Feed the crop, not the soil! : Explaining variability in maize yield responses to nutrient applications in smallholder farms of western Kenya

Crop productivity intensification in smallholder farming systems of sub-Saharan Africa (SSA) is urgently required to improve food self-sufficiency. Increased fertilizer use can address nutrient deficiencies that limit crop productivity in SSA. There is however large uncertainty in crop yield responses to fertilizer applications on farmer fields. This uncertainty has been linked to strong heterogeneity in soil fertility between and within farms. Fertilizer recommendations that account for this spatial heterogeneity are therefore required to better advise farmers, reduce investment and environmental risks for sustainable crop productivity intensification. The main objective of this study was to better understand and explain patterns of maize yield and yield responses to fertilizer applications under heterogenous fertility conditions in smallholder farming systems. This would allow for improved targeting of fertilizer applications, and enable better prediction of expected crop yield response to fertilizer use. A series of on-farm experiments assessing maize yield response to fertilizer application under variable soil fertility conditions were established on 23 farmers’ fields in Siaya, western Kenya across multiple seasons. Prior to experiment establishment, farmers were extensively interviewed to obtain information on past crop and nutrient management practices in selected fields. The experiment used was comprised of nutrient omission trials (NOTs) on farmer fields in Siaya to assess patterns of maize yield response to fertilizer applications of 150 kg ha-1 nitrogen (N), 40 kg ha-1 phosphorus (P) and 60 kg ha-1 potassium (K). In Phase 1, plots with treatments including control, PK, NK, NP and NPK were repeated for 7 consecutive seasons in the same plots. In Phase 2 of the experiment, a second set of NOTs including PK, NK, NP and NPK were established in every plot on 6 fields that were previously part of Phase 1. On 13 other fields from Phase 1, all plots received NPK in Phase 2. Yields and above ground biomass were measured every year, soil samples were taken in 2013, 2014, 2016 and 2018 and plant samples were taken in 2016 and 2018. Spatial-temporal patterns in yield and yield responses were studied and compared with soil and farmer characteristics. Yield response to soil nutrient supply was studied with the QUEFTS model, and the RC-P model was used to study fate of fertilizer P. Nutrient balances were calculated. The frequency and magnitude of maize yield response to fertilizer N, P and K varied strongly over space and time, yet observed patterns were not adequately explained by soil chemical parameters or texture. Fertilizing with N, P, and K substantially reduced observed spatial-temporal variability in maize yield response, and resulted in consistently enhanced maize yields. All fields were responsive to N, most fields to P and only 7 to K. On average, NPK yields were about 5 to 5.5 tons ha-1 in the short- and long rainy seasons respectively. Application of only NP or NK resulted in strongly declining yields within a few seasons, with large differences between farms in resilience of soil P and K stocks. Based on observed spatial-temporal patterns, we concluded that blanket fertilizer recommendations in such farming systems result in low fertilizer use efficiencies. We further concluded that current methods for soil analysis do not adequately explain the observed variation in maize yield response to application of N, P and K fertilizers under the highly variable soil fertility conditions encountered in smallholder farming systems. Accounting for past manure application in Phase 1 of the experiment improved our ability to explain the variation in maize yield response to fertilizer application. Mean maize yield response to N, P and K application was 2.8, 1.1 and 0.6 t ha-1 in fields with animal manure previously applied, and 2.3, 3.0 and 1.6 t ha-1 in farms without past manure applications over 7 cropping seasons. Differences in maize yield response in fields with and without past manure applications were mainly related to enhanced soil phosphorus (P) and potassium (K) supply, and larger recovery of applied nitrogen (N) in fields with manure previously applied. Based on these findings, we concluded that the strong influence of past animal manure application on yield response to fertilizer applications merits the inclusion of past manure application as a co-variate in analysis of yield response data from smallholder cropping systems of SSA. The Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model did not adequately estimate crop yield responses to fertilizer applications under variable soil fertility conditions. This was linked to poor estimation of soil N, P and K supply based on current relationships for potential soil nutrient supply in the QUEFTS model. In particular, soil organic carbon (SOC) and P-Olsen were poor indicators of crop N and P uptake from the soil. Maize grain yield in unfertilized control treatment plots provided better estimates of potential soil N, P and K supply, resulting in improved predictions of maize yield response to fertilizer applications. These findings suggest that the standard soil parameters analysed do not accurately inform on the soil fertility status of the field and are of little use for smallholder farmers. Improved relations for estimation of potential soil nutrient in QUEFTS are required for better prediction of expected maize yield response to fertilizer application under variable soil fertility conditions. Maize crops in strongly nutrient-depleted soils responded strongly to balanced NPK fertilization, with yields comparative to long-term means within three seasons. Placement of P fertilizer strongly improved recovery, reducing the need for larger soil P stocks on soils that will typically develop a large insoluble P pool under P fertilization. The RC-P model provided insights in long-term recovery of P and could describe the observed P uptake patterns reasonably well. We concluded that strongly nutrient depleted tropical soils such as those in Siaya with high clay contents that are typical for western Kenya, do not require prior investments to rebuild nutrient stocks and soil organic matter to substantially increase crop yields to 5-5.5 t ha-1. This has important implications for crop productivity intensification in SSA as a large proportion of soils under cultivation are strongly nutrient depleted, and earlier approaches have suggested the need for costly and capital intensive soil fertility replenishment. Results in this thesis clearly demonstrate that sustainable intensification of crop productivity on smallholder farms of SSA is very well possible on all fields under good management, even when soils are strongly nutrient depleted. However, the need for P and K fertilizers and amounts applied should be tailored to specific field conditions to reduce farmer costs in the short term. Accounting for past farm management and assessment of current yields under minimal or no fertilizer applications provides a means for improved targeting of fertilizer applications at the farm level. In the long term, farmers should aim for balanced fertilization to prevent mining of soil stocks. Simplified decision support tools that use field level information to develop improved estimates of fertilizer N, P and K requirements based on refined relationships between soil nutrient supply, nutrient uptake and yield, are required to derive fertilizer recommendations in future.</p

