Geology topics

Research about Iowa;Minnesota

Source-linked reports with geographic coverage including Iowa;Minnesota.

3 recordsLinked to original sources

USGS2013

Tallgrass prairie restoration: seeding for success

Tallgrass prairie is one of the most imperiled ecosystems on Earth. A 2004 estimate indicated that only 2.4 percent of the original northern tallgrass prairie remained in the United States. If tallgrass prairie and the species dependent on it are to survive, management must include restoration of cropland and degraded prairies, in addition to preservation of the few remaining fragments. Despite the importance of restoration and its long history (the first tallgrass prairie restoration was started in 1935 at Curtis Prairie in Wisconsin), few studies have been undertaken with the goal of refining restoration practice. This fact sheet contains the results of one such study, started in 2005, in which we compared three seeding methods (dormant-season broadcast, growing-season broadcast, and growing-season drill) fully crossed with low (10-), medium (20-), and high (34-species) seed mixes replicated 12 times on each of 9 former agricultural fields in Minnesota and Iowa. Plots were 12.2 x 12.2 meters (m) and occupied about 1.6 hectares (ha) (4 acres) of each field. A “successful” restoration is one in which cover and richness of planted species is maximized and cover of exotic and invasive species, especially the noxious weed Canada thistle (Cirsium arvense), is minimized. Details of the planting methods can be located in Larson and others (2011).

Iowa;Minnesota↗

USGS2012

Impacts of biofuels production alternatives on water quantity and quality in the Iowa River Basin

Corn stover as well as perennial grasses like switchgrass (Panicum virgatum) and miscanthus are being considered as candidates for the second generation biofuel feedstocks. However, the challenges to biofuel development are its effects on the environment, especially water quality. This study evaluates the long-term impacts of biofuel production alternatives (e.g., elevated corn stover removal rates and the potential land cover change) on an ecosystem with a focus on biomass production, soil erosion, water quantity and quality, and soil nitrate nitrogen concentration at the watershed scale. The Soil and Water Assessment Tool (SWAT) was modified for setting land cover change scenarios and applied to the Iowa River Basin (a tributary of the Upper Mississippi River Basin). Results show that biomass production can be sustained with an increased stover removal rate as long as the crop demand for nutrients is met with appropriate fertilization. Although a drastic increase (4.7–70.6%) in sediment yield due to erosion and a slight decrease (1.2–3.2%) in water yield were estimated with the stover removal rate ranging between 40% and 100%, the nitrate nitrogen load declined about 6–10.1%. In comparison to growing corn, growing either switchgrass or miscanthus can reduce sediment erosion greatly. However, land cover changes from native grass to switchgrass or miscanthus would lead to a decrease in water yield and an increase in nitrate nitrogen load. In contrast to growing switchgrass, growing miscanthus is more productive in generating biomass, but its higher water demand may reduce water availability in the study area.

Iowa;Minnesota↗

USGS2012

Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa

Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model SEAWAVE-Q, which accounts for seasonal and flow-related variability. Daily estimated concentrations generated from the model were used with daily streamflow to calculate daily and yearly loads. Acetochlor, alachlor, metolachlor, and their ESA and OXA degradates were generally present in >50% of the samples collected from both sites throughout the study. Their concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. Concentrations of the ESA and OXA degradates decreased from 3 to about 23% yr -1 . The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds during the study period, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed moved a greater percentage of the applied herbicides, especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage.

Iowa;Minnesota↗