While this year’s input costs are hitting the bottom line harder than most years, several things can help maximize production and justify the money invested in nitrogen (N).
Use a nitrogen stabilizer
Understanding how N can leave a field is important. Leaching, denitrification, and volatilization can lead to significant losses (15 to 90%) depending on soil types and growing conditions.1 If we knew in advance about the upcoming year’s weather, it would help take much of the risk out of farming. Since we can’t predict the weather with the amount of certainty we would like and N stabilizers can’t be applied after the fact, it is important to do your research and talk to your local seedsman to help understand when using a stabilizer is worth investing the extra money.
Pay attention to TOTAL soil fertility including pH
Liebig’s Law of the Minimum (most often represented as a wooden barrel with staves of different lengths) shows that the nutrient that is most deficient is the nutrient which limits yield (Figure 1).2 Nitrogen might often be the focus, but other nutrients could be causing the leak in the yield barrel. The only way to know if you have a leaky barrel is to have your field soil sampled.
Another interaction affecting nutrient availability (and yield potential) is soil pH. Most macro and micro soil nutrients are available when soil pH is between 6.5 to 7.5.6 Beyond this range, some nutrients are unavailable for plant uptake and yield is potentially limited. Furthermore, the bacteria responsible for the nitrification process are hindered at low pH, which decreases nitrate availability and forces plants to utilize ammonium, lowering N use efficiency.4 Table 1 shows the relative yield potential if your pH falls outside of this optimum range.
|Relative Yield (100 is best, 0 is worst)|
*Adapted from Smith, J.L. and Doran, J.W. 1996. Measurement and use of pH and electrical conductivity for soil quality analysis. Methods for Assessing Soil Quality. SSSA Special Publication Number 49. Soil Society of America.
Split application of nitrogen
Since N is mobile in the soil and subject to loss not only via leaching, but volatilization and denitrification as well, keeping N where it is needed can be difficult. Ideally, apply N as close to the period of rapid nutrient uptake. This provides a smaller window for loss to occur before it is used by the growing crop. Split N applications frequently lead to higher yield potential versus a single application. In irrigated operations, center pivots can apply N along with water. In rainfed environments, liquid coulter machines, 360 Y-Drop® nozzles, or even dry spinner spreaders work for applying N later in the season.
Lastly, it is important to revisit fundamentals. Nitrogen is primarily taken up through the roots. Therefore, anything that maintains root health can help maximize N applied. Soil insecticides and corn products such as SmartStax® corn or SmartStax® PRO technology can help limit rootworm damage. A solid herbicide program to minimize weed competition for water, sunlight, and nutrients should also be used.
Given the nature of this year, with supply and price issues, it is even more critical to dial in your N management program.
An excellent resource to help determine N rates is the Corn Nitrogen Rate Calculator sponsored by Iowa State University and associated with the Universities of Iowa State, Illinois, Michigan State, Minnesota, Purdue, The Ohio State, and Wisconsin.
1Bastos, L., Maharjan, B., Wortmann, C., and Ferguson, R. 2018. Nitrogen fertilizer stabilizers in corn. CROPWATCH. University of Nebraska-Lincoln. https://cropwatch.unl.edu/2018/nitrogen-fertilizer-stabilizers-corn.
2Greg Klinger, Shane Bugeja (Host). (Oct. 25, 2021). The Leaky Barrel (Episode 1) [Audio podcast episode]. In The Story of Nitrogen. University of Minnesota Extension. https://www.listennotes.com/podcasts/the-story-of/episode-1-the-leaky-barrel-Axp5azNXMPo/#transcript.
3Mullen, R. Liebig’s law of the minimum. Nutrient Science. eKonomics. Making Sense of Today’s Crop Nutrition Research. Nutrien®. https://nutrien-ekonomics.com/latest-fertilizer-research/liebigs-law-of-the-minimum/.
4Hoiberg, A. 2020. Back to the basics of soil pH. Calcium Products. https://www.calciumproducts.com/back-to-the-basics-of-soil-ph/.
5Smith, J.L. and Doran, J.W. 1996. Measurement and use of pH and electrical conductivity for soil quality analysis. Methods for Assessing Soil Quality. SSSA Special Publication Number 49. Soil Society of America.
6Jensen, T.L. 2010. Soil pH and the availability of plant nutrients. Plant Nutrition TODAY. International Plant Nutrition Institute (IPNI).
8Soil pH. Soil quality indicators. 2011. USDA Natural Resources Conservation Service. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/health/assessment/?cid=stelprdb1237387.
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SmartStax® PRO corn products will be commercially available for the 2022 growing season.
ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. B.t. products may not yet be registered in all states. Check with your seed brand representative for the registration status in your state.
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