All posts by tlriley3

Riparian Herbaceous Cover

Riparian herbaceous cover is defined by NRCS as grasses, grass-like plants and forbs that are tolerant of intermittent flooding or saturated soils and that are established or managed in the riparian or transitional zone between terrestrial and aquatic habitats.

The riparian zone is the area adjacent to perennial and intermittent watercourses or water bodies, considered by NRCS to be a minimum of 1.5 times a stream’s with or 15 feet for other water bodies.  For seasonal or short lived watercourses and water bodies, this zone extends to the center of the channel or basin.

Riparian herbaceous cover relies on grasses, sedges, rushes, ferns, legumes, and forbs tolerant of intermittent flooding or saturated soils established or managed as the dominant vegetation in the transitional zone between terrestrial and aquatic habitats.  The riparian herbaceous cover provides habitat for wildlife, improves water quality by acting as a filter for sediments and pollutants in surface water run-off, stabilizes stream banks and shorelines, and increases soil biomass’ net carbon storage.

Land owners often use the riparian herbaceous cover practice to remedy damage due to the riparian area having been altered or converted to cropland, pasture, or other commercial/agricultural practices that have changed the native plant community.  Proper application of riparian herbaceous cover requires research to select the appropriate perennial plants adapted to the riparian zone’s hydrological conditions and that provide the diversity required by the.  When establishing a herbaceous cover practice the riparian zone must be protected from haying, grazing, or similar practices until the desired plant community is well established.  After establishment of the herbaceous cover, land owners must use diligence in best management practices which limit haying, grazing, or similar practices, and avoid times when stream banks are vulnerable to livestock or mechanical damage.

Riparian herbaceous cover

Once established, riparian herbaceous cover has been shown to help reduce non-point source pollution from agricultural areas.  Healthy riparian herbaceous cover has been shown to reduce the total weight of sediment and nutrients in run-off from agricultural fields by 50 to 80%.  Research has shown other notable benefits of riparian herbaceous cover used as a filter for run-off including; reductions of total Phosphorous load of 50%, a 20 to 50% reduction of Ammonium, and about 50% reduction of the total Kjeldahl Nitrogen and Nitrate (R. B. Daniels and J. W. Gilliam 1996).  Further improving or protecting water quality is benefited by increasing the minimum riparian zone to 2.5 times the stream width or 35 feet for water bodies.  Management to control mass soil movement or concentrated flow erosion areas that may overload the riparian herbaceous cover’s filtering capacity prior to establishing a riparian herbaceous cover is also recommended.

Stream bank stability has been shown to greatly improve with a healthy riparian herbaceous cover as well.  Research has shown mechanical effects of  grass roots increasing soil strength and instances of up to a 70% improvement of stream bank stability (A. Simon and A. J. C. Collison 2002).  Native or accepted, introduced herbaceous species with deep, binding root mass have been shown to be optimum for strengthen streambanks and improving soil health.

If conditions requiring riparian herbaceous cover exist, there are financial incentive programs which may cost-share the expenses of the additional requirements.  Implementation of riparian herbaceous cover can be worked into an EQIP application package and may complement other conservation practices such as 580-Streambank and Shoreline Protection, 584-Stream Channel Stabilization, 382-Fence, 391-Ripariian Forest Buffer, 512-Pasture and Hayland Planting, 550-Range Planting, 393-Filter Strip, 472-Use Exclusion, 528A-Prescribed Grazing, or 314-Brush Management.

When performing a riparian herbaceous cover conservation practice there are several things that must be considered to achieve optimum results.  When choosing herbaceous plants preference should be given to native, locally adapted species that provide full ground cover, however, a tame, introduced species suited for the location can often be used as well.  Avoid plant species that may be hosts to undesirable pests.  Control trees and shrubs that may have the potential of dominating the riparian zone, as there are few woody plants in healthy herbaceous riparian zones.  Plant species diversity is crucial to maintaining a healthy habitat for wildlife in the riparian zone; special attention should be given to enhancing habitats of any possible threatened and/or endangered species; additionally consider seasonal changes and select plants accordingly.   Be mindful of how this practice will compliment the function of surrounding ecosystems, paying attention to the locations natural features which should be used to frame the vegetative structure and composition, and complement those natural features.  Finally establish alternate water sources and controlled access stream crossings for livestock to aid in maintaining a healthy herbaceous riparian cover.

In summary, riparian herbaceous cover is an important conservation and production practice that can be utilized in conservation programs. Riparian herbaceous cover is crucial to maintain a healthy stream system, by reducing sediment, nutrient, and pollution loads in run-off from agricultural production.  Healthy riparian herbaceous cover also provides habitat for many different aquatic and terrestrial organisms.  Careful selection of the proper deep rooting, native plant species, best suited for the riparian zone will provide the greatest benefits, filtering run-off, providing mechanical and hydrological stability to stream banks, and increases species diversity of the riparian zone.  For more information contact your local County Extension Office or your local USDA Service Center.

Daniels, R. B., Gilliam, J. W. “Sediment and Chemical Load Reduction by Grass and Riparian Filters” Soil Sci. Soc. Am. J.  (1996) 60: 246–251.

