Dry weather

I had a discussion with my brother yesterday about soil moisture.  He had recently been pulling up some fence posts that were buried about 18 to 24 inches.  He was finding water at the end of the posts.  Not just moisture, but free water.  With water so close to the surface, he was asking why his corn is "burning up." 

The corn is showing moisture stress for several reasons. 
1.  The heat.  We just came off of 4 days in a row of 100+ temperatures.
2.  Even though moisture seems to be within reach of roots, it takes a lot of energy to pump that water up to the top of a 7 or 8 foot plant.
3.  Shallow roots.  I sampled this summer until July 5.  I did not make one probe into dry soil during the spring and summer sampling season.  Soils below plow depth were saturated.  Roots do not grow in saturated soils.  When the rains quit coming they really quit.  Stressed plants were not able to put roots deeper as quickly as the surface dried out.  Average soils should have been holding 10 - 12 inches of water lets say on July 5.   That should have left plenty of water to make a good crop.  Quick drying, heat, and shallow roots appear to have done us no favors.  Here is another reason for tile drainage.  Tile removes saturation and allows deeper roots. 
4.  An additional consideration is that the crop ran out of nitrogen.  In some cases the nitrogen may be in the soil, but the roots could not get to it.  I base this on an observation today that some fields that were sidedressed about as late as possible are still green. 

I expect harvest to get underway full strength  tomorrow.  Lots of corn is dry.  Disease will affect standibility.  It is just time to go at it.