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Corn Nitrogen Response Curve

Nitrogen stabilizers

Nitrogen management has always been a challenge in high nitrogen demand crops such as corn and winter wheat.

The three pathways that can contribute to significant nitrogen loss are:

  • Volatilization (loss of ammonia nitrogen to the atmosphere from the soil surface),
  • Denitrification (which occurs when soils are saturated and in an anaerobic environment) and
  • Leaching (downward movement of nitrate nitrogen out of the rooting zone due to excessive rains)

The challenge has always been to make nitrogen available when the crop needs it and minimize the exposure of nitrogen to the weather scenarios that contribute to N loss. Consider the nitrogen response relationship for corn and winter wheat (below):

Corn nitrogen response curve

(Adapted from Richie, et.al, 2005, How a Corn Plant Develops).

Corn Nitrogen Response Curve

We often apply nitrogen early in the season before the crop actually utilizes it. For example, the demand for nitrogen in corn is at its peak at about the V10 growth stage (often around early to mid-July). Split-applying nitrogen has been a reasonably effective way to reduce the risk of nitrogen loss, however, with added application costs. Read more

winter wheat stand

Nitrogen on winter wheat

Nitrogen on winter wheat

Cereals are very responsive to nitrogen. However, over-application of nitrogen or applying too early on a thick stand of wheat can cause lodging, resulting in reduced yield, quality, and harvestability. The optimum rate of nitrogen for a particular field will depend on the type of wheat grown, past applications of manure or fertilizer, soil type, and crop rotation. Use general recommendations as a starting point but combine them with observation of crop growth and lodging tendency. The idea is to ensure nitrogen is available early and consistently though the major uptake period (which is node development though booting). Read more

Late Application of Nitrogen

Late season nitrogen application

Corn N ChartLate season nitrogen application has been a hot topic amongst farmers and uptake in this practice has increased in recent years. The expense and environmental impact has made growers think differently about nitrogen application.

Weather extremes has also caused growers to change the way they apply nitrogen to mitigate loses from excessive rainfall when applying all their nitrogen ahead of planting. Read more