Corn Yield Response to Nitrogen at Multiple In-Field Locations
- John P. Schmidt *a,
- Aaron J. DeJoiab,
- Richard B. Fergusonc,
- Randal K. Taylord,
- R. Kris Younge and
- John L. Havlinf
- a Dep. of Agron., Kansas State Univ., Manhattan, KS 66506
b Cascade Earth Sci., Spokane, WA 99214
c Dep. of Agron. and Hortic., South Central Res. and Ext. Cent., Univ. of Nebraska, Clay Center, NE 68933
d Dep. of Biol. and Agric. Eng., Kansas State Univ., Manhattan, KS 66506
e NC+, Moscow, KS 67120
f Soil Sci. Dep., North Carolina State Univ., Raleigh, NC 27695
Improving N management for corn (Zea mays L.) production with precision agriculture technologies requires that spatial N recommendations adequately represent in-field variability in N availability. Our objective was to evaluate corn response to increasing N rates in several in-field locations that represented the range of soil organic matter (OM) content in the field. In a 2-yr study, three center pivot–irrigated fields were selected in south-central Kansas and south-central Nebraska. Four or five locations were selected within each field. At each location, five or six N treatments (0–336 kg N ha−1) were surface-applied early in the growing season. The minimum N rate to achieve maximum yield varied by as much as 130 kg N ha−1 among in-field locations at three site-years. The least amount of N to achieve maximum yield did not coincide with locations representing greater soil OM. Yield response at two site-years was the same among in-field locations; however, mean yield among in-field locations varied by as much as 4.2 Mg ha−1, representing potential for improvement in N use efficiency. Leaf tissue N was below the critical threshold for 60 to 100% of observations at three different in-field locations but below the critical threshold for <35% of the observations at all other in-field locations. The reason for the discrepancy in N availability among in-field locations was not conclusively identified but was not only related to soil OM content. Variable N recommendations based only on soil OM is too simplistic to reflect variability in N availability within a field.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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