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Fluid Journal : Fluid Journal 1999-2001
Fall 1999 Uptake. Starter fertilizer significantly increased grain N uptake by 6 lbs/A due largely to increased grain yield. Grain N uptake was 18 lbs/A less when UAN was broadcast on the soil surface, compared to spoke-wheel injection. Corn after soybeans Yield. The significant interaction between row cleaners and starter fertilizer (10 gal/A 10-34-0) was due to yields being increased 9 bu/A when row cleaners were not used and only 4 bu/A when they were used. Or looking at the data in another way, row cleaners had no effect on yield when used in combination with the starter fertilizer, but had a slight effect when used alone. In this very favorable year, continuous corn yields on the average were only 4 bu/A less than for corn after soybeans. Surface residue. Coverage was high throughout the season. Residue coverage averaged 92 and 78 percent on April 22 and May 20, respectively (data not shown). Residue coverage still averaged greater than 50 percent on July 2 and greater than 40 percent on August 31 (Figure 3). Placement method of UAN did not affect residue coverage. Emergence. Corn emergence started 11 days after planting and was complete 4 days later. There was a very slight positive effect of row cleaners on emergence 2 and 3 days after emergence started (Figure 4). Plant height was not affected by row cleaners, but was 5.1 inches taller when starter fertilizer was used. Plant height for corn after soybeans was about 6 inches taller than it was for continuous corn. Grain moisture at harvest was reduced significantly (1.1 points) with the use of starter fertilizer but was not affected by row cleaners. N concentration was reduced by the use of starter fertilizer. However, the small differences were considered to have little practical effect. Unlike continuous corn, grain N concentration was not reduced by broadcast application of UAN. Uptake. Grain N uptake was not affected by row cleaners or starter fertilizer. When starter fertilizer was used Figure 2. Surface residue coverage as influenced by row cleaners and method of N application in continuous corn, Randall, et al., University of Minnesota, 1998. 90 80 70 60 50 40 30 UAN UAN UAN bdct + + RC RC 7/2 8/31 Figure 1. Corn grain yield as affected by row cleaners, starter fertilizer, and crop rotation, Randall, et al., University of Minnesota, 1998. 190 180 170 160 150 140 130 UAN UAN UAN UAN + + + SF RC SF + RC Continuous Corn SF=Starter fertilizer Corn after Soybeans RC=Row cleaner % Residue Yield - bu/A
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