FERTILIZATION OF LAWNS

Do not expect to have a good lawn unless you supply it with adequate nutrients

good growth. Lawns need regular fertilization to keep the grass growing and

weeds out.

The best way to determine a fertilization program for your lawn is to take a

soil test. Your county Extension agent will advise you on how to take a soil

sample and how to send it to the soil-testing laboratory. The report from your sample will be returned by mail and will tell you what mineral elements your lawn needs.

Fertilizer Analysis

Grass should be fertilized with nitrogen, phosphorus and potassium. Choose a fertilizer with the proper ratio of each of the nutrients to correspond to the soil test results. The fertilizer label must state the percentage by weight of nitrogen, phosphorus and potassium in that order. A 20-10-10 fertilizer has the mineral elements in the ratio of two parts of nitrogen, one part of phosphorus

and one part of potassium (2-1-1), as does a 10-5-5. The difference is that

weight for weight the 10-5-5 contains half as much fertilizer value as the 20-10-10, and twice as much would have to be used for the same results.

A 100-pound bag of 10-5-5 fertilizer contains 10 pounds of actual nitrogen

100 lb. x 10 percent nitrogen = 10 lb.), 5 pounds of actual phosphorus (100 lb.

x 5 percent phosphorus = 5 lb.), and 5 pounds of actual potassium (100 lb. x 5 percent potassium = 5 lb.). The amount of nutrients in any other fertilizer can

be determined in the same way.

Generally, a 3-1-2 or 4-1-2 ratio is considered best for use on Ohio lawns. The ratio need not be exactly a 3-1-2 or 4-1.2. For example, a 24.6-6 analysis approaches a 4-1-2 ratio, and a 10-3-7 grade is close to a 3-1-2 ratio. Substitutions of this type can be made without concern.

Types of Nitrogen

How do you choose between products with the same nutrient content? The big choice is between fast and slow release of the nitrogen fraction. The percentage of the total nitrogen that is water insoluble and that which is water soluble usually is listed on the fertilizer bag. In water soluble form, the nitrogen is available quickly, and in the insoluble form it is available slowly.

A good turf fertilizer contains some of each kind of nitrogen. The slow release portion provides nitrogen over a period of time but is not available to the plant during cool weather. The soluble fraction, or fast release, will provide nitrogen almost immediately after application and during cool weather. Something approaching 50 percent soluble and 50 percent insoluble is suggested.

Fertilizer Programs

Improved bluegrasses (Adelphi, Glade, etc.) and bentgrass lawns:

(August 15 - September 15) Apply 1 to 2 pounds of actual nitrogen per 1,000 square feet in a complete fertilizer of a 3-1-2 or 4-1-2 ratio or approximate equivalent. Examples of fertilizer to supply this amount are 20 pounds of 10-3-7 or 10-6-4, and 10

pounds of 20-5-5 or 20-8-8. Apply half the amount suggested above March 15 -

April 15, May 15 - June 15, or September 15 - October 15.

Common Kentucky bluegrass (Park, Delta, etc.) and similar lawns:

(August 15 - September 15) Apply 1 to 1 1/2 pounds of actual nitrogen per 1,000 square feet in

a complete fertilizer of 3-1-2-or 4-1-2 ratio or approximate equivalent. Apply

half the amount suggested above March 15 - April 15 and May 15 - June 15 or September 15 - October 15.

Red and tall fescue lawns:

(August 15 - September 15) Apply 1 pound of actual nitrogen per 1,000 square feet in a complete fertilizer of a 3-1-2 or 4-1-2 rate or approximate equivalent. Apply the same rate in April or May.

Fertilizer Burn

Any fertilizer may burn the turf if applied improperly. Fast release nitrogen is more likely to burn than slow release forms. To avoid burn, 1) Do not apply

more than 1 1/2 pounds of actual nitrogen per 1,000 square feet at one time;

2) Spread uniformly; 3) Do not overlap or spill fertilizer 4) Apply fertilizer

only when foliage is dry; 5) Water after application. Pulverized materials are

more likely to burn than pelleted or granulated materials.

Lime

Lime should be applied only when a soil test indicates a need for it. Excessive amounts of lime in the soil may be detrimental to the production of good turf.

When a soil test is made, apply the amount recommended. Lime will not reduce

the need for fertilizing. The presence of moss in the lawn does not necessarily indicate a need for lime.

Clipping Removal

It is advisable to return grass clippings to the lawn because they are a valuable source of nutrients. Research has shown that when clippings are removed, a

third more nitrogen fertilizer was necessary to maintain the same color and density as areas where clippings were returned. Furthermore, and contrary to popular belief, grass clippings to not contribute to thatch accumulation if the turf is maintained at its recommended cutting height and not more than a third of the leaf surface is removed at one mowing.

Prepared by: John R. Street

Extension Agronomist

The Ohio State University