While its true calcium may be King, all nutrients have an important part to play in plant health and high yields. I just saw an article on the lack of zinc in North American Soils. Of 4.4 million tests taken in 2010 37% showed less than 1 ppm Zn, with 16% of those less than 0.5 ppm. 

You can order the full IPNI report Soil Test leaves in North America 2010 by clicking on the previous link.

Zinc is a component of enzymes including auxins (plant growth hormones). It is essential to carbohydrate metabolism, protein synthesis and internodal elongation (stem growth). 

Here is a great post by AgriGold Hybrids on Zinc.

Here is a summary of the post:

... showed a 53 bushel increase in yield by adding one pound of zinc to a starter. 

...common symptoms associated with zinc deficiency in corn results in a white or yellow band that runs parallel with the mid rib. Other problems associated with zinc deficiency include:

There is also the hidden deficiency that has no symptoms.  Hidden zinc deficiencies are well documented in corn and reductions in yield can be up to 40%.  Therefore the best method to determine if zinc is deficient is by taking soil samples to determine the levels of zinc in the soil.

Calcium Product's Note: It is well documented that many deficiencies can take up to 2 weeks to show visual response and up to 2 more weeks to correct. This whole time you are losing yield you cannot recover.

Don't let your yields suffer from hidden hunger, make sure you include micronutrients as part of your fertility program.

Yield Starts Here is a blog for farmers, focusing on increasing yield and profitability by focusing on the soil. It is managed by Craig Dick, a Blogronomist and Sales and Marketing Manager at Calcium Products. Find other articles by Craig and guest writers at http://blog.calciumproducts.com/ .