Soil fertility

The introduction of harmful land practices such as intensive and non-prescribed burnings and deforestation by colonists created long-lasting negative results to the environment.

[5] However, studies suggest that chemical fertilizers have adverse health impacts on humans including the development of chronic disease from the toxins.

[7] Additionally, the water-soluble nitrogen in inorganic fertilizers does not provide for the long-term needs of the plant and creates water pollution.

As plant material and animal wastes are decomposed by micro-organisms, they release inorganic nutrients to the soil solution, a process referred to as mineralization.

Peer-reviewed and published scientific studies have shown that increasing CO2 is highly effective at promoting plant growth up to levels over 300 ppm.

Cronon continues, explaining, “Where mowing was unnecessary and grazing among living trees was possible, settlers saved labor by simply burning the forest undergrowth...and turning loose their cattle...In at least one ill-favored area, the inhabitants of neighboring towns burned so frequently and graze so intensively that…the timber was greatly injured, and the land became hard to subdue...In the long run, cattle tended to encourage the growth of woody, thorn-bearing plants which they could not eat and which, once established, were very difficult to remove”.

The practice of intensive land burning and turning loose cattle ruined soil fertility and prohibited sustainable crop growth.

[15] While colonists utilized fire to clear land, certain prescribed burning practices are common and valuable to increase biodiversity and in turn, benefit soil fertility.

Without consideration of the intensity, seasonality, and frequency of the burns, the conservation of biodiversity and the overall health of the soil can be negatively impacted by fire.

[18] As historian David Silkenat explains, the goals of Southern plantation and slave owners, instead of measuring productivity based on outputs per acre, were to maximize the amount of labor that could be extracted from the enslaved workforce.

Once these Southern farmers forced slaves to leach soils and engage in mass deforestation, they would discard the land and move towards more fertile prospects.

The environmental impact included draining swamps, clearing forests for monocropping and fuel steamships, and introducing invasive species, all leading to fragile ecosystems.

In the aftermath, these ecosystems left hillsides eroded, rivers clogged with sterile soil, and extinction of native species.

Silkenat summarizes this phenomenon of the relationship between enslavement and soil, “Although typically treated separately, slavery and the environment naturally intersect in complex and powerful ways, leaving lasting effects from the period of emancipation through modern-day reckonings with racial justice…the land too fell victim to the slave owner’s lash”.

In regions of dry climate like Sudan and the countries that make up the Sahara Desert, droughts and soil degradation is common.

[21] The details of Indigenous societies prior to European colonization in 1492 within the Amazonian regions of South America, particularly the size of the communities and the depth of interactions with the environment, are continually debated.

Dark Earth deposits have been found, through ethnographic and archaeological studies, to have been created through ancient Indigenous practices by intentional soil management.

There is much evidence to suggest that the development of ancient agricultural societies in the Amazon was strongly influenced by the formation of Dark Earth.

As a result, Amazonian societies benefitted from the dark earth in terms of agricultural success and enhanced food production.

The “results demonstrate the intentional creation of dark earth, highlighting how Indigenous knowledge can provide strategies for sustainable rainforest management”.

[citation needed] In Ghana and Liberia, it is a long-withstanding practice to combine different types of waste to create fertile soil that is referred to as African Dark Earths.

Soil scientists use the capital letters O, A, B, C, and E to identify the master horizons, and lowercase letters for distinctions of these horizons. Most soils have three major horizons—the surface horizon (A), the subsoil (B), and the substratum (C). Some soils have an organic horizon (O) on the surface, but this horizon can also be buried. The master horizon, E, is used for subsurface horizons that have a significant loss of minerals (eluviation). Hard bedrock, which is not soil, uses the letter R.
Desert east of Birdsville , Australia . Much of Australia is sparsely populated as its desert soils are mostly infertile; thus unable to support larger scale human habitation. [ 1 ] [ 2 ]
Global distribution of soil types of the USDA soil taxonomy system. Mollisols , shown here in dark green, are a good (though not the only) indicator of high soil fertility. They coincide to a large extent with the world's major grain producing areas like the North American Prairie States, the Pampa and Gran Chaco of South America and the Ukraine -to-Central Asia Black Earth belt.