Heinrich Schloms, GIS and soil scientist at VinPro spoke with Octavia Avesca Spandiel, about how soil mapping helps wine producers make informed planting decisions, improve vineyard performance, and strengthen long-term sustainability.
The success of a vineyard begins long before the first vine is planted. Decisions made during the planning phase influence production, profitability and sustainability for decades. This makes having a detailed understanding of the soil one of the most valuable investments a producer can make.
Advancements in soil mapping technology are giving South African wine producers a clearer picture of the variability within their vineyards. The information gathered helps identify the most suitable sites for planting while supporting decisions on soil preparation, drainage, irrigation, fertiliser programmes and long-term vineyard management.
Heinrich Schloms, GIS and soil scientist at VinPro, says modern soil mapping combines field observations with technologies such as Global Positioning Systems (GPS) and Geographical Information Systems (GIS) to accurately record and analyse soil variability across a farm.
“Soil mapping is the process of capturing in-field soil data, whether physical, chemical or biological, and mapping it to display the soil variability within the survey area,” he says.
Rather than assuming that an entire block has the same characteristics, producers can identify differences in soil depth, texture, drainage, and other properties that influence vine growth. This allows management decisions to be based on accurate information instead of assumptions.
Understanding the soil before planting
Schloms says that soil mapping supports almost every aspect of vineyard establishment.
“All aspects of farm planning can benefit from a proper soil map. When it comes to identifying the right location for the right crop or cultivar, the soil map is indispensable. Soil factors are taken into consideration when planning subsoil drainage, soil preparation, soil amelioration and irrigation,” he says.
The information allows producers to match cultivars and rootstocks to suitable soils while identifying areas that may require additional preparation before planting.
This is particularly important because soil conditions can change considerably across relatively short distances. Even neighbouring vineyards may have completely different soil profiles, affecting water movement, nutrient availability and root development.
Knowing these differences before planting allows producers to adapt their management practices to each part of the farm instead of applying a single approach across every block.
Preventing costly mistakes
Establishing a vineyard requires a significant financial commitment. Land preparation, irrigation infrastructure, planting material and labour all contribute to the investment cost, making correct site selection essential.
Schloms says soil mapping helps producers identify physical limitations before planting begins.
“Sites with well-drained soils are essential for healthy vine roots and ultimately healthy, productive vines,” he says.
He explains that wetness and salinity are among the most serious soil constraints affecting vineyard performance. Heavy hydromorphic clay soils that remain waterlogged cannot always be corrected through drainage or soil preparation.
“Grapevines are essentially desert plants. They do not tolerate wet soils. Where these constraints cannot be adequately addressed, it may be more profitable to use the land for grazing or annual crops rather than investing in a vineyard that will underperform,” he says.
Identifying unsuitable areas before planting reduces unnecessary expenditure and prevents years of poor production caused by soil limitations that cannot easily be corrected.
Schloms adds that avoiding unsuitable soils also benefits long-term sustainability by reducing unnecessary inputs and lowering the risk of vine failure.
Getting soil preparation right
A soil survey provides far more than a description of the soil profile. It also guides the work required before vines are planted.
Once soil characteristics have been identified, producers can determine whether deep tillage, drainage systems or soil improvement measures are required. Carrying out these interventions before planting gives young vines the best possible start.
Schloms says producers should see the survey as a planning tool that supports every major establishment decision.
“The information collected during a soil survey guides almost every important establishment decision. Getting these decisions right at the start gives vineyards the best opportunity to perform consistently over their productive lifespan,” he says.
Detailed soil information also allows producers to divide vineyards into management zones, ensuring that future inputs are applied where they are needed rather than uniformly across the farm.
Making fertiliser decisions with confidence
One of the greatest advantages of soil mapping is that it provides the preparation context needed to interpret soil analysis results correctly.
“Soil mapping does not just tell you what amendments are needed. It tells you whether those amendments will actually work under the soil conditions present. This distinction is critical,” says Schloms.
He points to gypsum as an example. Although it is widely used to reclaim sodium-affected soils, adequate drainage is essential for it to work effectively.
“On heavy clay soils with poor drainage, gypsum behaves differently. As a salt, it can actually contribute to soil salinity rather than solving the problem,” he says.
Lime applications also depend on careful planning. Where acidic subsoils are identified, lime must be incorporated into the soil during land preparation because it cannot move through the soil profile once the vineyard has been planted.
“If this opportunity is missed, subsoil pH cannot be corrected after the vineyard has been established,” he says.
These examples demonstrate why soil mapping is not simply about identifying nutrient deficiencies. It provides the information needed to determine whether planned interventions are appropriate for the soil conditions and whether they are likely to deliver the expected results.
Precision agriculture starts below the surface
Soil mapping also forms the basis of precision agriculture. Before soil samples are collected, specialists identify management zones by using information such as soil type, depth, organic matter content and subsoil limitations.
Representative samples are then collected from each zone and analysed by an accredited laboratory. The results are combined with information about the soil’s physical characteristics before fertiliser recommendations are developed.
“The same chemical reading can have very different implications depending on whether the soil is a well-drained sandy loam or a compacted clay,” says Schloms.
