Maize and sesbania production in relay cropping at three landscape positions in Malawi

The relay cropping of sesbania (Sesbania sesban) — a N2-fixing legume — with maize (Zea mays) has been proposed as a strategy to increase soil fertility and food production in densely populated areas in southern Africa. We determined the production of relay-cropped maize and sesbania at three landscape positions under researcher-designed and farmer-managed conditions in southern Malawi. Three landscape positions (dambo valley or bottomland, dambo margin with 12% slope) were examined in factorial combination with N sources for maize (no added N, relay-cropped sesbania, and calcium ammonium nitrate fertilizer). Relay cropping of sesbania with maize increased maize grain yield, as compared to unfertilized sole maize in two of three years. Split application of 96 kg N ha−1 as N fertilizer, however, was more effective than sesbania in increasing maize yields. Survival of sesbania seedlings and biomass production of sesbania were greater in the dambo valley and dambo margin than on steep slopes. Maize yields tended to be lower on steep slopes than in the dambo valley and dambo margin areas. Biomass production of sesbania and hence the potential benefits of intercropping sesbania with maize appear greater in the dambo valleys and dambo margins than on steep slope

Soil nitrate dynamics in relation to nitrogen source and landscape position in Malawi

Nitrogen is normally the nutrient most limiting production of maize (Zea mays) — the main staple food crop — in southern Africa. We conducted a field study to determine the effect of N sources on soil nitrate dynamics at three landscape positions in farmers' fields in southern Malawi. The landscape positions were dambo valley or bottomland, dambo margin, and steep slopes. The N sources were calcium ammonium nitrate fertilizer applied at 120 kg N ha−1, biomass from Sesbania sesban, and no added N. Sesbania biomass was produced in situ in the previous season from sesbania relay cropped with maize. Nitrate in the topsoil (0 to 15 cm depth) increased to 85 days after maize planting (mean = 48 kg N ha−1) and then decreased markedly. Application of N fertilizer and sesbania biomass increased soil nitrate, and nitrate-N in topsoil correlated positively with amount of incorporated sesbania biomass. The strongest correlation between sesbania biomass added before maize planting and topsoil nitrate was observed at 85 days after maize planting. This suggests that the sesbania biomass (mean N content = 2.3%) mineralized slowly. Inorganic N accumulated in the subsoil at the end of the maize cropping season when N fertilizer and sesbania were applied. This study demonstrated the challenges associated with moderate quality organic N sources produced in smallholder farmer's fields. Soil nitrate levels indicated that N was released by sesbania residues in the first year of incorporation, but relay cropping of sesbania with maize may need to be supplemented with appropriately timed application of N fertilize

Methylation pattern of CDH13 gene in digestive tract cancers

Recently, the loss of CDH13 (T-cadherin, H-cadherin) gene expression accompanied by CDH13 promoter methylation was identified in colon cancers. We examined CDH13 methylation in oesophageal and gastric carcinomas. Five of 37 oesophageal cancers (14%) and 23 of 66 gastric cancers (35%) demonstrated abnormal methylation of the CDH13 promoter. Abnormal methylation was frequently found in gastric cancers of patients at all clinical stages just as in E-cadherin, another of the cadherin family, suggesting that these cancers could be methylated at an early stage. These results suggested that CDH13 might play a variety of roles depending on the tissue type

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr BP; taken as AD 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr BP is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr BP and culminating at approximately 2,000 cal. yr BP, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr BP, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation–loss–accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system

Efficacy and Safety of Three Antiretroviral Regimens for Initial Treatment of HIV-1: A Randomized Clinical Trial in Diverse Multinational Settings

