SEGH Articles

SEGH2018 Prize Winners Series: Nswana Kafwamfwa

10 August 2018
Winner of a Best Poster Prize at SEGH2018: On-farm assessment of carbon stocks under sub-optimal and optimal input CA management in Mpongwe and Chisamba districts of Zambia - this installment of the Prize Winners Series is contributed by Nswana Kafwamfwa.

Kafwamfwa N., 2Chabala L. and 2Shepande C.

1.Zambia Agriculture Research Institute, Soils and Water Management Section., 2.The University of Zambia, School of Agricultural Sciences

Corresponding author:,

Conservation Agriculture (CA) is one of the promising practices being promoted for reducing the greenhouse gas effect in the face of climate change. This study sought to assess the amount of soil organic carbon (SOC) in CA and Conventional Tillage (CT) cropping systems under suboptimal and optimal input management in Mpongwe and Chisamba (GART) districts of Zambia. In the context of this study, optimal input management refers to agricultural production management were maximum available inputs are applied to the field while, suboptimal input management refers to management were the farmers use a blanket recommendation of inputs per hectare, e.g blanket fertilizer recommendation of four top and four basal fertilizers per hectare at small scale farmer level in Zambia. Composite soil samples were randomly collected at a depth of 20 cm to assess the C-stock in fields which have been under CA/CT between 3 and 7 years under suboptimal input management and between 12 and 18 years under optimal input management.

soil sampling zambia 2

 Kafwamfwa conducting soil sampling for the research project


Changes on selected soil properties over time were determined using standard laboratory procedures. The amount of soil carbon sequestered was assessed using the adjusted Land Use, Land-Use Change and Forestry (LULUCF) model. The results indicate that Conservation Agriculture (CA) fields had sequestered 1,424 kg SOC /ha,year while the Conventional Tillage (CT) fields had 392 kg SOC/ha,year, representing a threefold difference. At Golden valley Agriculture Research Trust (GART), SOC was 63,180 kg/ha after 15 years of CA compared to 50,622 kg/ha under CT over the same period. These findings suggest that CA can mitigate the effects of climate change by reducing the carbon emission resulting from the crop production practices. Further, there were significant differences between C-stocks under the 18 and 12 years CA fields under faidherbia albida (Musangu) trees at GART. The results also showed increased pH values under the eucalyptus field compared to the other fields at GART suggesting that pH increases when land use is changed from agriculture to forestry.

Kafwamfwa at the 34th International Conference of SEGH in Livingstone, Zambia

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • The society for environmental Geochemistry and health (SEGH): a retrospect 2019-02-22
  • Air quality and PM 10 -associated poly-aromatic hydrocarbons around the railway traffic area: statistical and air mass trajectory approaches 2019-02-19


    Diesel engine railway traffic causes atmosphere pollution due to the exhaust emission which may be harmful to the passengers as well as workers. In this study, the air quality and PM10 concentrations were evaluated around a railway station in Northeast India where trains are operated with diesel engines. The gaseous pollutant (e.g. SO2, NO2, and NH3) was collected and measured by using ultraviolet–visible spectroscopy. The advanced level characterizations of the PM10 samples were carried out by using ion chromatography, Fourier-transform infrared, X-ray diffraction, inductively coupled plasma optical emission spectrometry , X-ray photoelectron spectroscopy, field-emission scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy with energy-dispersive spectroscopy techniques to know their possible environmental contaminants. High-performance liquid chromatography technique was used to determine the concentration of polycyclic aromatic hydrocarbons to estimate the possible atmospheric pollution level caused by the rail traffic in the enclosure. The average PM10 concentration was found to be 262.11 µg m−3 (maximum 24 hour) which indicates poor air quality (AQI category) around the rail traffic. The statistical and air mass trajectory analysis was also done to know their mutual correlation and source apportionment. This study will modify traditional studies where only models are used to simulate the origins.

  • The geochemistry of geophagic material consumed in Onangama Village, Northern Namibia: a potential health hazard for pregnant women in the area 2019-02-18


    Ingestion of geophagic materials might affect human health and induce diseases by different ways. The purpose of this study is to determine the geochemical composition of geophagic material consumed especially by pregnant women in Onangama Village, Northern Namibia and to assess its possible health effects. X-ray fluorescence and inductively coupled plasma mass spectrometry were used in order to determine the major, and trace elements as well as anions concentrations of the consumed material. The geochemical analysis revealed high concentrations of aluminium (Al), calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), potassium (K), sodium (Na), and silica (Si); and trace elements including arsenic (As), chromium (Cr), mercury (Hg), nickel (Ni) and vanadium (V) as well as sulphate (SO42−), nitrate (NO3), and nitrite (NO2) anions comparing to the recommended daily allowance for pregnant women. The pH for some of the studied samples is alkaline, which might increase the gastrointestinal tract pH (pH < 2) and cause a decrease in the bioavailability of elements. The calculated health risk index (HRI > 1) revealed that Al and Mn might be a potential risk for human consumption. Based on the results obtained from the geochemical analysis, the consumption of the studied material might present a potential health risk to pregnant women including concomitant detrimental maternal and foetal effects.