Response of corn yield to irrigation and nitrogen and the relationship between yield and NDVI measured by aerial imagery
Abstract
Nitrogen (N) and water are among the key components that effect crop growth and yield outcome in the southern Great Plains. However, the effect of N and irrigation interaction on corn yields have not been studied in the area. The objectives of this study were to evaluate yield response of corn to various N and irrigation rates and interactions between N and irrigation, provide valuable insight on spatial variation across irrigation treatments in response to N, as well as evaluate the relationship between corn yield and normalized difference vegetation index (NDVI). The study was conducted at the McCaull Research and Demonstration Farm near Eva, in the Oklahoma Panhandle. The N treatments included five rates ranging from 0 to 336 kg N ha-1. The irrigation rates included 25, 32, 38 mm of water per irrigation event. The corn responded to N rates significantly each year of study. However, the yield response to irrigation was visible only in 2019, which despite receiving above normal rainfall early in the season recorded the lowest amount of rainfall in mid and late season among the three years of study. No irrigation response was observed in 2018 and 2020 due to adequate replacement of water deficits along with timely rainfall. There was no interaction in N and irrigation rates that impacted corn yield, suggesting that irrigation and N rates were influencing yields independently. The highest irrigation rate (38 mm) presented the largest variability of yield increase with an optimum N rate of 235 kg N ha-1for 2019 and 2020. In 2018, 336 kg N ha-1 was the optimum rate and showed the most variability within the 25 mm irrigation rate. A significant relationship in 2019 between NDVI and yield presented that the corn was in fact influenced by either irrigation or nitrogen while 2020 showed no true relationship. Over time Coefficient of Variation (CV) decreased with plant growth, supported by both 2019 and 2020 growing seasons. Our results indicate that despite the irrigation rates and capacities, corn yields in the Oklahoma Panhandle remain vulnerable to weather patterns and production scale mechanical challenges and relate to spectral reflectance measurements.
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- OSU Theses [15752]