University of Zimbabwe

About: University of Zimbabwe is a education organization based out in Harare, Harare, Zimbabwe. It is known for research contribution in the topics: Population & Acquired immunodeficiency syndrome (AIDS). The organization has 4378 authors who have published 6800 publications receiving 160720 citations. The organization is also known as: UZ & University College of Rhodesia and Nyasaland.

Nitrogen and phosphorus capture and recovery efficiencies, and crop responses to a range of soil fertility management strategies in sub-Saharan Africa

Abstract: This paper examines a number of agronomic field experiments in different regions of sub-Saharan Africa to assess the associated variability in the efficiencies with which applied and available nutrients are taken up by crops under a wide range of management and environmental conditions. We consider N and P capture efficiencies (NCE and PCE, kg uptake kg-1 nutrient availability), and N and P recovery efficiencies (NRE and PRE, kg uptake kg-1 nutrient added). The analyzed cropping systems employed different soil fertility management practices that included (1) N and P mineral fertilizers (as sole or their combinations) (2) cattle manure composted then applied or applied directly to fields through animal corralling, and legume based systems separated into (3) improved fallows/cover cropscereal sequences, and (4) grain legume-cereal rotations. Crop responses to added nutrients varied widely, which is a logical consequence of the wide diversity in the balance of production resources across regions from arid through wet tropics, coupled with an equally large array of management practices and inter-season variability. The NCE ranged from 0.05 to 0.98 kg kg-1 for the different systems (NP fertilizers, 0.16–0.98; fallow/cover crops, 0.05–0.75; animal manure, 0.10–0.74 kg kg-1), while PCE ranged from 0.09 to 0.71 kg kg-1, depending on soil conditions. The respective NREs averaged 0.38, 0.23 and 0.25 kg kg-1. Cases were found where NREs were[1 for mineral fertilizers or negative when poor quality manure immobilized soil N, while response to P was in many cases poor due to P fixation by soils. Other than good agronomy, it was apparent that flexible systems of fertilization that vary N input according to the current seasonal rainfall pattern offer opportunities for high resource capture and recovery efficiencies in semi-arid areas. We suggest the use of cropping systems modeling approaches to hasten the understanding of Africa’s complex cropping systems.

Immunity against HIV/AIDS, malaria, and tuberculosis during co-infections with neglected infectious diseases: recommendations for the European Union research priorities.

Abstract: Immunity against HIV/AIDS, Malaria, and Tuberculosis during Co-Infections with Neglected Infectious Diseases : Recommendations for the European Union Research Priorities.

L-carnitine and its functional effects in poultry nutrition

Abstract: L-carnitine has indispensable functions in intermediary metabolism and is received by endogenous synthesis and from exogenous sources. It plays an obligate role in fatty acid metabolism by directing fatty acids into the mitochondrial oxidative pathway through the action of specialised acyltransferases. In poultry production, L-carnitine has a multi functional purpose, which includes: growth promotion, strengthening the immune system, antioxidant effects and improving semen quality. The concentration of L-carnitine in animals varies widely across species, tissue type, and nutritional status of the animal. It has been suggested that the L-carnitine requirement may be increased under certain circumstances such as via higher performance, various stress conditions and where the diet is deficient in animal protein sources. The review of L-carnitine functions uniquely includes the main aspects of this consequential feed supplementary inclusion in poultry nutrition.

Effect of combined cattle manure and mineral nitrogen on maize N uptake and grain yield

