This research compared response to broadcast, dribbled, and injected sidedress N application in no-till corn to determine the most profitable strategy. Three sites were studied in each of three years (2002-2004). Sidedress N treatments were 0, 34, 67, 101, 134, 168, and 202 kg N/ha applied at the V-4 to V-6 stage using each of the 3 methods. Broadcast N was applied with floodjet nozzles relatively uniformly across row middles, while dribble and injection bands were positioned 15 to 23 cm to one side of each corn row. Optimum N rate was determined by linear-plateau regression. Across all site-years, year by placement method interaction effect on optimum N rate was statistically significant (p<0.1). In 2002, a relatively dry year, dribble applications were more efficient than the other 2 placement methods. In 2003, a relatively wet year, injected applications were more efficient than the other 2 methods. In 2004, application methods did not differ significantly. Previous research in other states found increased N-use efficiency with injected and/or dribbled bands, presumably banding reduces either immobilization in crop residues or volatilization losses. Surface residue sample analyses detected no difference in residue N immobilization between application methods. In addition, ammonia volatilization losses via static chamber/acid trap could only be detected prior to the first substantial rainfall at one site with soil pH 6.2 and in replicated overlimed plots at a nearby long-term soil fertility test. Volatilization losses may only be an issue for producers on mineral soils if liming to 6.2 or higher, most likely intentionally done if cotton is in the rotation. This study also supports our current RYE-based N recommendation scheme (17.8 to 22.3 kg N/Mg grain) and suggests that no-till farming will require similar amounts of N as conventional tillage.
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