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Fluid Journal : Fluid Journal 2002-2004
1 Fluid Journal Summer 2002 Dr. Achim Dobermann, et al. Are You Approaching Yield Thresholds? Nebraska researchers suggest the answer is "no." Increased plant populations and nutrients can bring higher corn yields, plus the added benefit of increased carbon sequestration. Figure 1. Corn grain yield as affected by crop rotation, fertility management, and final plant population density. CC = continuous corn, CS = corn/soybean, M1 = recommended, M2 = intensive, P1 = 28-30,000 pl/A, P2 = 36-41,000 pl/A, P3 = 44-47,000 pl/A. CS-M1 200 210 220 230 240 250 260 270 Grain yield (bu/A ) 1999 2000 2001 CS-M2 CC-M1 190 200 210 220 230 240 250 260 270 P1 P2 P3 Plant density Grain yield (bu/A ) CC-M2 P1 P2 P3 Plant density Summary: Current fertilizer recommendations that are based on a yield goal that is well below the yield potential threshold do not allow expression of full attainable yield that is possible at higher plant densities and more intensive nutrient management. Compared to current recommendations, high corn yields require higher plant density (40,000 to 44,000 plants/A) and greater N and K uptake per unit yield. High-yielding maize systems significantly increased the amount of crop residue added to the soil. The resulting increase in the amount of carbon added to the soil is likely to improve soil quality in future years. The potential to increase carbon sequestration is greatest in continuous corn systems with intensive management that supports high yield levels.Crop yield improvement must continue unabated well into the 21st century, not only to meet food and fiber needs of the nine billion people on earth in the year 2050, but also to minimize the conversion to agriculture of land now spared for nature. Globally important intensive agricultural systems such as rainfed and irrigated continuous corn or corn/ soybeans will play a key role in sustaining the future global food supply because present acreage corn and soybean yields are only about 50 percent of the estimated climatic- genetic yield potential of these crops. This yield gap will not be closed by genetic technology. Intensified crop
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