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Vol. 18 No. 3, Issue #69
Dr. Harold Reetz

 

Doubling Global Food Production: Are We Up To It?

Needed: some new champions for high-yield production to help raise the bar for the next decade.

Agriculture is faced with the challenge of doubling global food crop production between now and 2050--if not sooner--as a growing world population, improving global economies, and new uses for traditional food crops combine to add pressure to current food supplies. While this challenge may seem impossible, history tells us we have done it before. But success in achieving production increases of that magnitude will require a multidisciplinary, coordinated program. It will mean concerted efforts to improve resource efficiency and to fine-tune management systems to reduce or eliminate yield-limiting factors as well as develop site-specific management systems designed for soil/climate resources of a given field. Figure 1 is but one example of one crop regarding where we must go to avoid a world food crisis. My distinguished colleague Dr. Paul Fixen recently noted, “As we look forward, the challenge facing agriculture appears great indeed. The Millennium Project report states that the world will need twice as much food within 30 years. The World Bank predicts a need of 50 percent more food by 2030.”

Dr. Werner Nelson of the Potash & Phosphate Institute (PPI), now the International Plant Nutrition Institute (IPNI), was a leading advocate of high-yield management systems. Going to the field with Werner would often mean going to the best corn field and asking the question, “What’s the limiting factor here?” His legacy sweeps in the countless researchers and field agronomists who were influenced by this approach to improving yields and who continue to carry Werner’s passion for improving yields.
New genetics, from biotechnology and traditional plant breeding, has developed a potential for substantially higher yields. This has been demonstrated in recent years as yields have increased even under stress situations. Genetics expands the potential yield, but is only part of the story. Concurrent changes in agronomic practices are needed to fully realize that potential. Improved nutrient use efficiency through implementation of best nutrient management practices is also important. Traditional facts and principles of production need to be reviewed and revised under these new hybrids and varieties. Old thresholds for pest management may also come into question under the new genetics. Improved pest management helps to protect the potential yield of the system.

The challenge to increase corn yields was sparked in 1975 when Herman Warsaw of Saybrook, Illinois, surprised the world of agriculture by setting a new world record corn yield of 338 bu/A, a record he held until he broke it again in 1985 by producing 370 bu/A (Figure 2). Several farmers have surpassed Herman’s record in the past few years as genetics and technology have improved.

Part of Warsaw’s success was from his efforts to build the productive potential of his soil through increased nutrients in the profile with an aggressive fertilizer application program and improved tilth through careful management of tillage, crop residues, and livestock manure. His soil had a spongy feel under foot. Soil test nutrient profiles from a 1978 sampling are shown in Table 1.

Table 2 shows the soil test results from samples collected in 1985, the year Warsaw produced the 370 bu/A yield. P and K tests are well above University of Illinois recommendations. Nitrogen applied that year was approximately 485 lbs/A compared to the recommended level of 444 lbs/A (based on N at 1.2 lbs/bu of expected yield).

Was his 370 bu/A profitable? Table 3 shows a partial budget for the production costs on the record-breaking field. The 370 bu/A yield would be $925 at $2.50/bu; $1,125 at $3.00/bu. In fact, breakeven price for out-of-pocket costs was $1.25/bu and $1.60/bu if land charge is included. Yes, it was a very profitable system!

The PPI organized a series of meetings at the Warsaw farm, bringing together leading researchers from across the country and later sponsored a series of high-yield projects through the its newly formed Foundation for Agronomic Research (FAR). The PPI staff met annually with researchers to visit one of the sites to share experiences and results. This series helped guide numerous researchers, younger and older, to shift their thinking and their research programs toward defining high-yield management systems. Several of the researchers eventually achieved over 300 bu/A yields on their high-yield plots.

An attempt to duplicate the high-yield management approach used by leading farmers like Herman Warsaw was initiated at Purdue University in 1978. Drs. Kim Polizotto, Dave Mengel, and I designed a series of comparisons on a 20-acre site at the Purdue Agronomy Farm. By 1981, the third year of the study, corn yields had increased from 155 bu/A to 185 bu/A, and soybean yields had increased

from 55 bu/A to 85 bu/A. High fertility, deep-chisel plowing, high population, and genetic selections for high yields were the main factors in increasing yields.

During the 1980s interest in high-yield research declined, and because the leaders of these projects moved on to different research agendas or different jobs or retired, the high-yield production studies were terminated. Now, nearly 30 years later, we are finding interest in high-yield management systems is growing once again and a new group of researchers is beginning to reinstate such studies.

