Timothy R. Filley

Education and outreach (E&O) for integrative environmental sciences is most often organized around generic educational goals and evaluated through instruments designed for outcome-based learning interventions. This perspective argues for a different starting point: an E&O framework derived from the characteristic properties of the science with which it connects. For critical zone (CZ) science defined by vertical and lateral coupling, multi-scale integration, and socio-environmental relevance, this derivation generates an organizing architecture in which interdisciplinary, multi-scale, and stakeholder-engaged activities are essential. This framework also resolves methodological tension between pre/post outcome-based evaluations and sustained-trajectory evaluations, often treated as competing, to provide complementary evidence appropriate for different aspects of the framework. Developed in conjunction with two sequential scientific projects funded by the U.S. National Science Foundation : the Intensively Managed Landscapes CZ Observatory (IML-CZO, 2013–2021) and the Critical Interface Network (CINet, 2020–2026), the framework organizes ten activities along five derived dimensions. Over the 12 year period of the two projects, this approach has produced nested impact across individual, institutional, and societal scales, and that two specific mechanisms, institutional embedding and regenerative early-career development opportunities, explain how E&O activities and impacts outlive the scientific projects that produce them.

Organic amendments are key sources of nutrients in croplands and play an important role in maintaining soil organic carbon (SOC) stocks. Stabilization of SOC is mediated by environmental and management factors and may differ between mineral‐associated organic carbon (MAOC) and particulate organic carbon (POC). To quantify these patterns, we conducted a global meta‐analysis evaluating SOC, MAOC, and POC responses to long‐term organic amendments (animal manure or crop residues) in annual cropping systems. Overall, organic amendments increased SOC, POC, and MAOC relative to unamended controls. When analyzed using effect sizes, POC exhibited greater proportional responses than MAOC or bulk SOC, reflecting the smaller baseline size of the POC pool. Responses across all SOC fractions were greatest when control treatments did not receive mineral fertilizer. Amendment effects were strongest in surface soils (− ¹ . Analysis of absolute SOC stock changes (Δ Mg ha ^{− 1} ) revealed that MAOC accumulated carbon at approximately six times the rate of POC with increasing cumulative C inputs (0.06 vs. 0.01 Mg C ha ⁻¹ per Mg C input), indicating a substantially greater capacity for MAOC formation in annual croplands. These results demonstrate that repetitive C inputs drive the formation of MAOC, a more stable carbon pool critical for long‐term carbon storage.

Quinoa ( Chenopodium quinoa ) is a nutritious crop expanding in importance worldwide, though its capacity to accumulate cadmium (Cd) can put consumers at risk. The objective of this study was to identify genotypes that vary in Cd uptake and explore how domestication, saponins, and root-associated microbes could influence these differences. Twelve genotypes representing wild ancestors and modern landraces or cultivars from four distinct ecoregions were grown in a greenhouse trial using potting media amended with Cd. Differences in phenological developmental traits were recorded during growth, and plant biomass, microbial derived amino sugars in roots, and concentrations of Cd and other essential elements in grains were quantified at harvest. Phenological development of Ancestors were more adversely affected by Cd than modern genotypes, and Cd concentrations were higher in those developed later near coastal regions in South America and the United States, suggesting that quinoa become more tolerant over domestication and selection. Concentrations of several elements were also lower in the Ancestors vs. modern genotypes in response to Cd, indicating that modern genotypes may not downregulate root transporters as an adaptation to Cd stress. Fungal derived amino sugars were negatively correlated with Cd concentrations in the Coastal ecotypes which had the highest uptake, suggesting that the presence of root-associated fungi could help restrict translocation aboveground. Results of this study will provide breeders with new insights into factors that could aid in selecting for quinoa with low Cd-uptake. Early genotypes selected in the Altiplano region may be most useful in these breeding programs.

This study aimed to better understand how tillage row orientation with respect to dominant flow‐pathway along hillslope impacts runoff and the transport of different sediment size fractions. Experimental plots were constructed in contour ridge till (CRT) and parallel ridge till (PRT) sites to monitor runoff and sediment fluxes. Particle size fractions of the sediment, along with organic C and N contents were measured to quantify physical and chemical enrichment ratios for the two tillage orientations. In the CRT plot, tillage produced large oriented roughness elements along the contours, which acted as little check dams, while in the PRT site, the roughness elements helped confine and concentrate the runoff. In the CRT, the “check dams” resulted in a runoff coefficient of .03, while in the PRT, the flow confinement between rows produced a runoff coefficient of .82. Moreover, the erosion rates at the CRT site were 97% less than those in the PRT plot. Large contours produced finer sediment fractions due to the selective sorting in ponded furrows. More aggregate sediment fractions were present in the PRT site, which was dominated by rill erosion. Physical enrichment revealed selective entrainment of finer sediment particles during erosion. Finer‐grain particles with higher specific surface areas, attached more organic C resulting in chemical enrichment. Physical and chemical enrichment methods were found to be in good agreement. These findings suggest transport models that can simulate size fraction updates to the soil active layer can be used to estimate SOC redistribution and hence more accurate C budgets.

