Start Date

1-12-2015 12:00 AM

Description

High-yield corn production would not be possible without adequate nitrogen (N) supply. Unless corn follows established alfalfa, N application from fertilizer or manure is almost always needed in Iowa crop rotations with corn following soybean and corn following corn to meet crop demands. This N fertilization need is especially important considering the recent period of high rainfall years in Iowa where residual N is reduced and N response increased. In dry periods, such as the late 1980’s to early 1990’s, there were field situations where no response to applied N would occur, but that has not happened in the recent time period. For example, late-spring soil nitrate-N test levels when no manure or fertilizer was applied have been consistently below the test critical level in recent N rate research trials (94% below the critical level of 25 ppm nitrate-N from 1999-2014). This is a clear indication of the high N responsiveness in Iowa corn production.

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Dec 1st, 12:00 AM

Nitrogen input decisions with tight crop production margins

High-yield corn production would not be possible without adequate nitrogen (N) supply. Unless corn follows established alfalfa, N application from fertilizer or manure is almost always needed in Iowa crop rotations with corn following soybean and corn following corn to meet crop demands. This N fertilization need is especially important considering the recent period of high rainfall years in Iowa where residual N is reduced and N response increased. In dry periods, such as the late 1980’s to early 1990’s, there were field situations where no response to applied N would occur, but that has not happened in the recent time period. For example, late-spring soil nitrate-N test levels when no manure or fertilizer was applied have been consistently below the test critical level in recent N rate research trials (94% below the critical level of 25 ppm nitrate-N from 1999-2014). This is a clear indication of the high N responsiveness in Iowa corn production.