Looking Deeper Than Yield. Part 1 of 4. by The Duff Company

Looking Deeper Than Yield

Plant Nutrition in the 21st Century Article 1 of 4-part series to deliver insights on how fertilization is evolving.

Plant nutrition is a key component in increasing and sustaining crop yield. Introduction The first practice of plant fertilization probably came from empirical observation. Plants growing in places with accumulation of manure had better vigor and higher yields. The impact of spreading that manure to the whole field could be easily observed through a noticeable increase in plant vigor and yield. Imagining this learning experience unfolding offers the perfect summary for the evolution of plant nutrition. Advancements in chemistry and biology allowed the evolution from this empirical experience dealing with a single variable (manure) with large effects, to a more precise experimental observation of its main components (N, P and K) also with individual large effects. But as the knowledge further evolved, so did the resolution to measure and understand factors with smaller effects, like micronutrients. And with those, more sophisticated strategies to fertilize plants evolved. These include different formulations, delivery methods, timing of applications and more routine addition of micronutrients. A combination of superior genetics, optimum crop protection and more efficient mechanization has led to a 7-fold increase in corn yield the last 75 years in the United States. But as we continue to learn, it becomes clear that we must go beyond chemical fertilization to optimize plant nutrition. We must look more closely at the biology of the rhizosphere to help guide use in developing sustainable fertility strategies for the next half a century. Our knowledge about the soil microbiome, microbial mediation of soil functions, plant-microbe interactions, soil nutrient fixation and solubilization, along with the introduction

About the Authors Dr. Gloverson Moro

Director, Global Product Development Moro leads the expanding science and technology group at AgriThority, directing product development, fieldtesting, and regulatory services worldwide. His extensive experience spans seed development, biotechnology, crop protection, and regulatory management of teams in Latin America, Asia Pacific, and North America. He has multiple academic degrees including an MBA and Ph.D. in Molecular Biology. He is fluent in Portuguese, English and Spanish.

Dr. Dan Davidson

Product Development Manager Davidson applies his vast experience in technology adoption, communication and training to client projects. His compelling technical writing skills support clients’ technology transfer opportunities as well as the interpretation of field trial results. Davidson holds three degrees in agronomy: a bachelor’s degree from the University of Nebraska, a master’s degree from the University of Missouri, and a Ph.D. from Washington State University, followed by post-doctoral work at the University of Nebraska. A Nebraska resident, Davidson’s early agronomy career spanned eight years in Mexico, Liberia and Uganda.

Looking Deeper Than Yield

of biostimulants show that there are other venues to explore, making plant nutrition more efficient and sustainable. Furthermore, the notion of plant nutrition should be more associated with the soil, not just indexed to yield requirements. The way we look at soil resources and crop management is changing as growers embrace the benefits gained from improving soil health. Increasingly, growers are putting as much emphasis on farming the soil as farming the crop. Practicing soil health will foster regenerative and sustainable practices that protect the soil, our environment and the world’s food supply while improving a grower’s bottom line. The knowledge that brought us to where we are today will not take us into the future.

History Soil is our greatest natural resource and is the foundation of food production around the world. We quickly recognized how important this resource was 100 years ago with the advent of the Dust Bowl when drought combined with extensive tillage (plowing) left soil exposed to the ravages of wind. From that event was borne the Soil Conservation Service (SCS), the forebearer of today’s National Resource Conservation Service (NRCS). Over the past 70 to 80 years growers have been adopting numerous conservation practices to protect the soil and keep it in place, including minimum and no-till, terraces, contour farming, grassed waterways and buffer strips, to name a few. More recently practices have expanded to include both water conservation and surface water protection. Synthetic fertilizer was invented during the first half of the 20th century. The Haber-Bosch process, developed in the early 1900s, fixes atmospheric nitrogen with hydrogen to produce ammonia — a critical component in the manufacture of many chemical fertilizers. However, commercial production and adoption did not occur until after the second World War. Before, growers who recognized the contribution of nutrients rotated crops, included legumes in their rotation and applied manure or compost to their fields. These practices are still carried on today by organic producers. In the second half of the 20th century growers learned about fertilizer and how to apply it while universities developed early recommendations for nitrogen (N), phosphorus (P) and potassium (K) based on soil tests and yield targets. The ability to measure and understand the effects of those macronutrients allowed growers to incorporate fertility management to their routine practices. Pulling soil samples for analysis and using those to guide the fertilization regime became part of farming. Improved nutrient management contributed to the Green Revolution when new varieties, commercial fertilizers, agrochemicals, mechanization and irrigation were adopted. Increased yields and more sustainable food supply followed. While these approaches were cornerstones to sustain yield and food security, we did not fully understand the cost to the environment and our natural resources. Production of chemical fertilizers generates a considerable amount of effluents that can adversely affect ground and surface waters, as well as emission of gases containing nitrogen and sulfur, causing air pollution. As nutrients applied are carried off by surface waters or leached down into the soil and discharged via tile lines, they affect water quality that contribute to the creation of hypoxic dead zones in surface waters where aquatic life cannot exist. Furthermore, very little understanding existed about how soil chemistry could affect soil biology and, consequently, soil health. As before, the path forward in plant nutrition is being paved by the increase of scientific resolution. In chemistry: the understanding and the importance of the elements with smaller effects, as well as formulations and precise delivery that drive efficiency. In biology: the role microbials play to increase the efficiency of fertilization and to potentially replace chemical fertilizer. Finally, the growing concern with the environment is driving thought process not only about what is done, but how it is done.

