Sweet Corn - Getting the Most from
Your Fertilizer $$$

Overview
Results

Overview

Rising prices for fuel and fertilizer have many growers reevaluating their crop input costs. Nitrogen recommendations must meet the requirements for maximum yield, while helping growers to avoid costly over application and minimizing the risk of nitrogen losses into the environment.

Sweet corn nitrogen recommendations can be greatly affected by several different factors including, geographic location, soil type, organic matter and planting date. Nitrogen use efficiency trials were conducted in 23 sweet corn fields across Southwestern Ontario from 2003 to 2006.

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Results

Depending on the site, the Most Economic Rate of Nitrogen (MERN) ranged from 0 to 142 lbs/ac. On average, the maximum return on the nitrogen investment occurred at rates between 60 and 100 lbs/ac. Only 5/23 sites saw an economic response to nitrogen rates above 80 lbs/ac. While 8/23 sites showed almost no response to additional fertilizer nitrogen.

Based on this study, it appears that the early planted sweet corn sites, those planted in May, showed the greatest response to fertilizer nitrogen. Fields in June were considerably less responsive to nitrogen applications. This might be explained by warmer soil conditions and increased mineralization of nitrogen by soil microbes on the later planted fields, making them better poised to utilize naturally occurring soil nitrogen.

Soils with organic matter levels of less than 3% were also more likely to show an economic response to higher nitrogen application rates.

It is important to gain a better understanding of the relationships between crop yields and nitrogen response. If we can identify the factors that result in high nitrogen requirements, we will be able to develop more specific fertilizer recommendations that allow for high application rates when necessary, without risking costly over-application where high rates are not required for maximum yield.

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