Maheteme Gebremedhin

Fly ash (FA) is a coal combustion product with variable mineral composition, high alkalinity, and elevated enrichment of heavy metals (HMs) such as As, Se, Mo, Cd, and Pb. Fly ash greatly influences soil dynamics by altering soil pH, nutrient mobility, microbial activity, soil structure, and texture. This review evaluates phytoextraction as a sustainable and eco-friendly strategy for remediating FA-contaminated soils. It explores the physicochemical properties of FA, the impact of FA and associated heavy metals (HMs) on soil, the mechanisms of HM hyperaccumulation in plants, and the effectiveness of phytoextraction based on the bioaccumulation factor (BAF) and translocation factor (TF). Case studies from various regions demonstrate the great potential of hyperaccumulator species to extract toxic HMs from FA-impacted soils. However, challenges such as low metal bioavailability, limited field validation, and inadequate management of contaminated biomass hinder large-scale application. Future research should focus on optimizing biomass utilization, developing comprehensive hyperaccumulator databases, and advancing genetic and policy frameworks to enhance the scalability and effectiveness of phytoextraction.

Forests play a crucial role in carbon cycling, contributing significantly to global carbon cycling and climate change mitigation, but their capture strength is sensitive to the climatic zone in which they operate and its adjoining environmental stressors. This research investigated the carbon dynamics of a typical deciduous forest, the Daniel Boone National Forest (DBNF), in the Mixed-Humid climate of Kentucky, USA, employing the Eddy Covariance technique to quantify temporal CO₂ exchanges from 2016 to 2020 and to assess its controlling biometeorological factors. The study revealed that the DBNF functioned as a carbon sink, sequestering −1515 g C m⁻² in the study period, with a mean annual Net Ecosystem Exchange (NEE) of −303 g C m⁻²yr⁻¹. It exhibited distinct seasonal and daily patterns influenced by ambient sunlight and air temperature. Winter months had the lowest rate of CO₂ uptake (0.0699 g C m⁻² h⁻¹), while summer was the most productive (−0.214 g C m⁻² h⁻¹). Diurnally, carbon uptake peaked past midday and remained a sink overnight, albeit negligibly so. Light and temperature response curves revealed their controlling effect on the DBNF trees’ photosynthesis and respiration. Furthermore, clear seasonality patterns were observed in the control of environmental variables. The DBNF is a carbon sink consistent with other North American deciduous forests.

Open burning poses a significant threat to human health and the environment by releasing hazardous chemicals and exacerbating plastic pollution. Urgent action is required to address its pervasive impact and the substantial release of gaseous pollutants. Limited research has explored the demographic aspect of open burning behavior, with none specifically conducted in Kentucky. An analysis of open burning complaints reported to the Kentucky Division for Air Quality in 2015, 2019, and 2021 revealed no significant differences in reported incidents by month and county. Binary logistic regression analyses identified the urban vs rural divide as significant predictors of open burning incidents, while violations were influenced by both urban and rural factors and average household income. Unemployment rates and the percentage of individuals with less than a high school diploma did not significantly predict open burning violations. Targeted interventions at the state and local level, focusing on rural areas and economically disadvantaged communities, can effectively address and mitigate open burning issues.

In an effectively managed grazing system, goats as grazers can benefit the land's physical, chemical, biological, and economic aspects. However, little research has evaluated rotational and continuous goat grazing in Kentucky. This observational study investigated the impact of rotational and continuous grazing on forage production and goat performance. One group of 10 does was placed on a rotational pasture, and another group of 10 does were placed on a continuous pasture, each pasture measuring two acres. The pastures were side-by-side with similar forage types and compositions. Goat performance was measured by body weight and eye color score (FAMCHA). Forage production was measured weekly by collecting forage heights at three random spots in each pasture. The rotational grazing field displayed a more evenly grazing pattern, while the continuous field experienced overgrazing in some areas and overgrown of the less desired forage. Goats on the continuous field had a decrease in body weight, while the weights were more consistent in the rotational grazing field. The FAMACHA score was temporarily reduced on the rotational grazing pasture, indicating that properly managed rotational grazing may prevent anemia, possibly by reducing the shedding of gastrointestinal parasites. However, due to drought and lack of forage, the FAMACHA score of goats in the rotational grazing system reverted to its original status by the end, indicating that more extensive management and timely adjustments are necessary to ensure optimal goat performance. Our results suggest that rotational grazing may support more consistent forage yields and body weights of goats and has the potential to reduce the incidence of anemia and parasitic infestations in goats in Kentucky.