GPS-recorded sampling points are linked to GIS software to generate recommendation maps that can be uploaded to variable-rate application equipment. This allows fertiliser and soil amendments to be applied according to the requirements of each management zone instead of using a uniform application rate across the vineyard.
Apart from improving nutrient efficiency, this approach can help reduce unnecessary input costs while supporting more consistent vine performance.
Preparing vineyards for a changing climate
Climate variability is becoming an increasingly important consideration for wine producers. Schloms says soil mapping helps improve resilience before a vineyard is even established.
He says one of the most valuable investments producers can make is thorough soil preparation once suitable soils have been identified.
“Ripping and loosening the subsoil before planting allows vine roots to grow freely in all directions. This increases the volume of the soil that the root system can access, giving vines access to more water and nutrients during dry periods,” he says.
A larger rooting zone enables vines to draw on deeper moisture reserves during drought and periods of high temperatures, reducing stress when water becomes limited.
Soil mapping also identifies blocks with shallow soils, coarse textures or restrictive subsoil layers that naturally have a lower water-holding capacity.
“Knowing this before planting allows producers to improve soil preparation, adjust irrigation scheduling or set realistic yield expectations,” he says.
The information is equally valuable during periods of heavy rainfall. Areas prone to erosion can be identified before vineyards are established, allowing producers to timely incorporate measures such as contour planting, contour banks and cover crops into their management plans.
“The golden rule is never to leave the soil bare. Cover crops are one of the most effective and affordable tools producers have for protecting the soil surface,” Schloms says.
Terrain analysis can also identify low-lying areas where cold air settles, helping producers recognise sites that may be more susceptible to frost and plan accordingly.
Clearing up common misconceptions
Despite advancements in technology, Schloms says several misconceptions still influence decisions around vineyard establishment.
One of the biggest is the belief that any soil problem can be corrected with enough soil amendments. While issues such as acidity, compaction and sodicity can often be improved, some physical limitations cannot be overcome.
“Heavy, hydromorphic clay soils that remain waterlogged simply cannot provide the well-drained environment grapevines require. Planting on these soils will result in vineyards that consistently underperform,” he says.
Another misconception is that neighbouring farms have similar soils because they are located in the same production area.
Schloms says soil conditions in the Western Cape can change dramatically over only a few metres.
“The fact that a neighbouring farm is producing excellent grapes does not mean your soil conditions are the same. Every site deserves its own detailed survey before planting,” he says.
He says a detailed soil survey should be viewed as part of the planting process rather than an optional expense because it helps prevent costly mistakes before capital is committed.
From data collection to practical decisions
While technology has made collecting soil information easier, interpreting that information still requires specialist knowledge.
Schloms says one of the greatest challenges is ensuring that enough observations are collected during the survey. “In the field, sampling density matters enormously. Too few augering points or soil pits, and critical transitions between soil types are missed entirely,” he says.
Laboratory results also need to be interpreted alongside the soil’s physical characteristics. “A lime or gypsum recommendation that is appropriate for one soil type can be ineffective or even counterproductive on another,” he says.
He adds that recommendations only deliver value if they are implemented correctly. For example, lime must be incorporated to the correct depth during land preparation. If soil preparation is not carried out according to specification, the benefits of the survey can be significantly reduced.
“There are times when a producer has already committed emotionally and financially to a particular site, only for the soil survey to show it is unsuitable for vineyards. Those are difficult conversations, but it is far better to have them before planting than after,” he says.
Making technology available to more producers
Schloms says soil mapping is no longer limited to large commercial operations.
“Soil mapping is not reserved for large operations or well-capitalised producers. At VinPro, there are no barriers when it comes to farm size or budget. Every producer can access professional soil mapping services,” he says.
VinPro also offers a black economic empowerment support service funded by the wine industry, allowing qualifying producers to apply for assistance with professional soil surveys and planning.
He says improving access to these services enables more producers to make informed establishment decisions using scientific information instead of relying on trial and error.
Working together for better results
Although digital technology continues to evolve, Schloms says successful soil management depends on collaboration between specialists.
“The soil scientist, fertiliser supplier, precision spreading company, and soil preparation contractor each hold a critical piece of the puzzle. The future belongs to operations where these specialists work seamlessly as an integrated team,” he says.
He adds that technology alone cannot guarantee success.
“A variable-rate application prescription is only as good as the calibration of the spreader that carries it out. A soil amelioration plan is only as effective as the depth and quality of the ripping that follows,” he says.
As soil management becomes more specialised, he believes producers benefit from working with qualified professionals who can interpret soil data and ensure recommendations are correctly implemented.
Building stronger vineyards from the ground up
Every vineyard starts with decisions made before planting, and those decisions can influence productivity for decades.
Detailed soil mapping enables producers to understand the strengths and limitations of their land before investing in vines, irrigation infrastructure and production inputs. It also provides the information needed to prepare soils correctly, target fertiliser applications, improve water management, and reduce production risks.
Schloms says the knowledge and technology already exist to support better decision-making.
“The days of trial and error in soil management are over. The knowledge, the tools and the support structures already exist to get it right from the start. The challenge is making sure the right people work together to deliver that information and implement it correctly,” he says.
