The Effect of Straw Mulch on Simulated Simazine Leaching and Runoff

Abstract

In the Midwestern United States, winter hilling, consisting of two tillage activities per year, is required in vinifera-grape vineyards for winter protection. However, this practice often leads to severe soil erosion and pesticide offsite movement. The effectiveness of wheat straw mulch as a replacement for soil mounding was investigated as a way of providing winter protection and to mitigate pesticide leaching and runoff. A laboratory experiment was conducted where simazine was applied to wheat straw or bare soil and then followed by simulated rainfalls. When compared with bare soil, straw reduced simazine leaching and runoff by 40 and 68%, respectively. Adsorption or interception, or both, of simazine by straw were responsible for this effect. Additionally, straw reduced soil erosion by 95% and would largely reduce simazine runoff associated with sediment displacement. The first simulated rainfall contributed 70 and 34% of total simazine runoff from bare soil and straw, respectively. In conclusion, mulching with straw during winter months to provide winter protection could be an effective practice for controlling simazine offsite movement and soil erosion in vinifera vineyards.