Background:Antiretroviral regimens with simplified dosing and better safety are needed to maximize the efficiency of antiretroviral delivery in resource-limited settings. We investigated the efficacy and safety of antiretroviral regimens with once-daily compared to twice-daily dosing in diverse areas of the world.Methods and Findings:1,571 HIV-1-infected persons (47% women) from nine countries in four continents were assigned with equal probability to open-label antiretroviral therapy with efavirenz plus lamivudine-zidovudine (EFV+3TC-ZDV), atazanavir plus didanosine-EC plus emtricitabine (ATV+DDI+FTC), or efavirenz plus emtricitabine-tenofovir-disoproxil fumarate (DF) (EFV+FTC-TDF). ATV+DDI+FTC and EFV+FTC-TDF were hypothesized to be non-inferior to EFV+3TC-ZDV if the upper one-sided 95% confidence bound for the hazard ratio (HR) was ≤1.35 when 30% of participants had treatment failure.An independent monitoring board recommended stopping study follow-up prior to accumulation of 472 treatment failures. Comparing EFV+FTC-TDF to EFV+3TC-ZDV, during a median 184 wk of follow-up there were 95 treatment failures (18%) among 526 participants versus 98 failures among 519 participants (19%; HR 0.95, 95% CI 0.72-1.27; p = 0.74). Safety endpoints occurred in 243 (46%) participants assigned to EFV+FTC-TDF versus 313 (60%) assigned to EFV+3TC-ZDV (HR 0.64, CI 0.54-0.76; p<0.001) and there was a significant interaction between sex and regimen safety (HR 0.50, CI 0.39-0.64 for women; HR 0.79, CI 0.62-1.00 for men; p = 0.01). Comparing ATV+DDI+FTC to EFV+3TC-ZDV, during a median follow-up of 81 wk there were 108 failures (21%) among 526 participants assigned to ATV+DDI+FTC and 76 (15%) among 519 participants assigned to EFV+3TC-ZDV (HR 1.51, CI 1.12-2.04; p = 0.007).Conclusion: EFV+FTC-TDF had similar high efficacy compared to EFV+3TC-ZDV in this trial population, recruited in diverse multinational settings. Superior safety, especially in HIV-1-infected women, and once-daily dosing of EFV+FTC-TDF are advantageous for use of this regimen for initial treatment of HIV-1 infection in resource-limited countries. ATV+DDI+FTC had inferior efficacy and is not recommended as an initial antiretroviral regimen.Trial Registration:http://www.ClinicalTrials.gov NCT00084136

Maize production under tree-based cropping systems in southern Malawi: A cobb-douglas approach

A study was conducted in Zomba, Southern Malawi in 1996- 98 to evaluate the potential of tree-based green manure in increasing maize yields. Using data obtained from the study, a Cobb-Douglas maize production function was estimated with particular interest in the technical relationship between maize yield and the inputs (fertilisers, land and labour). Ordinary Least Squares regression techniques were used to perform the analysis. Returns to scale and elasticities of the inputs were estimated from the production function. Gross margins of the systems were analysed to give a relative indicator of profitability and food supply to the households. Results indicated that fertiliser, land and labour are significant factors of production in maize legume-based interplanting. The estimated coefficients for the input factors (ai) were non-negative (1.16, 0.21 and 0.14 for labour, land and fertiliser, respectively) indicating increased marginal productivity to the inputs. Returns to scale in all landscape positions show increasing returns that were significant at P = 0.05. Gross margin analysis showed that legume green manure with additions of 48 kg N ha-1 gave higher returns to labour (MK9.60 Mnhr-1) seconded by pigeon pea-based system (MK8.90). These results suggest that interplanting of maize with legumes increases maize yields. However, it is necessary to devise ways of saving labour and land so as to maintain or increase maize production per unit land.Key Words: Dambo, interplanting, landscape positions, Malawi, net benefits, production function, returns to scaleRésuméUne étude a été mené à Zomba, dans le sud du Malawi entre 1996 et 1998 qui avait pour but à évaluer le potentiel de fumier vert à base des arbres à accroître les rendements de maïs. En utilisant les données de l'étude, une fonction de production de type " Cobb-Douglas" a été estimée avec l'intêret particulier dans les relations techniques entre les rendements de maïs et les entrants (engrais, terre, et la main d'oeuvre). La technique de regression des moindres carrés ordinaires a été utilisée dans l'analyse. Les rendements d'échelle et les élasticités des entrants ont été estimées à partir de la fonction de production. Les marges brutes des systèmes ont été analysées pour donner un indicateur relatif de profitabilité et de l'offre alimentaire aux ménages. Les résultats ont montré que l'engrais, la terre et la main d'oeuvre sont des facteurs de production importants dans un système où l'on mélange sur la même parcelle les plantes légumineuses et le maïs. Les coéfficients estimés pour les facteurs de production (ai) étaient non-négatifs (1.16, 0.21 et 0.14 pour la main d'oeuvre, la terre et l'engrais respectivement) indiquant une productivité marginale croissante des entrants. Les rendements d'échelle à tous les niveaux de la pente montrent des rendements croissants qui sont significatifs à P= 0.05. L'analyse des marges brutes a montré que le fumier vert en y ajoutant 48 kg d'azote par hectare a donné les rendements les plus importants de la main d'oeuvre (MK 9.60 Mn par heure) suivi par le système basé sur les petits pois (MK8.90). Ces résultats suggèrent que le systeme de culture où l'on mélange les plantes légumineuses et le maïs sur la même parcelle abouti à l'accroissement des rendements de maïs. Toutefois, il est nécessaire d'inventer des moyens qui peuvent aboutir à economiser la main d'oeuvre et la terre pour maintenir ou accroître la production de maïs par l'unité de terre.Mots Clés: Dambo, Mélange des plantes sur une même parcelle, position de la pente, Malawi, benefices nettes, fonction de production, rendements d'échelle (African Crop Science Journal 8(4) 2000: 429-440

