Soil Degradation and Human Demise
Soil degradation and retrogression are two regressive evolution processes associated with the loss of equilibrium of stable soil. So we think that soil degradation and human demise are the end results if this kind of soil condition continues.
Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state.
- Soil is lost due to erosion from wind and water— for example, rivers washing upland or wind blowing dirt away.
Degradation is due to the replacement of primary plant communities by secondary communities. This replacement modifies the humus composition and amount and affects the formation of the soil.
- It is directly related to human activity.
What is Soil?
The definition of soil is “The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants.” .
Soil is one of the world’s most needed resources. We think about animals and this idea of going “plant only” but don’t understand that this might not be the best thing for ourselves and our environment.
When was the last time, if ever, we thought about soil health? It isn’t something that comes to mind as necessary, even when we think about human survival. Ask yourself what do humans need to survive? Water and food.
Water is found in natural bodies of water, but where do you get food from? Soil is required for plants, animals require plants, and as humans, we need to eat animals and plants.
The Soil Profile
As soils develop over time, layers (or horizons) form a soil profile. Most soil profiles cover the earth as two main layers—topsoil and subsoil.
Soil horizons are the layers in the soil as you move down the soil profile. A soil profile may have soil horizons that are easy or difficult to distinguish. 
Most soils exhibit 3 main horizons:
- A horizon: humus-rich topsoil where nutrient, organic matter, and biological activity are highest (i.e., most plant roots, earthworms, insects, and micro-organisms are active). The A horizon is usually darker than other horizons because of the organic materials.
- B horizon: clay-rich subsoil that is often less fertile than the topsoil but holds more moisture. It generally has a lighter color and less biological activity than the A horizon. Texture may be heavier than the A horizon too.
- C horizon: underlying weathered rock (from which the A and B horizons form).
- Some soils also have an O horizon, mainly consisting of plant litter accumulated on the soil surface.
The properties of horizons are used to distinguish between soils and determine land-use potential.
What is in the soil we use?
Soil contains air, water, minerals, and plant and animal matter, both living and dead. These soil components fall into two categories.
- In the first category are biotic factors—all the living and once-living things in the soil, such as plants and insects.
- The second category consists of abiotic factors, including all nonliving things—minerals, water, and air.
The most common minerals found in soil that support plant growth are phosphorus, potassium, and nitrogen gas. Other less common minerals include calcium, magnesium, and sulfur. The biotic and abiotic factors in the soil make up the soil’s composition.
The most significant component of soil is its minerals, accounting for about 45% of its volume. The most common ones are phosphorus, potassium, and nitrogen. While the less common ones are magnesium, calcium, and sulfur.
Water is the second essential component of soil. It makes up approximately 2% to 50% of the soil volume. It is vital for transporting nutrients to growing plants and soil organisms and facilitating biological and chemical decomposition. Soil water availability is the capacity of a particular soil to hold water available for plant use.
Organic matter is the next primary component found in soils at levels of approximately 1% to 5%. This matter is derived from dead plants and animals and has a high capacity to hold onto and provide the essential elements and water for plant growth. An organic matter has a tall “plant available” water-holding ability and CEC, which can enhance the growth potential of soils.
Gases and air are the following essential component of soil. They make up approximately 2% to 50% of the soil volume. Oxygen is necessary for root and microbe respiration, which helps support plant growth.
Carbon dioxide and nitrogen gas are also crucial for belowground plant functions like nitrogen-fixing bacteria. If soils remain waterlogged (where gas is displaced by excess water), it can prevent root gas exchange, leading to plant death, a common concern after floods.
Nutrient Depleted Soil
Nearly 99 percent of the world’s daily calorie intake can be traced back to the soil. The plants and animals we eat require soil to grow. Soil is vital for human survival, yet modern farming and agricultural practices quickly destroy it.
Worldwide, one-third of the Earth’s soil is at least moderately degraded, and over half of the land used for agriculture has some soil degradation.
