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 âweapons of mass destructionâ (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 humanityâs 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 OâKey 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 PM2.5 were reduced by >50% as compared with the prelockdown phase. In comparison with 2019 for the same period, the reduction of PM10 and PM2.5 is 60% and 39%, respectively. Among other pollutants, NO2 has been decreased by â53% and CO by â30% 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 PM2.5 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 soilâhuman healthâenvironment 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 foodâhuman healthâsoil 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: âWhen diet is wrong, medicine is of no use; when diet is correct, medicine is of no need.â Contextualizing the soil and farming system effects of SOC depletion indicates its strong significance to the productivity, sus...
