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Discussion in 'Pesticide & Herbicide Application' started by jphag, Sep 23, 2004.
When and why do you apply LIME?
Anytime we can schedule it, all year round. But especially in late fall after sports have ended, and in the early spring before sports have started. We routinely do lawns at the same time we're working on athletic fields. Our soil tests almost always indicate we need lime.
A soil test is always good to determine how much the soil is off. A good indication, though is if there are a lot of oak trees in the yard. Depending on the soil test, I normaly do lime in the fall and come back in the spring to add more...
We apply mid December through late January. Why?- what else are we going to do in the middle of winter. I have four full time, year-round employees and the winter lime app's are perfectly timed for keeping them busy in the off season. In Colorado, this may not be an option for you. We we only apply on days 40 degrees plus and start after frost has thawed. Agronomically speaking, lime can be applied almost any time of year. Lime is applied to increase the pH of acidic soils, thereby increasing microbial activity which increases the visual response to fertilization and helps the lawn to naturally break down thatch, a breading ground for insects and disease. In Northern Va., soil test are only needed for "problem" lawns, otherwise it is safe to assume lime is needed, our average pH is in the low 6's.
I think everyone covered the when. There is no real reason not to apply lime anytime you have the labor. The reaction of lime in the soil is rather slow and the effects are longer than fertilizer so you don't have the same urgency.
You should apply lime to raise the soil pH or level of acidity. Low pH (below 7.0) is acidic and most turf thrives at a pH of around 6.5 due to optimal nutrient availability. Some turf managers with patch disease problems try to keep pH a bit lower. Low pH has been shown to suppress patch disease but you don't want to be below 5.5.
A soil test will tell you how much lime you need to raise the pH a given amount. That is a function of the pH you are starting with, and the buffer capacity of the soil. Buffer capacity is the soils innate ability to resist a change in pH. Clay high CEC soils tend to have higher buffer capacity than sandy soils so you will need more lime for those.
The rule of thumb is you can use about 50 Lb. of standard ground ag lime/1,000 msf on most soils. If you use pelleted lime with oxides as well as carbonates you can use less since they are more active. There is a lime index on the product and standard ag lime is the benchmark. So for some products 35 Lb of pelleted may be equal to 50 Lb of the standard stuff. If you apply the full rate to get the soil back to 6.5 or so you probably won't need to apply but once every 2-5 years.
Using 50LB/1,000 is cumbersome and time consuming so very few service companies will apply 50 Lb/1,000 at once. Unless maybe they are trying to reclaim a strip mine and have a "lime emergency". An annual application of about 8 Lb/1,000 as a maintenance rate works OK if the pH is not too far below optimum to start. You need to counter act the natural soil genesis which creates acidity in many soils, as well as the acidification contributed by fertilizers.
Use a soil test on at least some properties to get a benchmark of where you're at and what you need. There are some pretty accurate pH meters in the $100-150 range if you so inclined. Some weeds such as Red Sorrel are well adapted to acid soils. If you know the acid tolerant weeds in your area they can tip you off that there might be a problem. Consider high Ca or calcitic lime. You want to have a high Ca to Mg base saturation for best results. Some dolomitic lime may have too much magnesium carbonate and not enough calcium carbonate. You don't want to saturate your soil with Mg.
RBuckwalter, welcome aboard! Nice post, lots of info. You state that a PH below 7 is acidic. I thought the higher numbers were acidic and lower numbers strong base? Lime brings numbers up, sulfur brings numbers down?
PR Fect you are on the right track but the numbers are flip floped. The pH scale is logrythmic from 0 to 14. There is a 10 fold change for each number. Seven is neutral, above seven is alkaline (basic) and below seven is acidic. So, a pH of 5 is ten times more acidic than a pH of 6. Lime brings the numbers up because it reduces acidity and sulfur brings them down because it contributes to acidity. Just remember that low pH is acid and high pH is akaline. You've got the rest.
Don't rely on ph meters! The rate of lime or sulfur to change the ph is different depending on the soil test, so you must have a soil test FOR EACH property. The soil test will also tell you to use dolimitic or calicitic lime depending on base saturation!
Just because you know what the soil ph runs usually in your area, YOU HAVE NO idea to what has been applied previously, so EACH property needs a soil test!!!!!!