Kansas Soil of the Month(s): The Eudora and Sarpy Complex
Summer in Kansas can be a complex time of year for farmers: crops are in the ground and growing (hopefully), insects and disease make an appearance (unfortunately), Kansas weather (no explanation needed), and many others. Turns out, summer is also complex for two certain ‘Soil of the Month’ authors, hence no July article and our combined offering of the July/August Soil of the Month – the Eudora-Sarpy complex.
Soils are “complex”
The Kansas River begins in Junction City (so named for the meeting of the Republican and Smoky Hill Rivers) and joins the Missouri River near Kansas City. The Kansas River Valley has very productive soils for agriculture, but the soils are highly variable over short distances. Eudora and Sarpy are two soil series often found side-by-side but are relatively different. Sometimes these two soils are so intermingled with each other that soil mappers describe that area as the “Eudora-Sarpy complex” (Figure 1).
Figure 1. This field adjacent to the Kansas River in Geary County, KS has variable soils. The area labeled 7031 is the Eudora soil, and the area labeled 7081 is the Sarpy soil. Graphic created using the NRCS Web Soil Survey.
Eudora vs. Sarpy
Eudora soils are Mollisols, and Sarpy soils are Entisols. In our first installment of this eUpdate series, we discussed these same two soil orders: the Ulysses (Mollisol) and Colby (Entisol), both soils of western Kansas. Travel across the state to the northeast and you will find the Eudora and Sarpy soils. Eudora soil has a large accumulation of soil organic matter as indicated by darker colors, while the Sarpy is a very young soil with minimal development (Figure 2).
The Sarpy series has nine inches of loamy sand in the surface horizons, and between 9 and 60 inches, it is fine sand. Notice in the Sarpy profile there is a second “A” horizon at the bottom of the profile. This is a buried soil horizon. Buried soil horizons were formed in place and then covered by recently transported material. Buried “A” horizons are not uncommon in soils found in floodplains.
The Eudora series has a silt loam texture in the upper 26 inches, and from 26-60 inches is very fine sandy loam. These soils are mapped right next to each other in the same field (Figure 1). However, Eudora is considered prime cropland (Class 1) while Sarpy is Class 4s if it is not irrigated. The “4” means that it has very severe limitations that restrict the choice of plants or requires very careful management, and the “s” means that there is a soil limitation in the rooting zone. In this case, the “s” designation means low moisture-holding capacity because of the high sand content.
Being prime farmland, Eudora soils are mostly cultivated, primarily to corn, grain sorghum, soybeans, and wheat. Native vegetation include tall grasses and a few deciduous trees. Eudora soils occur mostly along the Big Blue and Kansas Rivers in northeastern Kansas and their extent is around 66,000 acres. Sarpy soils typically have native vegetation consisting of thin stands of native prairie grasses and sandburs, with cottonwood and willow trees. Cleared areas are usually in pasture, with some portions cultivated to forage crops. You can find Sarpy soils mainly along the Missouri River and other major streams in Kansas, Nebraska, Missouri, Iowa, and Illinois. Its extent acreage is 88,200 acres total (USDA-NRCS Official Soil Series Descriptions)
Figure 2. Monoliths of the Eudora and Sarpy soil series. Photo by Kathy Gehl, K-State Research and Extension.
Soil formation and floods
For both soils, the parent material is alluvium, transported sediment deposited by rivers for hundreds or thousands of years. Floods, like wildfires, are natural occurrences that often provide ecosystem benefits. However, extreme events can be devastating. One of the most damaging floods in Kansas history occurred on July 13, 1951, often referred to as Black Friday. In some parts of the Kansas River Valley, 6 to 30 inches of sediment was deposited on fields and valuable topsoil was washed away. Most of the affected areas were plowed to great depths to mix the sandy deposits with the more fertile, silty soil beneath. Many lives were lost and around a half million Kansans were displaced. Farther away in Kansas City, the flood waters destroyed the Kansas City Stockyards and the Fairfax Airport, prompting the city to relocate the new airport that would later become the Kansas City International Airport. To sum up a long story, the 1951 flood resulted in the building of multiple flood control dams, including the Tuttle Creek Reservoir to the north of Manhattan. More information on this pivotal event in Kansas history can be found at the following websites:
Looking back over the last few months, here are the previous Soil of the Month articles.
What Kansas soil will be chosen for our September article? Stay tuned!
DeAnn Presley, Soil Management Specialist
Kathy Gehl, eUpdate Editor and soil scientist