Download PDF Summer Bridge on Smart Agriculture June 15, 2022 Volume 52 Issue 2 People everywhere rely on agriculture in one form or another – for food, animal feed, fiber, and other necessities. The summer 2022 articles describe precision indoor farming and alternative protein food systems, advances in food processing, genome editing, digitalization, sustainable and regenerative agriculture, the role of a circular economy, and the important role of policy. Sustainable and Regenerative Agriculture Tuesday, June 14, 2022 Author: A.G. Kawamura, Rattan Lal, Marty D. Matlock, and Charles W. Rice Protecting, restoring, and enhancing life on Earth begins and ends with the soil. Agricultural sustainability and regeneration have become common approaches for driving improvements in US and global food and agriculture supply chains. Multistakeholder organizations have emerged over the past 2 decades to provide coherent and effective strategies for reducing the environmental impacts of agricultural production.[1] Introduction Sustainable Agriculture The most common definition of sustainable agriculture is some variant of the Brundtland Commission’s call for sustainable development that “meets the needs of the present without compromising the ability of future generations to meet their own needs” (WCED 1987, §3:27). To achieve sustainable agriculture, organizations have adopted a continuous improvement strategy based on identifying key performance indicators (KPIs), benchmarking them at a point in time, setting time-bound improvement goals, developing a strategy to accomplish those goals, and monitoring KPI status. This continuous improvement process has no endpoint but rather provides a dynamic approach to addressing environmental, social, and economic challenges to agriculture as they emerge. Interest in sustainable agriculture engages stakeholders from across the food and agriculture supply chains to respond to environmental KPIs such as greenhouse gas emissions, water scarcity, soil erosion, water quality, biodiversity, and the plant-animal-human health nexus. These and other sustainability initiatives also implement KPIs for the social and economic domains, including worker safety, living wages, and community infrastructure. Regenerative Agriculture There isn’t a standard definition for regenerative agriculture, but it represents a holistic framework to understand and respond to global challenges in food and agricultural production at the production unit (farm) scale. It has been described as “farming and ranching in harmony with nature.”[2] Regenerative agriculture expands on sustainable agriculture to include outcomes from “Practices that (i) contribute to generating/building soils and soil fertility and health; (ii) increase water percolation, water retention, and clean and safe water runoff; (iii) increase biodiversity and ecosystem health and resilience; and (iv) invert the carbon emissions of our current agriculture to one of remarkably significant carbon sequestration thereby cleansing the atmosphere of legacy levels of CO2.”[3] Soil health is the key focus (Schreefel et al. 2020), which has led organizations to expand regenerative agriculture to include “building resilience of agro-ecosystems” (IPCC 2019). Putting Them Together for an Agricultural Renaissance Sustainable and regenerative agriculture complement each other with similar goals. Sustainable agriculture is based on outcomes and generally avoids dictating practices, while regenerative agriculture has both outcome- and practice-based approaches (Newton et al. 2020). Integrating these approaches is the way to accelerate an agricultural renaissance, by coordinating the intensification of production necessary to protect habitat for other life while feeding the world’s projected 2050 population of 10 billion (Pew Research Center 2022). Integration of the two approaches also recognizes the critical need to engage communities to protect and preserve their soils, rebuild production capacity on degraded lands, reduce the gap between realized and potential yield of a crop (the yield gap), protect water resources, reduce food waste, and restore woodlands and forests (Solutions from the Land 2021). Regenerative agriculture expands thinking about agricultural production to a metasystems understanding of the interconnected relationships between Earth and humanity. Regenerative agriculture in particular represents an expansion of systems thinking about agricultural production to a metasystems understanding of the interconnected relationships between Earth and humanity. Farmers, ranchers, and foresters must be recognized and engaged as the key stewards for any legitimacy of outcomes. A shared ethic among stakeholders is respect and value for soil conditions. It All Begins and Ends with the Soil “Soil health” is an anthropomorphic characterization of a complex ecosystem, defined as “an integrative property that reflects the capacity of soil to respond to agricultural intervention so that it continues to support both the agricultural production and the provision of other ecosystem services” (Kibblewhite et al. 2008, p. 685). A more ecologically accurate characterization of the complex and integrative elements of soil ecosystems that yield both human sustenance and ecosystem functions without degrading capacity would be “soil resilience.” Soil resilience is