Development of a Fertigation Program for Sprinkler-Irrigated Corn
1991
Gascho, G. J. | Hook, J. E.
Well-designed and -maintained center-pivot sprinkler irrigation systems can be used to make fertilizer applications on sands with little regard for soil moisture conditions. Nitrate-N may be lost by leaching when heavy rainfall occurs in irrigated corn (Zea mays L.) fields on sand. Splitting N applications decreases the NO⁻₃ available for leaching at any given time during the growing season. A 5-yr study was conducted to compare applications of N through the irrigation system (N fertigation) with applications by conventional means. Determining optimum timing of N fertigations in order to obtain highest yield was a major objective. Initial experiments compared “conventional” side-dress applications with an intensive fertigation program where N was applied weekly or biweekly. In those experiments the fertigation did not enhance corn yield. Comparison of the fertigation schedules with optimum N uptake data revealed that the lack of yield enhancement may have been due to applications that were too late to allow optimum uptake. Advancing the fertigation schedule so that 25% of the N was applied at planting and the remaining N was applied in four fertigations that preceded optimum uptake resulted in grain yields of 1 bu/lb N. When N was applied by fertigation, yields were significantly greater than those obtained by a conventional method where 25% was applied at planting and 75% in a single sidedress dribble application at the 6- to 8-leaf stage and the potential for NO₃-N losses was reduced. A portion of the response to N applied through irrigation may have been due to foliar absorption or to avoiding some undetected N losses from broadcast or dribble applications.
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