Customer case

A new step in resilience with DCM REDU-ACT against salt stress

About this client

Name

Joh. Stolwijk & Zonen

Sector

Substrates

Location

Boskoop (Netherlands)

Joh. Stolwijk & Zonen is a family-owned business located in the heart of the Boskoop nursery region, specialising in the supply of high-quality plants to professional garden centres and other nurseries. In recent years, however, the company has increasingly had to deal with issues related to soil salinity, because a large part of the plants is irrigated with surface water. This water has shown steadily rising salt concentrations, making plant cultivation more challenging. DCM REDU-ACT turned out to be a possible solution to this problem.

During cultivation, several Magnolia soulangeana trees showed browning along the leaf margins, a symptom commonly associated with leaf scorch. To gain better insight into the underlying cause, a trial was started using the new liquid product: DCM REDU-ACT. The objective was to evaluate whether this product could help plants cope more effectively with salt stress, while closely monitoring root growth and overall root system development.

Climate change increases the risk of salt stress

Magnolias can clearly be affected by salt stress, a phenomenon that is occurring in an increasing number of crops. In avenue trees, de‑icing salt is often the main cause, but the influence of climate change is becoming more significant. Longer periods of drought contribute to rising salinity levels and can increase the salt concentration in surface water. When plants are irrigated with this water, growth problems may occur. In addition, during dry conditions, seepage water rising from deeper soil layers can also contain higher salt concentrations. Although various initiatives are underway to improve surface-water quality, it remains important for nurseries to closely monitor water quality themselves. This allows them to identify risks early and apply timely treatments to limit damage caused by salt stress.

Stronger magnolias through a new approach

During the trial at Joh. Stolwijk & Sons, several Magnolia soulangeana trees were selected to study salt stress. The plants were potted into five-litre pots in the spring of 2024. To simulate saline conditions, salt was deliberately added to the irrigation water during a wet period. The effects became visible quickly: leaf scorch symptoms appeared, growth slowed down, and the root systems also showed clear signs of stress.

Some of the magnolias were treated with DCM REDU-ACT, a newly developed liquid organic fertiliser and an advanced version of the earlier product REDU-BAC. This product contains active components that help reduce salt accumulation in the substrate while simultaneously supporting the plant itself and stimulating soil life. Throughout the trial, substrate parameters were monitored regularly and the plants were visually evaluated. The results showed that the treated magnolias were significantly more resistant to salt stress than the untreated control plants.

The effectiveness of REDU‑ACT is based on a carefully balanced combination of specific amino acids, complex carbon chains and calcium oxide. Together, these components contribute to a stronger soil ecosystem and provide direct support to the plant, enabling it to cope more efficiently with salinity and other stress factors.

Untreated control - Without REDU-ACT

Untreated control - With REDU-ACT

Salt-treated object without Redu-act

Salt-treated object - With REDU-ACT

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It can prevent or remedy many problems, and because it is completely organic, the part that is not absorbed by the plant eventually breaks down completely.

From water quality to resilient plants

For Stolwijk, it is essential to understand which crops are particularly sensitive to salt stress. That is why water quality is monitored continuously. This allows potential salt-stress risks to be identified and action to be taken quickly when needed. "Our goal is to ensure that the plants we pot grow as strong and vital as possible before they aredelivered to landscapers, nurseries and garden centres. These customers usually have sufficient expertise to decide whether additional treatment is needed and are familiar with the soil conditions in their region, for example in areas where seepage water rises to the surface. Since we also export a large proportion of our plants, conditions vary considerably from one location to another. That is exactly why a product like DCM REDU-ACT is so valuable. It can prevent or solve many problems, and because it is fully organic, any part not taken up by the plant eventually breaks down completely."

From innovation to results

The spring of 2025 was exceptionally dry, which was clearly reflected in elevated salt concentrations in surface water. According to Stolwijk, salt levels measured in April were already comparable to those normally observed only in July. To minimise potential damage, Magnolia soulangeana trees will now be treated with DCM REDU-ACT shortly after potting, during the first irrigation. In addition, a follow-up trial has been started with a number of Acer palmatum trees to further evaluate the effects of this approach.

New

DCM REDU-ACT®

Reduces salt stress and stimulates soil life and growth

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