Physiographic features

Macon Ridge in extreme northeastern Louisiana and southeastern Arkansas is a 135-mile long prominent ridge that lies between the Boeuf and Tensas Basins. It reaches a maximum width of about 25 miles in northeastern Louisiana about 30 miles north of Sicily Island. The ridge is consistently higher on its eastern side where elevations are 20 to 30 feet higher than in the adjacent Tensas Basin (floodplain). On the western side, elevations of the ridge are approximately the same as those in the Boeuf Basin, and it is sometimes difficult to distinguish the two at the surface. Macon Ridge consists almost entirely of Early Wisconsin age glacial outwash and is a continuation of the valley train in the Western Lowlands” (Saucier, 1994).

Macon Ridge is a terrace that features level to gently undulating topography with steep scarps of uplands, floodplains, depressions, and drainageways. The entire area is located within the Mississippi Alluvial Valley section of the Coastal Plain Province of the Atlantic Plain. The entire Macon Ridge is underlain by Pleistocene-aged loamy and clayey braided stream alluvium from the “old” Arkansas River. The area mantled by loess on the eastern edge of the terrace rises 10 to 30 feet above the floodplains. The loess thins toward the west, and elevation decreases. The loess in the western part of Macon Ridge contains small mixtures of the older underlying braided-stream terrace alluvium, and in even lower elevations, the loess contains mixtures of recent clayey alluvium or is buried completely beneath recent alluvium (T. E. Allen, USDA-NRCS Richland Parish Soil Survey Report, 1993).

This PES occurs on silty broad flats and depressional areas on the Macon Ridge in Arkansas and Louisiana. Slopes are level (0 to 1%). The site occurs on terraces, flats, and depressions of the loess-mantled Macon Ridge braided-stream terrace. These soils are fine-silty to a depth of 80 inches or more, with a high content of sodium in the subsoil. These sites include floodplains, depressions and drainageways of Caney Bayou, Indian Bayou, Big Colewa Creek, Big Creek and Old Big Creek, Little Creek, Bee Bayou, Bulls Bayou, Muddy Bayou, Turkey Creek, Ash Slough, Daves Bayou, and Deer Creek.

Table 2. Representative physiographic features

Climatic features

The climate of North East Louisiana and South East Arkansas is warm and humid with a monthly precipitation that is well distributed throughout the year. The monthly precipitation mean is between 2.9 and 5.3 inches, with the lowest rainfall occurring from June through November. The following climatic data are averages from the three weather stations listed below. Temperature and precipitation may vary considerably from that listed for each month. Site specific weather data should be used for land management decisions. For site specific weather conditions, obtain data from a weather station close to the site.

Table 3. Representative climatic features

Climate stations used

• (1) EUDORA [USC00032355], Eudora, AR

• (2) RAYVILLE [USC00167691], Rayville, LA

• (3) WINNSBORO 5 SSE [USC00169806], Winnsboro, LA

Influencing water features

Hydrology on this site is very important and when water is limited by drought or removal by other means vegetative composition will be affected by soil chemistry. The Sodium (Na) and Aluminum (Al) that is present in the soils of this site will dictate growth, production and species composition in a more drastic manner when moisture is limited. This will be readily seen in cropland when prolonged dryness occurs and will present as areas within a field that are stressed or plants will die.

These sites are generally found in depressions where water from adjacent areas accumulates. This is also a contributor to the development of the sites because this runoff from adjacent areas can carry additional Al & Na. These accumulate when the water that carries them evaporates and leaves them behind to concentrate in the soil.

Soil features

Foley, Deerford

Soils of this site are poorly drained, Albic Glossic Natraqualfs (Foley), and somewhat poorly drained, Albic Glossic Natraqualfs (Deerford) that have a high content of sodium in the subsoil. These soils formed in silty material, water-reworked loess sediments of late Pleistocene Age. Slopes range from 0 to 2 percent. These very deep, slowly and very slowly permeable soils are found in broad flats and narrow depressional areas in the terrace uplands. Foley soil map units are considered hydric and the perched water table is within 1 to 3 feet of the surface during winter and spring months in normal years. Deerford soil map units are considered non-hydric and the perched water table is within 1 to 1.5 feet of the surface during winter and spring months in normal years. These soils are subject to none to rare flooding for brief duration.

Natraqualfs (sodium soils) are commonly found throughout the loessal regions of the U.S. The sodium in these soils originated from in-situ weathering of Na-rich feldspars of the parent loess. The natric soil horizons act as a root restriction layer. Natric horizons typically have compound soil structure consisting of prismatic parting to subangular blocky structure. The natric horizons are dense with firm consistency and brittleness. The horizons also have very low hydraulic conductivity and tend to perch water during wet periods. The natric horizons are often considerably drier than overlying horizons. It is important not only to recognize salinity stress and toxicity, but also to determine where the sodium problem is located in the soil profile. Accelerated erosion and land leveling can truncate the surface soil and expose the underlying natric horizons with disastrous consequences. (Pettry, 1998).

Bare soil areas in agricultural fields essentially devoid of vegetation, or containing stunted and dead plants, have been referred to as slick-spots, salt-spots, and deer licks. Areas range in size from less than an acre to entire fields. Crops have different sensitivities to elevated salt contents. Generally, cotton and bermudagrass are more tolerant than corn and soybeans. Seasonal changes in soil moisture affect the ability of crops to tolerate high salt levels. Greater soil moisture at spring planting may maintain low enough levels for plant establishment and growth; however drier conditions in mid-summer may concentrate salt levels to a point at which they become toxic to the plant. Plants stressed from high sodium levels often exhibit various symptoms of nutritional disorders due to competitive uptake of ions. The exposed surface soil commonly has a light-colored, bleached appearance and is vulnerable to accelerated surface erosion. Salt-impacted areas are not as evident in forests, but the impact can be seen in areas containing stunted trees.

