Nutrient removal by prairie filter strips in agricultural landscapes

Abstract

Nitrogen (N) and phosphorus (P) from agricultural landscapes have been identified as primary sources of excess nutrients in aquatic systems. The main objective of this study was to evaluate the effectiveness of prairie filter strips (PFS) in removing nutrients from cropland runoff in 12 small watersheds in central Iowa. Four treatments with PFS of different spatial coverage and distribution (No-PFS, 10% PFS, 10% PFS with strips, and 20% PFS with strips) were arranged in a balanced incomplete block design across four blocks in 2007. A no-tillage two-year corn (Zea mays L.) -soybean (Glycine max [L.] Merr.) rotation was grown in row-cropped areas beginning in 2007. Runoff was monitored by H flumes, and runoff water samples were collected during the growing seasons to determine concentrations of nitrate-nitrogen (NO 3 -N), total nitrogen (TN) and total phosphorus (TP) through 2011. Overall, the presence of PFS reduced mean annual NO 3 -N, TN, and TP concentrations by 35%, 73%, and 82%, respectively, and reduced annual NO 3 -N, TN, and TP losses by 67%, 84%, and 90%, respectively. However, the amount and distribution of PFS had no significant impact on runoff and nutrient yields. The findings suggest that utilization of PFS at the footslope position of annual row crop systems provides an effective approach to reducing nutrient loss in runoff from small agricultural watersheds. Runoff was monitored by H flumes, and runoff water samples were collected during the growing seasons to determine concentrations of nitrate-nitrogen (NO 3 -N), total nitrogen (TN) and total phosphorus (TP) through 2011. Overall, the presence of PFS reduced mean annual NO 3 -N, TN, and TP concentrations by 35%, 73%, and 82%, respectively, and reduced annual NO 3 -N, TN, and TP losses by 67%, 84%, and 90%, respectively. However, the amount and distribution of PFS had no significant impact on runoff and nutrient yields. The findings suggest that utilization of PFS at the footslope position of annual row crop systems provides an effective approach to reducing nutrient loss in runoff from small agricultural watersheds.

Prairie strips improve biodiversity and the delivery of multiple ecosystem services from corn–soybean croplands

“…In previous disciplinary papers we established that prairie strips in row cropland provided habitat for native biodiversity (22)(23)(24), improved soil quality (25), fostered desirable patterns of biogeochemical functioning and hydrological regulation (26)(27)(28)(29), and offered a low-cost agricultural conservation option for farmers and farmland owners relative to alternative best-management practices (30). Here, we sought to use a holistic, integrative approach to assess the effects of prairie strips relative to the proportion of the catchments they occupied.…”

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

“…At field scale, effectiveness may be lower because of larger drainage area to buffer ratios and longer slope lengths, leading to increased concentrated flow (Helmers et al, 2008(Helmers et al, , 2012. In Iowa, a long-term replicated field experiment quantified the effectiveness of different combinations of edge-of-field and upland prairie buffers in 12 small watersheds (areas of 0.47 to 3.19 ha; Helmers et al, 2012;Zhou et al, 2014). Reported trapping effectiveness was 96% for sediment (Helmers et al, 2012) and 82% for TP over five years (Zhou et al, 2014).…”

“…In Iowa, a long-term replicated field experiment quantified the effectiveness of different combinations of edge-of-field and upland prairie buffers in 12 small watersheds (areas of 0.47 to 3.19 ha; Helmers et al, 2012;Zhou et al, 2014). Reported trapping effectiveness was 96% for sediment (Helmers et al, 2012) and 82% for TP over five years (Zhou et al, 2014). A long-term Missouri study with three watersheds (areas of 1.65 to 4.44 ha), using a paired watershed approach, compared contour upland grass or agroforestry buffers (4.5 m width) to a control watershed .…”

AgBufferBuilder: A geographic information system (GIS) tool for precision design and performance assessment of filter strips

“…The field site is located in Jasper County in south central Iowa, a region of loess topsoils and rolling topography. The field measurements were made as part of the plot study described in Zhou et al (2010), Helmers et al (2011), andZhou et al (2014). This present investigation focused on seven of their plots.…”