the ability of soil ecosystems to continue to provide key functions under stress and to recover those functions after disturbance. Stressors on soils from agricultural activities result in cumulative impacts on four major soil ecosystem functions (Kibblewhite et al. 2008; Lal 2020a): physical and chemical structure, nutrient cycling, carbon transformation, and regulation of diseases and pests. These ecosystem functions are interdependent, nested somewhat in the order listed, and the product of soil environment and microbe interactions (soil biology). Practices such as conservation tillage, cover crops, and nutrient restoration implemented by producers directly drive the outcomes necessary for soil resilience. Nutrient depletion in soils from human activities contributes to yield losses, erosion, food insecurity, and human malnutrition. Physical and Chemical Structure of Soils The physical and chemical structure of soils determines the movement and interactions of gases and liquids, which in turn determine the ability of soils to support life below and above ground (Billings et al. 2021). The most important indicator of soil structure is aggregation (Bronick and Lal 2005), the process of soil particles forming into micro- (53–250 µm) and macroaggregates (251–2000 µm) (Tisdale and Oades 1982). Aggregation creates the structure of soils that results in the dynamic exchange of liquids and gases across the surfaces of mineral and organic matter in the soil ecosystem. When soils lose resilience or become degraded, they lose the capacity to cycle nutrients that support plant and microbial life. Loss of aggregation is often caused by mechanical disturbance, chemical disruption (particularly with sodium salts), weathering through freeze-thaw and wet-dry cycles, and compression. The mechanisms that create soil aggregates are complex and depend on geologic, chemical, biological, and climatic factors as well as soil management. Aggregates generally form from organic molecules attached to clay particles (or sometimes particulate organic matter) and ions (especially polyvalent ions) (Bronick and Lal 2005; Wilson et al. 2009). Plant roots and fungal hyphae create physical entanglement with soil particles and also create pore spaces between aggregates (Wilson et al. 2009). In addition to the formation of aggregates, soil fertility is dependent on other dynamics. Macro- and micro-aggregate formation and turnover drive biochemical reactions that govern labile and recalcitrant soil organic carbon (SOC) pools, which affect microbial and plant nitrogen dynamics (Lal 2008). Water infiltration is a function of bulk density and aggregation, and water-holding capacity is a function of clay type and organic matter. Taking into account all these factors, the formation or restoration of soil aggregates mediated by human activities is a key outcome of regenerative agriculture practices. Nutrient Cycling Nutrient cycling in soils—the source of human sustenance and thus the most critical feature of the soil ecosystem (Lal 2009)—is the process of movement of soil nutrients from the atmosphere and geosphere through the soil into the biosphere, where the nutrients cycle through ecosystems. Soil nutrients that support plant life—which in turn supports animal and human life—come from the atmosphere (carbon, hydrogen, oxygen, nitrogen) and geosphere (phosphorus, potassium, sulfur, calcium, iron, and the so-called micronutrients boron, manganese, chlorine, copper, molybdenum, selenium, and others). Removal of plant biomass from the ecosystem through harvesting or grazing, or of soil through erosion, depletes the nutrient stocks (especially nitrogen, phosphorus, and potassium) in the system. When nutrients are not replenished on cultivated cropland or grazed lands, the ecosystem must be replenished through mineral or organic fertilization (Tan et al. 2005). Nutrient-depleted soils result in plants that are more vulnerable to drought and disease and produce less biomass (forage and crops). Globally, nutrient depletion in soils from human activities is widespread (e.g., potassium depletion affects as much as 90 percent of harvested areas) and contributes to yield losses, erosion, food insecurity (Tan et al. 2005), and human malnutrition (Lal 2009). FIGURE 1 Carbon transformation pathways in soil, supporting nutrient cycling and carbon sequestration. Carbon Transformation Transformation of atmospheric carbon dioxide to phytochemicals such as glucose and other carbohydrates through photosynthesis is the basis of most life on Earth. Carbon transformation in the soil makes atmospheric carbon transformation possible. Carbon enters the soil as organic particulates from plants, animals, manures, and organic amendments and becomes SOC, which is the energy source for the soil microbiome (figure 1). Tillage transports SOC to deep soil where atmospheric exchange is limited and therefore carbon is sequestered. But agricultural practices over the past 100 years have resulted in the depletion of SOC pools by 25–75 percent (10–30 Mg/ha) (Lal 2013, 2018), a loss that impacts microbial activity, soil aggregation, and nutrient cycling (Denardin et al. 2022; Dynarski et al. 2020). Adoption of recommended management practices can restore SOC stock over a generational time scale (Lal 2008, 2018) while enhancing soil health and improving productivity (Lal 