Introduction to the Issue of Hypoxia in the Gulf of Mexico

In recent years there has been a growing concern about a large area of oxygen-depleted waters that develops seasonally in the Gulf of Mexico near the mouth of the Mississippi River. The size of the oxygen-depleted area varies from year-to-year and has extended from the mouth of the Mississippi River west to near the Texas border. Oxygen depletion in the nearshore Gulf can exceed 6,000 square miles in size and may form as early as February and last as late as October with the most widespread and persistent conditions occurring from Mid-May to Mid-September

Get acquainted with the Iowa CREP

The Conservation Reserve Enhancement Program (CREP), an offshoot of the original Conservation Reserve Program (CRP), is a voluntary program for agricultural landowners. Unique state and federal partnerships allow producers to receive incentive payments for installing specific conservation practices. Through CREP, farmers with eligible land receive annual rental payments and cost-share assistance to establish long-term, resource-conserving cover

Nitrate and Organic N Analyses with Second-Derivative Spectroscopy

Simple and reliable procedures have been developed for analyses of N03 , total N, and organic N in fresh waters. N03- is determined by second-derivative UV spectroscopy. Total N and organic N are determined based on secondderivative analyses of N03- following persulfate digestion. Resolution of organic N determinations was increased by using ion-exchange resins to remove N03- from samples with high concentrations of N03 prior to persulfate oxidation of the organic N

Improving Soil and Water Quality with Riparian Buffers

The agricultural landscape has four major sources of non-point source (NPS) pollutants. These are: 1) surface and subsurface runoff which carry sediment and agricultural chemicals to streams; 2) eroding streambanks which can contribute more than fifty percent of the sediment load to the stream; 3) field tile drains which contribute the highest concentrations of soluble agricultural chemicals to streams; and 4) livestock grazing of streamside or riparian areas which contribute to bank instability and add animal waste and pathogens to the water. Maintaining or establishing a forested or prairie buffer along streams and rivers provides more than just a beautiful landscape. While a considerable body of evidence confirms that existing vegetated streamside zones can be effective sinks for NPS pollution (Castelle et a!. 1994, Osborne and Kovacic 1993, Lowrance 1992, Cooper eta!. 1987, Jacobs and Gilliam 1985, Lowrance eta!. 1985, 1984, Peterjohn and Correll 1984), little information is available for restored or constructed streamside buffer systems. Designing and establishing the right combination of native trees, shrubs and grasses as buffer strips and integrating them with constructed wetlands, soil bioengineering and rotational grazing can improve water quality

Reconnecting Tile Drainage to Riparian Buffer Hydrology for Enhanced Nitrate Removal

Riparian buffers are a proven practice for removing NO3 from overland flow and shallow groundwater. However, in landscapes with artificial subsurface (tile) drainage, most of the subsurface flow leaving fields is passed through the buffers in drainage pipes, leaving little opportunity for NO3 removal. We investigated the feasibility of re-routing a fraction of field tile drainage as subsurface flow through a riparian buffer for increasing NO3 removal. We intercepted an existing field tile outlet draining a 10.1-ha area of a row-cropped field in central Iowa and re-routed a fraction of the discharge as subsurface flow along 335 m of an existing riparian buffer. Tile drainage from the field was infiltrated through a perforated pipe installed 75 cm below the surface by maintaining a constant head in the pipe at a control box installed in-line with the existing field outlet. During 2 yr, \u3e18,000 m3 (55%) of the total flow from the tile outlet was redirected as infiltration within the riparian buffer. The redirected water seeped through the 60-m-wide buffer, raising the water table approximately 35 cm. The redirected tile flow contained 228 kg of NO3. On the basis of the strong decrease in NO3concentrations within the shallow groundwater across the buffer, we hypothesize that the NO3 did not enter the stream but was removed within the buffer by plant uptake, microbial immobilization, or denitrification. Redirecting tile drainage as subsurface flow through a riparian buffer increased its NO3 removal benefit and is a promising management practice to improve surface water quality within tile-drained landscapes

Riparian buffer systems -- the basics

If you have a stream running through your farm, you may be interested in learning about a conservation technique that has gained the respect of many Iowa landowners and conservation professionals. It is called a riparian buffer system and involves planting trees, shrubs, and native grasses along streams to prevent sediment and chemicals from entering creeks and rivers

Riparian Management to Protect Water Quality

The agricultural landscape has four major sources of non-point source (NPS) pollutants. These are: 1) surface and subsurface runoff which carry sediment and agricultural chemicals to streams; 2) eroding streambanks which can contribute more than fifty percent of the sediment load to the stream; 3) field tile drain8 which contribute the highest concentrations of soluble agricultural chemicals to streams; and 4) livestock grazing of streamside or riparian areas which contribute to bank instability and add animal waste and pathogens to the water

Reconnecting riparian buffers with tile drainage (2)

This is a continuation of an earlier pilot project (E2010-01) where tile discharge was rerouted to allow subsurface flow through an established riparian buffer. This third year of observations allowed researchers to gather more data on nitrate removal using this system

Assessing the Need for a Riparian Management System (RiMS)

Riparian management systems (RiMS) often appear complex, and assessing your stream riparian area to design one can seem a daunting task. There are many design options for RiMS that can provide multiple benefits. The best option is the design that accomplishes the most for you, for the land, and for the community. This publication provides a list of tools and considerations to help you determine what kind of RiMS is best for you and your land.https://lib.dr.iastate.edu/extension_ag_pubs/1219/thumbnail.jp

Riparian Management for Water Quality, the Bear Creek Example: Getting the Message Out

While a considerable body of evidence confirms that exiting vegetated streamside zones can be effective sinks for nonpoint source pollution (Castelle et al. 1994, Osborne and Kovacic 1993, Lowrance 1992, Cooper et al. 1987, Jacobs and Gilliam 1985, Lowrance et al. 1985, 1984, Peterjohn and Correll 1984), little information is available for restored or constructed streamside buffer systems. To demonstrate the benefits of properly functioning riparian zones in the heavily row-cropped midwestern U.S., the Agroecology Issue Team of the Leopold Center for Sustainable Agriculture and the Iowa State Agroforestry Research Team (IStART) are conducting research on the design and establishment of integrated riparian management systems. The purpose of these systems is to restore the essential ecological functions that these riparian areas once provided. Specific objectives of such buffers are to intercept eroding soil and agricultural chemicals from adjacent crop fields, slow flood waters, stabilize streambanks, provide wildlife habitat, and improve the biological integrity of aquatic ecosystems