Technical Yearbook 2023

Functioning of the system • During irrigation the water flows in-line through the main supply line pipe to the drippers/regulators, and then downwards into the NOVAP diffuser. • The internal design of the NOVAP system distributes the water evenly in the soil. • The NOVAP diffuser starts with a water footprint of 75 x 150 mm. • The so-called hydrated bulb of a NOVAP diffuser has a radius of up to 750 mm wide and 1 200 mm deep depending on the soil type. • Capillary action can force the water to rise up to 150 mm above the NOVAP diffuser. • There is no evaporation of water, as the upper 100 - 150 mm of the topsoil layer remains dry. Advantages of NOVAP irrigation • No water is lost due to evaporation. • All irrigation water is directly available in the root zone of the vine. • Water savings of up to 50% can be achieved. • The weed stand is much lower (only through rain). Weed control costs are thus greatly reduced. • Irrigation time is shortened and this brings about a saving in electricity costs. • The humidity in vineyards is lowered. This increases pollination of the flowers and reduces fungal disease pressure. • Fertilisation is applied directly in the root zone. • Salinisation of soils is minimal. • The so-called sub-surface hydrated bulb overlaps over time and this creates a lateral water zone with a relatively constant temperature which is very beneficial for the functioning of the plant (improving uptake of nutrients for example).

Disadvantages of NOVAP • The cost of a NOVAP system is significantly higher than a regular drip irrigation system. • The fear remains of blockages occurring and that the damage will be discovered too late. The design of the NOVAP system eliminates the risk for sub-surface blockages. The only possible blockage could occur above the soil surface at the dripper/regulator. This can be caused by impurities in the water (lack of filter maintenance and so forth). Because the dripper is only used as a regulator, and not as a dripper, blockages will not occur due to calcification, as it is a closed system where no evaporation takes place. The chances of root blockages in the diffuser are extremely small, because the hydrophobic silica inside the NOVAP system pushes the water away and thus keeps it dry. If peroxide treatment as part of a normal maintenance routine is adhered to, it is very unlikely that a total blockage will occur. References https://www.wineland.co.za/underground-irrigation-at alvis-drift/

No roots visible on a diffuser that was taken out of the soil.

The road ahead for NOVAP in the wine industry The installation of about 30 ha on Alvi’s Drift in 2019 is the largest single project of underground drip irrigation that NOVAP has undertaken to date. According to NOVAP it is more common for a producer to first start with the installation of a block or two, familiarise themselves with the management thereof, and then gradually convert to a larger scale system. According to Alvi, the substantial water saving was his main consideration and he can now irrigate twice as many vineyards with the same amount of water. Surprisingly, the quality of the Chenin blanc was so high that the first vintage was bottled under his flagship range. Furthermore, the vigour obtained in the vineyards planted to NOVAP is exceptionally good for third-leaf vines. It appears that NOVAP underground irrigation is here to stay in vineyards and the fruit industry. The benefits and quality that can be achieved with this system, outweigh the initial higher input costs and water is also applied more effectively. 

For more information, contact Etienne Terblanche at etienne@vinpro.co.za.

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TECHNICAL YEARBOOK 2023