ABSTRACT Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern A... more ABSTRACT Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern Africa, one of the most extensive wetlands are dambos (seasonal wetlands) which occupy 20–25% of land area. However, there are very little data on GHG methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) emissions from dambos, and this study presents the first estimates from dambos in Zimbabwe. The objective was to evaluate the effects of catena positions; upland, dambo mid-slope and dambo bottom, on GHG emissions along an undisturbed dambo transect. Methane emissions were −0.3, 29.5 and −1.3 mg m−2 hr−1, N2O emission were 40.1, 3.9 and 5.5 µg m2 hr−1, while CO2 emissions were 2648.9, 896.2 and 590.1 mg m−2 hr−1 for upland, mid-slope and bottom catena, respectively. Our results showed that uplands were important sources of N2O and CO2, and a sink for CH4, while the dambo mid-slope position was a major source of CH4, but a weak source of CO2 and N2O. Dambo bottom catena was weak source GHGs. Overall, dambos were major sources of CH4 and weak sources of N2O and CO2.We concluded that, depending on catenal position, dambos can be major or minor sources of GHGs.
ABSTRACT Aim We test the hypothesis that land use and,climate are important,controls of nitrous o... more ABSTRACT Aim We test the hypothesis that land use and,climate are important,controls of nitrous oxide (N2O) emissions from savanna ecosystems, and that these emissions,can,be,represented,by,a mechanistic,model,of carbon,(C) and nitrogen (N) transformations. Location,Miombo,woodlands,in Zimbabwe,are part of widespread,woody
ABSTRACT Hairy vetch (Vicia villosa Roth) is an introduced temperate forage legume in Zimbabwe th... more ABSTRACT Hairy vetch (Vicia villosa Roth) is an introduced temperate forage legume in Zimbabwe that has no locally available commercial inoculant. In this study, Rhizobium leguminosarum bv. viceae strains MAR 1504, MAR 833 and MAR 346 available in Zimbabwe's strain bank were evaluated for nodulation and N2-fixing effectiveness in a sandy soil (Typic Kandiustalf). There was no significant difference in hairy vetch biomass (range: 3.4–4.5 g pot−1) and nitrogen (N) content between plants in acidic and limed soil, showing that soil acidity was not a major problem for hairy vetch productivity in the short term. Inoculation with R. leguminosarum significantly increased (p < 0.05) biomass production (range: 0.37–3.11 t ha−1) and enhanced N2 fixation of hairy vetch compared to the uninoculated control, which had no nodules and significantly less biomass. Hairy vetch fixed up to 66.5 kg N ha−1 in the field, and this amount may be made available for cereal crops as green manure. From the strains tested, MAR 833 and MAR1504 were more effective than MAR 346 in increasing the amount of N2 fixed per unit area and are thus recommended for further multilocation field testing in farmer's fields to allow conclusive identification of strains to use in commercial inoculant production.
... Other benefits of legumes, which should not be ignored, include reduced pest and weed occurre... more ... Other benefits of legumes, which should not be ignored, include reduced pest and weed occurrence, improved soil quality (Van Kessel and Hartley, 1999) and minimization of risk (Graham and Vance, 2000) and soil and water conservation. ...
ABSTRACT Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern A... more ABSTRACT Wetlands are major natural sources of greenhouse gases (GHGs). In central and southern Africa, one of the most extensive wetlands are dambos (seasonal wetlands) which occupy 20–25% of land area. However, there are very little data on GHG methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) emissions from dambos, and this study presents the first estimates from dambos in Zimbabwe. The objective was to evaluate the effects of catena positions; upland, dambo mid-slope and dambo bottom, on GHG emissions along an undisturbed dambo transect. Methane emissions were −0.3, 29.5 and −1.3 mg m−2 hr−1, N2O emission were 40.1, 3.9 and 5.5 µg m2 hr−1, while CO2 emissions were 2648.9, 896.2 and 590.1 mg m−2 hr−1 for upland, mid-slope and bottom catena, respectively. Our results showed that uplands were important sources of N2O and CO2, and a sink for CH4, while the dambo mid-slope position was a major source of CH4, but a weak source of CO2 and N2O. Dambo bottom catena was weak source GHGs. Overall, dambos were major sources of CH4 and weak sources of N2O and CO2.We concluded that, depending on catenal position, dambos can be major or minor sources of GHGs.
ABSTRACT Aim We test the hypothesis that land use and,climate are important,controls of nitrous o... more ABSTRACT Aim We test the hypothesis that land use and,climate are important,controls of nitrous oxide (N2O) emissions from savanna ecosystems, and that these emissions,can,be,represented,by,a mechanistic,model,of carbon,(C) and nitrogen (N) transformations. Location,Miombo,woodlands,in Zimbabwe,are part of widespread,woody
ABSTRACT Hairy vetch (Vicia villosa Roth) is an introduced temperate forage legume in Zimbabwe th... more ABSTRACT Hairy vetch (Vicia villosa Roth) is an introduced temperate forage legume in Zimbabwe that has no locally available commercial inoculant. In this study, Rhizobium leguminosarum bv. viceae strains MAR 1504, MAR 833 and MAR 346 available in Zimbabwe's strain bank were evaluated for nodulation and N2-fixing effectiveness in a sandy soil (Typic Kandiustalf). There was no significant difference in hairy vetch biomass (range: 3.4–4.5 g pot−1) and nitrogen (N) content between plants in acidic and limed soil, showing that soil acidity was not a major problem for hairy vetch productivity in the short term. Inoculation with R. leguminosarum significantly increased (p < 0.05) biomass production (range: 0.37–3.11 t ha−1) and enhanced N2 fixation of hairy vetch compared to the uninoculated control, which had no nodules and significantly less biomass. Hairy vetch fixed up to 66.5 kg N ha−1 in the field, and this amount may be made available for cereal crops as green manure. From the strains tested, MAR 833 and MAR1504 were more effective than MAR 346 in increasing the amount of N2 fixed per unit area and are thus recommended for further multilocation field testing in farmer's fields to allow conclusive identification of strains to use in commercial inoculant production.
... Other benefits of legumes, which should not be ignored, include reduced pest and weed occurre... more ... Other benefits of legumes, which should not be ignored, include reduced pest and weed occurrence, improved soil quality (Van Kessel and Hartley, 1999) and minimization of risk (Graham and Vance, 2000) and soil and water conservation. ...
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