It is food plot planting season, and many people are busy getting their seed in the ground. Around this time every year, habitat management forums are filled with questions, and more than a few pertain to the use of lime for adjusting pH. Here, I hope to cut through some of the myths surrounding this issue.
The Basics
First and foremost, the rest of this blog will be of little use if you didn’t test your soils beforehand. A soil test is cheap, and will prevent you from spending money on nutrients or lime where you don’t need it. Given that you have completed a soil test, take a look at the pH. A pH of 7.0 is neutral, and most food plot plantings grow best with a pH between 6 and 7. This varies somewhat depending on the species in the plot, however.
Soil pH influences nutrient availability, as many nutrients are locked up and not usable by plants in low pH soils. Additionally, some nutrients are available in toxic concentrations if the pH is too low. Therefore, it is important to adjust pH levels in plots. Limestone (or lime) is the material used to raise pH values, and it takes time to work. However, applying it just before planting is better than waiting! The upside to lime is that the benefits last several years (depending on the soil type and several other factors), so it can be viewed as an investment for food plot success.
Which Material is Best For Me?
After you check out the soil pH on your soil test results, take a look at the lime recommendations. The way these recommendations are calculated varies from state to state, but as a general rule of thumb, these rates are based on using lime with a Calcium Carbonate Equivalent (CCE) of 100%. CCE can be thought of as purity, and most states have laws requiring that lime materials report their CCE. To calculate the amount of lime actually needed, you can take the soil test recommendations and divide them by the CCE in decimal form (for example dividing by 0.9 in the case of lime with a CCE of 90%). In most cases, it will be fairly close to the soil test recommended rate.
(Above) On this test, the soil pH is 4.8, and 1.7 tons of lime is needed to raise the pH to a suitable level to grow soybeans. This rate may change based on the CCE of the liming material, however.
The most common question about lime relates to the use of pelletized lime. I often see questions about how fast it works, or how much you should use compared to pulverized (or ag) lime. I use pelletized lime on some of my smaller food plots where I need to spread it with a tractor. However, on larger plots, you are much better off paying a lime truck to spread pulverized lime! The total cost of most pulverized lime applications is between $40-60/ton delivered, depending on your location and the field size. However, the pelletized limestone alone will likely cost at least $150/ton, and often more. Unless you are dealing with small fields, hiring a spreader truck is the way to go.
Given the increased cost of pelletized lime, some are convinced it must be better in some way than typical pulverized lime. If it costs more, it must be better- right? Often, pelletized lime is made of dolomitic lime, which does have a slightly higher CCE value than pulverized lime. It is also made of finer material than pulverized lime, meaning it should work at a faster rate. Based on these two facts, pelletized lime is slightly more effective material. However, the difference is very small, as even the best pelletized lime products will require about 1,800 pounds of material to equal a ton of pulverized lime. This reduction in liming rate does not make up for the higher cost. Additionally, research has brought doubts about the difference in speed of reaction, as the finer material size is probably compensated for by the less even distribution of product with pelletized lime as opposed to pulverized lime. With that being said, lime should always be looked at as a long-term investment, as soil pH does not change immediately.
Conclusion
Based on these facts, pelletized lime should only be used on small plots that are impossible for a spreader truck to reach. It certainly has a place for most managers, but it is not the quick fix some make it out to be. Lime takes time to raise soil pH, regardless of the product that you choose to use. And the next time someone tells you that you only need 200 pounds of pelletized lime to equal a ton of pulverized lime, you can feel confident that they are only equivalent in cost, not effectiveness!
I like how you explained that a pH between 6 and 7 is the best level to grow food plot plantings. My aunt wants to start growing food in her backyard and had questions about her soil and its effectiveness in growing food. I will share with her what you said about the pH levels, thank you.
Awesome David, glad you found it helpful!