Formulation and in vitro evaluation of a mucoadhesive metronidazole dental gel for oral application

Periodontitis is inflammation of the supporting tissues of the teeth caused by microorganisms found in plaque. Metronidazole is commonly used for the treatment of periodontal diseases like gingivitis and periodontitis. Treatment of periodontaldisease orally using metronidazole tablets for a prolonged period can cause gastrointestinal disturbances in patients leading to poor patient compliance. This project aimed at formulating a mucoadhesive metronidazole dental gel preparation safe for use on the gums as a form of prophylaxis against infections caused by anaerobic bacteria after dental procedures. Formulation of the gel was carried out in the laboratory using different concentrations of Carbopol® 971P NF. The gels obtained showed acceptable uniformity of content, pH, spreadability, in vitro diffusion characteristics as well as mucoadhesive and organoleptic properties.Keywords: Metronidazole, mucoadhesive gel, oral applicatio

Pattern of major surgery among the elderly and aged patients seen in Kampala, Uganda

A cross sectional descriptive prospective study was conducted at three of  Kampala's tnain hospitals with the aim of determining the pattern of major surgery among the  elderly and aged patients over a six months period from 1" July to 31" December  1999. In the study, patients aged between 65 and 74 years were regarded as elderly while those aged 75 years and above were considered aged. A total of 196 patients  were included in the study. There were 152 (75.5%)males  and 46 (23.5%) females (M: F=3:1). More elderly patients than the aged were operated on. Only 25.3% of the emergencies. Operations on the  gastrointestinal tract were the commonest and   accounted for 36.9% of cases, followed by surgery of the genitourinary (30.8%) and cardiovascular (13.1%) systems. In 63% of cases, the operations were palliative. Wound sepsis was the commonest postoperative complication and accounted for  17.8% of all complications. There were 19 deaths, an overall mortality rate of 9.6%. Thirteen (68.4%) of all deaths occurred after operations on the gastrointestinal tract. The mean hospital stay was 11.6 days for both the elderly and aged. Both the short and long term outcome of both emergency and elective operations were good. The study confirmed that age should not be a contraindication to surgery

Molecular Characterisation and Antimicrobial Resistance Patterns of Escherichia coli Isolates from Goats Slaughtered in Parts of Kenya

