LOCATION NIRA               IA
Established Series
Rev. JAL-JWH-TWN
09/2008

NIRA SERIES


The Nira series consists of very deep, moderately well drained soils formed in loess. These soils are on short, convex to linear side slopes on interfluves on dissected till plains and on risers on loess-covered stream terraces in river valleys. Slope ranges from 2 to 18 percent. Mean annual air temperature is about 10 degrees C. Mean annual precipitation is about 900 millimeters.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aquic Argiudolls

TYPICAL PEDON: Nira silty clay loam, on a concave, northeast-facing slope of 7 percent, in a cultivated field. (Colors are for moist soil unless otherwise stated.)

Ap--0 to 18 centimeters; very dark gray (10YR 3/1) silty clay loam, gray (10YR 5/1) dry; weak very fine and fine subangular blocky structure; friable; few fine roots; few fine tubular pores; slightly acid; abrupt smooth boundary.

A--18 to 28 centimeters; very dark gray (10YR 3/1) silty clay loam, gray (10YR 5/1) dry; weak fine subangular blocky structure; friable; few fine roots; few fine tubular pores; slightly acid; clear smooth boundary. (Combined thickness of the A horizon is 25 to 49 centimeters.)

Bt1--28 to 41 centimeters; brown (10YR 4/3) silty clay loam; moderate fine subangular blocky structure; friable; few fine roots; few fine tubular pores; few distinct clay films on faces of peds; many distinct very dark grayish brown (10YR 3/2) organic coats on faces of peds; common fine faint grayish brown (2.5Y 5/2) redoximorphic depletions; few fine irregular masses of iron-manganese; moderately acid; clear smooth boundary.

Bt2--41 to 51 centimeters; brown (10YR 4/3) silty clay loam; moderate medium subangular blocky structure; friable; few fine roots; few fine tubular pores; few distinct clay films on faces of peds; common distinct very dark grayish brown (10YR 3/2) organic coats on faces of peds; many fine faint grayish brown (2.5Y 5/2) redoximorphic depletions; few fine irregular masses of iron-manganese; moderately acid; clear smooth boundary. (Combined thickness of the Bt horizon is 14 to more than 125 centimeters.)

Bg1--51 to 64 centimeters; olive gray (5Y 5/2) silty clay loam; moderate medium subangular blocky structure; friable; few fine roots; few fine tubular pores; few distinct very dark grayish brown (10YR 3/2) organic coats on faces of peds; many fine prominent yellowish brown (10YR 5/4), few fine prominent strong brown (7.5YR 5/8) and yellowish red (5YR 4/6) redoximorphic concentrations; few fine irregular masses of iron-manganese; slightly acid; clear smooth boundary.

Bg2--64 to 79 centimeters; olive gray (5Y 5/2) silty clay loam; weak medium prismatic structure parting to moderate medium subangular blocky; friable; few fine roots; few fine tubular pores; common fine prominent yellowish brown (10YR 5/4) and few fine prominent strong brown (7.5YR 5/8) redoximorphic concentrations; few fine irregular masses of iron-manganese; slightly acid; gradual smooth boundary. (Combined thickness of the Bg horizon is 40 to 75 centimeters.)

BCg--79 to 102 centimeters; olive gray (5Y 5/2) silty clay loam; weak coarse prismatic structure parting to weak medium and coarse subangular blocky; friable; few fine roots; few fine tubular pores; common fine prominent yellowish brown (10YR 5/4) and common fine and medium prominent strong brown (7.5YR 5/8) redoximorphic concentrations; few fine irregular masses of iron-manganese; slightly acid; gradual smooth boundary. (0 to 25 centimeters thick)

Cg1--102 to 140 centimeters; light olive gray (5Y 6/2) silty clay loam; massive; friable; few fine roots; few fine tubular pores; common fine and medium prominent yellowish brown (10YR 5/4) and many medium and coarse prominent strong brown (7.5YR 5/8) redoximorphic concentrations; few fine irregular masses of iron-manganese; neutral; gradual smooth boundary.

Cg2--140 to 200 centimeters; olive gray (5Y 5/2) and gray (5Y 5/1) silty clay loam; massive; friable; common medium and coarse prominent yellowish brown (10YR 5/4) and many coarse prominent strong brown (7.5YR 5/8) redoximorphic concentrations; few fine irregular masses of iron-manganese; neutral; clear smooth boundary.

TYPE LOCATION: Major Land Resource Area (MLRA) 108C-Illinois and Iowa Deep Loess and Drift, West Central Part, Keokuk County, Iowa subset; about 2 miles south of the town of Kinross; located about 1,340 feet west and 240 feet south of the northeast corner of section 34, T. 77 N., R. 10 W.; USGS Kinross topographic quadrangle; lat. 41 degrees 26 minutes 18 seconds N. and long. 91 degrees 59 minutes 22 seconds W., NAD 83.

