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Importance of Soil Organic Content

Updated on April 8, 2013
Adding sawdust to your soil is one way to increase the organic matter and tilth of the soil, but there are better ways.
Adding sawdust to your soil is one way to increase the organic matter and tilth of the soil, but there are better ways. | Source

Soil organic content has many benefits for improving soil characteristics and plant growth. The benefits go beyond improving the physical aspects of the soil and decreasing watering requirements, as there are improvements in the soil biology and the availability of nutrients.

There are good ways to help improve organic content and there are shortcuts that you can use like adding sawdust to your topsoil. These different options and their benefits and pitfalls are discussed below.

Soil Organic Matter Improves Soil Physical Characteristics

The presence of organic matter improves the physical characteristics of a soil in many ways that help support healthy plant growth. Here is a list of factors that improve with its presence:

  • Water holding capacity and water penetration
  • Tilth (ease of tillage, ability to work with the soil and support root growth) - This works with clay soils when organic matter is regularly added over a period of a few years.
  • Aeration - plant roots need air to support respiratory chemical functions
  • Increases the biological diversity in the soil which helps prevent some plant disorders
  • Increases the availability of nutrients to plants and microorganisms to make a healthy soil environment

Healthy plant growth from a healthy soil.
Healthy plant growth from a healthy soil. | Source

Organic Matter Effect on Soil Biology

As briefly mentioned above, organic matter provides a substrate to increase the biological activity in the soil. Microorganisms utilize various portions of the organic matter to support their growth, and in doing so, they provide nutrients for other organisms. There is also a positive effect on the binding of soil particles to each other as the result of soil biological activity. This helps improve soil structure, especially on loose, sandy soils. Soil aggregates can also improve clay soils.

As a result of biological activity on soil organic matter, a valuable compound called humus is formed. Humus is a complex substance composed of carbon, phenolics, proteins and lignin. The sub-components of humus have been show to help increase plant growth. This is discussed more thoroughly in the next section.

Plant root diseases are also reduced in soils which have significant biological activity associated with soil organic content. Because of the increased microbial diversity of the soil, there are higher numbers of organisms which can out-compete, and in some cases parasitize, disease-causing organisms like plant parasitic nematodes and water molds like Phytophthora and Pythium.

The Benefits of Improving Organic Matter Content in Farmer's Fields

Choosing the Proper Soil Organic Content to Add

As shown in the first photo above, some people add sawdust to their topsoil. This is okay if you can frequently add nitrogen to the soil, because the microorganisms that degrade it use up the available soil nitrogen. Thus, your plants will very likely show nitrogen deficiencies.

If you do have sawdust or any other non-degraded raw material like rice bran or peanut hulls, it is best to compost it for a while before you use it. Composted organic materials are better overall choices for organic soil amendments. The composting process may take more patience, but it will pay off to wait and use these materials when they can fully benefit the soil without robbing it of needed nutrients for plant growth.

Peat moss is used by many to improve soil characteristics, especially in potting soils. It differs from compost in that it has no significant nutrient contribution to the soil. This can be compensated for by using slow-release fertilizers or regular liquid fertilizer addition to the growing plants.

Lignite coal is an important source for humus.  It is being used in commercial agriculture to boost plant growth.
Lignite coal is an important source for humus. It is being used in commercial agriculture to boost plant growth. | Source

Effect of Humus on Plant Growth

Degraded organic matter makes a very valuable product in the soil - humus. Humus is a complex mixture of various chemicals that are rich in carbon. Humins and humic acid are the darkest compounds which lead to the darkening of topsoil due to the presence of organic matter. Humic acid is water soluble and it percolates through the soil profile more readily than the water-insoluble humins. Fulvic acid is also an important component in humus. All of these compounds have been implicated in causing increases plant root growth, and in some cases, yield. There are commercial liquid and granular products available on the market that are made from a lignite component called leonardite. These products are being tested and used in commercial agriculture now.

Poll on Organic Content Used

What do you use to improve the organic content of your soil? (if you use other materials, please add a few words in the comment section)

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    • LongTimeMother profile image

      LongTimeMother 4 years ago from Australia

      lol. I could build a wall out of this year's pumpkins, and mortar it with tomatoes. We have chillies in everything, plus strings of them drying. I have created as many things as I can think of with apples, given heaps of them away, and still have about 100 apples on the tree.

      My hens now expect crab apples to be a part of their daily diet forever, and my daughter thinks she'll die when there are no more raspberries etc in the garden.

      I've made more stir fries with asian greens, and created more versions of spinach quiches than I think I've made in my life. I harvested mountains of garlic earlier in the season, so there's plaits of garlic hanging everywhere - much to my husband's amusement.

      Carrots and potatoes and turnips and parsnips and lots of other goodies are still in the ground, and oranges and lemons are waiting patiently on their trees. I grow them in big tubs so we can drag them into the greenhouse away from the frost and have fresh citrus into winter. I have peas and beans etc that seem to be daring me to leave them long enough for them to explode, so I really must pick them soon.

      The cockatoos and other local birds beat me to the plums and apricots and some of the other stone fruit as part of their revenge for me netting the apple trees this year. Next year there will more nets in my orchard!

      Lots of lovely things in the garden this year. More than I thought possible actually. I'm very grateful to my pigs for doing such a good job of preparing a couple of new vegetable gardens in time for spring ... and equally grateful to my free range hens for not eating all the seeds that fell from the herbs and vegetables I left last season to self-seed. :)

      Gee, I should have written that in a hub and put photos in it. lol.

      PS. Costa Rica! Of course you can grow things year round. I apologise for assuming you shared the same climate as 99,9% of hubbers. I won't do that again!

    • Randy M. profile image

      Randy McLaughlin 4 years ago from Liberia, Costa Rica

      Actually LTM, where I am, the growing season is pretty much year-round. We have a rainy season Sept. to Nov., and things get going again after that. I am hoping that some people reading this in the northern temperate region will find this interesting at the moment. I may do an update or a related article again for the southern zones later in the year.

      So what were your prime fruits of harvest?

    • LongTimeMother profile image

      LongTimeMother 4 years ago from Australia

      I'm sure you must be celebrating at the start of your growing season. I'm just finishing up the summer harvest time here. It's been a good year. Good soil makes the world of difference. :)

    • Randy M. profile image

      Randy McLaughlin 4 years ago from Liberia, Costa Rica

      Thanks, baja2013. I just wrote an article on another site about what makes topsoil dark and this one surfaced in my mind. I thought it timely to write it. May you have many healthy plants this season!

    • baja2013 profile image

      Bajazid 4 years ago from Sarajevo, Bosnia

      Nice there is artcles like this, especially in the season start. Tomatoes are my favorite vegetable so maybe this year they will got some better treatment thanks to this hub.