The Truth About Lime

Being an age-old soil amendment, lime has undergone major scrutiny over the years. With regards to solubility and availability, lime must navigate major factors to become justifiable as a so-so soil amendment. These factors are soil moisture, oxygen, and soil and air temperature. Microbial activity helps as well. All the conditions that lead to oxidation. How well has the lime been refined and processed? Many think pulverized lime is the best. This type is very inexpensive, but is it the best form? Can you incorporate it into the profile of the root zone?

Aerification is not incorporation. In fact, in nearly all cases, pulverized lime is the worst thing you could apply to existing turf. Pelletized lime is no better. Incorporation must be implemented as well as optimal conditions for pelletized lime to release. Still today, we see this amendment being used at the wrong rates and wrong times. For pH increase, lime has much more data to support its use and corresponding rates to abide by versus that of gypsum. A buffer index helps greatly to understand the proper rates to use. The rule of thumb for lime: To raise pH effectively, there needs to be at least 150 lbs. per acre of available calcium in a carbonate form to even begin conditioning of the soil. Why is this? Such a high rate is needed because the calcium in lime must first oxidize in the soil to release. This could take years. It must also feed the plant that is growing there.

The turf or ornamental plant may need 4 to 5 lbs. of calcium per 1000 sq.ft. per year for a healthy diet. Lose any of this to insolubility and the plant’s calcium benefits: stronger more rigid cells, better water uptake and translocation, movement of nutrients, etc… suffer. pH will not effectively increase as expected. Rates for lime, regardless of whether it is dolomitic or hi-cal lime, start at 25 lbs. per 1000 sq.ft. for maintenance purposes. This should be done once or twice per growing season. For raising pH, apply 48 lbs. per 1000 sq.ft. Regardless of the pH, adding soil-applied calcium (along with foliar) is very important for the best plant/soil growth and health. Still today we see lime either not being used at all, or being used at such low rates that there is no chance to do any benefit to the turf or soil. VERDE-CAL®, being 100% soluble and 100% totally available to the plant and soil, makes the task of amending the soil easier and much more effective. This is done by reducing rates and providing the needed availability of the correct calcium source to modify or maintain proper calcium levels – 5 lbs. per 1000 sq.ft. for maintenance. Do this two to three times per growing season. Apply 10 lbs. per 1000 sq.ft. to raise calcium levels and thus affect pH. Do this once, and test again, to justify another application. Remember, it is not the total pounds of product applied that count; it is the total pounds of available and soluble nutrient that gets the results.

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