ISSUE 16 August 21, 2003
FALL APPLICATION OF N
Although I encourage people to sample fields soon after small grain harvest, that does not mean that early application of nitrogen is recommended. Fall anhydrous ammonia application should wait until about October 1 and only when soil temperature at 4 inches in depth, taken between 6 AM and 8AM is below 50 degrees F. Application of anhydrous before these conditions usually results in conversion of N to nitrate, which leads to leaching losses in late winter, early spring and denitrification in heavy soils. Application even after these conditions is not totally without risk, but the chances of going into freeze-up with mostly ammonium N are greatly increased.
Application of banded urea should be delayed until about one week following conditions favorable for anhydrous application. Incorporated broadcast urea should be delayed two weeks after conditions are favorable for anhydrous application.
THINGS HAVENíT CHANGED THAT MUCH IN 90 YEARS!
During a reading of a Colorado State Agricultural Experiment Station Bulletin on poor sugar beet quality due to excessive nitrates from 1912, I was amused to read the following passage regarding the treatment of salty soils:
"Our Colorado people read of the alkali questions of California and applied all of the statements relative to the California conditions to the facts in Colorado, which is not justified....In California they have found that application of land plaster, ground gypsum in quantities proportioned to the amount of sodic carbonate, black alkali, ameliorates the conditions. These parties" (people in Colorado) "applied land plaster in liberal quantity, perhaps as much as five tons per acre, whereas, the facts were that this land contained no sodic carbonate but was already so rich in gypsum that the mineral had crystallized out in little aggregates and veinlets, carrying many tons of it in each acre-foot of soil.....I abide by my statement made ten years ago that our alkali questions resolve themselves into questions of drainage." Wm. P. Headden, Col.Agr. Exp. Sta. Bull. 183, 1912.
I think Mr. Headden would feel right at home here today.
NDSU Extension Soil Specialist