It is easy to take soil for granted. Soil may be largely dense sticky clay, thin gritty sand, powdery silt, or loose woodsy loam. Whichever type, this existing soil constitutes the planting medium for your crop. To improve its ability to support and nourish plants, farmers strive to improve its structure and boost its fertility. Fortunately, there is humus which is often referred to as organic matter.

Humus Creates Soil

It is not a coincidence that the word humus is part of every farmers vocabulary and that compost piles, one source of humus, are part of their operation. Humus transmutes sterile dirt into fertile soil. Derived from organic matter of all kinds, humus is the life support system of soil. The presence of humus among mineral particles and air spaces enables soil to nurture plants. Humus creates a loose structure that simultaneously holds moisture and drains well. Humus also creates an environment that supports living organisms that convert soil nutrients into a form plant roots can use, building soil fertility. In short, humus brings soil to life.

In nature humus is constantly introduced into soil as plant debris, dead animals, and other organic matter that decomposes on the ground. Through the alchemy of bacteria, fungi, and other resident micro-life activity, this organic material is reduced by degrees to its soft, spongy essence, called humus. It permeates the top few inches of the soil through rains, earthworms and other macro-organisms, where it continually revitalizes the soil around plant roots. This natural cycle is repeated over the seasons, sustaining the great forests and other natural areas. Where there is lots of vegetation to decay and enrich the soil, such as in woodland areas, the soil is rich in humus and very fertile. Where there is little or no vegetation to provide the organic debris, such as at the seashore or in the desert, the soil has little or no humus and is lean, infertile.

In farming, where the natural vegetation has been removed or disturbed, this natural decay cycle is disrupted. Intensive planting of crops, turf grasses, and ornamental plants rapidly depletes soil of its existing humus content. Bare soil in beds is exposed to the harsh effects of sun, wind and hard rains, which further reduce its humus content and destroy its structure and fertility. To grow plants successfully, farmers must emulate nature, and constantly renew the soil by adding the depleted ingredient, humus.

Humus Solves Problems

There is no such thing as perfect soil. Every soil has problems in structure, texture, and/or chemistry that compromise its ability to nurture plants. The best way to confirm suspected soil problems is by having a soil sample sent to a lab for analysis. Their profile of the soil content and structure, pinpoint deficiencies. Fortunately, the addition of organic matter, or humus, can mitigate many of these problems.


Good soil is loose and crumbly because it has a lot of air spaces. Plant roots are able to penetrate soil deeply for extended drought resistance and stability. Air is also essential to the micro-life that lives on its organic content, and processes its nutrients to create fertility. Turf, for example, is often compacted, the air compressed from it by the weight of foot traffic, construction, mechanical turf equipment, and harsh weather.

Sandy Soil

Sandy soil has large particles with large air spaces between them. Therefore, it drains so quickly that it dries out quickly. Also, water-soluble nutrients leach out rapidly before the plants can use them. Humus incorporated into sandy soil acts like a sponge, absorbing and holding moisture and any nutrients dissolved in it.

Clay Soil

Clay soils are so thick because they have small particles, with correspondingly small air spaces, between them. They tend to stick together and cause water to fill up the air spaces. Since moisture does not drain from this soil well, plant roots rot. Adding humus to clay soils discourages the small particles from sticking so tightly. They aggregate into larger clumps, creating larger spaces, that drain more easily and hold air to improve soil texture.

Fluctuating pH Levels

The acidity or alkalinity of soils, expressed as pH, affects how accessible their nutrients are to plants. Reduced acidity (pH higher than 8.0), inhibits the uptake of iron, boron, copper and other elements necessary for plant health. Excessive acidity (pH lower than 6.0), discourages plant absorption of other nutrients. Alter pH levels by adding either, sulfur to increase acidity, or limestone to reduce acidity, in amounts indicated by soil test results. Because humus buffers soil against changes in its pH, adding a lot of organic matter to the soil will help maintain desirable pH levels.

Disease Pathogens in Soil

Soil rich in humus is alive. It supports active micro-organisms to process nutrients, and harbors beneficial macro-organisms, such as ants and ground spiders, that prey on soil-dwelling pest larvae and eggs. Humus creates a soil environment that supports beneficial nematodes and also bacteria. Many other microbes attack and control disease pathogens that lurk in the soil.

Infertile Soil

Soil becomes sterile over time, as its humus content is reduced by hot weather, removal of topsoil, or intense cultivation, without replacement of organic matter. The number and activity of micro-organisms in the soil is depleted. In their absence, the production of nutrients in the soil is severely curtailed, and it becomes sterile. While fertilizer provides nutrients to plants, it does not solve a soil fertility problem. Supporting micro-life in the soil is the long term solution.

Getting the biology right is the real key to effective use of humus. PureAg products are designed to compliment that role. Ideally, you want to have all of your inputs utilized by your plants when you farm. PureAg products can help you control your cost by assuring the inputs are being solubilized, and are bio-available to your plants, so you can better forecast your yields.