Looking Deeper Than Yield

Today Moving beyond the basic N, P, K is the science of today. Since the beginning of the 21st century much has changed about nutrient management including regulatory and environmental requirements. Soil sampling is commonplace, and the frequency of sampling has increased. The advent of precision agriculture introduced more detailed grid and zone soil sampling and variable rate applications that better match soil resources with the needs of the crop. We better understand the chemistry of the soil and how it influences nutrient availability while recognizing that today’s varieties are more efficient in capturing available nutrients to produce more with less. Tissue sampling is routine as a supplement to soil testing, to check whether crops have sufficient nutrient concentrations to sustain growth and meet yield expectations. While growers still primarily rely on N, P and K macro fertilizers, plant nutrition strategies now go beyond these basics. Applications of secondary macronutrients (Ca, Mg and S) and micronutrients are more common. When used, animal manures are now precisely applied more as a fertilizer rather than as waste disposal. Also, a broader range of more sophisticated formulations are marketed for different goals. Current concepts include combination starters, foliar cocktails for feeding the plant at later stages, and products that release nutrients more slowly to closely match crop demands while reducing the risk of loss. Other new technologies include sensors that predict needs and additives that keep nutrients available. Chemistry is not the only science that evolved regarding plant nutrition. The understanding of the soil as a living and breathing environment has brought the microbiome to the center stage. The capacity of microorganisms to make nutrients available in the soil is an alternative that can complement and supplement chemical fertilization. An example is the ability of soybean to fix and provide 50 to 60 percent of its own nitrogen (through symbiotic N fixation) with the remainder coming from the soil’s own resources or remaining fertilization from previous crops. As more complex symbiotic interactions between plants and microbials are identified and understood, other opportunities for enhancing nutrient availability and uptake are surfacing.

As plant nutrition reaches a new level of maturity and sophistication, the relevance of microbials also will increase. Chemical fertilization will not lose importance, but the combination with microbial agents will allow additional growth in yield, while sustaining a better environmental profile. Potentially, microbials can replace chemical fertilizers, improve nutrient availability and uptake by plants, provide bioremediation options and provide biostimulants to plants through symbiotic relationships. All of that with the potential to improve the overall soil health. The underlying science can still evolve and it is the best option to continue improving yield and farm profitability while meeting the environmental challenges. Again, it is not just about what is done, but how it is done.

Tomorrow Much more diverse nutrient manage ment options will become available to growers in the future, allowing them to manage the plant nutrition more holistically. As much as yield and farmer profitability remain the top priority, our increasing knowledge about soils, its microbiome and the need to protect our environment will drive changes to current practices. Providing nutrients to crops will be coupled with measures on managing soils as a whole ecosystem, making fertilization a more efficient and sustainable process, while reducing its environmental impact. The full concept of soil health will gain momentum.

Looking Deeper Than Yield

Strategies that make the current nutrition methods more efficient include: ● Microbial products that can either

foster the soil’s native microbiome to be more active in recycling carbon and nutrients or stimulate the plants to absorb more water and nutrients from the soil are making crops more resilient to environmental stress. Soil-based microbials promote a more efficient utilization of the available nutrients while reducing environmental loss and consequent impact.

● Nitrogen stabilization through

incorporation into stable organic nitrogen can reduce nutrient loss through leaching and volatilization.

● Late summer- and fall-planted cover crops capture and trap residual nitrate-N.

● Microbials can make minerals, like phosphorus, that normally tie up, become more available.

The understanding of biological processes is continuously evolving, opening the perspective of improving their efficiency for large scale utilization. As this happens, formulation technology that mixes different technologies will become even more relevant. New formulation technology can make it easier to deliver bio-based fertilizers and additives using equipment available to farmers and with the same simplicity as adding seed to a seed box or bin. This will ensure that products are most efficacious, and farmers will get the most return from their investment with the least amount of inconvenience. Our sources of nutrients will substantially change in the future. Microbial-based biological nutrient production will provide another source complementing chemical fertilization.

