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: knswana@yahoo.com, chitalu81.nk@gmail.com

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

  • Pollution characteristics and ecological risk assessment of 11 unheeded metals in sediments of the Chinese Xiangjiang River 2018-12-13

    Abstract

    With the change in global climate and environment, water scarcity has been of great concern around the word and exacerbated by serious pollution in water resources. Pollutants accumulated in sediments are threatening water safety and ecological security. Different from others focusing on prevalent heavy metals (Cu, Pb, Zn, As, Cd, Cr, Hg, etc.), in this study, some unheeded metal pollutants Tl, Sb, Mo, Sr, Co, V, Ti, Ca, Mg, Be and Li were monitored in sediments of the Xiangjiang River, China. It was found that there was no remarkable vertical variation with depth, but the seasonal characteristics of Tl, Sb, Mo, Be and Li. The enrichment, pollution and potential ecological risk of Tl, Sb and Mo were revealed by the enrichment factor (EF), geoaccumulation index (Igeo), pollution load index (PLIsite and PLIzone) and potential ecological risk index (RI). It is noticed that the pollution of Tl mainly occurred in summer at midstream and downstream and Mo pollution was much higher than Sb in summer and the reverse in other seasons. Additionally, sediment quality on east side was worse than on west side in Songbai section of the Xiangjiang River. For the first time, the toxic-response factor was figured out as Mo = 18, Tl = 17, Sb = 13, Sr = 6, Co = Be = 1, V = Li = 0, and importantly, the high potential ecological risk of Tl, Sb and Mo needs to be taken seriously for the comprehensive assessment on watershed environmental quality.

  • Editorial 2018-12-11
  • Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway 2018-12-11

    Abstract

    Samples of PM2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM2.5 was 93 ± 24 μg m−3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2 ng m−3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10 μg dL−1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5 μg dL−1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10−6).