A Closer Look at Nitrogen Loss
Nitrogen is crucial for the healthy development of corn. According to Purdue University Extension, rapid uptake of nitrogen by corn plants begins at V6, with the plant having taken up 70% of the total needed by silking. Corn plants deficient in nitrogen will have a yellow “V” that runs down the midrib of lower leaves to the center of the plant. Nitrogen is mobile in plants, so symptoms will begin on the lower leaves.
In severe cases, plants will be stunted, pale green to yellow in color, and will cause smaller ears with “tip back” and smaller kernels. Nitrogen deficiency can cause challenges with stalk quality and late-season standability, as the plants remove available nutrients from the plant to fill the ear.
There are 4 types of nitrogen loss:
- Leaching: Movement of nitrogen by water deeper through the soil profile. Nitrate and urea are both susceptible to leaching, and if rain and wet weather continue, nitrogen can move deeper through the soil profile and become unavailable to plant uptake.
- Volatilization: Soil surface loss when the nitrogen source contains urea forms that were not incorporated into the soil.
- Runoff: Movement of nitrogen by water to off-target areas. Nitrogen applied to the soil that was not incorporated either through tillage or a gentle rainfall are at risk from loss due to excess rainfall and runoff.
- Denitrification: Gaseous loss due to reduction of nitrates to nitrous oxide or nitrogen gas. Saturated soils create an anaerobic environment and the microorganisms will obtain oxygen by removing it from the nitrate, creating the gaseous forms of nitrogen, both of which are unavailable to plants. Temperature can affect the microbial activity in the soil, with cooler temperatures slowing the process and warmer temperatures increasing the rate of nitrogen loss due to denitrification.
To maximize yield, it’s essential to manage nitrogen loss and add additional nitrogen after a loss has been determined. Speak with your NK® retailer to determine a course of action for your fields.
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