Author
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Olness, Alan |
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LOPEZ, DIAN - UNIVERSITY OF MINNESOTA |
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Submitted to: Video
Publication Type: Other Publication Acceptance Date: 1/10/2001 Publication Date: 6/5/2001 Citation: OLNESS, A.E., LOPEZ, D. LEGUMES IN CORN - CAN THEY FIX NITROGEN FOR THE NEXT CROP? VIDEO. MORRIS, MN: USDA-ARS. 2001. Interpretive Summary: Nitrogen is a major requirement for crop and protein production. The supply of nitrogen is often inadequate to achieve best use of land for crops. It has often been suggested that legumes should be seeded with grass crops to take advantage of their ability to fix nitrogen from the air. However, such a crop system requires careful management. Planting legumes too soon results in competition with grain crops. Planting legumes too late results in poor production in northern climates. Planting legumes at flowering time in corn causes minor competition to the corn crop from the legume and encourages N fixation by the legume. Topping corn in the R-5 or hard dent growth-stage provides more light to the legumes and increases their growth. Under drought conditions, it also increases grain yield. Topping corn before the R-5 growth-stage results in severe yield reduction of as much as 30%. Nitrogen contained in legumes after corn harvest ranged from about 10 to 20 lbs per acre. Nitrogen contained in legumes is less likely to be los due to leaching or surface runoff of rain. Little or no nitrogen benefit was obtained from interseeded legumes for the successive crop. Legumes did improve the yield and quality of oats in the second year but this was due to a factor or factors other than nitrogen. Legumes such as medic clover, lupin and nitro Alfalfa are shade sensitive. Lupin failed to produce any forage after corn harvest. Hairy vetch produced more forage than other legumes when the corn yield was greater than 145 bu per acre and medic clover produced the most forage when corn yield was less than 145 bu per acre. Thus, in northern regions, if nitrogen fixation is the goal, legumes should be grown for longer time periods than usually needed. Producers will find this research of interest in managing their crops. Technical Abstract: Maize requires large amounts of nitrogen for optimal economic production. Most of the nitrogen in the U.S. is applied as commercial fertilizer with a cost exceeding $10 billion annually and with an average use efficiency of about 50%. An experiment was conducted at Morris, MN, to determine if legumes interseeded with maize at tasseling time could fix nitrogen for a successive crop. The legumes used were hairy vetch, nitro alfalfa, lupin, white clover, and black medic clover. Legumes were interseeded in a randomized block design in the first year. In the second year corn, oats or soybean were grown and supplied with 0, 40, 80, 120, or 160 lbs of N per acre. Lupin and white clover failed to establish and were deleted from the study. Hairy vetch, black medic clover and nitro alfalfa produced on average about 750 lbs of forage per acre. However, nitro alfalfa and black medic clover were sensitive to competition by corn and failed to produce any forage at corn yields in excess of about 175 bu per acre. At corn yields of less than 145 bu per acre, black medic clover produced the most forage and at yields greater than 145 bu per acre, hairy vetch produced the most forage. After corn harvest, legume forages, on average, contained about 10 to 20 lbs of N per acre. Successive crops showed little or no N response to the legume forage but oat yields were increased at applied N levels of less than or equal to 80 lbs per acre. The effect on oat yields appears to be due to some factor other than N. Topping the corn crop increased light intensity to the forage crop, hastened drying after frost, and when conducted at the R-5 growth stage, either increased yield or had no effect on yield. |