Potential seed size in many crops including major cereals is determined during early seed developmental stages. However, the stage at which final seed size is determined in soybean (Glycine max [L.] Merr.) under field conditions is not known. Hence, this study was conducted with the main objective to assess seed growth dynamics under controlled and increased assimilate supply conditions during different seed filling periods using two maturity group soybean cultivars. Treatments consisted of a control, and a de-podding (pod removal) treatment at weekly intervals after the beginning of the seed filling stage up until physiological maturity. Only four to six pods were maintained per plant in de-podding treatments in order to provide a higher assimilate supply to remaining seeds. A higher assimilate supply until around the mid-seed filling stage increased unit seed weight in both the cultivars, indicating that the maximum seed size in soybean crops is determined during the mid-seed filling stage. The increase in seed weight under higher assimilate supply was associated with an extended seed filling duration and a uniform seed filling rate over a longer period. The results also suggested a possible source limitation during the early seed filling stage in soybean, indicating opportunities to improve its yield using supplemental inputs and other improved crop cultivation practices.

This study addresses the pressing issue of nonpoint source water pollution in Kentucky, particularly associated with large-scale agriculture. Centered on the outer bluegrass region of Central Kentucky, the research examines the water quality of headwater streams during the agricultural season. The approach involves geospatial land cover classification using aerial imagery. Water quality data were collected during the agricultural growing season from May to October 2018. Land cover classification utilized ERDAS Imagine 2016 and ESRI ArcGIS 10.6 GIS software, while conventional water quality parameters were measured with a YSI ProDSS^® multiparameter water probe and a Marsh-McBirney Flo-Mate 2000 flow meter. Statistical analyses show significant differences in stream water chemistry, suggesting the impact of agricultural nonpoint source pollution. Forested streams exhibited more varied conditions, indicating a potentially better environment. As agricultural land percentage increased, water chemistry variation suggested a measurable threshold for changes. Significant differences in water quality between agricultural and forested streams highlight the potential benefits of expanding riparian zones beyond regulations. Enlarging these zones is proposed as a strategy to mitigate nonpoint source pollution in Kentucky’s waterways.

Intensive pasture management that aims at providing season-long forage while minimizing soil degradation is increasingly becoming an important grazing strategy in Kentucky. Typically, it involves the use of high-yielding warm and cool season forage species that are well suited to local soil and climate conditions, meeting the dual-purpose provision of high nutritional value while remaining resilient to grazing pressure and changing climate. Monitoring carbon exchange is a crucial component for effective pasture management to promote sustainable pastureland management practices. We hypothesized that pasturelands, when intensively managed, would exhibit a small but important CO₂ cumulative uptake year-round. We used the Eddy covariance method to measure the net ecosystem exchange of CO₂ (NEE) and productivity of an intensively managed pastureland at Kentucky State University Research and Demonstration station from 2015 to 2020. The study has two objectives: to quantify interannual variability in net ecosystem exchange, and examine the controlling environmental factors, in particular temperature, sunlight, and precipitation of NEE. Diurnal and seasonal fluctuations followed typical patterns of carbon uptake and release. Overall, the pasture site consistently was carbon sink except for 2016, in part due to a warmer winter season than usual, sequestering 1394 gCm⁻² over the study period. Precipitation and temperature were critical environmental factors underpinning seasonal CO₂ uptake and release. Of critical importance was the net carbon uptake during the non-growing season.

