Campbell Vaughn: A look at the nitty gritty on lawn fertilizers
jbrotton
Campbell Vaughn Columnist
I give advice regularly on how to do something and don’t usually get to see the real results of what I advocate. In Extension, we are constantly giving out recommendations for fertilizer types and rates (especially for lawns) hoping that the product is going to work well and give the client the desired results.
Turfgrass is completely out of dormancy this time of year and growing enough to at least need a weekly mowing. What an exciting time for lawn lovers like myself. In my own yard which is TifTuf bermuda in the back and St. Augustine in the front, I applied a 16-4-8 fertilizer about three weeks ago and watered it in like you are supposed to do and nothing much happened for a spell.
The bag of fertilizer had been around for a couple of years, so when the grass didn’t change color too much, I wondered if maybe the bag had gone bad. Last week, we had a nice rain with some serious heat and guess what? My lawn turned dark green and started growing. And when I say growing, I mowed after church on Sunday and again on Tuesday.
(Note to all: Adding nitrogen fertilizer to your turf will add to your grass-mowing workload. I do have a riding lawnmower, so it is a lot easier to ride 15,000 square feet than to push it.
After the period of not much happening after my fertilizer was applied, it got me to wondering what the actual shelf life is for fertilizers, so I went looking for answers.
When I say fertilizer, I am talking about products with some formulation of nitrogen, phosphorus and potassium with possibly some traces of other ingredients like calcium, iron, magnesium, etc. without an integrated pesticide. If stored properly, liquid fertilizers will last 8-10 years. Granular fertilizers, which are the ones we are most likely to use in the landscapes, could last indefinitely.
Storage of fertilizers
Proper storage would include keeping the material in a dry, cool and 100% shaded location. Keep the products in the original bag/container and seal it tightly to keep the moisture out. Also make sure to keep the fertilizer off the ground to avoid moisture and things that might live in the soil like mildew or fungi to attack. If you have an older bag of granular fertilizer and you have some clumping due to moisture, wear some gloves and break up the masses and all is well. If you have a liquid fertilizer and are seeing some sediment, make sure to shake or agitate the container well to dissolve the substance.
Pesticides incorporated into fertilizers like weed and feed products will have some type of chemical herbicide built into the product. With age, the fertilizer part will stay effective, but the pesticide ingredient will degrade in 1-4 years. Before using that weed and feed product that has been sitting in your garage since you were prepping for Y2K, check the label to see what shelf life is for the chemical embedded in the product before using it. This will help you from still having weeds in your lawn after spending a hot afternoon applying this antique bag of turf product.
Disposal of old fertilizer
If you are trying to dispose of those old bags of fertilizers that you are cleaning out of your grandfather’s garden shed, check with your local landfill on the best way to handle those products. And if they have been stored correctly, put them out on your lawn and get ready to start mowing.
Reach Campbell Vaughn, the UGA Agriculture and Natural Resource agent for Richmond County, by e-mailing [email protected].