Agricultural lime (aglime) is a soil amendment composed primarily of pulverized limestone, usually calcium carbonate or calcium oxide. Its function is to neutralize soil acidity by raising the pH level, which improves nutrient availability for turf and plants. When soil pH is too low (acidic), essential nutrients like nitrogen, phosphorus, and potassium become inaccessible to plant roots. Applying lime adjusts the soil environment to a more neutral range, typically 6.0 to 7.0, maximizing nutrient uptake and supporting healthy growth. The exact quantity of lime needed depends highly on the specific characteristics of the soil being treated.
The Essential First Step: Soil Testing
Before applying lime to a 1000 square foot area, a soil test is the only reliable way to determine the correct application rate. The test provides two key pieces of information: the current pH level and the soil’s buffering capacity. Buffering capacity is the soil’s resistance to a change in pH, influenced by its texture and organic matter content. Soils with a higher Cation Exchange Capacity (CEC), such as clay-heavy soils, are highly buffered and require more liming material than sandy soils to adjust the pH.
Soil testing kits are available through local cooperative extension offices or private laboratories. Professional lab results include a recommendation for the amount of lime needed to reach a target pH, typically 6.0 to 6.5 for most turfgrass varieties. Applying lime without this data is inefficient. It results in either under-liming, which fails to correct acidity, or over-liming, which can cause nutrient deficiencies by making elements like iron and manganese insoluble.
Calculating Lime Application Rates for 1000 Square Feet
The precise amount of lime required per 1000 square feet is based on the soil test recommendation, considering the starting pH, target pH, and soil type. For general guidance using agricultural limestone, if the soil pH is moderately acidic (around 5.5), an average loamy soil may require 40 to 50 pounds per 1000 square feet to reach a target pH of 6.5. Sandy soils, having lower buffering capacity, need less (25 to 30 pounds). Conversely, heavy clay soils are strongly buffered and might require 70 to 80 pounds per 1000 square feet for a significant adjustment.
Most standard recommendations cap a single application at 50 pounds of lime per 1000 square feet. If the total calculated requirement exceeds this amount, the application should be split into two or more separate treatments spaced several months apart. Splitting the application prevents potential nutrient shock and allows the initial layer of lime to begin reacting with the soil. Always follow the specific rate provided by the soil test report.
Understanding Lime Types and Formulations
The type of lime used affects the application rate and the chemical composition of the soil. The two most common forms are calcitic lime and dolomitic lime. Calcitic lime is primarily calcium carbonate, supplying calcium while neutralizing acidity. Dolomitic lime contains both calcium carbonate and magnesium carbonate, making it the preferred choice if a soil test indicates a magnesium deficiency.
Lime is also available in different physical formulations, which influence its ease of use and reaction speed.
Pulverized Lime
Pulverized or finely ground lime has a high surface area, allowing it to react quickly with the soil to adjust pH. However, it is difficult to spread evenly and is prone to dusting.
Pelletized Lime
Pelletized or granular lime is pulverized lime compressed into small, easy-to-handle pellets. This formulation spreads easily using standard equipment, but it reacts more slowly because the pellets must break down with moisture before neutralizing the soil acidity.
Best Practices for Spreading and Timing
Lime is a slow-acting amendment, requiring patience for results. The best time to apply lime is typically in the fall or early spring. Seasonal rainfall and freeze-thaw cycles help move the material into the soil profile. It often takes six to twelve months for the full pH-adjusting effect to be measurable, so planning ahead is necessary.
For even coverage across the 1000 square feet, using a drop or broadcast spreader is the most effective method. If a high rate of lime is required, divide the total amount in half. Apply the first half in one direction and the second half perpendicularly to the first pass. This technique significantly reduces the chance of uneven distribution, which can lead to patchy growth. Applying the lime to a slightly damp lawn and watering it lightly afterward will help settle the material and initiate the chemical reaction.