Mapping soil properties to advance the state of spatial soil information for greater food security on US Tribal Lands

Authors: FUENTES, BRYAN - University Of Arkansas; Ashworth, Amanda; NGUNJIRI, MERCY - International Fertilizer Development Center (IFDC); Owens, Phillip

Submitted to: Frontiers in Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2021
Publication Date: 7/6/2021
Citation: Fuentes, B., Ashworth, A.J., Ngunjiri, M., Owens, P.R. 2021. Mapping soil properties to advance the state of spatial soil information for greater food security on US Tribal Lands. Frontiers in Soil Science. 1. Artcle 695386. https://doi.org/10.3389/fsoil.2021.695386.
DOI: https://doi.org/10.3389/fsoil.2021.695386

Interpretive Summary: Information about soils is integral to sustainable soil management. There is a high level of spatially explicit soil information in the U.S. compared to emerging countries, however, not all of the U.S. has detailed, spatially resolved soil information, such is the case with Native American Tribal Lands. Therefore, fine resolution soil maps are needed for land-use decisions at farm and Tribal-levels for increased agricultural productivity and economic growth to combat food insecurity on U.S Reservations. USDA researchers set out to to create first ever high-resolution digital soil property maps of Quapaw Tribal Lands with limited data for sustainable soil resource management. A novel digital soil mapping approach was used to model the spatial distribution of 24 soil properties at 0-15 cm and 15-30 cm depths and was then compared to an off the shelf product (Gridded Soil Survey Geographic Database). These new sets of soil measured data and property maps are a considerable advancement in the current state of spatial soil information for Quapaw Tribal Lands. Overall, the novel mapping approach generally resulted in greater accuracy and resolution of soil property predictions. It is expected that these maps and future versions will be useful for soil, crop, and land-use decisions at the farm and Tribal-level for increased agricultural productivity and economic development.

Technical Abstract: Knowledge, data, and understanding of soils is key for advancing agriculture and society. There is currently a critical need for sustainable soil management tools for Native American Tribal Lands. Tribal Reservations have basic soil information and limited access to conservation programs provided to other U.S producers. The objective of this study was to create first ever high-resolution digital soil property maps of Quapaw Tribal Lands with limited data for sustainable soil resource management. We used a digital soil mapping (DSM) approach based on fuzzy logic to model the spatial distribution of 24 soil properties at 0-15 cm and 15-30 cm depths. A digital elevation model with 3 m resolution was used to derive terrain variables and a total of 28 samples were collected at 0-30 cm over the 22,880-ha reservation. Additionally, soil property maps were derived from Gridded Soil Survey Geographic Database (gSSURGO) for comparison. When comparing properties modeled by DSM to those derived from gSSURGO, the DSM approach resulted in lower root mean squared error (RMSE) for percent clay and sand at 0-15 cm, and for cation exchange capacity, percent clay, and pH at 15-30 cm. Conversely, gSSURGO-derived maps resulted in lower RMSE for cation exchange capacity, pH, and percent silt at the 0-15 cm depth, and percent sand and silt at the 15-30 cm depth. Although, some of the soil properties derived from gSSURGO had lower RMSE, spatial soil property patterns modeled by DSM were in better agreement with the topographic complexity and expected soil-landscape relationships. In addition, the proposed DSM approach developed property maps at high-resolution that set the baseline for versioning and production of new spatial soil information for the Quapaw Tribal Land. It is expected that these maps and future versions will be useful for soil, crop, and land-use decisions at the farm and Tribal-level for increased agricultural productivity and economic development.