RANGE IN CHARACTERISTICS:
Thickness of the mollic epipedon--25 to 49 centimeters
Depth to carbonates--more than 200 centimeters
Depth to paralithic contact--more than 200 centimeters
Clay content in the particle-size control section (weighted average)--27 to 35 percent
Sand content in the particle-size control section (weighted average)--less than 5 percent
Rock fragment content--0 percent

Ap or A horizon:
Hue--10YR
Value--2 or 3
Chroma--1 or 2
Texture--silty clay loam
Clay content--30 to 35 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral

AB or BA horizon (when present):
Hue--10YR
Value--3
Chroma--2 or 3
Texture--silty clay loam
Clay content--30 to 35 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral

Bt or Bw horizon:
Hue--10YR
Value--3 or 4
Chroma--3 or 4
Texture--silty clay loam or silt loam
Clay content--24 to 40 percent
Sand content--less than 5 percent
Reaction--strongly acid to neutral

Bg or Btg horizon:
Hue--2.5Y or 5Y
Value--5 or 6
Chroma--1 or 2
Texture--silty clay loam or silt loam
Clay content--25 to 34 percent
Sand content--less than 5 percent
Reaction--strongly acid to neutral

BCg and Cg horizon:
Hue--2.5Y or 5Y
Value--5 or 6
Chroma--1 or 2
Texture--silty clay loam or silt loam
Clay content--25 to 30 percent
Sand content--less than 5 percent
Reaction--moderately acid to neutral

COMPETING SERIES: These are the Arrowsmith, Bearpen, Brenton, Edwardsville, Elburn, Grundelein, Hacreek, Harco, Higginsville, Keller, Lafayette, Lawndale, Lisbon, Lismod, Loran, Mundelein, Muscatune, Raub, Rooks, Rowley and Shannondale series.
Arrowsmith--have carbonates within a depth of 100 centimeters
Bearpen--have a sand content of more than 5 percent in the lower third of the series control section
Brenton--have a sand content of more than 15 percent in the lower third of the series control section
Edwardsville--have a clay content of 18 to 25 percent in the lower third of the series control section
Elburn--have a sand content of 15 to 70 percent in the lower third of the series control section
Grundelein--have a sand content of 75 to 98 percent in the lower third of the series control section
Hacreek--have hues of 2.5YR or 10YR in the lower third of the series control section
Harco--have carbonates within a depth of 100 centimeters
Higginsville--are in areas that have a mean annual air temperature range of 12 to 14 degrees C and a mean annual precipitation range of 900 to 1,020 millimeters (see remarks)
Keller--have a sand content of more than 5 percent in the lower third of the series control section
Lafayette--have a rock fragment content of more than 5 percent in the lower third of the series control section
Lawndale--have a sand content of 80 to 95 percent in the lower third of the series control section
Lisbon--have a sand content of more than 20 percent in the lower third of the series control section
Lismod--have carbonates within a depth of 100 centimeters
Loran--have a paralithic contact of shale within a depth of 150 centimeters
Mundelein--have carbonates within a depth of 100 centimeters
Muscatune--have a matrix hue range of 10YR or 2.5Y and matrix chroma range of 2 to 4 in the lower third of the series control section (see remarks)
Raub--have a sand content of more than 15 percent in the lower third of the series control section
Rooks--have carbonates within a depth of 100 centimeters
Rowley--have a clay content that averages 18 to 27 percent in the particle-size control section
Shannondale--have a sand content of more than 15 percent in the lower third of the series control section

GEOGRAPHIC SETTING:
Parent material--loess
Landform--short, convex to linear side slopes on interfluves on dissected till plains and on risers on loess-covered stream terraces in river valleys
Slope--2 to 18 percent
Elevation--155 to 460 meters above sea level
Mean annual air temperature--8 to 11 degrees C
Mean annual precipitation--840 to 965 millimeters
Frost-free period--170 to 205 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mahaska, Otley, and Taintor soils.
Mahaska--are at higher elevations on broad interfluves and average 35 to 42 percent clay in the particle-size control section
Otley--are at higher elevations on interfluves and side slopes and average 35 to 42 percent clay in the particle-size control section
Taintor--are at higher elevations on interfluves and upland flats and are saturated from .3 meter to the surface during the wettest periods of normal years

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained--a frequently saturated zone occurs within depths of 0.6 and 1.0 meter in the wettest periods of years when precipitation is within one standard deviation of the 30 year mean of annual precipitation and this saturation is considered apparent
Saturated hydraulic conductivity--1.0 to 10.0 micrometers per second

USE AND VEGETATION:
Most areas are cultivated. The principal crops are corn, soybean, small grain and grass-legume hay. The native vegetation is mixed big blue stem, little blue stem, switchgrass, and other grasses of the tall grass prairie.

DISTRIBUTION AND EXTENT:
Physiographic Division--Interior Plains
Physiographic Province--Central Lowlands
Physiographic section--Dissected till plains
MLRAs--Illinois and Iowa Deep Loess and Drift (108)
LRR M--southern and southeastern Iowa
Extent--large

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Indianapolis, Indiana

SERIES ESTABLISHED: Keokuk County, Iowa, 1971.

REMARKS:
Particle-size control section--the zone from a depth of 28 to 51 centimeters;
series control section--the zone from the surface to a depth of 150 centimeters.

Diagnostic horizons and features recognized in this pedon are:
mollic epipedon--the zone from the surface of the soil to a depth of 28 centimeters (Ap and A horizons);
argillic horizon--the zone from a depth of 28 to 51 centimeters (Bt1 and Bt2 horizons);
cambic horizon--the zone from a depth of 51 to 102 centimeters (Bg1, Bg2, and BCg horizons);
udic moisture regime.

Cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.

Differentia between Nira, Higginsville, and Muscatune series needs further study.

Classification change from fine-silty, mixed, superactive, mesic Oxyaquic Hapludolls based on field study and the presence of clay films in the argillic horizon and absence of an eluvial horizon.

Taxonomy version--Keys to Soil Taxonomy, tenth edition, 2006

ADDITIONAL DATA:
Laboratory data--National Soil Survey Laboratory, Lincoln, Nebraska - user pedon IDs 83IA0030023, 95IA107002, and 07IA001001 (http://ssldata.nrcs.usda.gov/).


National Cooperative Soil Survey
U.S.A.