Simon, A., Collison, A. J. C. “Quantifying the mechanical and hydrologic effects of riparian vegetation on streambank stability” Earth Surface Processes and Landforms (2002) V. 27 I. 5: 527-546

– Lee Riley

Deep Tillage

Deep tillage is defined by NRCS as performing tillage operations below the normal tillage depth to modify adverse physical or chemical properties of a soil. This practice does not apply to normal tillage practices to prepare a seedbed.

Deep tillage, commonly referred to as deep plowing, in-row subsoiling, strip-tillage, paratilling, subsoiling, ripping, or row-till, is not performed as a part of the normal tillage. This practice applies to land having adverse soil conditions which inhibit plant growth, such as compacted layers formed by field operations, restrictive layers such as cemented hardpans (duripan), in the root zone, overwash or deposits from wind and water erosion or flooding, or contaminants in the root zone.

Deep tillage is an important practice in Southeastern Arkansas where soil in the plant root zone has been contaminated with chloride where irrigation-well-water containing greater than 100 ppm of chloride has been used. Deep tillage allows downward movement of water and chloride below the root zone which provides relief from chloride toxicity, especially in soybean. However, this is a corrective action and it is recommended to have well water tested for chlorides and other soluble salts before using for irrigation to prevent chloride build-up in soils.
Deep tillage operations should be performed when soil moisture is less than 30 percent of field capacity, at the maximum depth the tillage will be done.

Deep tillage for fracturing restrictive soil layers should be performed at least 1 inch below the restrictive layer with equipment such as chisels, subsoilers, bent-leg subsoilers, or rippers capable of reaching the required depth.

Burying soil deposits left from flood overwash or erosion deposits is performed with large moldboard or disk plows capable of reaching sufficient depths. Mixing soil deposits from flood overwash or erosion deposits is performed with a large twisted point chisel, moldboard plow, or disk plow. Mixing requires the affected area to be plowed at least twice the depth of the surface soil deposits being mixed.

Deep Tillage to reduce plant growth inhibiting soil contaminates uses large twisted point chisel, moldboard plow, or disk plow capable of reaching the required depth to mix uncontaminated soil with the contaminated, to evenly distribute the contaminate, reducing its concentration to a level the crop can tolerate.

Deep Tillage offers many conservation benefits as well, including

• Bury or mix soil deposits from wind or water erosion or flood overwash.

• Reduce concentration of soil contaminants, such as chloride which inhibit plant growth.

• Fracture restrictive soil layers.

• Reduce transport of sediment borne pollutant(s) offsite

John Deere Tractors tilling soil

These benefits will vary with soils, crops, climate, severity of conditions necessitating remediation, and other factors. However, these benefits are important to increasing long-term profitability and sustainability of areas with adverse physical and chemical soil properties. The USDA-NRCS provides financial incentives for deep tillage (Practice 324) through programs such as the Environmental Quality Incentives Program (EQIP).

Some considerations should be made when considering deep tillage for hard pan layers. There are other preventative measures that can be taken to limit the need of deep tillage. Access control (practice 472) such as reducing traffic, especially heavy loads (greater than 6 tons/axle), the use of radial tires with a larger contact patch on equipment instead of bias-ply tires, and conducting normal tillage when soil moisture is less than 50% of field capacity have all been shown to help reduce compaction. Deep rooted plants that can be worked into a crop rotation (practice 328) or used as a cover crop (practice 327) can also aid in penetrating soil hardpan layers. Deep soil tillage, excessively deeper than the hardpan does not promote increased yields, requires excessive amounts of tillage energy, and increases the potential of future compaction from nearby vehicle traffic.

Other considerations should be taken into account when using deep tillage to mix flood overwash, especially when the overwash layer is too thick to effectively mix with the original soil profile. Some instances require physical removal of the overwash and/or land smoothing (practice 466) to redistribute the overwash over a larger area in which it can be incorporated. Common equipment used for mixing the overwash into the soil profile generally cannot uniformly mix more than 6 inches of overwash. Situations in which infertile overwash is mixing with the original soil profile, the infertile overwash can be amended with the addition of organic matter such as cover crops (practice 327), manure, other nutrient management practices (practice 590), as well as maintaining high crop residue levels from conservation practices such as no-till (practice 329) to enhance the soil rebuilding process.

Deep tillage can result in some unfavorable soil conditions as well. While deep tillage can distribute unfavorable contaminates in the root zone to a plant tolerable levels, other sometimes unfavorable soil materials such as calcium, gypsum, and excessive sodium can be brought to the surface. Deep tillage should not be preformed if these unwanted materials are within the range of the deep tillage depth. Additionally, the equipment used in deep tillage is also very destructive to the physical characteristics of the soil and can create a soil condition more susceptible to compaction.

Deep tillage is not necessarily performed with each planting season, and should only be performed when attempting to mitigate issues/concerns similar to those listed above. If conditions requiring deep tillage exist, there are financial incentive programs which may cost-share the expenses of the additional tillage requirements. Implementation of deep tillage can be worked into an EQIP application package and may complement other conservation practices such as 472-Access Control, 328-Crop rotation, 327-Cover crops, 466-Land smoothing, 590-Nutrient Management, 329-No till

In summary, deep tillage is an important conservation and production practice
in Arkansas and can be utilized in conservation programs. Deep tillage is crucial to maintain a healthy root zone in compacted soils, and key to incorporating surface soil deposits into the root zone. For more information contact your local County Extension Office or your local USDA Service Center.

— Lee Riley