Slow Release Fertilizer Use

Charles H. Peacock

Jason Hinton

The purpose of this research is to evaluate controlled release nitrogen materials. Nutrisphere is a liquid additive (maleic-itaconic copolymer, calcium salt) rmixed in urea to provide a slow release coating. This was compared to uncoated urea and two slow release standards, UFlexx and UMaxx which are stabilized nitrogen fertilizers specifically for the turf and ornamental markets formulated with two proprietary inhibitors that minimize nitrogen loss. These materials include a unique inhibitor that blocks urease, dicyandiamide, which helps to minimize nitrogen loss to the atmosphere, allowing time for rainfall and irrigation to effectively transport nitrogen to the root zone for plant utilization. Once in the soil another inhibitor, NBPT (N-(n-Butyl)-thiophosphoric triamide) keeps it in a plant available form ensuring no other losses occur due to denitrification or leaching. UFlexx and UMaxx differ in the concentration of the inhibitors in each product.

 

The complete treatment list is as follows:

Fertilizer Treatment                 Rate                 Application Date(s)

Nutrisphere Urea 46-0-0         1 # N/M           May 20

Nutrisphere Urea 46-0-0         1 # N/M           May 20, July 22

Nutrisphere Urea 46-0-0         2 # N/M           May 20

Nutrisphere Urea 46-0-0         2 # N/M           May 20, July 22

Urea 46-0-0                             1 # N/M           May 20

Urea 46-0-0                             1 # N/M           May 20, July 22         

Urea 46-0-0                             2 # N/M           May 20

Urea 46-0-0                             2 # N/M           May 20, July 22         

UFlexx 46-0-0                         1 # N/M           May 20

UFlexx 46-0-0                         1 # N/M           May 20, July 22         

UFlexx 46-0-0                         2 # N/M           May 20

UFlexx 46-0-0                         2 # N/M           May 20, July 22         

UMaxx 47-0-0                                    1 # N/M           May 20

UMaxx 47-0-0                                    1 # N/M           May 20, July 22         

UMaxx 47-0-0                                    2 # N/M           May 20

UMaxx 47-0-0                                    2 # N/M           May 20, July 22         

Nontreated

 

Ratings that were taken on this trial included turf quality on a 1-9 scale, with 9 being the best. NDVI readings were also taken with a Crop Circle and a chlorophyll meter was used to obtain an index value. Both of these measurements give an indication of green growth.