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NOTE: To get off this list, send email to majordomo@aqua.ccwr.ac.za with the body of the message containing the line: unsubscribe sowacs Clint Shock writes ================== Friends, For what it is worth, polyacrylamide has proven benefits for seed emergence through reduction in soil crusting. Soil water potential is a desirable measurement for this application. Clint -- Dr. Clinton C. Shock 1059 SW 2nd Ave. Ontario, OR 97914, USA Telephone (541) 889-7057 http://www.shockfamily.net Email ccshock@fmtc.net At work Clinton.Shock@orst.edu > > From: Leonard Ornstein <lenornst@pipeline.com> > ===8<==============Original message text=============== > The only effect of the polyacrylamide granules is to provide more > moisture retention per unit volume of soil than in their absence. Any > tensiometer will return the true matric potential in the soil, > independent of the presence or absence of the polyacrylamide. > > For well-aerated, open-textured potting medium, a matric potential of > about -0.1 atmospheres (bars) will encourage rapid germination at > temperatures above 25 degrees Celsius. Such conditions also encourage > mold growth, so an application of an appropriate fungicide is > recommended. > > I don't agree with Bruce; A matric potential readout, which measures > water availability to the plant, rather than a volumetric readout, is > to be preferred. > > Len Ornstein >