Holdrege Soil, Nebraska's State Soil

At right: Winter wheat near harvest stage on Holdrege soil.

Introduction

In 1979, the Nebraska Legislature found that designating one soil, representing the soil resource of the state, would benefit the people of the state. The Holdrege soil selected take its place with the goldenrod, the meadow lark, and the cottonwood as representatives of one of our very important natural resources.

Soils in the Holdrege series are recognized by features of their "profile" (created by horizontal layers) that are the result of the prairie environment. They are suggestive of soils formed under mixed grasses, in a climate where moisture stress is common, but where enough movement of water through the profile has resulted in downward movement of clays and lime. These processes have led to a soil with a thick, dark colored topsoil, a clay enriched subsoil and a substratum that contains free lime. Holdrege soils are among the most extensively cultivated soils in the state. Presently, nearly all Holdrege soils are cultivated. A very large part is irrigated. Corn and grain sorghum are the principal row crops. Winter wheat is the most commonly grown small grain. Their natural fertility, desirable tilth, and the landscape on which they exist join with irrigation water and the skillful management of Nebraska farms to provide a valuable agricultural resource.

Holdrege soils exist on 1.8 million acres (.72 million ha) of landscape in central Nebraska. They were initially separated from other soils during soil surveys of Phelps County in 1917. A good example of a Holdrege soil profile can be seen 325 feet north and 250 feet east of the southwest corner, sec. 25, T. 6 N., R. 19 W., 6th principal meridian.

Holdrege soils are well drained, but will hold between 10 and 11 inches (25.4-28 cm) of water available to the plants within a 5 foot (150 cm) depth. Some additional statistics about them are presented in Table 1.

Table 1: Some Features of the Holdrege Soils
Slope	0-3% (for 75% of their area), range 0-11%
Intake rate of water	moderately low
Permeability	moderate (0.6-2.0 in/hr.)
Soil reaction	medium to slightly acid (surface layer) neutral (subsoil) moderately alkaline (underlying material)
Capability class	I-IV, depending on irrigation and slope
Erosion hazard	slight 0-3% slopes moderate 3-6% slopes severe 6-11% slopes
Uses	irrigated row crops (corn), dryland wheat and sorghum, some native rangeland
Predicted Yields1, corn	150 bu/A irrigated, 0-1% slopes 28 bu/A, dryland, 3-6% slopes
Predicted Yields1, wheat	40 bu/A dryland, 0-1% slopes 30 bu/A, 3-6% slopes
Predicted Yields1, grain sorghum	130 bu/A irrigated, 0-1% slopes 40 bu/A dryland, 3-6% slopes
1From Soil Survey Staff. 1966.  Soil Survey Laboratory Data and Descriptions for some soils of Nebraska.  Soil Survey Investigative Report #5, SCS, USDA.

The chemical properties of Holdrege soils (Table 2) are those of a soil that formed under grasses in a climate where dryness is a fact of life that cannot be ignored. The lack of acidity in the soil accompanied by a limey subsoil and a relatively high amount of organic matter (around 3 percent under native grass) in the top soil attest to a low amount of leaching, to a recycling of basic elements by grass roots, and to a high level of native fertility.

Table 2: Some Chemical Properties of the Holdrege Soils1
Horizon	Depth in inches	pH	Organic C Carbon2 %	C.E.C.	Extractable Cations				Base Sat. %
					Ca	Mg	Na	K
Ap	0-7	6.6	1.7	19.5	11.7	3.9	0.1	1.8	90
A	7-13	7.1	1.3	24.0	17.0	5.2	0.1	1.0	97
Bt1	13-16	6.8	0.9	25.1	17.3	6.5	0.1	1.0	99
Bt2	16-24	7.1	0.5	24.5	16.5	6.8	0.1	1.2	100
Bt3	24-30	7.7	0.3	22.7	17.1	6.6	0.1	1.4	10
BC	30-34	8.5	0.2	21.8	Calc	Calc	0.2	1.5	Calc
BCk	34-42	8.6	0.2	20.0	Calc	Calc	0.2	1.7	Calc
Ck	42-60	8.8	0.1	19.8	Calc	Calc	0.3	2.1	Calc
1From Soil Survey Staff. 1966.  Soil Survey Laboratory Data and Descriptions for some soils of Nebraska.  Soil Survey Investigative Report #5, SCS, USDA. 2O.C. x 1.728 = % organic material

Sand content is quite low, as is expected of soils formed in loess (Table 3). Nearly all of the sand that exists is very fine sand and since silt is the major component of the mineral part, Holdrege soils are silty. Even so, clay content is high enough to bring about a high water and available nutrient holding capacity.

Table 3: Some Physical Properties of the Holdrege Soil
Horizon	Depth in inches	Sand %	Silt %	Clay %	Textual Class	Available water capacity In/in	Water held at 15 A3 %
Ap	0-7	16.6	61.4	22.0	sil1	0.22-0.24	9.9
A	7-13	12.0	58.4	29.6	sicl2	0.18-0.20	13.5
Bt1	13-16	13.3	55.3	31.4	sicl	0.18-0.20	14.4
Bt2	16-24	11.2	58.9	29.9	sicl	0.18-0.20	13.5
Bt3	24-30	13.1	62.1	24.8	sil	0.20-0.22	11.8
BC	30-34	14.9	64.3	20.8	sil	0.20-0.22	11.0
BCk	34-42	16.2	65.1	18.7	sil	0.20-0.22	10.3
Ck	42-60	16.8	64.5	18.7	sil	0.20-0.22	9.8
1sil = silt loam 2sicl = silty clay loam 3Water held at 15 atmospheres of tension.  This means that a force 15 times that of the atmosphere is required to remove the water.  This is the "permanent wilting point," or point where most plants cannot get water.  It is used as the lower boundary of available water, and is governed by the clay and organic matter content in Holdrege soils.

Because of properties that reflect the conditions under which they formed, Holdrege soils are in the Mollisol Soil Order. Mollisols are mostly soils of the grasslands. They are rich in basic elements, such as calcium, magnesium, and potassium. Their family name is fine-silty, mixed, mesic Typic Argiustolls. "Fine-Silty" indicates that the subsoil is between 18 and 35 percent clay with less than 15 percent sand. The term "mixed" suggests that no one kind of mineral is most important in their mineral part. "Mesic" refers to an average annual soil temperature of between 8o and 15oC (46-52oF.)

Earlier classifications of soils in the United States referred to Holdrege soils as Pedocals and Chernozems.  Such soils are typical throughout the world on the vast steppe regions.  Here, before irrigation, nearly all cultivated land was used to grow wheat and stretched to the horizons.  Before that, prairie supported buffalo and countless other wild creatures.  The Holdrege soil profile is the result of that environment.  The landscape is the result of geologic processes operating over tens of thousands or more years.  This is a soil of which we can be proud.  It is one for which we must care, for it and other like it must stain our agriculture - and our culture - for uncounted generations to come.

Approximate extent of the Holdrege soil in Nebraska.

Holdrege soil profile.  Note the dark color and thickness of the surface layer (mollic epipedon), and the presence of lime (light spots) in the subsoil. Soil photograph by Andrew R. Aandahl, and landscape photograph by Professor  David Lewis, used with their permission.

Source

This brochure was prepared by the Nebraska Society of Professional Soil Scientists.