vegetable growing techniques
Key reasons why corn crops fail
While corn is relatively easy to grow I believe there are three key factors why people fail to grow good corn.  They are :-

Corn cobs failing to pollinate properly.
Corn is wind pollinated, meaning that if the male corn pollen is not blown onto the sticky silks of the female corn ears then the corn cobs will not pollinate properly.  This causes the corn kernels to not swell up. 

The most common reason for this is planting corn in a single row.  If corn is planted in a single row at right angles to the prevailing wind direction then the corn's male pollen will be blown away from your female corn ears,  which will result in a poor germination rate.  The same result will occur if you don't plant enough corn. 

SOLUTION : Plant your corn in a block formation of a number of rows rather than a single row.  You also need to plant at least eight corn in any one planting.

Slugs and snails eating the young corn seedlings
While mature corn is pretty hardy young corn seedlings are particularly susceptible to attack by slugs and snails.

SOLUTION A : Plant at least three seeds for every mature corn plant you want to grow and thin out to the strongest plant.  The slugs and snails are unlikely to get all the seedlings.

SOLUTION B : Limit the damage slugs and snails can do by using the Three D' - Deter, Defend, Dynamite pest control method.

Corn planted too close together and not getting enough water
While factors such as disease, zinc deficiency and soil pH imbalance can stunt the growth of corn the most common reason for stunted corn plants and small corn ears  that I have come across is corn being planted too close together.  Another key reason is not enough water.

SOLUTION : Plant your corn at the proper spacing for corn or use my suggested spacing for Growing Corn in a Raised Bed.  Make sure your corn plants have enough water, especially when the corn ears are swelling out.