Soil Science, Integrated Systems and Nyle Brady's Clarion Voice and Legacy

On 24 November 2015 Soil Science lost one of its giants, Nyle C Brady. Nyle was elected President of both the American Society of Agronomy and of the Soil Science Society of America. As Director General at the International Rice Research Institute (IRRI) in the Philippines (1973-1981) he contributed much to the original green revolution. He oversaw the transition to a second-generation of green revolution soil management and plant breeding designed to overcome some of the shortcomings of the first generation. He worked to begin collaborations between IRRI and agricultural scientists in China at a time when that country was quite closed to the outside world.

During the 1980’s, as Senior Assistant Administrator for Science and Technology at the U.S. Agency for International Development, Nyle was a fierce champion of North-South scientific cooperation to promote sustainable resource use and agricultural development. He also recognized the need to protect the ability of soils to provide ecosystem services, especially in the tropics, and called for development of alternatives to slash and burn agriculture. During the 1990’s Dr. Brady, then in his 70’s, continued to be active in the SSSA provide, often providing a steady voice of reason that bridged and inspired generations of soil scientists.

Despite all these positions of leadership, Nyle himself observed that he was best known for his work, starting in 1950, on the classic soil science textbook, The Nature and Properties of Soils. Dr. Brady’s early career research and his experience with plant breeding programs at IRRI convinced him that soil science would benefit greatly from collaboration with plant science (and vice versa). This conviction shaped his approach to writing The Nature and Properties of Soils. When I began as Nyle’s coauthor in 1993, he was amendable to expanding that outlook to include integrating Soil Science with Ecology, Earth and Environmental Sciences. I found that Nyle was always open-minded and willing to go where the scientific evidence led.

Each edition of the textbook has reflected a greater understanding of the intimacy and complexity of soil integration with all Earth systems, from hydrology and water quality, to atmosphere and climate change, to biodiversity and biogeochemical cycles. In some ways the evolution of our textbook paralleled the apparent Soils Renaissance of the early 21st century which has seen the number of scientific publications on soils and public interest in soils soar. Yet, at the same time, formal soil science academic programs and departments were shrinking and, in some cases, disappearing at universities in North America and around the world. It has become increasingly recognized that soil science has a central role to play in understanding and managing biogeochemical processes, climate change, biodiversity, water resources, and other great natural resource challenges. One of the joys (and challenges) of teaching soils is to use this complex system to help students see connections and become aware of context.

Ecosystems research - including agro-ecosystems, and by extension, food security research - is being dramatically transformed by the emergence of new insights and paradigms about what we long thought were settled basic truths. The conceptual changes - some completely upending established models - are partially driven by the development and adoption of new analytical tools, ranging from metagenomics to x-ray tomography and abetted by increasingly sophisticated statistical analyses of the resulting huge amounts of data.
The application of these tools to soils questions in ecosystems research may not always be carried out by those that would identify themselves as soil scientists. As these scientists grapple with how particular soil processes influence ecosystems, it is important that they have internalized a broad and integrated view of soil science. Whatever specialty they bring to the ecosystem analysis team - molecular biology, chemistry, physics, hydrology, microbiology, pedology - scientists also need to see the context of their specialty within the larger complex soil system. Even in interdisciplinary teams it is important that each member be able to keep sight of the whole- that the soil physicist understand the landscape, that the molecular biologist understand soil horizons, etc.

Furthermore, the integration of plant and soil sciences that Dr. Brady championed has never been more compelling. The cover crop revolution sweeping North American agriculture is all about managing plants to improve soils - rather than the other way around. Soil physical and chemical properties take on new dimensions when they are considered as defining root and microbial habitat. In fact the boundary between plant and soil has become blurred so that it is a grievous distortion to imagine one without the other. In fact, the boundary between plant and soil becomes blurred as we learn more about the rhizosphere and plant-microbial community interactions. Is a mycorrhizal network plant or soil? What about the layer of root exudates that shapes the physics, chemistry and biology of the soil system? In most contexts (hydroponics and Mars soils, notwithstanding), plants cannot exist, function or truly be studied in the absence of soils - and vice versa.