Domestic food and sustainable design:a study of university student cooking and its impacts

In four university student kitchens over twenty-one days, we captured participants' food preparation activity, quantified the greenhouse gas emissions and direct energy connected to the food and cooking, and talked to participants about their food practices. Grounded in this uniquely detailed micro-account, our findings inform sustainable design for cooking and eating at home and quantify the potential impacts. We outline the relation of the impacts to our participants' approaches to everyday food preparation, the organisation of their time, and the role of social meals. Our technique allows evaluation of opportunities for sustainable intervention design: at the appliance, in the digitally-mediated organisation of meals and inventory management, and more broadly in reflecting upon and reshaping diet

INTAKE AND DIGESTIBILITY OF LOW QUALITY RHODES GRASS HAY AND GROWTH OF SHEEP AS AFFECTED BY BROWSE SUPPLEMENT AND MAGADI TREATMENT

An experiment was conducted at Bunda College, Malawi, to determine the effect of magadi (a sodium sesquicarbonate- Na2CO3, NaHCO3.2H2O) treated forages on their intake and digestibility and growth of sheep. Rhodes grass (Chloris gayana Kunth), Cedrela (Toona ciliata, M. Roem) and Sesbania [Sesbania sesban (L) Merr]. Samples were each treated with 0% (control), 5% or 10% magadi suspension. In this text Rhodes grass, sesbania and cedrela shall be abbreviated as R, S and C, respectively. Polyethylene glycol (PEG) a tannin complexing agent, was mixed with a sample of C and S to compare its effect on gas production with samples treated or not treated with magadi. Thus, the treatments were R0, R5, R10, S0, S5, S10, C0, C5, C10, SPEG and TPEG. The 11 treatments (each 500mg forage in 100ml syringes) were incubated in cattle rumen liquor at 390C for 96 hours. The 10% magadi treatment lowered gas production compared to the control. However, the C5 treatment produced more gas (93.5ml) than the TPEG (76.7ml), while the S5 treatment produced slightly less gas (104.9ml) than the SPEG (108.6ml). It was concluded that magadi suppresses the antinutritional components of forage thereby facilitating degradation of the feed, but the 10% magadi level lowers the rumen degradation. In the intake and digestibility trials, 100g of ground S0, S5, S10, C0, C5 and C10 treatments were each mixed with 100g maize bran in 1:1 ratio daily. The R0, R5 and R10 hays were basal feeds, and were fed to correspond with the magadi levels of the respective treatments (e.g., R5 fed with S5 or C5). The results indicated that dry matter and organic matter intake as well as urine production increased significantly (p< 0.05) with increased magadi level and sesbania supplementation However, the magadi treatment depressed the digestibility of crude protein. The growth trial lasted for 60 days, and the expected growth rate was 150g per day. The Rhodes grass hay was not treated with magadi. Seventy percent Maize bran and 30 % treated forage (S0, S5, S10, C0, C5 and C10) were mixed and four intact male sheep of average weight of 40.8 ± 7.2Kg were assigned to each ration. The expected growth rate was not achieved at the end of the trial. The difference between the treatments within the two browses and among the three levels of magadi treatment were not significant. However, sesbania supplementation and magadi treatment tended to increase growth rate of the sheep. (UNISWA J Agric: 2000 9: 22-33

Intercropping perennial legumes for green manure additions to maize in southern Malawi

(African Crop Science Journal 1999 7(4): 355-364