Question
Hi
I planted a high yielding disease resistant variety of corn, proper land preparation and pest and disease control measures were used. At harvest the yield obtained was 50% less than I expected. What are three factors that could be responsible for low yield.  

Answer
The most probable reasons are a lack of phosphorus in the soil; poor drainage; interplanting of different species; and inadequate pollination of the silks.

Corn, more than most other vegetables, depletes the soil of nutrients by the end of the growing season. Most gardeners feel very strongly about rotating their crop every three years and replacing the corn with a less demanding plant, such as beans or lettuce. If your space is limited, it is imperative that you replenish the soil with organic matter, and feed the corn with a high phosphorus fertilizer every 15 days once the corn is knee high.

Replenishing the soil also aids with drainage. Clay soils tend to retain water, which in turns saturates the roots. This makes it very difficult for the plants to draw in nutrients and oxygen.

Also, make sure the corn is planted no further than 18" apart. If growing in smaller gardens, I always recommend blocks of 16. This helps ensure that the silks receive sufficient pollen from the tassels.

Finally, make sure you are not interplanting sweet corn with one of the new enhanced SE or supersweet hybrids. Once they cross-fertilize, the harvest is greatly compromised. According to the breeders, different varieties should be planted a minimum of 50' apart to ensure isolation.

I hope this answered your question. Please write again if I can ever be of assistance.

Regards,

Mike