Combat Rising Fertilizer Costs With Soil Organic Matter
2022 has certainly been challenging for the lawn care industry, with the double-whammy of extremely high fertilizer costs and limited supply. After a break from the high costs of 2008, global demand has increased. We will have to periodically contend with higher prices and shortages for the foreseeable future.
Like in 2008, lawn care professionals have adjusted how they do things. They’ve reduced rates and cut back on the amount of phosphorus, potassium, and slow-release they use. These changes can help buffer the higher costs in the short run, but what about the long term?
The higher gasoline prices aren’t going away soon, which has compelled more people to change their driving habits and buy electric vehicles or vehicles with better fuel economy. Likewise, many in our industry are looking at ways to combat higher prices by being more sustainable. There are many high-tech ways to have sustainable lawn care, but one of the easiest and most overlooked ways is unlocking the benefits of soil organic matter.
Soil organic matter (SOM) is the residue of plants, animals, and microbes in various stages of decomposition in the soil. As these materials break down, they release nitrogen and other nutrients back to the turf.
On average, soils around the ATS geography contain about 2–4% SOM. This percentage may not seem like much, but an acre of turf with a six-inch root zone can contain 40,000 to 80,000 pounds of SOM. What does that mean for the turf?
Each percentage of SOM can supply turf with 10 to 20 pounds of nitrogen, one to two pounds of phosphorus, and 0.4 to 0.8 pounds of sulfur per acre per year. That means you could harness soil organic matter to supply as much as 25% of a lawn’s annual nitrogen needs. In addition, SOM can absorb 90% of its weight in water, add structure to the soil, and increase the overall nutrient holding capacity of the soil.
SOM is the primary reason we can get away with things like cutting back on fertilizer from time to time without catastrophic results. However, we don’t want to abuse this benefit and should look at ways to utilize it more effectively.
SOM in a turfgrass site will mineralize at a rate of about 0.5% per year. At a minimum, you want to replace that, but it’s best to increase it if possible. You can do this in a variety of ways. You can use fertilizers that contain organic matter. You can also topdress with organic matter, but one of the easiest ways is recycling or mulching grass clippings. Just keep in mind that it takes 10 pounds of organic matter (OM) to produce one pound of SOM. It’s best to apply at least 20 pounds of OM per thousand square feet per year. Regular aeration also helps incorporate this organic matter into the soil.
When it comes to organic matter, beware of biochar. Biochar is a mineral form of carbon, which is very different from organic matter and can potentially have negative effects on soil. Opt for fertilizers containing organic matter derived from plant and animal waste because the microbes can easily break it down. Granular fertilizers that contain OM are concentrated and pelletized, making them easy to apply at relatively low rates. Compost topdressing is another good option, but it’s not as easy to work with as a granular fertilizer product.
Again, one of the easiest ways to do this is by mulching grass clippings. During the growing season, healthy turf will generate up to 1,800 pounds of grass clippings per thousand square feet. That can contribute about 200 pounds of SOM per thousand square feet per year.
Whatever your goal, consider incorporating one or more of these ideas into your program. Not only will it prevent these materials from heading to the landfill, but your turf will thank you for it!
Sam Weil
Sales Representative
