Introduction
Global climate change caused marked alterations in the planet’s ecosystem, posing a danger to food production. Climate change was associated with significant temperature changes, rise in atmospheric carbon dioxide (CO2) concentration, fall in pure water supplies, and soil erosion (Ramesh et al., 2019). Climate changes resulted in prolonged droughts and sandy winds in many parts of the planet, leading to soil degradation, reducing land fertility. Soil erosion and loss of topsoil can also be attributed to agricultural activities because of historical variations in the management of croplands in different countries (Vanwalleghem et al., 2017). Furthermore, scientists have been suggesting for a long time that using land for agricultural purposes increases greenhouse gas emissions (Searchinger et al., 2018). Carbon dioxide emission may worsen the climate change crisis, and soil destruction can cause food scarcity across the continents. Soil erosion is caused by multiple factors such as deforestation, unsustainable agricultural practice, and overgrazing (Borrelli et al., 2017). Topsoil loss caused by increased activity of our civilization can result in food insecurity due to a decrease in food production and alter carbon cycling, creating a long-term effect on the Earth’s climate.
Causes of Topsoil Loss and Erosion
Intensification of land use for food production during the last century caused drastic loss of topsoil and soil erosion. As previously mentioned, the leading causes of soil erosion include deforestation, overgrazing, and intensive land use for crop production (Borrelli et al., 2017). Certainly, soil erosion is a natural process, but natural destructive forces are always balanced with soil production (Vanwalleghem, 2017). The problem with excessive topsoil loss is that, for centuries, people have been only inhabiting places suitable for food production. Therefore, specific long-term anthropogenic activities were primary contributors to topsoil loss, which now endanger the planet and the people.
The soil erosion rates have been investigated and quantified by geologists based on the amount of soil eroded per large area in a given period. For example, the geologic rate of soil erosion in the United States was 7Mg ha-1 yr-1, and China had soil erosion rates of more than 15Mg ha-1 yr-1 in 2012 (Nearing et al., 2017). The rates of soil erosion increased by about 10% in South America due to deforestation and agricultural land use (Borrelli et al., 2017). To illustrate the extent of the damage from expansion farmlands, the geological erosion rate 16,000 years ago at the US territory was about 0.90Mg ha-1 yr-1 (Nearing et al., 2017). These numbers demonstrate the dramatic increase in soil erosion, which means that land productivity may be affected, resulting in lower food production and even famine.
Effect of Topsoil Loss on Food Production
Historically, lands were used by people for obtaining food either from natural resources or through farming. In the ancient world, when a land’s resources were exhausted, people moved to different places to continue their agricultural activity. However, establishing states and borders restricted free migration; therefore, farmers had to use the same land for years until the complete depletion of soil resources (Vanwalleghem, 2017). Continuous use of lands for farming resulted in soil erosion, affecting the fertility of the lands and food production.
Food production in agriculture has depended chiefly on the quality and richness of the soil content. Soil consists of organic and mineral substances that enable plant growth (Ramesh et al., 2019). Its organic content determines the soil’s quality because organic matter maintains physical stability and chemical equilibrium in soil essential for land productivity (Ramesh et al., 2019). When soil is exposed to physical damage and chemical pollution, the land can no longer serve human farming activity.
Soil erosion due to natural factors and irrational anthropogenic use of land often lead to decreased food production. If one needs to predict soil erosion and food production dynamics, the soil utilization should be evaluated from the perspective of its static and dynamic properties (Vanwalleghem, 2017). When soil is perceived as static in the first prediction model, the land resources may flatten out and decrease with time. When soil is considered dynamic, its resources may become scarce in response to erosion due to natural and artificial factors (Vanwalleghem, 2017). The dynamic model examines soil erosion more deeply; thus, it may more accurately predict soil hardening and productivity loss.
Topsoil Loss and Carbon Cycling
Greenhouse gas emission is one of the primary ecological problems that resulted in global warming and climate change. As mentioned previously, temperature changes, inconsistent rainfall patterns, and rising atmospheric CO2 severely affected food production and agriculture. Soil contains more carbon in organic form than the atmosphere and plants combined (Viscarra Rossel et al., 2019). Therefore, soil’s contribution to global carbon cycling should be closely monitored because recent carbon dioxide emission estimates showed that 30% of all CO2 released is caused by deforestation and agricultural land use (Ramesh, 2019). Many researchers determined that soil can sequester or release CO2 into the atmosphere depending on environmental conditions (Ramesh et al., 2019). For example, soil in places with high temperatures has a higher tendency to release carbon than to capture it from the atmosphere resulting in poor soil organic content and higher greenhouse gas emissions (Viscarra Rossel et al., 2019). However, global warming is not the only contributor to carbon dioxide loss from the soil. The effect of physical destruction of the soil on carbon dioxide emission should also be discussed.