Soil organic carbon (SOC) is going through rapid reorganization due to anthropogenic influences. Understanding how biogeochemical transformation and erosion‐induced SOC redistribution influence SOC profiles and stocks is critical to our food security and adaptation to climate change. The important roles of erosion and deposition on SOC dynamics have drawn increasing attention in the past decades, but quantifying such dynamics is still challenging. Here we develop a process‐based quasi 3‐D model that couples surface runoff, soil moisture dynamics, biogeochemical transformation, and landscape evolution. We apply this model to a subcatchment in Iowa to understand how natural forcing and farming practices affect the SOC dynamics in the critical zone. The net soil thickness and SOC stock change rates are −0.336 (mm/yr) and −1.9 (g C/m²/year), respectively. Our model shows that in a fast transport landscape, SOC transport is the dominant control on SOC dynamics compared to biogeochemical transformation. The SOC profiles have “noses” below the surface at depositional sites, which are consistent with cores sampled at the same site. Generally, erosional sites are local net atmospheric carbon sinks and vice versa for depositional sites, but exceptions exist as seen in the simulation results. Furthermore, the mechanical soil mixing arising from tillage enhances SOC stock at erosional sites and reduces it at depositional ones. This study not only helps us understand the evolution of SOC stock and profiles in a watershed but can also serve as an instrument to develop practical means for protecting carbon loss due to human activities.

The role of tillage practices on soil aggregate properties has been mainly addressed at the pedon scale (i.e., soilscape scale) by treating landscape elements as disconnected. However, there is observed heterogeneity in aggregate properties along flowpaths, suggesting that landscape scale hydraulic processes are also important. This study examines this supposition using field, laboratory and modeling analysis to assess aggregate size and stability along flowpaths under different management conditions: (1) tillage-induced abrasion effects on aggregate size were evaluated with the dry mean weight diameter (DMWD); (2) raindrop impact effects were evaluated with small macroaggregate stability (SMAGG_STAB) using rainfall simulators; and (3) these aggregate proxies were studied in the context of connectivity through the excess bed shear stress (δ), quantified using a physically-based landscape model. DMWD and SMAGG_STAB decreased along the flowpaths for all managements, and a negative correspondence between the proxies and δ was observed. δ captured roughness effects on connectivity along the flowpaths: highest connectivity was noted for parallel-ridge-till flowpaths, where δ ranged from 0–8.2 Pa, and lowest connectivity for contour-ridge-till flowpaths, where δ ranged from 0–1.1 Pa. High tillage intensity likely led to an increase in aggregate susceptibility to hydraulic forcing, reflected in the higher gradients of aggregate size and stability trendlines with respect to δ. Finally, a linear relationship between DMWD and SMAGG_STAB was established.

Tree taxa and pyrolysis temperature are the major controllers of the physicochemical properties of the resultant pyrogenic organic matter (PyOM) produced in fire-prone forests. However, we know little about how these controls determine the residence time of PyOM once introduced to soil. In this study, we tracked the fate of ¹³C-enriched red maple (RM) or jack pine (JP) wood and PyOM, produced over a range of temperatures (200, 300, 450, or 600 °C) added to soil from a northern temperate forest in Michigan, USA. Pyrolysis temperature was the main controller of PyOM-C mineralization rates, with mean residence times (MRT) ranging from ~4 to 450 years for both taxa. The PyOM-C mineralization rates for both taxa and the pyrolysis temperature correlated positively with PyOM_w (leachable C content); however, the potential PyOM_w contribution to net PyOM-C mineralization was lower for JP (14–65%) than RM (24–84%). The correlation between PyOM_w and mineralization rate was strongest where carbonization and the thermochemical conversion of carbohydrates and non-lignin phenols was most pronounced during pyrolysis for each taxa (300 °C for JP and 450 °C for RM). Contrary to expectations, the addition of a labile C source, sucrose, to the soil did not enhance the decomposition of PyOM, indicating that soil microbes were not energy limited in the soil-PyOM system studied (regardless of pyrolysis temperature). Our results showed that while the first-order control on PyOM decomposition in this soil is pyrolysis temperature, wood taxa did affect PyOM-C MRT, likely in part due to differences in the amount of reactive water-soluble C present in PyOM.

The environmental fate of functionalized carbon nanomaterials (CNM) remains poorly understood. Using ¹³C-labeled nanomaterial we present the results of a study investigating the mineralization and microbial uptake of surface-functionalized C₆₀ (fullerols) in agricultural soils with contrasting properties. Soil microcosms rapidly mineralized fullerol C, as determined by ¹³C-content in the respired CO₂, with higher fullerol mineralization in an organic, clay-rich soil versus a silty, low C soil (∼56.3% vs ∼30.9% fullerol C mineralized over 65 days). By tracking the enriched ¹³C from fullerol into microbial phospholipid fatty acids (PLFA) we also report, for the first time, the incorporation of nanomaterial-derived C into soil microbial biomass, primarily by fungi and Gram-negative bacteria. While more fullerol C was incorporated into PLFA in the organic C-rich soil (0.77% vs 0.19% of PLFA C), this soil incorporated fullerol C into biomass less efficiently than the silty, low C soil (0.13% and 0.84% of assimilated fullerol C, respectively). These results demonstrate that, in contrast to pristine C₆₀, surface functionalized C₆₀ are unlikely to accumulate in surface soils and are readily mineralized by a range of soil microorganisms.