2020b). SOC in upper soil is transformed by microbial metabolism to become soil organic matter (SOM), a complex matrix of organic materials that contain as much as 50 percent SOC and high concentrations of crucial nutrients (Lal 2018, 2020a). SOM can be a critical factor in plant-available water in the root zone as it supports increased porosity, allowing greater water infiltration during precipitation and less runoff and erosion. Thus SOM and porosity make the soil more climate resilient (Lal 2018, 2020b). The dynamic exchange of nutrients through the soil microbiome occurs in pore spaces and flow paths from soil aggregates, which provide liquid and gas exchanges that are necessary for plant growth. Soluble SOM can leach to deep soil to be sequestered from the atmosphere. The carbon transformation process that creates SOM increases aggregate formation, nutrient availability, and carbon sequestration potential, and supports a diverse microbial community. Regulation of Diseases and Pests The role of soils in regulating plant diseases and pests is a form of allelopathy, the inhibitory or stimulatory biochemical influence of one species on another in an ecosystem. Many plants have evolved strategies to exude sugars and other substances from their roots into the rhizosphere to support beneficial rhizobacterial, fungal, and insect communities and inhibit deleterious ones. Some plant leaves leach chemicals into the soil with similar beneficial impacts (Sturz and Christie 2003). In addition, soil biotic and abiotic parameters impact plant disease suppression (Janvier et al. 2007). The relationship between SOM and plant disease is becoming clearer. Biofertilizers (combined organic, humic, and nutrient fertilizers) provide a plant-beneficial consortium against fungal pathogens (Tao et al. 2020). Organic amendments that promote populations of Pseudomonas and Streptomyces, for example, have been demonstrated to suppress wilt-causing Verticillium (Bonanomi et al. 2018). Priority innovations in data acquisition include sensors for subfield monitoring of soil density, pH, temperature, moisture, SOC, and nutrients. The complexity of these interactions makes simple causal relationships difficult to demonstrate across diverse soil and cropping systems. This complexity is often interpreted as uncertainty about the relationships, and thus becomes a barrier to policy and practice implementation that support soil resilience. But there is little uncertainty that the impact of agricultural cultivation is often the loss of the soil biodiversity that supports regulation of plant disease and pests (Billings et al. 2021). Preserving and restoring soil biodiversity and resiliency is key to increasing yields while preserving soil biome health (Waqas et al. 2020). The Path to Resilient Soils Management (or mismanagement) of life systems, resources, and water has defined the practice of agriculture from the beginning in the pursuit of productivity for human benefits. It is increasingly understood that such single-minded motivation is not sustainable. A new, integrated framework of understanding is essential to make better decisions for better outcomes. This new framework cannot be created just by collecting more data or developing a new sensor, but rather requires development of a more holistic way of understanding and managing the dynamic soil ecosystem. The exploration of soil ecosystem dynamics, indicators of soil health, and soil resilience has expanded exponentially in the past decade (Karlen et al. 2019; Rice et al. 2021). This new way of understanding the dynamic interactions between the physical, chemical, and biological processes in soil has resulted in the emergence of a renaissance in soil sciences (Hartemink and McBratney 2008). Integration of the four soil ecosystem functions into a metasystem understanding of soil dynamics is accelerating the emergence of this renaissance in soil ecosystem management with the aim of enhancing resilient soils.[4] Because soil is equated to land in most societies and largely held in private ownership, developing portfolios of practices that increase high-value functions in soils, such as sequestration of atmospheric carbon, will require high-resolution decision support systems (DSSs) for land owners and managers. Such systems require more sophisticated data acquisition methods and models than are currently available (Amelung et al. 2020). Decision making to support resilient soils may benefit from a dynamic soil information system (DSIS) with high temporal and geospatial resolution (NASEM 2021). Priority innovations in data acquisition to support the DSIS include sensors for subfield monitoring of soil bulk density, pH, temperature, moisture, SOC, and plant-available nutrients at multiple depths and at high temporal and spatial resolutions. These data will need to be integrated into a decision support model populated with both historic and current land uses and practices. While the combined DSIS-DSS database and model will be dynamically integrated with precision agriculture data acquisition systems—providing planting, cultivation, and yield data at subfield (square meter) spatial resolution—an active artificial intelligence model will learn to make risk-based recommendations for land managers. Combined with a growing toolbox of technologies, these integrated data acquisition and model