Soil Nitrogen for Lawns

How to increase nitrogen in soil

How to increase soil nitrogen is easy without having to rely on chemical fertilizers. Organic fertilizers raise nitrogen in your lawn but the grass plant can only absorb inorganic forms of n.

Nitrogen (n) in soil is what makes grass-green. Nitrogen the most important of the lawn nutrients and is easily applied as organic fertilizer. It represents the first letter of N-P-K. It is essential in building proteins such as chlorophyll. Turf lacking in soil nitrogen will turn yellow, in part because the chloroplasts are not functioning properly.

nitrogen in soil

Grass can only use soil nitrogen in its inorganic form, which is what synthetic step programs deliver.

Organic matter is food for the microbes in the soil. They in turn break the organic matter down and turn N into its inorganic form and feed the plant.

Both synthetic nitrogen fertilizer and organic lawn nitrogen fertilizer form produce the same results. Synthetic is harmful to the environment as it leaches through the soil and organic is healthy, slowly increasing levels and sustaining.

Two forms of N are available, ammonium and nitrates. Grass plants prefer their lawn nitrogen in nitrate form. A good portion of the soil food web releases N in ammonium form but it is quickly converted “fixed” to nitrate through bacteria. Grass likes its soil slightly acidic and acidic soil is more bacterial than basic soil, which is fungal.

A side note on soil nitrogen:

  • Grass, annuals and vegetables like bacterial soil.
  • Trees, shrubs and perennials like fungal soil.

Adding correctly made compost teas will help a soil lean more towards bacterial.

Having over 5% organic matter will generally result in adequate amounts of soil nitrogen needed for a healthy grass.

nitrogen in grassNot bagging your clippings while your mowing supplies your lawn with an additional free 1 pound of organic nitrogen.

Grass clippings feed the bacteria in the soil. The clippings break down quickly, feed the bacteria, which hang around the rhyzosphere. The bacteria turn the broken down clippings into inorganic nitrogen raising your levels.

Depending on the size of your lawn, a step program bag of lawn fertilizer can cost you $20-$50 dollars per application. By leaving the grass clippings down you just saved the cost of at least one bag of fertilizer not to mention helping the environment.

Soil Nitrogen Cycle

Nitrogen is the most abundant element by far in the atmosphere comprising 79% percent of it. In its available gaseous form it is of no use to organisms. The N must be “fixed” it can be of any use. The high energy of lightning strikes can convert the gas into its usable form and we already talked about how bacteria converts ammonium into nitrate but N can also be “fixed” by certain plants most people would consider to be weeds.

Legumes such as white clover and vetch are considered “nitrogen-fixing” plants where they take N out of the air and make it available in the soil.

Sure when clover flowers it’s not the most attractive thing on a lawn but the benefits outweigh any slight inconvenience. Besides clover leaves are a nice dark green and fills any bare spots in your lawn nicely. Considering how clover can raise soil nitrogen, it’s much more attractive than that of thistle or plantain who offer nothing. Plus, clover can be a difficult weed to eradicate with organic or synthetic herbicides.

soil nitrogen

Earthworm castings will also provide this free organic nitrogen fertilizer. So, as you can see there are plenty to increase the levels of nitrogen in your grass without doing anything. Just leave or mulch your grass clippings when you’re mowing and stop using chemicals lawn fertilizers and pesticides.

Are you thinking you no longer have to apply fertilizer?

Did you have your soil tested yet?

If your results come back and your organic matter is a minimum of 5% and your having problem then you should be concentrating on applying more biology either through more compost or compost teas.

Your soil test does come with N levels but it’s not a clear indication of its availability to the plant. Fluctuation in soil temperatures throughout the year, make it difficult to test accurately. The best way to determine if your lawn is in need of N is simply by observing the color, density and vigor.

Organic lawn fertilizers that raise levels of soil nitrogen are:

  • Alfalfa meal
  • Blood meal
  • Fish hydrolysate
  • Chicken manure
  • Corn Gluten
  • Cotton seed meal
  • Soybean meal
  • Compost

Here we go into more depth regarding organic fertilizers.

Besides compost, the above products are available as stand alone or mixed together. I prefer a blend where different microbes have different appetites. If there is something involving your lawn you want to keep happy, it’s your microbes! They are the ones responsible for increasing levels of soil nitrogen.

grass nitrogen

Most grass types do well with around 3 pounds of lawn nitrogen applied per 1000 sq. feet per year. It should only be applied at 1 lb. per 1000 sq. feet at a time.

Grass loves soil nitrogen, some varieties more than others. New seed varieties are always being developed that naturally have a darker green color. The appearance will appease us while it requires less fertilizer applications to raise levels of n.

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