Geeky Look at Grass Fertilizer
and Reasons Why Lawns Deteriorate

Turf-type Buffalo Grass

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. The answer is yes and no. Some new products are making it much easier.

You should not expect a quality lawn like the one in the photo above without regular maintenance and applications of a quality lawn fertilizer.

Lawns need specific nutrients to survive. Once the immediately available soil nutrients are consumed they will need to be replaced. 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.

Soil microbes are at work producing more nutrients. This occurs when soil elements and organic material is broken down into substances the plants can use. this is explained in more detail below. 

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 these nutrients are low, one 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?"

That's a great question. The answer is 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, grass stems, leaves, decomposed fallen trees and branches, and other decaying organic matter. As these organic materials break down they continually release nutrients. In addition, the unmown grasses in natural grasslands have deeper and more extensive root systems.

Lawns 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, most organic matter is 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 without grass fertilizer.

Most lawns and sports turf simply can’t keep up without some type of grass fertilizer. Without fertilization, the result over time is the grass thins out prompting the need for renovation to bring the lawn back to its previous condition.

For soil microorganisms to be working at their peak, they need moisture, calcium, and quality organic matter as a source of food that also becomes food for plants. 

For all the geeky types, like me, here is a deeper explanation:  Here's what must occur if your do not use grass fertilizer.

As an example, if your 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. Shed roots, grass blades, etc break down and release nutrients back into the soil.

The more nutrients that are needed for plant growth, the more your grass must grow at optimum levels. 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 take over. 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. (Photo taken by Russ James)

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?

Look over our pages on Agri-Gro Natural Biostimulants and Soil Enhancers. They are amazing and can stimulate soil organisms by several thousand percent in as little as 24 hours. Please see the links to the left. 

Consider using quality organic fertilizers.

There are many certified organic grass 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. Poor quality soil will slow them down. For most people who do not use Agri-Gro Products or maintain soil nutrients,  the will probably notice the soil microorganisms are best in the warmest months.
  • Doing nothing or using grass clippings and mulched leaves as the source or nutrients may not provide all the needed nutrients for cool season grasses in fall when they need them the most.

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.

Using AgriGro Biostimulants

Agrigro products speed the breakdown of organic matter by greatly increasing the amount of soil microorganisms and their activity. Many more nutrients can be released into the soil meaning less fertilizer is required to maintain a beautiful lawn.

This is an incredible new approach to lawn care. (Although it has been used on field crops for years.) It can give you a great looking lawn that is more resistant to disease, while using less fertilizer.

Professional golf course superintendents say they have decreased their fertilizer by 30% while increasing turf quality.

Agrigro products can be applied with a simple garden sprayer or hose end sprayer.

Developing a Lawn Fertilization Program

Secrets to Using Less Fertilizer While Improving Uptake


Nitrogen Sources for a Green Lawn


Organic Compost

Compost has many benefits including a source of nutrients. The right blend of organic compost also has a tremendous ability to suppress grass diseases. Find the specifics on what the compost should include, how much to apply and information on how to make it yourself.

Calculating Fertilizer Rates


Spreader Calibration Made Easy


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New products and approaches are making it easier to maintain a beautiful lawn using less fertilizer. Learn how on this page.