systems describe pathways forward (figure 2) and support the convergence of knowledge, new technologies, and integrated understanding. FIGURE 2 Soil management to achieve sustainable and regenerative agriculture. GHG = greenhouse gas. Reprinted with permission from Solutions from the Land (2021). The Way Forward: Opportunities and Needs Many producers recognize the complex and dynamic interactions that drive soil resilience, but these interactions have only recently been recognized across the scientific community (Bonanomi et al. 2018; Giller et al. 2021). Creating a science-based framework for understanding and managing the metasystems that create resilient soils requires full stakeholder engagement. It is imperative to translate science into action through (i) active involvement of the private sector, (ii) policy interventions supporting farmers’ decision making that enhances soil health, and (iii) provisions for payments for ecosystem services (e.g., for carbon sequestration). FIGURE 3 Catalytic model for an agricultural renaissance. Reprinted with permission from Solutions from the Land (2021). The catalytic model (figure 3) developed by Solutions from the Land describes the pathway from the current state to the desired future state. The first step is to recruit conveners who have a clear understanding of the challenges and opportunities from the DSIS. Conveners are trusted organizations that can mediate location- and context-driven conversations between stakeholders (interested and affected parties) to increase understanding of complex problems and identify potential pathways to reconciliation. Action plans developed by the conveners through the multistakeholder process should be developed in such a manner that they can be championed by organizations with resources and authority to act. The way forward demands disciplined focus and determined action to achieve the promises of sustainable and regenerative agriculture approaches. The connections between more data, a better understanding of the unique dynamics in each soil production system, and crop production resilience need to be embraced and incentivized. The innovations and integrations necessary to accelerate the soil renaissance will require novel public-private partnerships with strong commitments to public sharing of data and knowledge for the more than 2 million US farmers and 570 million farmers around the world who generate and curate these data. Improved knowledge and understanding will encourage the replication and scalability of successful practices for sustainable and regenerative agriculture. Ultimately the people who manage the soils are the farmers who till the land, the land owners who put marginal lands in conservation programs, and the agencies who support them. Protecting, restoring, and enhancing life on Earth begins and ends with the soil. References Amelung W, Bossio D, de Vries W, Kögel-Knabner I, Lehmann J, Amundson R, Bol R, Collins C, Lal R, Leifeld J, and 10 others. 2020. Towards a global-scale soil climate mitigation strategy. Nature Communications 11:5427. Billings SA, Sullivan PL, Hirmas DR, Zhang X, Faria Tavares de Souza L, Guthrie AA, Unruh MA, Lang KA, Swantek TA, Li L, and 3 others. 2021. Towards a predictive understanding of the biotic drivers of soil structure [Abstract]. ASA, CSSA, SSSA Internatl Annual Mtg, Nov 7–10, Salt Lake City. Available at https://scisoc.confex.com/scisoc/2021am/meetingapp.cgi/ Paper/132851. Bonanomi G, Lorito M, Vinale F, Woo SL. 2018. Organic amendments, beneficial microbes, and soil microbiota: Toward a unified framework for disease suppression. Annual Review of Phytopathology 56:1–20. Bronick CJ, Lal R. 2005. Soil structure and management: A review. Geoderma 124(1-2):3–22. Denardin LGdO, Martins AP, Flores JPM, Alves LA, Pires CB, Machado DR, Anghinoni I, Carvalho PCF, Kuzyakov Y, Rice CW, Chabbi A. 2022. Fertilization effects on soil microbial composition and nutrient availability in integrated rice-livestock production systems. Applied Soil Ecology 174:104420. Dynarski KA, Bossio DA, Scow KM. 2020. Dynamic stability of soil carbon: Reassessing the “permanence” of soil carbon sequestration. Frontiers in Environmental Science 8:514701. Giller KE, Hijbeek R, Andersson JA, Sumberg J. 2021. Regenerative agriculture: An agronomic perspective. Outlook on Agriculture 50(1):13–25. Hartemink AE, McBratney A. 2008. A soil science renaissance. Geoderma 148(2):123–29. IPCC [Intergovernmental Panel on Climate Change]. 2019. 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[1] In the United States examples include Field to Market (https://fieldtomarket.org/), the Stewardship Index for Specialty Crops (https://www.stewardshipindex.org/), and the US Roundtable for Sustainable Beef (https://www.usrsb.org/), [2] https://www.nrdc.org/stories/regenerative-agriculture- 101 [3] https://regenerationinternational.org/why-regenerative- -agriculture/ [4] https://www.farmfoundation.org/ About the Author:A.G. Kawamura is founding cochair of Solutions from the Land. Rattan Lal is distinguished university professor of soil science, College of Food, Agricultural, and Environmental Science, Ohio State University. Marty Matlock is professor of biological and agricultural engineering, University of Arkansas. Charles Rice is university distinguished professor, Department of Agronomy, Kansas State University.