Use of drinking water treatment residuals as a potential best management practice to reduce phosphorus risk index scores.
The P risk index system has been developed to identify agricultural fields vulnerable to P loss as a step toward protecting surface water. Because of their high Langmuir phosphorus adsorption maxima (P(max)), use of drinking water treatment residuals (WTRs) should be considered as a best management practice (BMP) to lower P risk index scores. This work discusses three WTR application methods that can be used to reduce P risk scores: (i) enhanced buffer strip, (ii) incorporation into a high soil test phosphorus (STP) soil, and (iii) co-blending with manure or biosolids. The relationship between WTR P(max) and reduction in P extractability and runoff P was investigated. In a simulated rainfall experiment, using a buffer strip enhanced with 20 Mg WTR ha(-1), runoff P was reduced by from 66.8 to 86.2% and reductions were related to the WTR P(max). When 25 g kg(-1) WTR was incorporated into a high STP soil of 315 mg kg(-1) determined using Mehlich-3 extraction, 0.01 M calcium chloride-extractable phosphorus (CaCl(2)-P) reductions ranged from 60.9 to 96.0% and were strongly (P < 0.01) related to WTR P(max). At a 100 g kg(-1) WTR addition, Mehlich 3-extractable P reductions ranged from 41.1 to 86.7% and were strongly (P < 0.01) related to WTR P(max). Co-blending WTR at 250 g kg(-1) to manure or biosolids reduced CaCl(2)-P by >75%. The WTR P(max) normalized across WTR application rates (P(max) x WTR application) was significantly related to reductions in CaCl(2)-P or STP. Using WTR as a P risk index modifying factor will promote effective use of WTR as a BMP to reduce P loss from agricultural land.
Dayton
E A
EA
School of Natural Resources, The Ohio State University, Columbus, 43210, USA. Dayton.15@osu.edu
Basta
N T
NT
D000327:Adsorption; D000383:Agriculture / Q000379:methods*; D002122:Calcium Chloride / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012307:Risk Factors; D012987:Soil; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
D012987:Soil; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002122:Calcium Chloride