Nitrogen Levels in Winter Wheat

Maintaining adequate nitrogen levels in cereals is critical to maximize yield.   Heads begin to develop early in the plant’s life cycle at GS 30 (stem elongation).  Inadequate available N causes tiller abortion with resulting lowered harvest population. During the grain fill period uptake of nitrogen from the soil is significantly less than during stem elongation.  Nitrogen  re-mobilization from the vegetative parts  of the plant contributes significantly to the nitrogen in the grain. Practically speaking this means that you need to have your N available early enough for the plant to take it up into the tissue. When the plant reaches GS 50 (heading) the nitrogen in the leaves will be mobilized to contribute to grain filling.

Wheat Growth Stages and N Uptake

Like everything in nature it is also important to look at the balance of nutrients in the plant. Excess available nitrogen can cause lodging and disease, so understanding soil mineralization,  timing, form, and amount are critical factors in proper management. Tissue testing is the best way to determine if you have maximized the amount of nitrogen in the plant to improve the chances of maximum grain fill. It will also allow you to determine imbalances with other nutrients in the plant.

Plant Tissue Report:

Plant Tissue

To allow you to better understand N levels in plant tissue we are following a few sites. You can view them here: Nitrogen Levels in Winter Wheat

Sources:

Field Facts: Spring Nitrogen Management of Soft Red Winter Wheat, Pioneer Agronomy Library

Nitrogen Management for Winter Wheat:
Principles and Recommendations, Virginia Co-Operative Extension

 

Proof in the Pudding

Over the past several months we have analysed a number of dairy samples for fecal starch either in combination with a TMR to determine digestibility, or on it’s own for a fecal starch determination. Dr Jim Ferguson (University of Pennsylvania) estimates that 5% fecal starch is considered adequate, but 2-3% is optimal. As you can see in the summary of 70 samples below there are plenty of samples that fall into all three categories (optimal, adequate & inadequate). The fecal starch results mimic the CSPS samples we did in the fall (click here to see those results), which makes sense given that CSPS and fecal starch are inversely related. If you have a lower CSPS you tend to have a higher fecal starch value and if you have a higher CSPS you tend to have a lower fecal starch. 


If you are interested in taking fecal samples click here for sampling instructions, happy sampling!