The Importance of Grass Fertilizer
A Look at Why Lawns Deteriorate

With the added restrictions being placed on grass fertilizer and lawn chemicals in some states, some may be asking if lawns can be maintained properly without fertilizer or added nutrients. If that is what you decide, you should know the process of how grass declines. You should not expect a quality lawn like the one in the photo above without regular maintenance and applications of a quality grass fertilizer.

Lawns need specific nutrients to survive. Once soil nutrients are used, they need to be replaced, either naturally or by the addition of grass fertilizers. Since grass cannot physically move to find better growing conditions, the nutrients must always be within the reach of their roots or the grass can decline.

The nutrients needed in the largest amounts are nitrogen (N), phosphorus (P), and potassium (K) and are the primary elements in a bag of fertilizer. Of these three, nitrogen is needed in the greatest amount. If a soil test shows they are low, the only solution is to add them. Without supplemental grass fertilizer or organic additions, the grass must rely on the natural process of creating these elements.

Why Lawns Often Decline Without Grass Fertilizer

Some have asked, "Forests and grasslands aren't fertilized and they do well, why not lawns?"

The ecology of forests and grasslands are very different from the ecology of home lawns. Forests and grasslands have years of accumulation of shed roots, stems, leaves, decomposed fallen trees and branches, and other decaying organic matter that continually release nutrients as they decompose. In addition, the unmown grasses in natural grasslands have deeper and more extensive root systems.

Lawns, on the other hand, do not have the same collection of organic matter. Fallen leaves and other organic debris are removed. To complicate things, many lawns are built on extremely poor soil. For lawns, organic matter is primarily derived from shed roots and stems, grass clippings, mulched leaves, thatch, dead microorganisms and insects, and other biodegradable material. This places tremendous pressure on the natural process to consistently produce enough nutrients to maintain healthy grass. Most lawns, sports turf or high maintenance grasses simply can’t keep up without some type of grass fertilizer. The result is that over time the grass thins prompting the need for renovation to bring the lawn back to its previous condition.

To explain further: Without supplemental grass fertilizer, then by necessity, everything must depend on the other. For example, if a particular lawn grass needs 4 to 6 lbs of nitrogen a year for strong health and vigor, then the grass must produce the majority of the organic matter to meet the nutrient needs. This means that plant growth processes, including root and blade shedding and tiller growth, must remain at optimum levels. Unfortunately, in most cases this is not possible. Without sufficient nutrients the grass will slow its growth rate of new tillers in an effort to conserve energy. This always leads to thinning.

Thinning grass allows opportunity for broadleaf weeds and grassy weeds to germinate and thicken. The above photo shows foxtail weeds that have overtaken a lawn. Weeds compete for space, nutrients, water, and air and some weeds are extremely aggressive. It doesn’t take long before the grass quickly deteriorates. Without proper care it takes an average of three years for a lawn to go from a thick, well-maintained and manicured lawn to one that has thinned and is loaded with weeds.

What are Some Things We Can Do?

Organic Grass Fertilizer

Remember, not all fertilizers are created equally. You should consider using an organic fertilizer.

There are many certified organic fertilizers and synthetic/organic blends on the market. Dry, granulated fertilizers are easiest to apply using only a lawn fertilizer spreader. Liquids organic lawn fertilizer, such as fish emulsion fertilizer, are absorbed through the leaf blades and tend to be short lived. It is usually marketed as garden fertilizer.

Relying solely on natural organic lawn fertilizer has some drawbacks, depending on your grass type and what your lawn care goals are. Here are a few:

• Organic fertilizers can be more expensive.
• Some homeowner varieties are lower in quality than professional varieties and may have a lower nitrogen content.
• Most rely on the activity of soil microorganisms to release their nutrients. Microorganisms go dormant in winter when soil temperatures drop below 40 degrees. This means they are best in the warmest months.
• May not provide all the needed nutrients for cool season grasses in fall when they need them the most.

This is where professional organics really shine. Bridge products are a great compromise having both organic and synthetic nutrients. Bridge products contain a large amount of organic matter plus the added nitrogen sources for cooler weather when microbes are not active. It is also great for grass types that need higher amounts of nitrogen to maintain optimum health.

Top Dressing Lawns

A second option is to top dress your lawn with organic matter. Please see our page on Top Dressing Lawns for step by step instructions and tips. The material you use is important. Some organic materials are very low in nitrogen and other nutrients.

A major benefit to top dressing lawns is its ability to amend clay or sandy soils, especially when top dressing is used in conjunction with core aeration. When added to sandy soils, it absorbs water and adds nutrients. Remember, however, that organic matter is food and will be consumed. You should top dress your lawn annually for the best results.

Here are other things to consider:

• Although extremely beneficial, top dressing lawns is more time consuming and labor intensive than applying organic fertilizer.
• Like other organics, it depends on soil microorganisms to break down the organic matter and release its nutrients.
• The nutrient level of different composted manures or garden wastes vary considerably from batch to batch. It is generally less consistent than quality organic fertilizer.