Biological Nitrogen Fixation (BNF) is the most common example. Legume crops form a symbiotic relationship with rhizobia bacteria. Soybean, alfalfa, clover and other crops rely on BNF to meet their N requirements. But the goal is to expand these biological processes to other crops and nutrients. When these processes become efficient, microbials can completely replace all, or a good portion of, chemical fertilization. One such large scale example of BNF completely replacing N fertilization already exists in Brazilian soybean production. There inoculating soybean seeds with rhizobia bacteria has completely replaced the application of commercial nitrogen. Our evolving knowledge on these biological processes, coupled with the power of new genetic manipulation technologies such as genome editing, promises to unleash the potential of greater biological nutrient production. Biostimulant products can stimulate plant biological processes, increase efficiency and improve plant growth, yield, quality and potentially resilience to abiotic and biotic stresses. Coupled with a strong nutrition, biostimulants can provide that extra edge. Nutrient recycling is an option that also should become more relevant. That may happen through microbial residue digestion in the field or through waste and sewage recycling. High-yielding grain crops like corn and wheat produce a lot of residue that is slow to break down, ties up valuable nutrients and impedes planting or emergence of the next crop. Biological technologies can speed up decomposition of a previous crop’s residue, releasing valuable carbon and nutrients back into the soil while improving crop plantability the following season. These products include microbes, feedstock, or enzymes, either alone or in combination. Additionally, several commercial companies now process sewage and other organic wastes, recovering valuable nutrients and carbon to create products that compete equally with existing chemical fertilizers. This advancement deserves merit on at least three fronts: (1) it reduces the environmental impact of sewage discharges, especially in water, where the excess of nutrients has led to the creation of dead zones, like the one in the Gulf of Mexico. (2) it has the potential to reduce the need of mining for nutrients such as P and K, thereby reducing the respective environmental impact; and, (3) it offers an alternative source of nutrients which have limited reserves that are being quickly depleted, like the case of P.

Looking Deeper Than Yield

Conclusion: The yield increase in agriculture in the last century as a process can be compared to the evolution of life expectancy in the overall human population. Both were the result of the combination of better nutrition, better health protection and an environment artificially set to allow the survival and performance. But as agriculture evolved, a better analogy would be with high performance athletes. Modern varieties and hybrids are a small subset of the overall plant population selected for high performance. Obvious differences aside, that same occurrence happens with high-performance athletes: a small subset of the overall population has above-average physical attributes and abilities. Nutrition is a vital component of their extra-human performances and their diet is different than that of a healthy, regular human being. That includes not only the necessary calories, but also additional elements, supplements, and stimulants, all aiming to optimize their performance. The same approach should be applied to plant nutrition. Based on the always evolving knowledge available, the best combination of factors going beyond the major elements should be considered in supplying a balanced nutrition to plants aiming to maximize their yield. Today this includes a

combination of macro and micronutrients and microbials. The future points to an even more complex set of options. This is what will drive that extra‑performance. Today one should consider not only the what, but also the how. As environmental and regulatory pressures build, the increase of options with less impact is inevitable. This gives the utilization of microbials an edge into the future. Potential reduction in nutrient runoff and carbon footprint and increased efficiency in nutrient usage will be factors to be considered when making fertilization choices in the future. In fact, the overall concept of soil health also comes into play. Going back to the human analogy, the notion of what is a healthy environment is changing and driving new behaviors. In same way, the acknowledgement that the soil is the main asset and should be preserved will also drive agricultural practices in the future. The challenge is not how to manage the increase in number of variables, digital tools and growing amounts of information. The challenge is to translate that knowledge into common, day-to-day farming practices.

References Ayoub, A.T., 1999. Fertilizers and the environment. Nutrient Cycling in Agroecosystems 55, 117–121 (1999). https://link.springer.com/article/10.1023/A:1009808118692

National Ocean Service, Hypoxia. https://oceanservice.noaa.gov/hazards/hypoxia/

Wikipedia, Green Revolution. https://en.wikipedia.org/wiki/Green_Revolution

Singh, B., Ryan, J., 2015. Managing Fertilizers to Enhance Soil Health. IFA. https:// www.fertilizer.org/images/Library_Downloads/2015_ifa_singh_ryan_soils.pdf

NRCS, Healthy Soil for Life. https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/ health/

Loneragan, J.F., 1997. Plant nutrition in the 20th and perspectives for the 21st century. Plant and Soil Vol. 196, No. 2, pp. 163-174. https://www.jstor.org/stable/i40113524

Briney, A., 2020. History and Overview of the Green Revolution. ThoughtCo. https:// www.thoughtco.com/green-revolution-overview-1434948

Encyclopedia.com, Soil Conservation Service (SCS), https://www.encyclopedia.com/ economics/encyclopedias-almanacs-transcripts-and-maps/soil-conservationservice-scs

Wikipedia, History of Fertilizer. https://en.wikipedia.org/wiki/History_of_fertilizer McGuire, A., 2020. How does regenerative agriculture reduce nutrient inputs? Center for Sustaining Agriculture and Natural Resources. Washington State University. http://csanr.wsu.edu/how-does-regenerative-agriculture-reduce-nutrient-inputs/

Digital imaging and evaluation is one of our many product and field development services. See What We Do on our website. 11125 N Ambassador Dr Kansas City, MO 64153-2033 United States

Franzen, D.W., Professor Soil Science, NDSU Extension Soil Specialist. 2018. Soil Sampling as a Basis for Fertilizer Application. https://www.ag.ndsu.edu/ publications/crops/soil-sampling-as-a-basis-for-fertilizer-application

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