Posted 4/7/2021 08:48 (#8937743 - in reply to #8937724) Subject: RE: How fast will urea volatilize
Here is some work from Montana.
Surface soil moisture is a major contributor to broadcast urea’s volatilization. This has been shown in cool season broadcast urea applications in semi-arid regions of Montana (5). Largest losses (30 to 44 percent of applied N) occurred after urea was applied to wet or snowy soil surfaces (Figure 3), followed by a period of slow drying with little or no precipitation. Losses were less (10 to 20 percent of applied N) when urea was broadcast on dry soil followed by only light scattered rainfall (<0.33 inch) and losses were least (<10 percent of applied N) when applied to a dry surface followed within two weeks by at least 0.75 inch of rainfall. Surfaces can be considered dry if there is insufficient moisture to dissolve the urea granule