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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

Assessing winter wheat survival

Assessing winter survival in wheat

Assessing winter survival in wheat Factors affecting winter survival in wheat The ability of winter wheat plants to survive winter often depends on each plant’s ability to tolerate low temperatures. Winter wheat plants go through a process called ‘cold acclimation’ in the fall during which each plant acquires the ability to withstand the cold temperatures […]

Managing Fusarium Head Blight at harvest

Fursarium Spores WheatThe less infected kernels that go into storage the better, and the greater of a chance a grower will have for not getting docked to a lower grade of wheat.

Combine tips and notes

  • Higher fan speeds are needed to blow infected kernels out the back. Ridgetown College has done studies on fan speeds, and there is a tenfold decrease in the amount of Fusarium damaged kernels in a sample when the fan speed is at maximum blast. But with that comes challenges of losing good healthy kernels.
  • Research from Ohio State showed combine fan speeds between 1375 and 1475 RPM and the shutter opening at 3.5 inches received the lowest discounts at elevators from FHB damaged wheat kernels and DON levels in the harvested grain.
  • Reduce combine speed. Having the combine traveling at a slower speed, will allow better separation between the good and bad kernels.
  • In fields which are severely affected by leaf diseases, the lower test weight of the grain may make it more difficult to separate normal kernels from Fusarium damaged kernels.

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Snow mould in winter cereals


Holly Loucas, Agronomist, DOW Agroscience

What is snow mould?

Snow moulds are cold-loving fungi that can attack many economic plants under a cover of snow.

Pathogen biology

WinterMouldChartThe important species of snow moulds that infect winter wheat are Microdochium nivale and Typhla spp.

Gray snow mould (Typhula spp) is the less damaging form of snow mould. It is able to survive throughout hot summer months as sclerotia under the ground or in plant debris.

Pink snow mould (Microdochium nivale) is usually more severe than gray snow mould. It can survive the summer months in decayed plant debris as spores or mycelium. Read more

Wheat field

Late Planted Winter Wheat

During years when soybeans are harvested later than expected or environmental conditions delay field work, winter wheat is generally skipped in the rotation or planting is rushed. When planting winter wheat later than the recommended planting dates, even more care should be taken to ensure yield potential is not lost.

Planting date

In general, delaying planting past the recommended planting window can cost a producer from 0.6 to 1.1 bu/day. It is best to strive to plant around these dates (See figure 1).

planting dates map

Figure 1: Optimum Planting Dates in Ontario.

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