The piece on Nitrogen below came to me by way of Kevin Van Trump's excellent daily newsletter.  If you're not getting it – you should be!  It's filled with great stuff everyday.  Click here to check it out.

A Deeper Look At Nitrogen Loss: With all of the rain and wet fields there's a ton of talk and speculation circulating inside the trade about nitrogen loss caused by leaching or denitrification and just what it means for the U.S. corn plant. A few of my friends over at Pioneer sent me a terrific article by Dan Emmert, Agronomy Trials Manager, that does great job of explaining some of the bigger concerns and what we should be doing as producers to help curtail some of the losses. Below are a fe of the highlights, but I encourage you to go HERE and read in full-detail. Hope this provides some insight:

• Nitrogen (N) is essential to plant growth. As a constituent of protein, it is instrumental in critical plant functions from germination to senescence. As a component of the chlorophyll molecule, nitrogen has a primary role in photosynthesis and therefore yield accumulation in crops. Unfortunately, this critical plant nutrient can be easily lost from the soil by leaching or denitrification when excessive rainfall occurs
• Wet conditions in May and June delayed many planned side-dress applications and promoted losses of previously applied nitrogen. When this occurs, producers must decide if an additional N application is warranted to avoid the risk of reduced yield. Recent wet springs and resulting yield losses demonstrate the importance of making the correct decision
• Optical Sensors – Recently improved optical sensors can help assess N deficiency and the amount of N needed to optimize crop response. These crop sensors, mounted on N-application equipment, work by emitting modulated light of the appropriate wavelength onto plants then measuring how much of that light is reflected back to the sensor. This measure of “crop greenness” correlates with plant chlorophyll content. Estimating chlorophyll content also estimates crop N status, as the two are closely linked.
• Anhydrous ammonia applied just prior to periods of prolonged soil saturation is less prone to denitrification than urea or UAN.
• Nitrogen Rescue Program – If choosing to broadcast the rescue Nitrogen, urea is the product of choice. This is because other N sources – ammonium nitrate (NH4NO3) and UAN solution – cause extensive leaf burning when broadcast (Figure 4). Studies have shown that this leaf injury often results in yield loss. Urea is much safer to broadcast, usually resulting in only minimal crop injury.
• Bottom-Line: The greater the N deficiency and the longer it goes uncorrected, the greater the potential for yield loss. Early-season N stress can result in irreversible yield loss (Binder et al., 2000). This is due in part to a reduction in the number of kernel rows per ear, which is determined when ear shoots are set, usually between V5 and V8 (Strachan, 2004). If the deficiency is not corrected, yield loss is inevitable. On the other hand, rescue N applications prior to tasseling have proven to be effective at recovering yield.
• Why We Still Need Rain: Studies clearly show that rescue applications during the late vegetative stages can result in increased yields and economic returns. However, it is important to remember that dry conditions after the rescue N application can limit the effectiveness of additional N because water is needed to move N into the root zone.
  Is It Too Late? Nitrogen applications after R1 (silking) are generally not encouraged, as some studies have shown that economic yield response to N fertilization seldom occurs after pollination. However, under severe N deficiency, some response may occur to applications of low rates of N (30 to 60 pounds) as late as three weeks after pollination.