Browsing by Author "Tshuma, Flackson"

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    Effects of long-term (42 years) tillage sequence on soil chemical characteristics in a dryland farming system
    (Elsevier, 2021) Tshuma, Flackson; Rayns, Francis; Labuschagne, Johan; Bennett, James; Swanepoel, Pieter Andreas
    No-tillage can improve soil quality but can also increase the stratification of soil chemical parameters. Nutrient uptake by crops might be limited when nutrients are stratified, especially in semi-arid or Mediterranean regions. To reduce stratification, infrequent tillage could be considered. However, there is a paucity of information on the effects of long-term infrequent tillage on the stratification of soil chemical parameters. This study aimed to assess the effects of long-term infrequent tillage on the stratification of selected soil chemical parameters to a depth of 300 mm. The research was conducted on a long-term (42 years) research site at Langgewens Research Farm in South Africa. Seven tillage treatments were investigated: continuous mouldboard ploughing to a depth of 200 mm, tine-tillage to 150 mm, shallow tine-tillage to 75 mm, no-tillage, shallow tine-tillage every second year in rotation with no-tillage, shallow tine-tillage every third year in rotation with no-tillage and shallow tine-tillage every fourth year in rotation with no-tillage. Tillage treatments had differential effects on the distribution of soil chemical parameters. The mouldboard plough prevented stratification of most soil chemical parameters, such as soil acidity, soil organic carbon (SOC), extractable P, exchangeable Ca and Mg and cation exchange capacity (CEC). However, mouldboard ploughing also led to significantly lower SOC stocks and extractable P stocks. The SOC stocks and extractable P stocks of the no-tillage treatment were not significantly different from those of the infrequent tillage treatments. Overall, the infrequent tillage treatments were no better (P > 0.05) than the no-tillage treatment as infrequent tillage could not effectively ameliorate the stratification of most soil chemical parameters and did not increase the stocks and stratification ratios of SOC and extractable P.
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    The influence of soil salinity on regeneration of annual Medicago pastures in the Swartland area of South Africa
    (Stellenbosch : Stellenbosch University, 2017-03) Tshuma, Flackson; Swanepoel, Pieter Andreas; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Soil is a critical aspect in food security and represents the difference between survival and extinction of all living organisms. However, most environmental reports suggest that various agricultural activities are responsible for soil degradation and thus can hinder sustainable food production. Soil salinity can be caused by agricultural activities, and it has become a major global concern. Farms in the Swartland area of the Western Cape province in South Africa have soil salinity problems which is affecting farm productivity and profitability. This study aimed at evaluating the influence of soil salinity on the regeneration of annual medic (Medicago spp.) pastures. The study was carried out on two farms which practice conservation agriculture in the Swartland area. The study highlights the changes in medic productivity in terms of seed production, seedling establishment and herbage production across a soil salinity gradient. The low productivity (saline) soils had the lowest (P < 0.05) medic seed numbers, seedling establishment and herbage yield compared to the medium and high productivity (none saline) soils. The use of gypsum was not effective in the alleviation of soil salinity, therefore, the use of salt tolerant legumes such as messina (Melilotus siculus), on the saline soils was recommended.