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Fluid Journal : Fluid Journal 1996-1998
Fall 1997 applied with the fertilizer in the irrigation water at recommended rates. Treatments were randomized within the level basins and there were five replications. On the 1986 plot outside the level basins, split applications were made between the rows, with the N and inhibitor mixed before application. The plots were cultivated and furrowed following this application. Planting. The level basin plots were planted in 24-inch rows with Funks G4507 in 1983 and 1984, and with DeKalb 656 in 1986. The furrowed plots were planted in 30-inch rows with DeKalb 656, and with five replications. N as catalyst Nitrogen has two major roles: 1. Establishment of yield capacity 2. Establishment and maintenance of photosynthetic capacity. Researchers have noted that in cereals an adequate N supply during early growth stages is important in determin- ing the number of ears per unit area. Researchers have further suggested that sink (kernels) sizes may frequently limit crop yields. The supply of reduced N to the ear during reproductive growth is important in the establishment of a viable sink. However, a balance between N in the vegetative plant parts and the N supply to the developing sink must be achieved to allow maximum productivity. It has been suggested that continued input of N into the plant is responsible for the maintenance of leaf duration and continued photosynthetic activity. The availability of current photosynthate and reduced N ensures the longer duration of grain fill. The end result is a higher yield per plant. Another conclusion drawn from research is that the loss of N from corn leaves to the stalk and ear is a major cause of senescence. A long period of grain-fill could be facilitated by a large N supply in leaves at the start of rapid grain filling. A large N supply in leaves should allow a more appropriate redistribution of N to support ear development and leave more N in the leaves to maintain the photosynthetic apparatus. _________________________________ Dr. Olsen is soil scientist, emeritus, USDA/ARS; Champion is extension agent, Dr. Pearson is professor, and Colus is associate professor, Colorado State University. ! Table 1. Chemical properties of Youngston Ravola fine sandy loam used in corn fertility experiments. __________________________________________________________ pH 7.8 Organic matter (%) 1.6 NaHCO3- extractable P (ppm) 14 K, exchangeable (ppm) 110 NO3-N, soluble in 2N KCL (ppm) 27 DTPA extractable nutrients (ppm): Fe 23 Mn 8 Zn 7 Yield -- bu/A 280 260 240 220 200 180 160 N-Serve® added Figure 1. Corn yields as affected by split UAN applications with and without nitrapyrin (N- Serve), Olsen, et al., USDA/ARS, Fruita, CO, 1986. 100 on 7/7 100 on 8/5 100 on 4/19 200 on 7/9 N rate -- lbs/A and application date
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