Natric soils commonly have poor physical conditions due to dispersive properties associated with sodium that negatively impact reclamation. The poor physical conditions reduce permeability to air and water movement. These adverse properties give rise to the observable physical characteristics of the soil being sticky when wet and hard when dry. Early reclamation of sodic soils used ponded water to leach salts below the root zone in arid regions, but these practices often required long periods of time and could not flush the salts due to low soil permeability. Sodium must be displaced on the soil exchange complex and leached from the soil to remediate the Na-toxicity and improve physical conditions. Gypsum is commonly used for reclamation of sodic soils. The amount of gypsum need to displace sodium depends on soil texture, cation exchange capacity, and sodium content. Large quantities of organic matter incorporated into the soil at gypsum application can increase replacement efficiency. The organic matter improves soil structure and drainage, increases cation exchange capacity and water holding capacity (Pettry, 1998).

Table 4. Representative soil features

Animal community

.

Hydrological functions

.

Recreational uses

.

Wood products

.

Other products

.

Other information

.

Inventory data references

.

Other references

Allen, T. E., USDA-NRCS Richland Parish Soil Survey Report, 1993

Autin, W. J., Burns, S. F., Miller, B. J., Saucier, R. T., & Snead, J. I. (1991). Quaternary geology of the lower Mississippi Valley. The Geology of North America, 2, 547-582.

Cowardin, L. M., Carter, V., Golet, F. C., & LaRoe, E. T. (1979). Classification of wetlands and deepwater habitats of the United States. US Fish and Wildlife Service FWS/OBS, 79(31), 131.

Daigle, J.J., Griffith, G.E., Omernik, J.M., Faulkner, P.L., McCulloh, R.P., Handley, L.R., Smith, L.M., and Chapman, S.S., 2006, Ecoregions of Louisiana (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey (map scale 1:1,000,000).

Ezell, A. W., & Hodges, J. D. (1995). Bottomland hardwood management: Species Site Relationships. MSU Extension Service Publication 2004.

Saucier, R. T. (1994). Geomorphology and Quarternary Geologic History of the Lower Mississippi Valley. Volumes 1 and 2. ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB.

Schumacher, B. A., B. J. Miller, and W. J. Day. "A chronotoposequence of soils developed in loess in central Louisiana." Soil Science Society of America Journal 51.4 (1987): 1005-1010.

McCraw, David J., and Whitney J. Autin. Lower Mississippi Valley, Loess: A Field Guide. Inqua Commission on Loess, 1989. Emerson, F. V. (1918). Loess-depositing winds in Louisiana. The Journal of Geology, 26(6), 532-541.

Frost, C. C. Presettlement Fire frequency regimes of the United States: A First approximation. Fire in ecosystem management: Shifting the paradigm from suppression to prescription, ed. TL Pruden and LA Brennan, 70-81.

Guyette, R. P., Stambaugh, M. C., Dey, D. C., & Muzika, R. M. (2012). Predicting fire frequency with chemistry and climate. Ecosystems, 15(2), 322-335. Heinrich, P. V., (2008), Loess Map of LA, Louisiana Geological Survey

Kochian, L. V., Pineros, M. A., & Hoekenga, O. A. (2005). The physiology, genetics and molecular biology of plant aluminum resistance and toxicity. In Root Physiology: From Gene to Function (pp. 175-195). Springer Netherlands.

Latimore S. (1996). THE RARE AND SENSITIVE NATURAL WETLAND PLANT COMMUNITIES OF INTERIOR LOUISIANA. Louisiana Natural Heritage
Program, Louisiana Department of Wildlife & Fisheries, Baton Rouge, Louisiana.

Louisiana Natural Heritage Program, Louisiana Department of Wildlife & Fisheries, (2009) The Natural Communities of Louisiana

Miller, B. J., Day, W. J., & Schumacher, B. A. (1986). Loesses and loess-derived soils in the Lower Mississippi Valley. Guidebook for soils-geomorphology tour.

Miller, B. J., Lewis, G. C., Alford, J. J. & Day, W. J. (1984) Loesses in Louisiana and at Vicksburg, Mississippi. Guidebook for Friends of the Pleistocene Field Trip.

Muery, E. (1998), ANALYSIS OF PRESETTLEMENT NATURAL PLANT COMMUNITY TYPES OF THE MACON RIDGE OF LOUISIANA.

Pettry, D. E., & Switzer, R. E. (1998). Sodium soils in Mississippi.

United States Salinity Laboratory Staff, USA, USDA (1954), Diagnosis and improvement of saline and alkali soils, USDA Agriculture Handbook 60, 1954, 160 pp.

USDA Agriculture Handbook 296. (2006). http://soils.usda.gov/MLRAExplorer. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin

USDA Natural Resources Conservation Service. Published Soil Surveys from Catahoula, Franklin, Richland and West Carroll Parishes. Various publication dates.

USDA Natural Resources Conservation Service. Web Soil Survey, http://websoilsurvey.nrcs.usda.gov/app. USDA NRCS Soil Survey Division. Washington, DC. 2008.

Contributors

D Charles Stemmans
Dwayne Rice
Wayne Roberts
Rachel Stout Evans

Acknowledgments

The Macon Ridge Technical Team did an outstanding job of utilizing existing data and knowledge to develop site concepts. They also provided the needed sections of the descriptions, review and comments of them.