Objective: To determine the antibiotic resistance patterns of pathogenic Escherichia coli on goat meat carcass at Huruma and Kiserian abattoirs in Kenya.Design: Laboratory based study.Setting: Huruma and Kiserian abattoirs in Kenya,Subjects: 400 slaughtered goats inspected by veterinary health officers and approved for human consumption.Methods: A Total of 400 slaughtered goats which were inspected by veterinary health officers and approved for human consumption were  sampled from Huruma and Kiserian abattoir. Goat carcass swabs were collected by passing each swab tissue on four parts of the carcass mainly neck , right and left forelimbs, right and left hind limbs, and brisket.Results: A total of 54 E. coli isolates were isolated and confirmed to be pathogenic. The percentage of isolates resistant to various microbial agents was recorded as follows: ampicillin (26 %), amoxycillin-clavulanic acid (17%), tetracycline (15%), chroramphenicol (4%), and ceftrixone (2% each). All Escherichia coli isolates were susceptible to gentamicin sulphamethaxazole-trimethomprin, kanamycin, cetriazididine (CAZ,30ìg), ciproxacin, nalidixic acid and chloramphenicol. Isolates were resistant to one or more of the antibiotics tested. Among the drugs tested, resistance was more frequently observed against ampicillin, amoxycillin-clavulanic acid, tetracycline, ceftrixone and chroramphenicol antibiotics.Among the isolates 26(48%) were positive for the stx1 gene, 19(35%) had the eae gene, 10(19%) possessed est gene, while 8(15%) harboured elt gene. Overall five isolates (10%) possessed aspu gene and two (4%) had aggR gene. No isolate possessed ipah gene.Conclusion: This study demonstrated that there is a significant level of antimicrobial resistance in pathogenic E. coli isolated from goat meat from Huruma and Kiserian abattoir. This indicates that goat meat from abattoirs could pose a risk of transmission of pathogenic antibiotic resistant strains to human. Poor hygienic standards and indiscriminate use of antimicrobials are the two main reasons for the presence of resistant pathogens in goat carcasses. Recommendations: Implemention of appropriate hygiene measures  to control contamination of meat with pathogenic E. coli.Key words: Escherichia. coli pathotypes, Antibiotic resistance, Goat meat, Abattoir

Water Quality and Management Practices among Parents/ Guardians in Households with Children Aged under Five Years in Munyaka Slum Eldoret

Treating water at the household level has been shown to be one of the most effective means of preventing water-borne disease. Promoting household water treatment and safe storage (HWTS) ensures that vulnerable populations take charge of their own water security by providing them with the appropriate knowledge and tools. The main objective of the study was to assess household water quality management practices among parents/ guardians in household with children aged under five years. The specific objectives were; to establish socio-demographic characteristics of parents/guardians with children aged under five, to establish community’s perception and practice towards improving water quality and to determine if there is biological contamination of household water. This was a cross-sectional study of parents/ guardians in the households with children aged under- five years. Interviewer administered questionnaires were used to collect data on socio-demographic characteristics of parents/guardians, level of education, occupation, income, marital status, number of children, age range of children, and household water quality management practices: training on water safety practices, place of training, major source of drinking water for children, practices for water safety and reasons for not practicing water safety.  Water samples were collected and analysed for biological contamination. Data was coded and entered using SPSS version 19. A correlation analysis was done between socio-demographic characteristics, and water quality management practice and also relationship between biological quality of water and household water quality management practices. Data were analysed and represented in tables, graphs and pie charts. A total of ninety six (96) households participated in the study. 84 (96.9%) of the respondents  were married, 56 (58.3%) had attained primary education while 47(49%) indicated they were in business or unemployed, 82 (85.4%) earned an income of ten thousand shillings or less, 50 (52%) had  two or three children. 62 (64.6%) had undergone some form of training on water safety whereby most were trained in schools. 41 (42.7%) of households practiced  boiling, 7 (7.3%)  chemical treatment, 1 (1%) hand washing before handling drinking water.  Most households 91 (94.8%) in Munyaka slum used stored water collected from eight (8) communal piped water points. The samples collected from the 8communal water points tested negative for coliform bacteria. At the household level,  10 (10.4%) samples of water  had coliform bacteria contamination above 10 counts/100ml which is not fit for drinking while 15 (16%) of water samples tested positive for E.coli. There was a strong positive correlation between socio-demographic characteristics and household water quality management practices variables whereby Pearson’s r was 0.778. There was a strong positive and significant correlation between biological quality of waterand Household water quality management practices.(r = 0.836, p= 0.000) Majority of the households in Munyaka with children aged under five years had parents/guardians who were married, had primary level of education, were either unemployed  or in business with an income of less than 10,000 Kenyan shillings. Majority of parents/guardians had received training on water safety but few practiced water treatment. Contamination of drinking water occurred during storage. Keywords: Water quality, Household water treatment and Storag

Utilization of community-based outpatient addiction treatment programmes in Kenya

This paper examines a number of outpatient addictions treatment programmes developed in various regions of Kenya. The uptake of outpatient services at four sites between 2007 and 2010 has been examined. A field-based follow-up survey was administered to determine abstinence rates among clients who participated in treatment. Factors involved in recovery outcomes are discussed. Utilization of outpatient addictions treatment and retention in services increased over the three-year period, and field-based follow up with clients showed 42% abstinence rates. Key Words: Outpatient treatment, Alcohol, Drug, Addiction recovery, HIV, Keny

Factors influencing cervical cancer screening in a Kenyan Health Facility: a mixed qualitative and quantitative study

