Written by Mike Hamilton, CCA
Soil reserves refer to nutrients that are bound to soil particles and are not presently available to plants. Maintaining a soil reserve full of nutrients is like harboring a bank account frozen by law enforcement. To access your currency reserve, you must act. The action required in the soil to access its reserves is called mineralization.
Before we delve into this topic, it’s essential to understand that applying fertilizer with the goal of changing the level and balance of nutrients accumulated in the soil reserve is virtually impossible once the turf is established, especially once the soil’s nutrient-holding capacity reaches 3 or higher. At this point, small amounts of granular fertilizer are designed to bypass natural and chemical mineralization to provide the soil with a periodic release of soluble nutrients attached to the carrier through hydrolysis.
The process of soil mineralization is essential for releasing bound-up nutrients crucial for turf growth. Natural mineralization occurs when microorganisms in the soil consume and digest organic matter, converting nutrients into a form that plants can use. This function releases all the essential nutrients, both cation and anion, that would otherwise be unavailable to plants. Therefore, it is necessary to maintain healthy soil with high levels of microbial activity to ensure these nutrients are available for plant uptake. Investing in soil health and microbial activity can lead to healthier turf that can overcome abiotic and biotic stress. Improved plant growth without chemical controls provides a more sustainable environment and reduces the golf course’s carbon footprint.
Once mineralized nutrients are absorbed by the plant, they are used for various functions such as growth, reproduction, and defense. However, some nutrients may also be lost due to leaching or erosion. Maintaining the proper balance of nutrients in the soil is crucial to ensuring that your turfgrass is getting the most out of the nutrients in the soil. But how do these nutrients get into the soil reserve?
On irrigated turf, the nutrient reserve is built mainly from the irrigation water source. Irrigation water purity and quality are significant in soil quality and plant health. However, nutrients can also enter soil reserves through natural processes such as rainfall, decomposition of organic matter, atmospheric fixation, fertilizer applications, and chemical reactions.
Soil ionic charge is necessary for attracting and holding onto essential ions for plant growth. If the soil is charged correctly, these vital nutrients will be available to your turfgrass. However, if you maintain the right balance of nutrients, you can assist your turfgrass get the nutrients it needs to thrive.
Fortunately, or unfortunately, based on your opinion, chemical controls and reactions to reduce stress and ensure plant health are effective and relatively rapid.
Synthetic fertilizers can furnish nutrients such as nitrogen, phosphorus, and potassium, essential for plant growth. However, the level at which these nutrients are provided is very unpredictable; synthetic fertilizers dissolve in water and penetrate the soil, where the roots can absorb them. They must be used responsibly to avoid soil degradation, nutrient toxicity, and environmental pollution.
Due to their low pH, chemical and organic acids rapidly mineralize nutrients and release them from the restraint of soil ions. Depending on the pH of the acid, these are powerful tools to boost the mineralization of nutrients in the soil. By carefully controlling the amount of acid used, it is possible to lower the soil’s pH level, creating a more acidic environment conducive to releasing critical minerals that plants need to thrive. More available nutrients can improve plant health but may also cause adverse challenges from overuse.
Chemical acid must be used responsibly and cautiously, as excess use can cause soil toxicity and environmental damage. The lower the acid’s pH, the more powerful it is and the more vigilant you need to be. To get the most out of chemical acid, it is recommended to consult with a professional before making any substantial changes to soil composition. My suggestion when testing any product with either a negative or positive response is to test it on a small scale and for a predetermined period before using it on a large scale. Going all in immediately with something as harsh as chemical acid has the potential to risk job security.
Several products can be used to mineralize nutrients stored in soil reserves, but which one is most appropriate for your unique challenges? You have the authority to decide, so do your homework and make the best decision based on your knowledge. Here are some facts to keep in mind when searching for an answer.
Biological solutions to complex soil challenges are typically slow and require patience to achieve healthy and quality playing conditions. However, chemical solutions mimic biological controls almost instantly after application.
To meet the demands of the golfing public, superintendents are required to harvest turfgrass plants daily in a permanently altered state. Because of this unique standard of maintenance, Superintendents frequently have to bypass biological solutions in favor of chemical controls to prevent turf loss.
Plants and microorganisms have a symbiotic relationship. Plants feed microbes, and microbes keep plants alive and protect them from predators. There is nothing more magical to me than letting nature do its thing. Yet, when you harvest a crop daily, cut it down to 1/10th of an inch, and grow it in soil with a limited amount of organic matter, there is no possible way that plants can supply enough food to support a sufficient microbiome without a need for chemicals.
So, how could a superintendent even consider a biological-only program? With new soil testing methods used to detect microbial deficiencies, rapid research and understanding of soil biology and plant physiology, and the development of products to increase, balance, and strengthen microbial populations, we are getting closer every day to making biological-only programs possible.
So, why should a superintendent consider reducing their turfgrass dependency on chemicals? Chemical controls work practically every time they are used. However, every chemical application damages the soil biology and is potentially hazardous to many non-targeted organisms, including animals. The insects and diseases controlled by chemicals will eventually become genetically resistant to the chemicals targeting them. In the process, the pest mutated into different organisms that were no longer affected by the chemical. Therefore, manufacturers are forced to use other chemistries to control mutated organisms. This usually leads to more potent chemicals with a longer residual time in the soil.
In conclusion, to maintain a healthy and vibrant golf course, consider the importance of soil nutrients. By understanding how these nutrients get into soil reserve, how they are mineralized, and how they get into the plant, you can develop effective fertilization strategies for your turfgrass. With the right balance of nutrients, you can ensure your turf’s long-term health and sustainability. So go ahead and give your turfgrass the nutrients it deserves!
Mike Hamilton, CCA
Turf Dietitian, Inc
239-707-9974
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