm, the quality of evidence was moderate, while that for antimicrobial impregnated shunts was very low. Conclusion: Antimicrobial prophylaxis using systemic antibiotics or antimicrobial impregnated shunts is effective in preventing neurosurgical site infections. Antimicrobial impregnated shunts are too expensive for our study population. Key words: systematic review, meta-analysis, antimicrobial prophylaxi