South Africa Archives

2023 Chile, Florida, South Africa

Single and basal crop coefficients for estimation of water use of tree and vine woody crops with consideration of fraction of ground cover, height, and training system for Mediterranean and warm temperate fruit and leaf crops

Authors: Pereira, L. S.,; Paredes, Paula; Oliveira, C. M.; Montoya, Francisco; López-Urrea, Ramón; Salman

This paper reviews the research on the FAO56 single and basal crop coefficients of fruit trees and vines performed over the past twenty-five years and focus on Mediterranean and warm temperate trees and vines. Two companion papers (López-Urrea et al., (2023) Single and basal crop coefficients for estimation of water use of tree and vine woody crops with consideration of fraction of ground cover, height, and training system for temperate climate fruit crops. Irrig Sci (submitted); Paredes et al. (2023) Single and basal crop coefficients for estimation of water use of tree and vine woody crops with consideration of fraction of ground cover, height, and training system for tropical and subtropical fruit crops. Irrig Sci (submitted)) are dedicated, respectively, to Temperate and to Tropical and Subtropical trees and vines. The main objective of the paper is to update available information on single (Kc) and basal (Kcb) standard crop coefficients, and to provide for updating and completing the FAO56 tabulated Kc and Kcb. The Kc is the ratio between non-stressed crop evapotranspiration (ETc) and the grass reference evapotranspiration (ETₒ), while Kcb is the ratio between crop transpiration (Tc) and ETₒ. The selection and analysis of the literature were performed considering only studies that adhere to the FAO56 method, thus computing ETₒ with the FAO Penman–Monteith ETₒ equation, the ASCE grass ETₒ, or another equation that could be properly related with the former, and ETc, or Tc, was obtained using properly accurate field measurements on crops under pristine or eustress conditions. The crops considered refer to Mediterranean (grapes and olive) and warm temperate areas (avocado, citrus, persimmon, loquat, and tea) fruit and leaf crops. Papers satisfying the above conditions were selected to provide for standard Kc and Kcb data. Preferably, studies should report on the crop cultivar and rootstock, planting density or plant spacing, fraction of ground cover (fc), crop height (h), crop age and training systems. Additional information was collected on pruning and irrigation method and strategy. The ranges of reported Kc and Kcb values were grouped according to crop density in relation with fc, h, and the training system, namely vase, hedgerow, or trellis systems. Literature collected Kc or Kcb values were compared with previously tabulated Kc and Kcb values, namely in FAO56, to define the standard Kc and Kcb values for the referred selected crops. The tabulated values are, therefore, transferable to other locations and aimed for use in crop water requirement computations and modeling, mainly for irrigation planning and scheduling, and for supporting improved water use and saving in orchards and vineyards.

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2024 South Africa

Life Cycle Assessment of an Avocado: Grown in South Africa-Enjoyed in Europe

Authors: Blaauw, Sheldon A.; Broekman, André; Maina, James W.; Steyn, Wynand J. v. d. M.; Haddad, William A.

"Food production is known to have significant environmental impacts, with the main contributors residing in the farming and transportation life cycle phases. Of the various food products transported around the world, avocados have increasingly gained attention as a high-commodity superfood. Avocados require specific climatic and agricultural conditions for farming, with the most fertile land and conditions located outside Europe. Consequently, most avocados consumed in Europe are imported over vast geographical distances, with little information available to quantify the environmental impacts of this imported superfood. This paper aims to present the most detailed life cycle assessment results of an avocado cultivated, grown and harvested in the Limpopo Province of South Africa and exported to the European market for sale and consumption. A life cycle assessment was developed for the farming, harvesting, handling, packaging, ripening, transportation, and carbon sequestration potential of the avocado, and it was used to conduct a holistic life cycle assessment. Input data was obtained through an 18-month data collection campaign across the relevant stakeholders. A baseline 'business-as-usual' scenario is focused on throughout this study, and scope for optimisation is identified for each life cycle phase where applicable, accompanied by uncertainty analyses. Results show a total carbon input of 904.85 kg CO₂e/tonne. Mitigating this, 521.88 kg CO₂e/tonne is offset, resulting in a net carbon footprint of 382.97 kg CO₂e/tonne with uncertainty ranges of −23.22 to +58.69 kg CO₂e/tonne, normalised to 57.45 g CO₂e/avocado grown in South Africa and sold in Europe. The environmental impacts of the avocado industry under consideration are largely mitigated by the ""nature first"" philosophy of the farming and logistics enterprises, which have made significant investments in reducing emissions. Sensitivity analyses indicate that implementing large-scale renewable energy, using alternative packaging instead of cardboard, and selling avocados unripened could further enable the farming enterprise to achieve Net Zero objectives. These measures could reduce baseline emissions from 382.97 kg CO₂e/tonne to a theoretical −68.54 kg CO₂e/tonne, representing a 117.9% decrease. Although this study does not quantify climate change impacts, qualitative analyses suggest that climate change will have a net negative effect on the avocado industry in South Africa. These regions, typically located in micro-climates, are projected to become wetter and warmer, adversely affecting crop phenology, pest control, road conditions, management complexity, farmer livelihoods, and food security. The study recommends large-scale implementation of the optimisation strategies identified to achieve Net Zero objectives and the development of proactive climate change mitigation strategies to enhance the resilience of avocado supply chains to future stressors. These insights are crucial for policymakers, industry stakeholders, and consumers aiming to promote sustainability in the avocado market."

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1995 South Africa

Bioenergetics, respiration cost and water relations of developing avocado fruit

Authors: Blanke, M.M.; Whiley, A.W.

Avocado fruit of cultivars with different susceptibility to physiological fruit disorders were examined in situ for respiration, stomatal conductance, transpiration and xylem water potential. Therein, attached fruit of cv. Fuerte (susceptible to mesocarp discolouration) were compared with Hass (susceptible to small fruit) over the 3-month period from anthesis until the fruit reached 60 g fresh matter:1. Avocado fruit respired more CO2 in the dark than in the light due to fruit photosynthesis. Respiration

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2020 South Africa

Water use of an intermediate and a mature avocado orchard

Authors: Mazhawu, E.; Clulow, A.D.; Taylor, N.J.; Savage, M.J.

The scarce water resources in South Africa are vulnerable to the increasing pressure of a changing climate. The recent drought experienced in South Africa (2014-2017) has negatively affected the fruit industry, highlighting the need to optimise water use efficiency (WUE) as well as accurately estimate water use. With avocado production in South Africa being export-oriented and dependant on irrigation, proper water management is vital to minimising water use, while maintaining fruit yield and quality.

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