Land cover change is prevalent in the eastern Kentucky Appalachian region, mainly due to increased surface mining activities. This study explored the potential change in land cover and its relationship with stream discharge and sediment yield in a watershed of the Cumberland River near Harlan, Kentucky, between 2001 and 2016, using the Soil and Water Assessment Tool (SWAT). Two land cover scenarios for the years 2001 and 2016 were used separately to simulate the surface runoff and sediment yield at the outlet of the Cumberland River near Harlan. Land cover datasets from the National Land Cover Database (NLCD) were used to reclassify the land cover type into the following classes: water, developed, forest, barren, shrubland, and pasture/grassland. Evaluation of the relationship between the land cover change on discharge and sediment was performed by comparing the average annual basin values of streamflow and sediment from each of the land cover scenarios. The SWAT model output was evaluated based on several statistical parameters, including the Nash–Sutcliffe efficiency coefficient (NSE), RMSE-observations standard deviation ratio (RSR), percent bias (PBIAS), and the coefficient of determination (R²). Moreover, P-factor and R-factor indices were used to measure prediction uncertainty. The model showed an acceptable range of agreement for both calibration and validation between observed and simulated values. The temporal land cover change showed a decrease in forest area by 2.42% and an increase in developed, barren, shrubland, and grassland by 0.11%, 0.34%, 0.53%, and 1.44%, respectively. The discharge increased from 92.34 mm/year to 104.7 mm/year, and sediment increased from 0.83 t/ha to 1.63 t/ha from 2001 to 2016, respectively. Based on results from the model, this study concluded that the conversion of forest land into other land types could contribute to increased surface runoff and sediment transport detached from the soil along with runoff water. The research provides a robust approach to evaluating the effect of temporal land cover change on Appalachian streams and rivers. Such information can be useful for designing land management practices to conserve water and control soil erosion in the Appalachian region of eastern Kentucky.

Nearly all the current winter wheat–soybean cropping systems occurring in the southeastern United States (SE) region are rainfed, as such, precipitation (P) underpins energy partitioning. We investigated, using the eddy covariance technique, the seasonal and interannual variability and rate and trend of energy partitioning, i.e., sensible and evapotranspiration (ET), for rainfed soybean and winter wheat cover cropping at Winfred Thomas Agricultural Research Station (WTARS) in Hazel Green, Alabama. Yearlong cumulative ET of 493, 743, and 746 mm during 2007, 2008, and 2009 relative to cumulative precipitation of 567, 1280, and 1356 mm y⁻¹ resulted in a higher mean ET/P ratio of 0.87, in 2007, medium 0.58 in 2008, and lowest 0.55 in 2009. Mean daily ET for the cover crop and soybean ranged between 1.70 and 2.44 mm d⁻¹ and 1.82 to 2.83 mm d⁻¹, respectively. Overall, our findings suggest total and seasonal precipitation distribution were major controlling factors in the partitioning of the energy and water budgets. This study provides evidence that changes in rainfall frequency and intensity in the SE will likely alter the regional croplands hydrology with implications on water resource management decisions in rainfed agriculture.

Soil erosion is the displacement of soil’s upper layer(s) triggered by a variation in topography, land use and soil types, and anthropogenic activities. This study selected the Marrowbone Creek-Russel Fork watershed in eastern Kentucky to estimate the mean annual soil loss over eight years (from 2013 to 2020) utilizing the Universal Soil Loss Equation (USLE). We included monthly precipitation, soil survey, digital elevation model (DEM), and land cover data to estimate the parameters of the USLE. The mean annual soil loss for the study area ranged from 1.77 to 2.91 Mg ha⁻¹ yr⁻¹ with an eight-year mean of 2.31 Mg ha⁻¹ yr⁻¹. In addition, we observed that developed land cover classes were less erosion-resistant than undeveloped land cover classes over the observation period. The results of this case study in our small watershed that has been historically impacted by upstream coal-mining activities are comparable to the results from similar studies in other geographic regions. However, we suggest other researchers conduct similar studies using robust data to determine the applicability of the USLE model and validate the results in developing measures to address soil loss issues.