In the modern world soil is continually coming under attack. That might sound alarmist, but the fact that it isn’t on the front page of the newspaper, doesn’t mean that the quality of soils is not being degenerated across the world at an ever-increasing rate. If the soil is the earth’s skin, a complex ecosystem that is the anchor for life on the planet, the human race appears to be treating it with disdain.
Poor Agricultural Practices
Modern agricultural practices tend to degrade the soil, leading to high rates of erosion and loss of topsoil and nutrients. For instance, overgrazing by animals, which are often overstocked, can reduce ground cover, which exposes soil to the eroding elements of rain and wind, as well as compacting the land. Monocultures – the growing of a single crop – are very detrimental to soil quality, as it does not provide enough variety to maintain a healthy ecosystem both above and within the soil. Because crops are grown for as much harvest as possible, they do not self-mulch, while a single crop is more susceptible to pests and diseases. Thus, farmers use artificial fertilizers and biocides to protect their investment.
Such effects are magnified by destructive ploughing techniques. Ploughing that inverts the topsoil and the subsoil so that the poorer quality subsoil forms the surface layer means that plants have a poorer quality growing medium, and the soil is much more prone to erosion. This erosion can have the knock-on effect of clogging up streams and rivers. As the land loses fertility, farmers are forced to move on, often clearing more natural ecosystems in order to plant monocultures, and the process starts again, each time leaving another patch of earth unproductive.
Removal of Vegetation
Closely related to such destructive agricultural practices, but also problematic on a smaller scale as well, is the removal of vegetation from the land, thus leaving the soil exposed. In nature, soil wants to be covered. Plants find a way to colonize soil, which provides them with a location to grow and benefits the soil. Removing vegetation degrades the soil in several ways.
Firstly, it means the surface of the soil is exposed to forces of erosion, such as wind and rain. This removes the healthy topsoil, which is the primary growing medium for plants as it contains the most organic matter. It also means that the soil receives more direct sunlight, causing the moisture in the soil to evaporate. Without a cover crop, the soil is also exposed to animal hoofs, which compacts the soil making it harder for any rain that falls to penetrate the soil.
The removal of surface vegetation also affects the salinity of the soil. Salts that the plants would normally use as nutrients remain in the soil and accumulate in greater proportion closer to the surface. This turns the soil toxic.
With the removal of vegetation, the soil also does not benefit from the positive influences that the plants have on it directly. Plants help improve the quality of the soil, with their roots helping to open the soil’s structure to allow gases and water to percolate down, and their leaves, when they fall, becoming extra organic matter added to the soil.
Use of Biocides
Organic fertilizers used in permaculture gardens – like compost and mulch – nourish life in the soil. They foster the growth of bacteria, microorganisms, fungi, insects, and plants of many species. Biocides, as the name suggest, destroy life. The term refers to chemical products that are used in agricultural or home garden system to kill living organism. So they include pesticides, weed killers, herbicides and fungicides.
While the use of biocides rather goes against the principles of permaculture, such as respect for all life, for trying to use the methods of nature to build a harmonious ecosystem (such as attracting predatory insects to control a pest population), the primary reason biocides harm soil is their longevity. Some biocides can remain in the soil for decades. And because they are inorganic, they cannot be transformed by plants or animals into a form that becomes part of the organic cycle.
The use of artificial fertilizers on crops has helped farmers to increase yields, but that increase is actually at a cost of abundance. A high yield of a single crop actually serves to negatively impact upon the health of the soil. This is because a single species does not use all the fertilizer; it is unable to absorb everything that is in the product. This means that a significant proportion of the fertilizer remains in the soil after the crop has been harvested. Scientists have found that the accumulation of some of the chemicals used in such fertilizers changes soil composition and disrupts the balance of microorganisms in the soil. This then stimulates the growth of harmful bacteria at the expense of beneficial kinds, further depleting the quality of the soil. Over several plantings and applications of the fertilizer, this accumulation makes the land unproductive.
Some of the fertilizer that remains in the soil can also have a negative impact elsewhere, by leaching into groundwater and from there into rivers, streams and other water bodies. Because or its insoluble properties, the fertilizer does not get diluted and in fact provides nutrients for algae, which can choke water bodies of oxygen and prevent sunlight from penetrating the surface. This turns that water into a ‘desert’ much like the soil that has been exposed to the artificial fertilizers.
If you wish to heal land that has been over-exposed to artificial fertilizers, you need to plant a cleansing crop before you grow food there. Crops such as hay are adept at absorbing the excess fertilizer, although you should carry out tests to check levels of chemical, particularly nitrogen before planting food crops. You may need to plant more than one cleansing crop to heal the soil.
Permaculturists − by respecting the unique characteristics of soil ecosystems, by seeking to heal degraded and damaged soil, and by working to increase the health of the soils under their stewardship – can play an important role in helping to reverse the degradation of the earth’s skin.