Fertilizing Your Home Lawn

Photo from lawnandbugs.com

All of the rain this spring has slowed down our planting progress drastically.  However, one thing that is has not put a halt to, is our grass growing.  With the beginning of mowing season here many of us want to create beautiful, lush lawns that are more appealing than our neighbors.  But before you go out and throw the nitrogen to it, be sure you understand what nutrients your home lawn needs by soil sampling and know when is the best time to fertilize.

Soil sampling is easily accomplished with some very simple tools.  All that is required to take a soil sample is a clean bucket and either a soil probe, a shovel, or a trowel.  We have soil probes available for use at the Extension Office. Take soil from 10 to 15 random spots throughout the lawn. The goal in collecting soil is to get a comprehensive sample, which represents the entire lawn. Be sure to test flower beds or areas of known soil variations separately as to not skew the test results. Take samples to a depth of 2 to 3 inches (4-6 inches on newly tilled soils) and remove the plant material. Break the samples up in the bucket and thoroughly mix the soil together.  You can then bring your samples to the extension office (we will supply you with bags free of charge in which to place the soil) and the results will be returned to you within a few weeks.

Once you know what nutrients your lawn needs, how do you know which fertilizer to buy?  The analysis on the fertilizer bag tells you the percent nitrogen (N), phosphate (P205) and potash (K20) in the fertilizer, in that order.  For example, a fertilizer with a 32-0-4 analysis contains 32 percent N, 0 percent available P2O5, and 4 percent soluble K2O.  Slow release nitrogen sources will only release a small amount of fertilizer at a time. The benefits of slow release fertilizers include less nitrogen losses from leaching and volatilization, reduced burn potential on the turf, and ewer applications required to maintain soil fertility. However, the amount of the slow-release nitrogen is usually a quarter to half of the total amount of nitrogen in the bag. So although slow-release nitrogen makes applications safer, such a small amount would not provide noticeable availability of nitrogen over the long term.

Most specialty fertilizers can be applied and measured exactly the same as you would a farm fertilizer. The same is true with specialty organic fertilizers, with the exception that they would need to be applied earlier in the fall as warm conditions are required for release of these materials. Most of these fertilizers have a low percentage of nitrogen or are fortified with urea, a quick-release source of nitrogen. Fertilizers with greater than 50 percent WIN (water insoluble nitrogen) can be considered true slow release sources. These sources can be applied at slightly higher rates than soluble fertilizers. There will not be a rapid greening of the lawn with these products as is common with quick release fertilizers. Cost will be 3 to 5 times higher per pound of nutrients for slow release fertilizers.

Late spring into summer is the best time to fertilize warm-season grasses such as bermudagrass and zoysiagrass, since they perform best during hot summer months.  However, the best time to fertilize cool-season lawns (Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue) in Kentucky is during the autumn. These grasses all grow optimally during cooler weather and can best utilize nutrients at this time of year. The turf develops a better root system, becomes very dense, and has much better late fall and early spring color if nitrogen is applied in the fall. If the window to apply nitrogen in the fall is missed, an application during the following spring will improve greenup. Even if some fall nitrogen was applied, applying a half rate of nitrogen in late May or early June in years with heavy spring rainfall may help improve or maintain color.

For more information about soil sampling and fertilizing your home lawn, contact the McLean County Cooperative Extension Service at (270)273-3690.  Educational programs of the University of Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability or national origin.



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