Studying the retention of inorganic N after last year’s drought was revealing. An Illinois team of researchers determined from 151 samples statewide that an average equivalent of 140 lb of N per acre was left over from 2012! (More than half was resident in the top foot of soil while the rest was in the second foot.)
The study also looked at how much of that N was being lost this spring and found that between 20 – 50 lb/ac had been lost. The researchers speculate that some may be below the two-foot depth but said that with spring rains, drain tiles were showing dramatic increases of nitrates.
What the article didn’t mention is that annual ryegrass and other cover crops are superb crops to soak up that N available in the soil.
For more information about annual ryegrass, click here.