The Soil-Human Health-Nexus

Rattan Lal, Rattan Lal

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000326338
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Botany
• Index: Biological Sciences

The term "soil health" refers to the functionality of a soil as a living ecosystem capable of sustaining plants, animals, and humans while also improving the environment. In addition to soil health, the environment also comprises the quality of air, water, vegetation, and biota. The health of soil, plants, animals, people, and the environment is an indivisible continuum.

One of the notable ramifications of the Anthropocene is the growing risks of decline in soil health by anthropogenic activities. Important among these activities are deforestation, biomass burning, excessive soil tillage, indiscriminate use of agrochemicals, excessive irrigation by flooding or inundation, and extractive farming practices. Soil pollution, by industrial effluents and urban waste adversely impacts human health. Degradation of soil health impacts nutritional quality of food, such as the uptake of heavy metals or deficit of essential micro-nutrients, and contamination by pests and pathogens. Indirectly, soil health may impact human health through contamination of water and pollution of air.

This book aims to:

Present relationships of soil health to human health and soil health to human nutrition.

Discuss the nexus between soil degradation and malnourishment as well as the important links between soil, plant, animal and human health.

Detail reasons oil is a cause of infectious diseases and source of remedial measures.

Part of the Advances in Soil Sciences series, this informative volume covering various aspects of soil health appeals to soil scientists, environmental scientists and public health workers.

1 The Soil–Human Health Environment Trinity

Rattan Lal

The Ohio State University

Contents

1.1 Introduction

1.2 Soil Organic Matter in Relation to the Health of Soil and the Environment

1.3 Historic Depletion of the Terrestrial C Stock

1.4 Soil Organic Matter Depletion and Soil/Environment Degradation

1.5 The Soil–Human Health Nexus

1.6 Interconnected Vicious Cycles Prevalent in Degraded Soils of Agroecosystems

1.7 Choice of Entry Points for Breaking the Vicious Circles

1.8 Enhancing Human Nutrition by Soil Management

1.9 Research and Development Priorities

1.10 Conclusions

References

1.1 Introduction

The prime soil resources are finite, unequally distributed globally, and fragile upon land misuse and soil mismanagement. Humanity, despite all of its scientific advances and modern discoveries in every aspect of the terrestrial and extra-terrestrial processes, is even more fragile than the soil on which it depends. This truism has been documented by the rapid spread of the COVID-19 pandemic which paralyzed 8 billion people over a short span of 10 months from December 2019 to September 2020, and there is no end in sight. As of September 20, 30 million people had tested positive and ~ 1 million had perished. The mighty COVID-19 does not differentiate between rich or poor nations, developed or developing countries, scientifically advanced or less progressive societies, and even among those with or without the so-called “weapons of mass destruction” (WMDs). As a matter of fact, COVID-19 is the WMD that humans have yet to get their grip on. Surprisingly, humanity also has a short-lived memory. Not only has it forgotten the demise of once thriving civilizations (i.e., Mesopotamia, Indus, Maya, Aztec), but the transient nature of humanity’s memory is vividly demonstrated by complacency not of the relatively distant plague, smallpox, and HIV but also more recent Ebola, Zika, and other pandemics of modern era.

The societal lockdown enforced by COVID-19 has not only documented the vulnerability of the economy of all rich and poor nations alike but also how rapidly the atmospheric chemistry responds to the industrial shutdown. By the end of March 2020, within 3 months of onslaught of COVID-19 on humanity, the atmospheric concentration of NO₂ declined over several cities in Europe (Abnett 2020; Holcombe and O’Key 2020). The concentration of NO₂ levels is a contributing factor to coronavirus fatalities (Ogen 2020). Furthermore, seasonal changes in the atmospheric concentration of CO₂, as shown by the Keeling curve, may also be affected by the long-term shut down. It is estimated that the global fossil fuel use would have to decline by 10% for a full year to show up in carbon dioxide concentrations of only about 0.5 parts per million (Monroe 2020). Across the whole year, Betts et al. (2020) estimated that CO₂ levels will rise by 2.48 parts per million (ppm), which is 0.32 ppm smaller than if there had been no lockdown. This decrease is equivalent to 11% of the expected rise (Betts et al. 2020). Disappointingly, carbon dioxide recorded at the Mauna Loa Observatory in Hawaii reached 417 parts per million (ppm) in May 2020, higher than the record of 414.8 ppm set last year (Reuters 2020).

