Corn Response to Nitrogen Fertilizer as Affected by Planting Date and Hybrid

Abstract

Producers of the eastern Corn Belt are often forced to either delay corn (Zea mays, L.) planting or replant due to unfavorable early season growing conditions. In these situations producers may decrease N rates due to decreased yield potential or switch to short season hybrids to reduce the risk of frost injury prior to maturity. Hybrids with differing yield potential may have different N requirements, but definitive research to determine the impact of hybrid selection on N response is lacking. Field experiments were conducted in Ohio during 2006 and 2007 to evaluate if corn grain yield and stalk lodging attributed to N fertilizer is affected by hybrid or planting date. This experiment evaluated two planting dates (late April/early May and early/mid‐June), with subplots comparing N fertilizer rates (0, 60, 120, and 180 lb N/acre), and sub‐subplots containing corn hybrids of differing maturities (104, 108, 109, and two 113 days relative maturity). In 2006, planting date did not affect the economically optimum N fertilizer rate (EONR), although late planted corn did produce lower grain yields. In 2007, late‐planted corn was less responsive to N with the optimum N rate being 38 lb N/acre less than early‐planted corn. Differences in N response between hybrids were noted, but optimum N rates were not markedly different.

Variability in Corn Yield Response to Nitrogen Fertilizer in Eastern Canada

“…This is consistent with the results of Lauer et al (1999) who reported that grain corn yields decreased with later planting date. In our study, the increase in yield between the two groups of site-years could be explained by the planting date (Mullen et al, 2010), but other parameters such as soil types, hybrids and weather conditions may be involved (Almaraz et al, 2008;Ziadi et al, 2013;Tremblay et al, 2012;Woli et al, 2016). The EONR for the site-years planted before mid-May ranged from 180 to 237 kg N ha -1 (Table 4).…”

“…This suggests that an optimum planting date tends to increase EONR. Knapp and Reid (1981) and Mullen et al (2010) have reported that late-planted corn (late May-early June) in New York had lower grain yields and lower N fertilizer requirements than corn planted in late April/early May. The increase in EONR above the current provincial N recommendation also means that the average yield potential for this group of site-years exceeds the provincial average for which the current recommendations were developed by CRAAQ.…”

“…Additional N with variable rates N Source for variable rates † Timing of variable rates Mullen et al, 2010;Schmidt et al, 2011). The linear-plateau was used to estimate the EONR for 6 of 37 site-years, where it fit better than the quadratic-plateau.…”

“…Corn planted between late April and mid-May was more responsive to N than corn planted after midMay. Mullen et al (2010) studied corn response to fertilizer N in a 2-yr study, as affected by planting date and hybrid. They observed that in 1 of the 2 yr, corn planted in early May was more responsive to applied N than corn planted in early June.…”

“…A similar observation was also reported by Eckert and Martin (1994), indicating that delayed planting reduced yield in each site-year, and almost always reduced the quantity of N required to obtain optimum yield. Late planting can decrease the EONR, but the year-to-year variability in N demand cannot be ignored (Mullen et al, 2010).…”