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Fluid Journal : Spring 2011
4 The Fluid Journal Spring 2011 Summary: As the world's greatest producer of corn, U.S. agriculture is obligated to pursue both higher yields and sustainable production practices. The United Nations predicts that the global human population will increase by more than 30 percent to 9 billion by 2050. Agricultural researchers and policy makers estimate that grain yields must increase by 70 to 200 percent to meet demands of a growing population that is increasingly demanding a meat-based diet. While low-input, low-intensity farming systems preserve soil resources and meet most definitions of agricultural sustainability, these systems often sacrifice yield potential. For the world's three staple food crops (rice, wheat, and corn) we must find ways to increase, not decrease the yield per unit of cropped land. Based on increased net primary productivity, improved nutrient use efficiency (NUE) and suitable conservation practices, high-population corn systems may be more environmentally sustainable than current production systems when managed appropriately and when restricted to the most suitable land. By assessing agricultural sustainability in terms of the energy resources embodied in long- and short-term energy/carbon plant fractions, we present a research approach to agricultural intensification that pursues higher yields, biofuel production potential, and preservation of our soil and water resources. Involves agricultural intensiﬁcation that pursues higher yields, biofuel production potential, and preservation of our soil and water resources. The Fluid Journal • Ofﬁcial Journal of the Fluid Fertilizer Foundation • Spring 2011 • Vol. 19, No. 3, Issue #73 Drs. Laura F. Gentry and Fred E. Below Achieving 300 Bu/A Corn Sustainability Based on United Nations predictions that the human population will increase by 30 percent by 2050, scientists and policy makers conclude that we will need to increase 2009 grain yield levels by up to 200 percent to meet demands of a growing population that is increasingly demanding a meat-based diet. According to the USDA's October 2010 Grain World Market Report, the United States produced 55 percent of the world's corn last year. Over 40 percent of American-grown corn came from Iowa, Illinois, Nebraska, and Minnesota. As the world's greatest producers of corn, we are obligated to pursue both higher yields and sustainable production practices. Academic thought regarding sustainable farming of staple crops is shifting from a low-input, low-intensity philosophy to a system of intensification. The low-input, low-intensity method preserves soil resources, yet sacrifices yield potential. This may be acceptable for most commodities, but for the world's three staple food crops (rice, wheat, and corn) we must find ways to increase, not decrease, the yield per unit of cropped land. The new philosophy of intensification pursues higher yields exclusively on land best suited for crop production and uses agricultural practices that protect the soil resource and enhance efficiency of nutrient uptake. Our research approach in this report evaluates corn grain for feed and food, stover for feed and biofuel production, and below ground root and exudates to return soil organic matter and support a larger soil biological community (bacteria, fungi, nematodes, earthworms, etc.). Improving efficiency It is widely recognized among growers that losing agricultural inputs via leaching, denitrification, erosion, and runoff is wasteful economically, agronomically, and environmentally. Research shows that improved NUE and other agricultural inputs are well within our grasp. As Tilman, et al., (2003) point out, U.S. corn yields increased by nearly 40 percent from 1980 to 2000 without any increase in nitrogen (N) fertilizer application. Tilman, et al. go on to predict that advances in plant breeding, biotechnology, and crop and soil management will account for future increases in global crop production without negative environmental consequences. Doubling yields? Edgerton (2009) predicts that the combination of marker- assisted breeding, biotechnological traits, and continued advances in agronomic practices will make it possible for the U.S. to double corn yields over the next two decades. This advancement in yield entails a 10-ton/ha (167 bu/A) yield increase over the current U.S. corn yield average. Edgerton estimates that about 80 percent of the increased yield gain will be the result of introducing new biotechnological traits and marker- assisted breeding practices. New corn hybrids with genetic traits that offer greater tolerance to herbicides, insect feeding, pathogens, drought, low soil fertility, and other plant stressors will create the potential for yield increases. Plant population. To realize the full potential of new genetics, modern hybrids must be grown at higher plant populations than their predecessors. Increasing corn plant populations has been shown to improve N and phosphorous (P) use efficiency as well as uptake of other agricultural inputs such as sulfur (S), fungicides, and insecticides. Evidence also suggests that increasing corn plant populations using narrower corn rows
Early Spring 2011