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

  • Health risks and source identification of dietary exposure to indicator polychlorinated biphenyls (PCBs) in Lanzhou, China 2019-09-19

    Abstract

    Polychlorinated biphenyls (PCBs) are widely present in multiple environmental media even long after the phaseout, posing a health risk to the general population. Dietary intake is the major exposure route of PCBs; however, information is limited regarding PCBs in food that people directly consume. This study aims to measure personal exposure to indicator PCBs, evaluate the health risks, and identify their sources in a typical metropolitan city in China. Multi-day food samples were collected from 21 subjects in Lanzhou, Gansu Province, in two seasons using the duplicate plate method. Samples were extracted and analyzed for seven indicator PCBs using gas chromatography/mass spectrometry. Average daily doses (ADDs) of ∑7PCBs were estimated using Monte Carlo analysis with food intake information. Results show that PCB-118 and PCB-180 were the major congeners in food samples with average concentrations of 1.42 and 1.11 ng/g, respectively. The average (± SD) ADD of ∑7PCBs was 26.47 ± 22.10 ng/kg day among adults aged 18–69 years and displayed small variation across age groups. Comparing with the chronic RfD of 7 ng/kg day, 67% of people had their ADDs exceeding this threshold. The median cancer risk was 5.52 × 10−5, and 51% of residents had risks exceeding the action level of 10−4. The principal component analysis identified waste incineration, gasoline engine production, and leakage of #1 PCBs as the major PCBs sources. In conclusion, a large portion of Lanzhou residents has high non-cancer and cancer risks from dietary exposure to PCBs, which warrants control actions targeting these major sources.

  • Comprehensive assessment of heavy metals pollution of farmland soil and crops in Jilin Province 2019-09-18

    Abstract

    As a major agricultural province in China, it is necessary to study the content of heavy metals in farmland soil and crop in Jilin Province and to evaluate the risks to ecology and human health. This study presented the work completed on 79 soil samples, 10 rice samples, 66 maize samples and 15 soybean samples collected from Jilin Province farmland and evaluated six heavy metals (Zn, Cu, Pb, Cd, Hg and As) concentrations. The results showed that the concentrations of the six heavy metals in farmland soil and crop samples from Jilin Province basically met the soil standards and food health standards of China. The agricultural soil pollution spatial distribution was the most serious in the south of Jilin Province and the lightest in the west. The non-carcinogenic risks faced by children eating crops were higher than those of adults, but the carcinogenic risks were lower than those of adults. Both of the two health risks to adults and children from eating crops were very limited. The results would help determine the heavy metals pollution in farmland soil in Jilin Province efficiently and accurately and helped decision makers to achieve a balance between production and environmental regulation.

  • Sustainability of agricultural and wild cereals to aerotechnogenic exposure 2019-09-14

    Abstract

    In recent decades, the problem of the constantly increasin level of anthropogenic load on the environment is becoming more and more acute. Some of the most dangerous pollutants entering the environment from industrial emissions are heavy metals. These pollutants are not susceptible to biodegradation over time, which leads to their accumulation in the environment in dangerous concentrations. The purpose of this work is to study the sustainability of cultivated and wild plants of the Poaceae family to aerotechnogenic pollution in the soil. The content of heavy metals in couch grass (Elytrigia repens (L.) Nevski), meadow bluegrass (Poa pratensis L.) and soft wheat (Triticum aestivum) plants grown in the impact zone of Novocherkassk Power Station has been analyzed. Contamination of cultivated and wild cereals with Pb, Zn, Ni and Cd has been established. It has been shown that the accumulation of heavy metals is individual for each plant species. An average and close correlation have been established between the total HM content and the content of their mobile forms in the soil and their content in plants. For the plants studied, the translocation factor (TF) and the distribution coefficient (DC) of HM have been calculated. The TF is formed by the ratio of the concentration of an element in the root plant dry weight to the content of its mobile compounds in the soil. The DC value makes it possible to estimate the capacity of the aboveground parts of plants to absorb and accumulate elements under soil pollution conditions and is determined as the ratio of the metal content in the aboveground biomass to its concentration in the roots. TF and DC values have shown a significant accumulation of elements by plants from the soil, as well as their translocation from the root system to the aboveground part. It has been revealed that even within the same Poaceae family, cultural species are more sensitive to man-made pollution than wild-growing ones.