Abstract: The effectiveness in increasing N recovery by maize ( Zea mays L.) of N fertiliser (0, 60, 120 kg N ha-1 annum-1) and aerobically composted cattle manure (0, 12.5 Mg ha-1 annum-1 or 37.5 Mg ha-1 applied only in the first year) was determined when the two N sources were applied separately or in combination. A field experiment was established on a moderately leached sandy loam soil (Typic Kandiustalf) over three seasons, and N uptake was determined fortnightly from 4 weeks after planting (WAP) until harvest. Net N recovery during plant growth increased with N application rate (up to 90 kg N ha-1 in first season and up to 60 kg N ha-1 in second and third seasons). Net N recovery from manure during the growing period was relatively poor. There was no net recovery (up to 12 WAP) from annual application of manure during the first season and from first year application of the large rate of manure in the second season. Combined application of manure and N fertiliser increased net N recovery in all growing seasons (up to 120 kg N ha-1) above that achieved by separate applications of both N sources. There was a manure by N fertiliser interaction that enhanced N recovery, in two treatment combinations during the first season (low manure rate) and in the second season, and this was attributed to some non-N nutrient effects of the manure. Highest percentage increases in total N recovery at harvesting were observed when manure was combined with the low N fertiliser rate (60 kg N ha-1) (av. 58% in first season, 63% in third season) and limited further increases were recorded when the N fertiliser rate was doubled (120 kg N ha-1) (av. 15% in first season, 32% in third season). It was concluded that aerobically composted cattle manure from the smallholder farming areas of Zimbabwe was a poor source of N for maize growth in the short-term, even at high application rates. Combined application of manure with judicious use of N fertiliser can be positively exploited by smallholder farmers in Zimbabwe and other countries of sub-Saharan Africa, to increase yields through enhanced efficiency of use of scarce nutrient resources. Key Words: Aerobic composting, N mineralisation, N recovery, Zea mays RESUME L'efficacite dans l'augmentation de N du retablissement du ma?s ( Zea mays L.) de fertilisant N (0, 60, 120 kg N ha-1 annum-1) et le fumier de vache aerobicallement composte (0, 12,5 Mg ha-1 applique seulement en premiere annee) etait determinee quand les deux sources de N etaient appliquees separement ou en combinaison. Une experience sur le terrain etait etablie sur un filtre de terre de sol sable (Typic Kandiustalf) au dela de trois saisons, et la consommation de N etait determinee bimensuellement a partir de quatre semaines apres la plantation (WAP) jusqu'a la recolte. Le retablissement net de N pendant la croissance de la plante a augmente avec le taux d'application de N (jusqu'a 90 kg N ha-1 en premiere saison et jusqu'a 60 kg N ha-1 en seconde et troisieme saisons). Le retablissement net de N a partir du fumier durant la periode de croissance etait relativement pauvre. Il n'y avait pas retablissement (jusqu'a 12 WAP)a partir de l'application annuelle durant la premiere saison et a partir de la premiere annee d'application du large taux de fumier dans la seconde saison. L'application combinee du fumier et du fertilisant N a augmente le retablissement net dans toutes les saisons de croissance (jusqu'a 120 kg N ha-1) au dela de celui accomplit par les applications separees de deux sources de N. Il y avait un fumier par l'interaction du fertilisant N qui a ameliore le retablissement de N, dans deux combinaisons de traitement pendant la premiere saison (faible taux de fumier) et dans la seconde saison, et ceci etait attribue aux non effets des substances N du fumier. Les augmentations elevees du pourcentage dans le retablissement total de N a la recolte etaient observees quand le fumier etait combine avec le faible taux de fertilisant N (60 kg N ha-1) (av. 58% en premiere saison, 63% en troisieme saison) et davantage augmentations etaient enregistrees quand le taux de fertilisant etait double (120 kg N ha-1) (av. 15% en premiere saison, 32% en troisieme saison). Il etait conclu que le fumier de vache aerobicallement composte des fermiers des petites surfaces du Zimbabwe etait une pauvre source de N pour la croissance de ma?s a court terme, meme aux taux d'application eleves. L'application combinee du fumier avec un usage judicieux du fertilisant N peut etre positivement exploitee par les petits fermiers au Zimbabwe et autres pays de l'Afrique sub-Saharienne, pour augmenter les rendements a travers l'efficacite amelioree de l'usage des rares ressources des substances. Mots Cles : Compost aerobic, mineralisation de N, retablissement de N, Zea mays African Crop Science Journal Vol.11(4) 2003: 289-300