Organic matter consists of dead forms of organic material, living parts of plants and living microbes and soil animals (Soil Health). It works as a reservoir of water and nutrients in the soil; it also assists in reducing surface crusting and compaction, and increases water infiltration into the soil (Funderberg).

Organic matter enhances water and nutrient holding capacity and improves soil structure. Managing for soil carbon can enhance productivity; environmental quality and can reduce the impact of natural phenomena (Soil Quality Institute).

Organic Matter or Organic Material

Though it may be perceived as the same thing, organic matter and organic material are not one in the same. Organic material is “anything that was alive and is now in or on the soil” (Funderburg). In order for organic material to become organic matter it must be decomposed into humus form. Microorganisms create humus by converting organic material into a resistant state of decomposition (Funderburg).

Organic material is unstable in the soil. As it decomposes, it changes form and mass readily, up to 90 percent of it disappears because of decomposition. On the other hand, organic matter is stable in the soil. It has been decomposed until it is resistant to further decomposition, usually only 5 percent mineralizes per year. Note, that the rate increases if temperature, oxygen and moisture conditions become favourable for decomposition of organic matter. (Funderberg).

Soil with organic matter
Soil without organic matter


Outlined below are the many benefits to adding organic matter to your soil:

  • Nutrient Supply
    Each percent of organic matter releases nutrients into the soil. For each 1% increase; 20 to 30 pounds of Nitrogen, 4.5 to 6.6 pounds of Phosphorus pentoxide and 2 to 3 pounds of Sulfur can be released into the soil per year. Nutrient release occurs more often in the spring and summer; therefore the summer crops benefit more from organic matter mineralization than winter crops.
  • Water-Holding Capacity
    Organic matter has the ability to hold up to 90 percent of its weight in water, which is advantageous because not only does it hold large amounts of water, it also releases most of the water to the plants. An increase of 1 percent of organic matter holds an additional 16,500 gallons of water per acre (Sullivan).
  • Soil Structure Aggregation 
    Organic matter causes soil to clump and form soil aggregates, thereby improving soil structure. Having better soil structure causes permeability to improve, which results in an increase in the soil’s ability to take up and hold water.
  • Erosion Prevention
    Data used in the universal soil loss equation indicates that increasing soil organic matter from 1 to 3 percent can reduce erosion by 20 to 33 percent (Funderberg).

Building soil organic matter can be a long-term process, but the end does justify the process. Below are some of the ways to build organic matter:

  • Reduce or Eliminate Tillage
    Tillage increases erosion and speeds up the decomposition of organic matter. Decomposition is increased because tillage increases the aeration of the soil and creates an increase of microbial action.
  • Reduce Erosion
    Organic matter erodes when soil erodes. By preventing topsoil erosion, organic matter can also be saved.
  • Soil-Test and Fertilize Properly 
    Correct fertilization practices increase the growth of plants, and in turn increase root growth. Roots help to build and maintain organic matter, even when the top growth is being removed.
  • Cover Crops
    Cover crops can help to build and maintain organic matter (Funderburg).

Outlined below is an example of how to increase the amount of organic matter in one acre furrow slice of soil by 1 percent.
Depth of Soil = 6.7 inch
Mass of Soil = 2,000,000 lbs
Mass of Organic Matter Needed = (Mass of Soil)(Percentage of Organic Matter)
= (2,000,000lbs)(0.01)
= 20,000lb

Mass of Compost(cu yd) = 880 lbs/cu yard
Compost contains 50% organic matter
Mass of Compost Needed = 40,000lb

Compost Needed = Mass of Compost Needed/Mass of Compost(cu yd)
= (40 000lb)/(880lbs/cu yd)
= 45 cu yd/acre

1 cu yard = 324 sq ft at 1’’
45 cu yard = 14,580 sq ft at 1’’
43,560 sq ft = 1 acre

Therefore 45 cu yds covers 1/3 inches on 1 acre.


Organic matter not only releases nutrients into the soil but it also provides water holding capacity, improved permeability and prevents erosion. Nitrogen, Phosphorus pentoxide and Sulfur are among the nutrients that are released into the soil. As well, organic matter can hold up to 90 percent of its weight in water, which it releases to the plants. Organic matter also causes soil to form aggregates, this results in an increase in water retention ability, erosion is also prevented.

There are many ways to maintain soil organic matter. A reduction in the use of tillage can significantly decrease the erosion and decomposition of organic matter. Reducing erosion in general also keeps organic matter available for longer. Proper fertilization increases the growth of plants and roots, which help to maintain organic matter. Also, cover crops and the addition of compost can help to maintain organic matter in the soil.

Organic matter is a necessary and vital aspect of having healthy and workable soil. A quality supply of organic matter is beneficial to crop and forage production.

Works Cited

Funderburg, Eddie. "What does Organic Matter do in Soil." The Samuel Roders Nobel Foundation (2012)Print.

Patriquin, David. "Water, Soil and Organic Matter: A Complex Relationship." Print.

Nitt, Andrew. "What is an "Acre Furrow Slice of Soil?"." PennState Turf (2010)Print.

Soil Health. "Soil Organic Matter." Gogama Screening ProjectWeb. 2012.

Sullivan, Preston. "Drought Resistant Soil." NCAT (2002)Print. Author Unknown. "Managing Soil Organic Matter the Key to Air and Water Quality." Soil Quality Institute.