Soil profile health in the Palouse soil series: Carbon, nitrogen, nutrients,and aggregates

Authors: NAASKO, KATHERINE - Washington State University; TAO, HAIYING - University Of Connecticut; PAN, WILLIAM - Washington State University; REGANOLD, JOHN - Washington State University; Huggins, David; MADSEN, ISAAC - Washington State University; SULLIVAN, TARAH - Washington State University; Wills, Skye

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2023
Publication Date: 10/11/2023
Citation: Naasko, K., Tao, H., Pan, W., Reganold, J., Huggins, D.R., Madsen, I., Sullivan, T., Wills, S.A. 2023. Soil profile health in the Palouse soil series: Carbon, nitrogen, nutrients,and aggregates. Agrosystems, Geosciences & Environment. 2023 (6). Article 20421. https://doi.org/10.1002/agg2.20421.
DOI: https://doi.org/10.1002/agg2.20421

Interpretive Summary: Assessments of soil health usually concentrate on the surface 15 to 30 cm of soil. However, deep soil health (>30 cm) is important in dryland cropping regions to deep-rooting crops and soil microbial communities. We evaluated how management and climate impact soil carbon, nitrogen, nutrients and soil aggregates in deep soil cores (up to 85 cm in depth) in the Palouse soil series in the Palouse River watershed. Here we found that no-till (NT) sites had more active soil C and soil aggregation than conventionally-tilled (CT) sites and illustrated that deep soil health is important to support deep rooting crops including winter and perennial cropping systems. Furthermore, both soil carbon and nitrogen fractions were more sensitive than total carbon and nitrogen to management and climate factors. Our study illustrates the importance of sampling deeper than surface soil depth increments (>30) to understand how management impacts soil health in dryland production systems. This research will be important to the USDA Natural Resource Conservation Service, and both agribusinesses and producers interested in soil health.

Technical Abstract: Deep soil health (>30 cm) is important in dryland cropping regions to deep-rooting crops and soil microbial communities. We evaluated how management and climate impact soil carbon, nitrogen, nutrients and soil aggregates in deep soil cores (up to 85 cm in depth) in the Palouse soil series in the Palouse River watershed. Compared to three conventional till (CT) sites, three no-till (NT) sites had at least 2x higher permanganate oxidizable soil C (POXC) concentrations in the top and second soil depth increments, and 1.9x, 1.2x, 1.3x, and 1.3x higher fast-wet mean weight diameter of soil aggregates (MWDfast-wet), cold-water extractable C (CWC):TC, hot-water extractable C (HWC):TC, and hot-water extractable N (HWN):TN averaged up to 85 cm deep. NT and CT sites with highest precipitation had 2x higher MWDfast-wet and mineralizable soil C (MINC) compared to NT and CT sites with lowest precipitation averaged up to 85 cm. Compared the average of NT and CT sites, a centrally located unfertilized perennial grass (PG) strip had 1.2x higher slow-wet MWD of soil aggregates (MWDslow-wet) averaged up to 85 cm, at least 2.3x higher ACE protein in individual soil depths, at least 1.9x higher CWC: cold-water extractable N (CWN) in the third soil depth, and 1.4x higher NO3-:TN in the fourth and fifth soil depth. Our study illustrates the importance of sampling deeper than surface soil depth increments (>30) to understand how management impacts soil health in dryland production systems.