12/16/2025

The Harrell’s R&D team conducted numerous research trials this past year to explore potential new offerings and learning more about the value of our current products. Our work in 2025 included an investigation with the objective of helping plants tolerate high salinity.

2 Big Research Findings from 2025

In previous work, we have learned that EarthMAX® Organic helps turfgrass acclimate to high salinity. To continue our investigation in 2025, we dove into the potential effect of Cal Plus on bentgrass tolerance to high salinity with some very interesting results.

Cal Plus Research - Enhance Salt Stress Tolerance

The treatments included:

1. Fertilized control (0.15 lbs. N/1000 ft2 biweekly) + salt stress

2. Cal Plus at 3 oz/1000 ft2 applied biweekly + salt stress

3. Cal Plus at 9 oz/1000 ft2 applied biweekly + salt stress

4. Fertilized control, non-salt stress

In summary, applications of Cal Plus at 3 and 9 fl oz/1000 ft2 improved leaf color, clipping production, and improved the plants’ natural use of photosynthetic pigments, as well as supported the plants’ ability for photochemical efficiency, antioxidant SOD activity, and root health and viability. Cal Plus at both rates improved leaf Ca, S, and Mg content and also leaf N content at the higher rate.

Overall, the results of this study indicated foliar application of Cal Plus at the two rates may improve salt stress tolerance by enhancing the plants natural physiological fitness, leaf color, and root viability in creeping bentgrass.

Fig. 1. Turf quality responses to Antisalt and Cal Plus in creeping bentgrass under salt stress (December 3, 2024).

Fig. 2. Root growth responses to Antisalt and Cal Plus in creeping bentgrass under salt stress (December 3, 2024).

Stress Relefe Research – Improving Turf Quality

The Harrell’s R&D department also investigated the potential for Stress Relefe to aid turfgrass tolerance to low light/shade conditions.

The treatments included:

1. Fertilized control biweekly (0.10 lbs. N/1000 ft2 from fertilizer 28-8-18 biweekly)

2. Stress Relefe (K acetate) 3 fl oz/1000 ft2/week + fertilized control biweekly

3. Stress Relefe (K Acetate) 3 fl oz/1000 ft2/biweekly + fertilized control

4. Stress Relefe (K Acetate) 6 fl oz/1000 ft2/biweekly + fertilized control

In summary, foliar application of Stress Relefe (potassium acetate) improved turf quality, photochemical efficiency, leaf chlorophyll content, leaf protein and nonstructural carbohydrate content when compared non-treated control in creeping bentgrass under shade stress conditions. Stress Relefe (potassium acetate) treatments also improved root biomass relative to the control.

Foliar application of the potassium acetate product at 3 fl oz/1000 ft2 weekly or biweekly and 6 fl oz/1000 ft2 biweekly improved root biomass relative to the control. The greatest root biomass was found in the grass treated with Stress Relefe (potassium acetate) at 3 fl oz/1000 ft2 biweekly.

Photo 1. Turf quality response to potassium acetate application as measured at the end of the trial (day 56).

Photo 2. Root growth response to potassium acetate application as measured at the end of the trial (day 56).

Connect with your Harrell’s Rep

Our R&D department runs numerous research trials throughout the year, all with the goal of creating the most effective products for your operation. We ran a lot of trials in 2025 and have made some exciting strides in product development, and we are greatly looking forward to serving you through product development and support in 2026.

If you have any further questions about trials conducted this year or regarding any of our products, reach out to your local Harrell’s Rep or one of our Directors of Agronomy.