Pollution levels declined across cities in India because of the lockdown related to COVID-19. Mahato, Pal, and Ghosh (2020) reported that concentrations of PM₁₀ and PM_2.5 were reduced by >50% as compared with the prelockdown phase. In comparison with 2019 for the same period, the reduction of PM₁₀ and PM_2.5 is 60% and 39%, respectively. Among other pollutants, NO₂ has been decreased by −53% and CO by −30% during the lockdown phase (Mahato, Pal, and Ghosh 2020). Goswami (2020) outlined four environmental changes in India due to the COVID-19 lockdown: (i) the air quality index in Delhi dropped from 90 in the worst-case scenarios to below 20 in May because 11 million registered cars were taken off the roads, and factories and constructions were stopped, and the PM_2.5 concentration declined from 71% to 26%; (ii) South Asian river dolphins, listed among endangered species, were spotted at different locations in Kolkata Ghats; (iii) thousands of flamingos were seen in Mumbai; and (iv) the water of the river Ganges was of a drinkable quality (Goswami 2020). Cities of Europe also reported cleaner air during the lockdown (Abnett 2020).

Therefore, prudential management along with a planned reduction in the use of fossil fuel and its substitution by noncarbon fuel sources may bring about the much-needed decline in the increase of the atmospheric concentration of greenhouse gases (GHGs). This is an important lesson that must be fallowed upon by the policymakers after the COVID-19 pandemic. Such a rapid response indicates a possibility that a strong commitment to recarbonization of the terrestrial biosphere (i.e., soil, vegetation, and wetlands) at a global scale (Lal et al. 2018) may also make a measurable impact on the atmospheric chemistry within a foreseeable future. Admittedly, the tragic pandemic of COVID-19 cannot be dubbed having a silver lining, but the fact that atmospheric chemistry can be altered rapidly provides strong motivation toward adoption of negative emission technologies (NET).

Improvement of soil health, through conversion of degraded and agriculturally marginal lands to restorative ecosystems (i.e., by afforestation and set-aside or land retirement programs) and adoption of recommended management practices (RMPs), is a pertinent example of NET. These strategies would restore soil organic matter (SOM) content because of the progressive development of the positive soil/ecosystem carbon (C) budget on a decadal scale. The positive soil C budget would restore soil health and strengthen the provisioning of essential ecosystem services (ESs) for an effective functioning of nature via nutrient cycling, increase in activity and species diversity of biota, water purification and renewability, and above all, sequestration of atmospheric CO₂ into SOM and in the above and below-ground biomass. Therefore, the objective of this chapter is to deliberate the soil–human health–environment trinity, and how restoration of the soil health can simultaneously improve the resilience of humanity through improvement of the environment and functioning of nature. The specific objective of this article is to deliberate the impact of soil degradation caused by SOC depletion on the nutritional quality of crops and on human health.

1.2 Soil Organic Matter in Relation to the Health of Soil and the Environment

Soil components have an important impact on human health (Nieder, Benbi, and Reichl 2018). An important among these components is soil organic carbon (SOC) content. In conjunction with afforestation of degraded and agriculturally marginal lands, enhancing and sustainable management of SOC stock on depleted agricultural soils is critical to mandatory reduction in the atmospheric concentration of carbon dioxide (CO₂) and other GHGs (i.e., nitrous oxide or N₂O and methane or CH₄). The SOC stock and its management is a critical climate variable (IPCC 2019). Whereas measuring SOC stock requires access to facilities and understanding of the processes, there is also a large variation in SOC concentration and stock at soil scape or landscape levels because of the large variations in control factors both vertically and horizontally even at short distances.

Yet, credible assessments of SOC stocks are needed to understand the impact on a range of pedological processes whose degradation may lead to reversal of ESs (Figure 1.1) which are essential to human and nature. Assessment of SOC stocks and their temporal changes are also needed to evaluate impacts on atmospheric concentrations of GHGs in relation to anthropogenic climate change. A severe decline in SOC stock, below the critical threshold for the specific land use and soil type, can create numerous disservices (Figure 1.2) with adverse impacts on human well-being and nature functions. The strong food–human health–soil nexus (Figure 1.3), affecting human and the planetary health, necessitates restoration and sustainable management of SOC stock at soil scale, landscape, farm, regional, national, and global scale. The nexus between soil health and food quality, and that of diet quality and human health, has been recognized in ancient cultures. An Ayurvedic proverb is a pertinent example of this interconnectivity: “When diet is wrong, medicine is of no use; when diet is correct, medicine is of no need.” Contextualizing the soil and farming system effects of SOC depletion indicates its strong significance to the productivity, sus...