Background: Cervical cancer is the commonest cause of cancer-related morbidity and mortality among women in developing countries in sub-Saharan Africa. Screening for cervical cancer among HIV infected women is crucial as they are more at risk of developing the disease and progressing faster once infected with Human Papilloma Virus (HPV).Methods: We aimed to determine the factors affecting the utilization of cervical cancer screening among HIV infected women above 18 years of age at Kenyatta National Hospital by conducting a cross-sectional mixed quantitative and qualitative methods study. Descriptive and inferential analysis was carried out on quantitative data to determine significant associations with cervical cancer utilization. Qualitative data were analyzed after coding for significant clauses and transcribing to determine themes arising.Results: Three hundred and twenty eight of the total 387 women enrolled reported they had been advised by their health providers to go for screening. However, only 179 (46%) reported cervical cancer screening.  Women were more likely to report cervical cancer screening if recommendation by a staff was made (p <0.001), and prior to joining KNH CCC (p <0.001). Qualitatively the main barrier to screening included fear of screening due to concerns about excessive pain or bleeding, lack of proper communication on screening procedures and long waiting timeConclusions: The utilization of cervical cancer screening services was low despite high rates of health care recommendation. The women were more likely to utilize the service if recommendation from the health care worker was made, and if they had ever screened before

Effects of postharvest handling practices on quality of groundnuts and aflatoxin contamination

The increased cases of aflatoxin contamination are exacerbated by poor post-harvest management practices, coupled with adverse climatic conditions at harvest and post-harvest stages. This study therefore was carried out to improve safety and quality of groundnuts from aflatoxin contamination, through use of proper postharvest handling practices. Specifically the study determined the effects of harvesting dates and drying methods on aflatoxin contamination. Field experiments were carried out both at Chitedze and Chitala Agricultural Research Stations in Malawi during 2017/2018 growing season. A randomized complete block design in a split plot arrangement with three harvesting dates as the main plot and four drying methods as the sub-plots replicated three times was used. Groundnut was assessed for kernel infection by Aspergillus flavus, and level of aflatoxin contamination. Significantly low levels of about 0.5μg/ Kg of A. flavus infection and aflatoxin contamination were observed at 90 days after sowing (DAS). Higher aflatoxin contamination of up to 5μg/ Kg was observed at 80 DAS, and 10 days late after physiological maturity (100 DAS). This study also identified Mandela cock, aframe drying rack as effective drying method that can reduce aflatoxin contamination in groundnuts by 75 %. Moreover, Mandela cock drying method was shown as the most effective compared to A-frame and drying rack drying method. Current study therefore recommends for adoption of timely harvesting at physiological maturity, and drying using either Mandela cock or A-frame and drying rack. Further studies need to be carried on biological control of aflatoxin contamination

A practical guide for collecting farmers socio-economic and agronomic data: an AfSIS Project field protocol

One of the aims of the AfSIS (Africa Soil Information Service) project is to document farmers’ characteristics and practices to determine their ability to engage in effective soil and crop management. This document outlines how agronomic surveys are integrated with knowledge of farmers’ condition, wealth, status, access to knowledge, and access to markets, using pre-designed questionnaires and field surveys, and including the use of Global Positioning System-based field surveys and Geographic Information Systems

Maize response to macronutrients and potential for profitability in sub-Saharan Africa

The final publication is available at Springer via http://dx.doi.org/10.1007/s10705-015-9717-2Sub-Saharan Africa (SSA) is plagued by low productivity and little research is available on the attainable responses and profitability to applied nutrients under variable environments. The objective of this study was to determine the attainable maize grain response to and potential of profitability of N, P and K application in SSA using boundary line approaches. Data from experiments conducted in SSA under AfSIS project (2009–2012) and from FAO trials database (1969–1996) in 15 countries and constituting over 375 different experimental locations and 6600 data points are used. Both response to fertilizer and value cost ratio (VCR) are highly variable and no more than 61 % cases for N, 43 % for P and 25 % for K attain VCR of 2 or more. Also, based on the recent AfSIS data, VCR exceeds 1 in just 67 % (N), 57 % (P) and 40 % (K) of the cases, even when best management practices are applied on a research farm, and interest rates are zero. Chances for profitability are highest when soil organic carbon is 1–2 % and control maize grain yield is 1–3 t ha−1 but also depends on relatively static soil properties (primarily texture and mineralogy) that are not under farmer control. We conclude that return on investment of macronutrient fertilizer is highly variable and can be substantially increased by helping farmers decide where to apply the fertilizers. Consequently, farmers need access to information on factors influencing economic returns of fertilizer use in order to make the right decisions