4 Science and Technology for Sustainable Agriculture

Ensuring that everyone has access to healthy and nutritious foods without further reducing biodiversity and damaging the environment will require major changes in many aspects of food systems. Yields on agricultural land will need to go up while the pollution from agricultural production declines. Agriculture will need to become a net sink rather than a source of greenhouse gas emissions by sequestering carbon in ecosystems and in the soil. The environmental effects of livestock production will need to be reduced while the nutritional benefits of animal-source products are maximized. People will need to eat more fruits and vegetables while reducing the large amounts of food that are wasted today.

As the 2019 National Academies of Sciences, Engineering, and Medicine report Science Breakthroughs to Advance Food and Agricultural Research by 2030 pointed out, creating a sustainable global food system will require the development and application of many new technologies and the continued pursuit of new scientific knowledge.¹ This chapter describes some of the many beneficial agricultural technologies that already exist and are on the horizon. The next chapter examines policies that will be needed to deploy those technologies and move toward a sustainable food system.

DATA-INTENSIVE AGRICULTURE

An approach known as precision agriculture offers great potential to improve yields, reduce costs, and minimize environmental damage. Mapping farms for soil moisture, temperature, nutrients, and other indicators using ground sensors, drones, and instruments on farm equipment can provide actionable insights for farmers, suppliers, and distributors. The measurement of ground conditions combined with remote sensing and the observation of weather patterns can optimize irrigation, fertilizing, weeding, and pesticide applications. Data gathered from farms can inform the development of better livestock, advisories based on artificial intelligence, and ways of monitoring technology usage. Simulation technologies can model scenarios to inform planning and prepare for contingencies.

The main barrier to precision agriculture, especially for smallholder farmers, is the cost of data collection, but the costs are dropping rapidly. For example, connectivity to instruments in the field

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¹ NASEM (National Academies of Sciences, Engineering, and Medicine). 2019. Science Breakthroughs to Advance Food and Agricultural Research by 2030. Washington, DC: The National Academies Press.

could be provided by devices that embed signals in unused television channels, many of which are vacant in rural areas.² Drones are available for $1,000 or less and can cover large areas quickly, and instruments carried by tethered balloons are even less expensive. New artificial intelligence and machine learning techniques can interpolate missing data from sensors, such as satellite data where clouds block views of the ground. Better connections between farmers and central databases can transfer data in both directions so that farmers can benefit from the analyses of the data collected on their farms and from best practice recommendations.

Farmers will also need education and training to be able to use these technologies and the information they provide, which implies, in part, working with young people to encourage them to get interested in farming and in applying these technologies. Also, the data collected by precision agriculture and the information generated from that data will be valuable and will need to be protected, with an equitable allocation of the benefits derived from that information. Some of the data can be anonymized, though this is a difficult challenge, because the data are so closely tied to location and to applications. Computer scientists will need to work with agricultural scientists and with farmers to overcome such challenges and to formulate experiments that can inform the development and deployment of technologies.

Beyond precision agriculture, a wide variety of other advanced technologies could be applied to agriculture to enhance sustainability.^3,4 New applications of technology could provide decision support to farmers and consumers, help connect the biological sciences with fields such as engineering and materials science, and ensure that data-collection methods are affordable and practical. Technologies such as robotics, artificial intelligence, process engineering, and synthetic biology could come together to shift the paradigm from “food produced by agriculture” to “food produced by manufacturing.” High-tech, three-dimensional vertical farms could efficiently produce clean and organic food within urban centers. Foods requiring less energy to produce could be grown near the point of consumption to reduce transportation costs, with energy-dense commodities produced near energy sources such as hydroelectric and solar power. Synthetic milk and meat products, insect and microbial bioreactors, marine algal culturing, biofortified foods, the use of insects for livestock feed, and closed-loop livestock production could enhance diets while reducing the environmental impacts of agriculture. A new green revolution could be based on science, ecological efficiency, and the careful management of food production and distribution. Nutrition, yields, and environmental outcomes could all benefit by maximizing the efficiency of the food system as a whole.⁵

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² Roberts, S., P. Garnett, and R. Chandra. 2015. Connecting Africa Using the TV White Spaces: From Research to Real World Deployments. The 21st IEEE International Workshop on Local and Metropolitan Area Networks.

³ European Environment Agency. 2020. The European Environment—State and Outlook 2019. Knowledge for Transition to a Sustainable Europe. Luxembourg: Publications Office of the European Union.