Another contributing factor to the increase in carbon dioxide emission can be soil erosion and topsoil loss. Carbon turnover in soil depends on various factors, including organic content, pH, temperature, moisture, altitude, degradation, and anthropogenic management of the land (Ramesh, 2019). Physical, chemical, or organic degradation result in rapid carbon turnover in soil, which means that soil erosion and topsoil loss due to various reasons reduces sequestration of CO2 from the atmosphere and increases greenhouse gas emissions (Ramesh, 2019). The loss of topsoil results in carbon dioxide emission because most soil organic matter is located in deeper layers (Ramesh, 2019). Therefore, when the surface layer is eroded, any unfavorable conditions such as high altitude or drought can cause CO2 emission. Constant exposure of eroded soil to adverse consequences of climate change results in more significant greenhouse gas emissions to the atmosphere, which aggravates global warming, further promoting climate change.
Role of Tillage Methods in Soil Erosion and CO2 emission
The no-till and full-till are the two main tillage techniques used in farming. The difference between these two techniques is that full-tillage involves the soil’s inversion, while no-tillage does not require plowing to plant seeds (Ogle et al., 2019). Growing rates of geologic erosion elicited an increased concern in scientific communities that started exploring ways to diminish the damage and prevent a global catastrophe. For example, the scientific community suggested that using the no-till technique instead of the full-till method can reduce topsoil loss and CO2 emission (Ogle et al., 2019). According to Ogle et al. (2019, p.2), the no-tillage method “increases the mass of the soil in the upper layer, compared to a soil that is ploughed,” reducing topsoil erosion. Moreover, researchers suggested that because this technique captures carbon in the soil’s surface layers, it reduces atmospheric carbon dioxide emission (Ogle et al., 2019). Therefore, using this farming technique appeared to be a possible solution for the drastic consequences of unsustainable agriculture. However, further explorations in this issue were not univocal, making scientists reconsider their assumptions about these tillage techniques.
The no-till method was believed to be superior to the full-tillage farming technique in preventing soil erosion. However, recent studies did not find a statistically significant difference in greenhouse gas emissions from soil cultivated using either full-till or no-till farming methods. The studies showed that the no-till method could sequester more carbon in soil and reduce carbon dioxide emission only in a warm and moist environment but not at cold temperatures (Ogle et al., 2019). The full-till technique was superior in preventing greenhouse gas emissions in a cold and dry climate (Ogle et al., 2019). Although no-tillage farming enables preserving soil’s porous and organically rich composition, its effectiveness largely depends on the environment (Ramesh, 2019). Both farming methods appear to be efficient in carbon sequestration from the atmosphere under different conditions.
Ways to Reduce Damage from Topsoil Loss
The substantial damage to climate and food production from soil erosion and topsoil loss requires the global community to adopt sustainable agricultural practices to prevent further harm. Global society started to modify land use using more carbon-efficient methods and policies to lower greenhouse emissions (Searchinger, 2018). One possible way to reduce CO2 emissions to the atmosphere is to use no-till farming techniques, especially in a warm and humid climate (Borrelli et al., 2017). Minimizing excessive carbon dioxide leak from the soil may reduce the progression of global warming. Another way is temporarily removing croplands from use to restore soil fertility (Permaculture Day, 2012). Restoration of soil productivity can prevent future issues with food production, preventing possible famine. Lastly, soil restoration and increasing crop production without the extension of croplands can be achieved with modern biotechnology techniques (Vanwalleghem et al., 2017). Employment of sustainable agriculture and biotechnology methods will prevent further soil erosion, improve crop production, and minimize the damage to the climate.
Conclusion
Overall, agriculture’s intensification caused significant soil damage, increasing topsoil loss and greenhouse gas emissions that reduced land productivity. Soil erosion and topsoil destruction can occur due to natural processes, but most soil destruction was caused by anthropogenic activity. Since soil is rich in organic carbon, topsoil loss provoked substantial greenhouse gas emissions to the atmosphere, contributing to global warming and climate change. Furthermore, physical erosion altered soil’s chemical and biological properties, reducing land fertility and food production. There are several possible ways to minimize further soil erosion and prevent its damage. These ways are using the no-till farming technique to lessen soil’s physical destruction, remove damaged lands from use to allow restoration, and implement biotechnology methods to restore soil composition and increase land fertility.
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