5/11/2021 - By Dr. Raymond Snyder

POLYON®, an enhanced-efficiency, controlled-release fertilizer source, release plant nutrients at a highly predictable rate under specified conditions. The release mechanism is solely dependent upon the temperature that the POLYON® granule experiences in the turf canopy/soil. Factors such as microbial activity and water content (once the minimum threshold of 6% volumetric water content is met) do not impact the release rate of POLYON®. The reliance on a single variable helps to make POLYON® an extremely consistent, dependable, and predictable plant nutrient source.

So, how does an unexpected change in the weather affect POLYON®s nutrient release? To help answer that question, Harrell’s® and Virginia Tech University investigated the potential for a dramatic increase in temperature following a POLYON® application. Dr. Zhang, plant and environmental science, Virginia Tech, used his growth chambers to simulate both unstressed conditions (72/61 degrees Fahrenheit day/night) and heat stress (100 degrees Fahrenheit day 12 hr/82 degrees Fahrenheit night) during this study. The heat stress period was imparted one week after initial treatment, to simulate a dramatic rise in temperature following a POLYON® application to ‘L-93’ creeping bentgrass, with the heat stress period lasting for 8 weeks.

In the unstressed, cool temperature condition, POLYON® 43.5 mini released at an average rate of 0.08 lb N/1000 sq ft and POLYON® 41-0-0 mini released at 0.05 lb N/1000 sq ft.

In the stressed, hot temperature condition, POLYON® 43.5 mini released at an average rate of 0.14 lb N/1000 sq ft and POLYON® 41-0-0 mini released at 0.11 lb N/1000 sq ft.

Treatments:

Growth chamber #1:

(72/61 degrees Fahrenheit (d/n), 65% RH, light intensity 400 µmol m^-2 s^-1)

1. Fertilized control (0.15 lb. N per 1000 sq ft as liquid solution every 14 days from 28-8-18).
2. Single POLYON® mini 43.5 application as solid granule at 1 lb. N/1000 sq ft (2.299 lb. POLYON® mini 43.5 product/1000 sq ft) at day 0.
3. Single POLYON® mini 41 application as solid granule at 1 lb. N/1000 sq ft (2.439 lb. POLYON® mini 41 product/1000 sq ft) at day 0.

Click images for enlarged view

Nonstressed "cool" condition 72 degrees Fahrenheit day/61 degrees Fahrenheit night

Nonstressed "cool" condition 72 degrees Fahrenheit day/61 degrees Fahrenheit night

Growth chamber #2:

(100/82 degrees Fahrenheit (d/n), 65% RH, light intensity 400 µmol m^-2 s^-1)

1. Fertilized control (0.15 lb. N per 1000 sq ft as liquid solution every 14 days from 28-8-18).
2. Single POLYON® mini 43.5 application as solid granule at 1 lb. N/1000 sq ft (2.299 lb. POLYON® mini 43.5 product/1000 sq ft) at day 0.
3. Single POLYON® mini 41 application as solid granule at 1 lb. N/1000 sq ft (2.439 lb. POLYON® mini 41 product/1000 sq ft) at day 0.

Click images for enlarged view

Heat Stressed "hot" condition 100 degrees Fahrenheit day/ 82 degrees Fahrenheit night

Heat Stressed "hot" condition 100 degrees Fahrenheit day/ 82 degrees Fahrenheit night

Dr. Zhang summarized his findings below:

“In summary, POLYON® mini 43.5 and POLYON® mini 41 had better leaf color and higher chlorophyll content than regular fertilizer applied biweekly, especially under heat and drought stress conditions. No differences were observed in clipping production and root biomass between the treatments. POLYON® mini 43.5 improved leaf protein content under normal growing conditions. The POLYON® mini 43.5 and POLYON® mini 41 enhanced root viability under stress conditions. The grass fertilized with POLYON® mini 43.5 and POLYON® mini 41 may uptake water and nutrients more efficiently and sustain higher chlorophyll due to greater root viability, especially under stress conditions.”

Even under the stress of summer heat, POLYON® controlled-release fertilizer is reliable and you can trust the results which will come from it no matter the extreme conditions. If you need help to find the POLYON® controlled-release fertilizer product which is right for you, reach out to your Harrell's Rep.