⁴ Cui, Z., H. Zhang, X. Chen, C. Zhang, W. Ma, C. Huang, W. Zhang, G. Mi, Y. Miao, X. Li, Q. Gao, J. Yang, Z. Wang, Y. Ye, S. Guo, J. Lu, J. Huang, S. Lv, Y. Sun, Y. Liu, X. Peng, J. Ren, S. Li, X. Deng, X. Shi, Q. Zhang, Z. Yang, L. Tang, C. Wei, L. Jia, J. Zhang, M. He, Y. Tong, Q. Tang, X. Zhong, Z. Liu, N. Cao, C. Kou, H. Ying, Y. Yin, X. Jiao, Q. Zhang, M. Fan, R. Jiang, F. Zhang, and Z. Dou. 2018. Pursuing sustainable productivity with millions of smallholder farmers. Nature 555:363–366.

⁵ Benton, T. G., and R. Bailey. 2019. The paradox of productivity: How agricultural productivity promotes food system inefficiency. Global Sustainability 2(e6):1–8.

BIOTECHNOLOGIES

Genetic technologies and other advanced biotechnologies offer tremendous potential to improve agriculture, particularly if they are integrated with agronomy and agroecology. Examples of possible advances include crops and livestock resistant to high temperatures and drought, protection against new and emerging pests and disease, greater efficiency in water use, increased nutritional value in foods, and reduced fertilizer use.

Many such biotechnologies are already available or under development. For example, a new technique known as “speed breeding” has shortened the cycle from seed to seed.⁶ Agricultural biotechnologies are being developed that can insert new genes into cells, edit and delete targeted genes, and alter multiple genes at once while avoiding breeding bottlenecks and the loss of diversity in crop populations.

An example of these biotechnologies involves the protection of crops from pests. One way that grasses such as maize, rice, and wheat protect themselves from herbivores is by taking up silicon from the soil and depositing it within plant cells and in spines and hairs on the plant surface, so that herbivores are less likely to consume the plant. Higher levels of silicon also protect against drought and salinity stress, though the mechanisms behind these effects are not fully understood. Domestication has reduced silicon levels in plants by a small amount, but these defenses largely remain in place.⁷ Genetically modifying how plants use silicon could therefore provide possible mechanisms of pest resistance and drought resistance. This research has already led to inexpensive methods of increasing the supplies of silicate in soils to mitigate salt stress and improve yields, such as through the application of silicate-rich steel furnace slag.⁸ Success in applying such methods will require not only technological advances but also integrating crop breeding and genetic approaches with agronomical practices and practical advice for farmers.

New tools that deliver DNA, RNA, or proteins into plant cells could enhance the use of genetic technologies in producing new food, bioenergy, or medicinal applications. A plant transformation technology that is independent of plant species, efficient, nonpathogenic, and nonintegrating (in that the DNA being introduced into the cell would not integrate into the plant’s DNA) would be especially valuable.⁹ An example of such a technology is the ability to use new nanomaterials to

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⁶ Watson, A., S. Ghosh, M. J. Williams, W. S. Cuddy, J. Simmonds, M-D Rey, M. A. Md Hatta, A. Hinchliffe, A. Steed, D. Reynolds, N. M. Adamski, A. Breakspear, A. Korolev, T. Rayner, L. E. Dixon, A. Riaz, W. Martin, M. Ryan, D. Edwards, J. Batley, H. Raman, J. Carter, C. Rogers, C. Domoney, G. Moore, W. Harwood, P. Nicholson, M. J. Dieters, I. H. DeLacy, J. Zhou, C. Uauy, S. A. Boden, R. F. Park, B. B. H. Wulff, and L. T. Hickey. 2018. Speed breeding is a powerful tool to accelerate crop research and breeding. Nature Plants 4:23–29.

⁷ Simpson, K. J., R. N. Wade, M. Rees, C. P. Osborne, and S. E. Hartley. 2017. Still armed after domestication? Impacts of domestication and agronomic selection on silicon defences in cereals. Functional Ecology 31(11):2108–2117.

⁸ Johnson, S. N., S. E. Hartley, J. M. W. Ryalls, A. Frew, J. L. DeGabriel, M. Duncan, and A. N. Gherlenda. 2017. Silicon-induced root nodulation and synthesis of essential amino acids in a legume is associated with higher herbivore abundance. Functional Ecology 31(10):1903–1909.

