If you’ve look closely at your sum graph on your commercial corn fields, you will notice that we lowered our refill line now that the crop is past pollination and moving towards maturity. We are often asked why and how we do that. There are some very sound agronomic principles behind finishing the season with a 65% depleted profile (UNL Recommendation). One is that a dry soil will compact less during the harvest. Also, if the soil is dry at black layer and we start to get rains during harvest you can get back into the field much quicker than those fields that entered Black Layer with a full profile. Drier soils also allow for more freezing and thawing in the winter, helping improve soil structure. And, one of the most important reasons is applying water that is not needed, COSTS MONEY.
All that being said, achieving that 65% depletion goal and making sure we have enough water to get us to black layer requires some careful agronomic planning. Because of the tall corn canopy and the dropped leaves on the soil surface, evaporation is very limited. To dry down the soil profile, we need to rely on the plants to extract moisture. And since little ET takes place after Black Layer we must dry it down before physiological maturity.
To do that we first must estimate when Black Layer will happen. We use charts like the one below to help. Here you see the projected BL (Black Layer) date (September 14th) of a 113 hybrid planted April 25th in Hall County. Of course, the two critical pieces of information here are hybrid maturity and planting date. This is why we are adamant about getting that data into the system early in the season.
