Lawn grasses often need the assistance of fertilizer and other soil amendments to grow healthily. One such amendment is lime, essentially ground limestone used to adjust the pH of a given soil. Like other fertilizers, careful use is essential to grass health as using too much or too little lime can cause deleterious effects on your lawn grass. With some careful consideration, however, you can avoid these problems by recognizing the telltale signs of over-liming on lawn grass.
Lime and Grass
As noted, lime is used to adjust the pH of soils. More specifically, lime is used to increase a soil's pH when it is too low to support healthy grass growth. Ideal soil pH is highly variant on geographic area and on the type of grass you are growing, but in general a soil pH between 6.0 and 7.0 is ideal. Commercially available soil pH testers can indicate the acidity or alkalinity of the soil underneath your lawn; if your soil registers below 6.0, lime can be an effective means for attaining the ideal soil acidity.
Effects of Over-Liming
Grasses grow well within an ideal soil acidity range, meaning that an overly acidic soil can be just as problematic as one that is not acidic enough. An overly alkaline soil will trap nitrogen, phosphorus, iron, manganese, boron, copper, zinc and other plant nutrients in a state that plants cannot absorb them. The effects of these nutrients being deprived from grass plants results in brown and yellow spots, reduced vigor and increased susceptibility to grass diseases.
Treating an Overlimed Lawn
If your lawn has broken out in yellow and brown patches and you believe the cause to be over-liming, little can be done short of adjusting the amounts of lime you use to restore soil acidity to ideal levels and allow your lawn to grow back on its own. Unless damage from over-liming was particularly severe, the grass will resume healthy growth over successive seasons, though you may need to use another soil amendment to make soil less alkaline.
The amount of lime to use depends on several factors, such as your climate, your geographic area, the species of grass you are growing and the type of lime you purchased. Always follow the labeled instructions on the lime you purchase, and adjust liming to the individual needs of your grass and soil.