| Ammonia emission from cattle urine should be minimal. It's only released upon hydrolysis of the urea primarily via bacterial decomposition, which isn't going to happen if it's collected and bottled. In theory cattle urine should be no different from using the same concentration of urea. If diluted before use the free ammonia released should be no more harmful than if using a urea based fertilizer. Having said that, as urea needs to be broken down before it can be used, it probably won't be as efficiently taken up by the orchids as ammonium/nitrate based fertilizers. Compared to the finer potting mixes and soils that urea based fertilizers are normally used with, epiphyte bark/rock mixes are much more porous and subject to moisture fluctation, which no doubt results in less less water hold time for the fertilizer and less bacterial activity per volume of mix. End result, much more urea should be flushed from the pot before the plant gets around to taking it up compared with simpler nitrogenous ions.  |