Biannual fertilizing is part of regular yard maintenance to increase the nutritional value in the soil. Grass needs lots of nitrogen and a pH of around 6.5 to 7.0 in order to absorb the nitrogen and remain green. Using lime with fertilizers about every four to six years controls soil acidity, while enhancing the nutritive level of the soil.
Fertilizers contain nitrogen, phosphorus and potassium. Grasses need nitrogen to photosynthesize. The average formula needed is 3-1-2. The first number in the formula is nitrogen; the second number is phosphorous, which supports flowers and fruiting; and the third number is the potassium which creates a strong root structure. Grasses are grown for their green color, so nitrogen is most important; very little phosphorus is needed as grass is not grown for its flowers.
Lime is a naturally occurring compound that is mined and ground from limestone bedrock. It lowers the soil's acidity and adds calcium and magnesium, which are naturally alkaline compounds. Turf does not grow well in highly acidic environments because nutrients are bound up in the soil. Lime neutralizes the acidity and helps release the nutrients to the roots. Lime should be applied to soil before seeding or laying sod to provide optimal soil pH for grass.
Application of Lime
Application rates will vary depending upon soil tests for pH levels, but a good average is 40 lbs. of lime to every 1,000 square feet of lawn. It can be applied with a drop or spinner spreader, but it is important to apply it evenly. A good way to ensure evenness is to apply half of the product in one direction and the other half in the opposite direction. This method reduces overlap which may cause nutritive deficiencies. The benefits of lime will last four to six years, so annual application is not necessary.
Calcitic and Dolomitic are the most common lawn limes used to add calcium and magnesium to the soil. Calcitic lime is higher in calcium while dolomitic lime provides calcium and magnesium equally. Dolomitic lime is a better acid neutralizer than calcitic.
Fertilizing together with lime is not recommended because it causes high alkalinity and nutritive deficiencies in the soil. It is best to first assess the soil and apply the fertilizer and lime separately. The two compounds can be applied during fall at appropriate rates and concentrations to assure that the specific soil and grass needs are being met.