Due to intense, mismanaged farming, soil nutrients are declining.
- Nitrogen stores have decreased by 42 percent
- Phosphorus by 27 percent
- Sulfur by 33 percent.
Plants require these nutrients for photosynthesis, enzymes, protein synthesis, and more to grow optimally.
As a result of declining soil fertility and selective breeding, the nutritional contents of some fruits, vegetables, and grains have also been compromised.
- In a 2004 study using USDA data, 43 garden crops were analyzed to compare nutritional content in 1950 versus 1999. Some nutrients were unchanged, but calcium, phosphorus, iron, riboflavin, and vitamin C were lower in 1999 compared to 1950, ranging from a 6 percent to 38 percent drop .
The protein content in corn declined from 30 percent to 50 percent from 1920 to 2001, while the starch content increased .
Modern Agriculture and Soil
The current agriculture methods produce higher yields but deplete and erode soils. Currently, industrial agriculture is destroying the soil. It is being destroyed at 100 to 1,000 times the rate where it is replenished. It is according to the United Nations estimates. According to their report, we only have 60 years left of harvest in many farming regions.
What contributes to soil degradation and human demise?
- For example, legume crop residues can be converted into nitrogen by soil bacteria, reducing the need for synthetic nitrogen-based fertilizers.
Additionally, monocropping can threaten food security. With a single crop species on millions of acres, one disease could potentially wipe out an entire food system.
Instead of using organic fertilizers, including crop rotations, cover crops, and manure, modern farms require massive amounts of synthetic fertilizers to grow crops continually.
- Nitrogen-based fertilizer production has increased by 9.5-fold since 1960. Fertilizer production consumes fossil fuels in a very energy-intensive process, with non-negligible environmental consequences.
Not all the fertilizers applied are used up by the crops. Fifty percent or more of the nitrogen leaches into the environment. Many inorganic fertilizers destroy soil microbes that have roles in soil homeostasis.
- Ammonia, nitrate, and other nitrogen residues make their way to groundwater, rivers, and eventually, the ocean. They reduce oxygen levels, increase algae growth, and damage or death to aquatic life.
Farms today till fields to remove crop residues, flatten the land, and generally mix up the topsoil. However, tilling reduces microbe populations in the soil, promotes soil erosion, and releases greenhouse gases. Today, 93 percent of the world’s cropland uses tilling-based methods for production.
Herbicides, Pesticides, and Fungicides
- Additionally, pesticide residues make their way into water systems and food. Many health problems have been linked to pesticide exposure, including asthma, neurological issues, and even cancer.
- The most well-known herbicide is glyphosate, which is applied to crops for hundreds of millions of pounds each year. Glyphosate has profound environmental and health consequences, covered in this article.
- Unfortunately, the importance of ruminant animals has been almost forgotten. Due to rocky terrain, hills, and climate, much of the world’s land isn’t even conducive for growing crops.
- In contrast, cows, sheep, and goats can often thrive on these marginal lands. Yet these areas aren’t being fully utilized to raise ruminants for food and to sequester carbon properly. Instead, we have concentrated animal feeding operations, or CAFO, where grazing is limited, cows are fed grain residues from an outlying farm.
Unity Between the Human Body and Soil
To learn more about soil degradation and human demise, watch the full Episode 96 in this video 👇
02:08 Soil Degradation and Human Demise
07:25 What is soil?
09:54 The layers of soil
12:35 The essential life-building blocks in soil
16:43 Nutrient Depleted Soil
20:37 Soil Erosion: Monoculture
21:58 Soil Erosion: Synthetic Fertilizers
24:21 Soil Erosion: Tillage-Based Farming
25:19 Soil Erosion: Herbicides, Pesticides, and Fungicides
27:35 Soil Erosion: Mismanaged Grazing
30:14 Unity Between the Human Body and Soil
35:20 Wrapping up the episode