Influence of Turfgrass Coverage on Nutrient and Pesticide Transport as Affected by Water and Sediment Displacement during Surface Runoff

• Main Author: Borst, Steven Michael
• Other Authors: Longstreth, David
• Format: Others
• Language: en
• Published: LSU 2011
• Subjects: Horticulture
• Online Access: http://etd.lsu.edu/docs/available/etd-11022011-164027/

Turfgrass systems such as roadsides, home lawns, and golf course roughs can vary in surface coverage. Nutrient and pesticide applications applied to these systems may pose an increased risk to adjacent water supplies from surface runoff. Therefore the objectives of this research were: 1) determine the effect surface coverage has on nutrient, pesticide, and sediment runoff and, 2) evaluate the impact of pesticide solubility on runoff losses at varying turfgrass coverages. Surface runoff research commenced in 2010 and 2011 with experimental units consisting of six turfgrass coverages (0, 25, 50, 75, and 100%) and untreated bare soil. Coverages each received a granular fertilizer, atrazine, azoxystrobin, monosodium methyl arsenate (MSMA), pendimethalin, simazine, and S-metolachlor treatment. Simulated rainfall was applied at 7.38 cm hr -1 with runoff collected and analyzed for dissolved nitrogen (DN), total nitrogen (TN), dissolved phosphorus (DP), total phosphorus (TP), total solids (TS) and each pesticide applied. Runoff volumes and TS loading decreased as turfgrass coverage increased from 0 to 100% turfgrass coverage. Total solids decreased from 1078 and 873 kg ha-1 from 0% coverage to 35 and 14 kg ha-1 at 100% turfgrass coverage in 2010 and 2011, respectively. Turfgrass coverage did not affect TN and TP with 5.76 kg N ha-1 and 5.60 kg P ha-1 lost at 100% turfgrass coverage. As turfgrass coverage increased DN and DP losses accounted for greater portions of total losses with decreasing sediment bound nutrients losses. Greater than 56% of DN and DP occurred during the first 15 min after the onset of runoff (AOR). Higher water soluble pesticides were more susceptible to loss during surface runoff. MSMA losses of 25.7% at 100% turfgrass coverage were 7 times greater than the highest pendimethalin losses observed. Similar to soluble nutrients, > 56% of dissolved pesticides were lost in the first 15 min AOR. Total atrazine losses of 12.5 and18.3% compared to total simazine losses of 10.1and 5.7% for 0 and 100% coverage respectively, indicate the importance of maintaining greater turfgrass coverage for reducing sediment bound pollutants. However, turfgrass coverage may not be as effective for reducing dissolved pollutant transport.