Fe-Mn concentrations in upland loess soils in mid-continental north America: A step towards dynamic soil survey

Authors: ZHOUDONG, JIANG - Shenyang Agricultural University; WANG, QUIBING - Shenyang Agricultural University; LIBOHOVA, ZAMIR - Natural Resources Conservation Service (NRCS, USDA); Adhikari, Kabindra; BRYE, KRISTOFOR - University Of Arkansas; SUN, ZHONGXIU - Shenyang Agricultural University; SUN, FUJUN - Shenyang Agricultural University; JIANG, YINGYING - Shenyang Agricultural University; Owens, Phillip

Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2021
Publication Date: 3/18/2021
Citation: Zhoudong, J., Wang, Q., Libohova, Z., Adhikari, K., Brye, K.R., Sun, Z., Sun, F., Jiang, Y., Owens, P.R. 2021. Fe-Mn concentrations in upland loess soils in mid-continental north America: A step towards dynamic soil survey. Catena. 202:105273. https://doi.org/10.1016/j.catena.2021.105273.
DOI: https://doi.org/10.1016/j.catena.2021.105273

Interpretive Summary: Iron-manganese concentrations in soils have been used to infer soil drainage and hydrology. These Fe-Mn concentrations are not present in all soils in the same concentrations. This was a large area study to determine common factors that create conditions where Fe-Mn concentrations are formed. Understanding where Fe-Mn concentrations tend to form in the landscape is important for improving decisions about proper use of soils that have limitations due to wetness. Therefore, in this study, a machine-learning method was combined with pedological knowledge to assess the occurrence and spatial distribution of Fe-Mn concentrations in soils. Using data from 3,966 samples the results indicated that rainfall, evapotranspiration, temperature and landscape position had an effect on Fe-Mn formation. A better understanding of hydrology can improve land-sue management decisions.

Technical Abstract: Iron-manganese concentrations are common morphological indicators of soil oxidation-reduction reactions and are widely used to infer soil hydrology. The factors determining occurrence and distribution of Fe-Mn concentrations at continental scale have been rarely studied. The objective of this study was to determine the relative importance of soil-forming factors on the occurrence and distribution of Fe-Mn concentrations in upland loess soils in mid-continental North America. A total of 3966 soil profiles were collected from the National Soil Information System database (NASIS). A decision tree (DT) model was used to analyze the relationships between the covariates (climate, soil properties, and organisms) and the presence of Fe-Mn concentrations. The accuracy of the DT model based on the validation dataset was 79%. The combination of annual precipitation and temperature was identified as the most important climatic factor influencing the occurrence and distribution of Fe-Mn concentrations and showed a complex interaction with soil properties at multiple scales. Soil properties related to potential wet to saturated soil conditions were also important for the occurrence of Fe-Mn concentrations. Fe-Mn concentrations occurred more in mesic areas with high precipitation and low soil internal drainage rates, than in frigid and thermic areas with low precipitation and high soil internal drainage rates. Results demonstrated the importance of using soil pedogenesis knowledge in the selection of environmental covariates and the interpretation of DT model results. Understanding where Fe-Mn concentrations tend to form in the landscape will contribute to improving decisions about proper use of soil that may be limited by wetness.