South Africa Wine Technical Yearbook 2025

FIGURE 4: Hutton soil.

FIGURE 5: Kroonstad soil form.

FIGURE 6: Water movement taken up in a duplex soil with a sandy loam top layer and a clay bottom layer after two hours (a), four hours (b) and eight hours (c). The slow movement of the water in the clay causes more lateral movement of water in the topsoil as the irrigation time progresses.

remain the same, however: determine the dimensions of the root zone by investigating profile pits, take the texture class

into consideration, as well as root distribution and the stone fraction, to calculate an estimated irrigation duration.

Summary It is clear that the wide variety of soil types, as well as irrigation delivery options, can have a drastic effect on irrigation duration. The producer should therefore have a good knowledge of the soils and soil differences on the farm. It is also imperative to perform the necessary soil preparation during vineyard establishment. The purpose of soil preparation is to address any chemical or physical aspects limiting root growth. If such root growth limitations are uplifted during soil preparation, and the correct irrigation system is installed, this allows for optimal utilisation of the soil and water resources, better

buffer capacity against heatwaves and better growth and yield potential. Of course, there are many options in terms of devices to measure soil water content. If these measurements are interpreted correctly, it is a handy tool to determine irrigation duration. The Handbook for Irrigation of Wine Grapes in South Africa ( https://sawine.co.za/research development-and-innovation-rdi/knowledge-transfer/e books/) is a comprehensive publication which discusses all aspects of irrigation. It is a summary of many years of research. The industry also has consultants and service providers with the necessary experience to guide producers in this regard. 

For more information, contact Gert Engelbrecht at gerte@vinpro.co.za. Reference https://wineland.co.za/irrigation-duration-time-to-give-water-but-how-much-is-enough/

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TECHNICAL YEARBOOK 2025