High-yield systems for the next decade must be finely tuned management systems. As yields increase, the need to measure and manage for the variability in the crop field also increases. More components of the system must be adapted to the specific variability of the field. Site-specific management becomes

more essential. This was the basis for the development of IPNI’s InfoAg Conference series. New technologies and new management tools make it possible to respond to the within-field variability more directly than ever before. Finely-tuned systems take advantage of all the resources available.

What is the maximum potential yield for corn? Based on the physiology of the corn crop, some researchers have estimated that the maximum potential, given perfect weather for the entire growing season, is just over 600 bu/A. Dr. Richard Johnson, former agronomist for John Deere & Company, estimated the theoretical maximum yield for Midwestern corn to be about 490 bu/A. The following assumptions were used in that estimate:

• 120- to 130-day growing season; 90 days of full canopy cover
• Daily solar energy input of 20 billion calories/A
• Leading to 625 lbs/A of dry matter produced per day (allowing for 1/3 of carbon dioxide to be re-released in respiration)
• 25% of dry matter used in root production; 55% of remaining above-ground dry matter goes to produce grain
• A corn crop producing 625 lbs/A/day of dry matter would yield 490 bu/A of #2 corn
• Areas with higher solar radiation would have increased yield potential.

Further elaboration on the physiological aspects of high corn yields was provided by Dr. Richard Hageman, University of Illinois plant nutrition specialist. After studying the mineral nutrition characteristics of the corn hybrid (FS 854) used by Herman Warsaw, he concluded:

• The high soil test K level in Warsaw’s field helped maintain the plant growth regulator activity that keeps N uptake and use functioning at full capacity two weeks longer at the end of the growing season
• With lower K levels, the N uptake system begins to decline, and the photosynthetic enzyme, RuPD carboxylase (the primary N storage compound in corn leaves), begins to be broken down to supply the N needs of the developing grain
• This deterioration of the photosynthetic mechanism of lower leaves leads to less sugar supply to the roots, further decreasing the ability to absorb water and nutrients
• Warsaw’s high soil K levels kept lower leaves healthy about two weeks longer, leading to increased yield potential.
  

Successfully increasing corn yields for any given site depends upon identifying yield-limiting factors and then systematically eliminating them one-at-a-time through implementation of better management practices.

Nutrient management is obviously a major part of a crop management system. The fertilizer industry has adopted a global framework of nutrient best management practices. The framework is called the “4 Rs”

of nutrient management: Right Source; Right Rate; Right Place; Right Time. The puzzle pieces in the center of Figure 3 illustrate the interlocking relationship among the practices, and then items listed around the diagram are some of the key performance indictors to be measured and monitored to ensure the management system meets the environmental, economic, and social goals of the farmer and society.

The Global Framework for nutrient best management practices adopted worldwide by the fertilizer industry helps explain the relationships among cropping system objectives and the various performance indicators of improved nutrient management.

Not until 1999, fourteen years later, was Herman Warsaw’s yield eclipsed. An Iowa farmer by the name of Francis Childs was the official winner of the 1999 National Corn Growers’ Association Non-Irrigated Corn Yield Contest, posting a yield of 393.7 bu/A.

Plant stand. His final plant stand was 44,000 plants/A. One of the most important things you can do is ensure uniform seed placement, depth, and good seed-to-soil contact to obtain a uniform seedling emergence. Non-uniform plants will do nothing but compete against one another all season long.

Planting speed. Childs planted his test area at 2 mph. The rest of his farm was at 4 mph. Even though we have improved planters today, we should not plant faster than 5 mph.

Plow. Childs used a modified “mini-moldboard” plow that plows 13-14 inches deep and leaves at least 30 percent residue on top. A healthy, high organic matter soil will maintain its structure longer following sub-soiling and will improve nutrient availability, drainage during wet times, and moisture retention during dry times. It is important to realize that increasing organic matter in our soils goes hand-in-hand with profitable farming. It takes time to build it but it can be done with good manure management, crop residue management, and high fertility.

Fertility is an area that must not be compromised. Childs, like Warsaw, had high soil test levels and increased soil tilth from his tillage and residue management systems.

What do we need to do in the future to continue on the quest for maximum corn yields? The secret is in paying attention to details, working to identify limiting factors, and using site-specific management improvements to systematically eliminate the barriers to increasing yield. The pressures to grow more corn will continue as will the economic pressures to improve efficiency, plus there will be environmental pressures to do all of this with less impact on our natural resources. We need to expand production system research to learn how to combine the new genetics, new management practices, and new technology tools to build the best site-specific management systems for each cornfield. We need to rebuild the passion for increasing yields among farmers and their advisers, to challenge them to set higher goals for yield, efficiency, environment, and sustainability.

Dr. Reetz is Director of External Support and FAR for the International Plant Nutrition Institute in Monticello, Illinois.