⁹ Landry, M. P., and N. Mitter. 2019. How nanocarriers delivering cargos in plants can change the GMO landscape. Nature Nanotechnology 14:512–514.

transfer DNA, RNA, or proteins through plant cell walls with a high level of control over the molecules being delivered. For example, the introduction of the genome-editing molecule CRISPR-Cas9 using this technique could enable the modification of genes without the usual need for extensive breeding programs to eliminate DNA introduced into the genome through other techniques.¹⁰ Such a technique could be used to modify the traits of a wide range of commercially valuable crops, from wheat and cotton to spinach and arugula (rocket). It also could be used to address critical global issues in not only food production but also advanced biofuels and the synthesis of medical therapeutics.

Compared with the use of natural or induced genetic variation, targeted changes in DNA have many advantages when the genes that control the traits are known.¹¹ For example, modifications of flowering have the potential to improve the agronomic properties of many crops. To take a specific example, the modification in tomatoes of the genomic network that controls flowering can modulate plant size and yield in ways that are not possible with traditional breeding techniques. Such techniques can be used, for example, to create plants that can be grown through urban agriculture in vertical farming systems.

Grand challenge problems in biotechnology, while ambitious, could yield very high returns. An example would be the introduction of nitrogen-fixing capabilities directly into crops to reduce the use of nitrogen fertilizers and to boost yields where fertilizer use is currently suboptimal. Many of the genes that would be involved in fixing nitrogen in crops already exist because they play other roles in these plants. Another option would be to modify the microorganisms present in soil that live in association with plants and provide them with nitrogen and other nutrients. Modifying these associations could also increase the sequestering of carbon in soil, enhancing soil health while also increasing yields. (Box 4-1 presents more information about the possible uses of biotechnology to enhance soil health and fertility.)

Another potentially transformative step would be the development of crops with much higher photosynthetic efficiency, which could enable large improvements in yields. As a specific example, researchers are working on lowering the energetic cost of photorespiration, with the installation of a synthetic photorespiratory pathway improving yields by up to 25 percent.¹² Tests of this concept have shown potential, and many other opportunities exist to engineer more efficient photosynthesis.

Many crops produced using genetic technologies have already been approved and are in widespread use. Though the rate of progress has been limited by cost and by regulatory burdens, further advances could greatly enhance the sustainability of food systems. Particularly important will be increased knowledge of the genetic and environmental bases of phenotypes and the integration of this knowledge with better understanding of ecosystem-based approaches to agriculture.

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¹⁰ Demirer, G. S., H. Zhang, N. S. Goh, E. González-Grandío, and M. P. Landry. 2019. Carbon nanotube–mediated DNA delivery without transgene integration in intact plants. Nature Protocols 14:2954–2971.

¹¹ Eshed, Y., and Z. B. Lippman. 2019. Revolutions in agriculture chart a course for targeted breeding of old and new crops. Science 366(6466):705.

¹² South, P. F., A. P. Cavanagh, H. W. Liu, and D. R. Ort. 2019. Synthetic glycolate metabolism pathways stimulate crop growth and productivity in the field. Science 363(6422):45.

THE SOCIAL SCIENCES

Science and technology for sustainable agriculture include the social sciences. The emerging field of climate adaptation requires scenario and policy analyses. Efforts to change diets require interdisciplinary assessments of incentives and preferences. Changing the behavior of farmers and other actors in food systems requires understanding of incentives and barriers to change.

An important policy question that involves the social sciences is whether a keystone intervention could drive a transformation to sustainable agriculture or whether many complementary interventions are needed. For example, anti-smoking campaigns typically have involved many interventions, including education, taxes, regulation, and alternative products. How many policies would be needed to transform food systems from a business-as-usual model to an agrobiodiverse, regenerative, food-secure, equitable, and just system? Could a keystone intervention take the form of governmental initiatives, international coordination, or education and training to give people the skills they need to adopt sustainable and healthy diets?

Some policy levers are undoubtedly powerful, such as price changes created by a carbon tax, but whether they are enough to achieve the needed changes is unknown. For example, a carbon tax might do little to address biodiversity or the production of unhealthy foods, instead requiring multiple policy actions to achieve the desired outcomes. That said, events external to a system can sometimes produce rapid change, as has occurred with the coronavirus pandemic.

Another important question is how a transformation to sustainability can be just and fair both within and across countries. For example, many people are employed in the fossil fuel industry around the world. How can their needs and values be accommodated within such a transformation? The modeling of the entire food system and its links to other society systems could help reveal the dynamics of those systems and how they impact food availability and access (see Figure 4-1).