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Within‐Field Variability in Optimum Nitrogen Rate for Corn Linked to Soil Moisture Availability
Author(s) -
Schmidt John P.,
Sripada Ravi P.,
Beegle Doug B.,
Rotz C. Alan,
Hong Nan
Publication year - 2011
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2010.0184
Subject(s) - zea mays , limiting , grain yield , moisture , water content , agronomy , environmental science , geology , geography , biology , geotechnical engineering , meteorology , mechanical engineering , engineering
Understanding the interaction between yield response to N and other growth‐limiting factors is essential to improving spatially dependent N fertilizer applications. Our objective was to evaluate the impact of soil moisture variability on the economically optimum N rate (EONR) for corn ( Zea mays L.). Corn grain yield response to N was determined at each of 10 locations along a hillslope in central Pennsylvania (2005–2007). Volumetric soil water content (θ p , 0–90‐cm depth) was also determined at each location approximately weekly between mid‐June and August. The mean EONR ( n = 10) was 117, 140, and 169 kg N ha −1 in 2005, 2006, and 2007, respectively, while the range in EONR among locations each year was 147, 69, and 146 kg N ha −1 , respectively. The mean θ p ( n = 10) was between 15 and 25 cm in 2005, 23 to 37 cm in 2006, and 21 to 27 cm in 2007. While there was greater temporal change in the mean θ p in 2006, the smaller variability among locations during the drier growing seasons of 2005 and 2007 was more relevant to differences in EONR. The EONR in 2005 and 2007 was strongly related ( r 2 = 0.74 and 0.71, respectively) to the change in θ p at each location as determined during a defining drying and wetting cycle in June and July. During the relatively wetter 2006 growing season, the EONR was not related to changes in θ p Greater water availability during drier growing seasons increased the EONR.