Compost Amendment to Control Runoff From Turf Rob Harrison Univ of Washington Rob Harrison Ecosystem Sciences Division College of Forest Resources University of Washington Seattle WA USA Phil Cohen, Bruce Jensen, Kyle Kolsti, Steve Burgess, Mark Grey and Chuck Henry

Big Problems: Rob Harrison Univ of Washington Lake Sammamish is increasingly polluted and subject to eutrophication P in runoff is considered the problem

direct sources of P: soil erosion human and animal waste fertilizers lower infiltration of water aggravating problems: increased peak runoff septic tanks

“turf on till” phenomenon on Alderwood and related soil types aggravating problems: highest native P soil concentrations in the U.S. lack of permanence in turf establishment large amounts of water used to establish and maintain turf

turf industry estimates that... did you know? 18 $billion per year spent on turf establishment and maintenance growth rate for industry is 35% per year very little recycled material is used,but use is growing rapidly 1) 2) 3)

increase water percolation primary needs: decrease erosion and runoff reduce use of phosphorus fertilizer

establish plots to turf approach: run natural and manmade storm events evaluate runoff 1) total amounts 2) periodicity 3) chemistry

sites:

changes in soil:

Event Collection Periods

May 25-26, 1995 two storm events total storage (liters)

May 25-26, 1995 two storm events total storage (liters)

May 25-26, 1995 two storm events

May 31-June 3, 1995 two storm events

Conclusions: Rob Harrison Univ of Washington Compost amendment increased water retention in soil and lag times of response to storms, though antecedent conditions are important Compost amendment appears to be a permanent improvement, not so with inorganic fertilizer amendment Total P runoff from compost-amended sites was less, though P concentrations were sometimes higher

Future directions: Rob Harrison Univ of Washington What are implications on a watershed basis? Will the properties of the unamended site improve with time? Is the compost treatment permanent?