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Johan Barnard   Dr.  Research or Laboratory Scientist 
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Johan Barnard published an article in August 2018.
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Henry Jordaan

17 shared publications

Department of Agricultural Economics, University of the Free State, Posbus 339, Bloemfontein 9300, South Africa

Jonannes Hendrikus Barnard

2 shared publications

Department of Soil- and Crop- and Climate Sciences, University of the Free State, Posbus 339, Bloemfontein 9300, South Africa

Pascalina Matohlang Mohlotsane

1 shared publications

Department of Agricultural Economics, University of the Free State, Posbus 339, Bloemfontein 9300, South Africa

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Article 0 Reads 0 Citations Water Footprint Accounting Along the Wheat-Bread Value Chain: Implications for Sustainable and Productive Water Use Benc... Pascalina Matohlang Mohlotsane, Enoch Owusu-Sekyere, Henry J... Published: 31 August 2018
Water, doi: 10.3390/w10091167
DOI See at publisher website ABS Show/hide abstract
Efficient and wise management of freshwater resources in South Africa has become critical because of the alarming freshwater scarceness. The situation requires a thorough examination of how water is utilized across various departments that use water. This paper reports on an examination of the water footprint and economic water productivities of the wheat-bread value chain. The assessment methodology of the Water Footprint Network was employed. The findings reveal that 954.07 m3 and 1026.07 m3 of water are utilized in the production of a ton of wheat flour in Bainsvlei and Clovelly in South Africa. The average water footprint for wheat bread was 954.53 m3 per ton in Bainsvlei and 1026.53 m3 per ton in Clovelly. More than 99% of the water is used in producing the grain at the farm level. The processing stage of the value chain uses less than 1% of the total water footprint. About 80% of all the water utilised along the wheat bread value chain is attributed to blue water. The findings revealed a significant shift from green water consumption to higher blue water use, and this is a major concern for water users and stakeholders along the wheat-bread value chain, given that blue water is becoming scarce in South Africa. The groundwater contributes about 34% and 42% of the average total water footprint of wheat at the farm level in Clovelly and Bainsvlei, respectively, suggesting the need to have an idea of the contribution of groundwater in water footprint evaluation and water management decision of farmers. This insight will aid in minimizing irrigation water use and pressure on groundwater resources. A total of ZAR 4.27 is obtained for every m3 of water utilized along the wheat-bread value chain. Water footprint assessment has moved away from sole indicator assessment, as a deeper awareness of and insight into the productive use of water at different stages has become vital for policy. To make a correct judgment and to assess the efficient and wise use of water, there is a need for catchment- or region-specific water footprint benchmarks, given that water footprint estimates and economic water productivities vary from one geographical area to another.
Article 0 Reads 0 Citations Water and salt balances of two shallow groundwater cropping systems using subjective and objective irrigation scheduling Johannes Hendrikus Barnard, Leon Daniel Van Rensburg, Alan T... Published: 06 November 2017
Water SA, doi: 10.4314/wsa.v43i4.06
DOI See at publisher website ABS Show/hide abstract
Evidence suggests that, in general, subjective rather than objective irrigation scheduling decisions are adopted by farmers. Irrigators have ‘calibrated’ themselves with years of experience to irrigate subjectively according to perceived crop water requirements. This study aimed to determine the associated benefits of objective versus subjective scheduling of two shallow groundwater cropping systems. Weekly measurements included rainfall and irrigation amounts, soil water content, groundwater table depth, artificial drainage volumes, and electrical conductivity of irrigation water, groundwater and drainage water. Simulations of evaporation and transpiration were done with the SWAMP model. Based on soil water and salinity status, matric and osmotic stress during the four cropping seasons is considered unlikely. When rainfall-plusirrigation was compared to evapotranspiration, objective scheduling resulted in an under-supply of 15%, and rainfall and shallow groundwater served as supplementary water sources. Subjective scheduling did not use rainfall efficiently as a source of water and resulted in an over-supply of 10%. Approximately 50% less salt was leached with objective compared to subjective irrigation scheduling. Under shallow groundwater conditions, irrigating subjectively according to crop water requirement results in excessive irrigation, salt addition and leaching compared to objective scheduling. Farmers can address some of the environmental problems associated with irrigation by adopting objective scheduling and reducing the leaching fraction (< 0.15) of shallow groundwater cropping systems.Keywords: evapotranspiration, leaching, salinity, water conservation, water degradation
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