About

Ann C. Wilkie is a Research Professor in the Department of Soil, Water, and Ecosystem Sciences at the University of Florida, within the Institute of Food and Agricultural Sciences. Her research investigates and develops bioremediation techniques for agricultural and industrial wastes, with an emphasis on microbial and environmental factors influencing biodegradation. Her current focus includes livestock waste management technology aimed at odor control, energy production, nutrient recovery, and water quality improvement. Wilkie's work contributes to sustainable practices in bioenergy, waste management, and environmental protection, with numerous publications highlighting her expertise in biogas potential evaluation, nutrient recovery, and algae-based biofuels.

Research topics

• Environmental science
• Chemistry
• Waste management
• Pulp and paper industry
• Biology

Selected publications

• Kenaf Core as an Alternative Soilless Growing Medium: A Review

  Plants · 2026-02-23 · 1 citations

  articleOpen accessSenior authorCorresponding

  Kenaf (Hibiscus cannabinus) core, an abundant renewable byproduct rich in cellulose and hemicellulose, has emerged as a candidate to replace or supplement peat and coco coir in soilless culture. This review synthesizes the physical, chemical, and biological performance of ground kenaf core and benchmarks it against conventional substrates. Kenaf core exhibits low bulk density (0.06 to 0.15 g cm−3), high total porosity (approximately 90%), and substantial plant available water (approximately 42%), supporting root aeration and water supply. Its pH (6.0–7.2) is near optimal for most crops, whereas electrical conductivity (EC) (3.2–4.7 dS m−1) can exceed recommended ranges for salt-sensitive species, which necessitates pre-leaching or blending. Growth studies show comparable shoot and root performance in blends containing 20 to 70% kenaf, with composted kenaf often outperforming raw core. Pure kenaf generally requires more frequent irrigation and may shrink at high proportions. We outline processing variables such as core purity, particle size, composting, and leaching that govern stability and plant response, identify critical data gaps (including standardized EC and pH methods, and long-term shrinkage), and frame a sustainability agenda. Practically, studies to date indicate that pre-leached kenaf core, incorporated at up to about 70% by volume into peat or coir-based blends with structurally stable components such as perlite, can maintain growth and quality for several ornamental and bedding crops under greenhouse and nursery conditions. At the same time, reports of poor performance in some conifers and early suppression in direct-sown vegetables underscore that the suitability of kenaf-based substrates remains crop specific and dependent on material processing and management.

  PublisherOA PDFDOI

• Evaluation of Composted Kenaf-based Growing Media for Coleus Production

  Journal of Environmental Horticulture · 2026-03-01

  articleOpen access

  Abstract The search for sustainable alternatives to peat-based substrates in horticulture has intensified due to environmental concerns, rising costs, and limitations of peat resources. Consequently, there is a continued need for alternative media. This study evaluated composted kenaf ( Hibiscus cannabinus ) growing media, formulated with food and landscape waste (Mix A: 40% kenaf, Mix B: 30% kenaf), as substitutes for commercial Promix BX in the production of coleus ( Solenostemon scutellarioides ‘Wasabi’). Cuttings were grown in 25%–100% composted kenaf-based media for five weeks. Growth parameters, shoot and root biomass, media pH, electrical conductivity (EC), and nutrient composition were measured. Composted kenaf-based media supported coleus growth equal to or greater than the control, especially with higher proportions of Mix B, linked to elevated nitrogen and potassium. Although pH and EC were initially higher in kenaf-based mixes compared to Promix BX, both levels decreased over time and did not impair plant growth or quality. Despite lower phosphorus and some micronutrient concentrations compared to Promix BX, these findings suggest that composted kenaf-based substrates can serve as a promising, sustainable alternative to peat-based media for ornamental plant cultivation, provided that nutrient balance and pH are further optimized. Species used in this study: Kenaf ( Hibiscus cannabinus L .), Coleus [ Solenostemon scutellarioides (L. ) Codd].

  PublisherDOI

• Uptake and Elimination of 7 Selected PFAS in Eisenia Fetida Exposed in Artificial Soil

  Bulletin of Environmental Contamination and Toxicology · 2026-04-18

  article
  PublisherDOI

• Kenaf: Opportunities for an Ancient Fiber Crop

  Agronomy · 2024-07-16 · 16 citations

  articleOpen accessSenior authorCorresponding

  Hibiscus cannabinus (kenaf) is an annual fiber crop grown in warm seasons and known for its remarkable productivity; it has been cultivated worldwide for thousands of years as a fiber source. While every part of the plant can be utilized for some purpose, its primary significance lies in the diverse applications of its cellulosic fiber. Kenaf features a blend of long bast and short core fibers, rendering it suitable for various industrial uses. Initially utilized for cordage and livestock feed, kenaf’s applications have expanded over the last century to encompass its utilization as paper pulp, biocomposites, textiles, biomass energy, seed oil, filtration aids, industrial absorbents, and even as a component of potting medium or as a potential source of medicine. Although traditionally a niche crop, the discovery of its diverse applications positions kenaf for rapid expansion in production in the upcoming decades. This article aims to explore the manifold applications of kenaf, highlighting those with the greatest future potential and discussing those that hold promise for commercial-level application with additional research.

  PublisherOA PDFDOI

• Common Pollutants in Stormwater and Actions that Homeowners Can Take to Reduce Stormwater Pollution

  EDIS · 2023-09-25

  articleOpen accessSenior author

  This publication explains what happens when stormwater runoff enters constructed environments, its impacts on water bodies, and how individuals can take steps to lower their own stormwater runoff footprint. This guide can increase awareness of ways to reduce each person's role in water quality impairment by stormwater pollution. This publication is intended primarily for urban residential readers and does not focus on agricultural runoff.

  PublisherOA PDFDOI

• Reducing Cement Plant Emissions via Algae Cultivation and Anaerobic Digestion

  UF Journal of Undergraduate Research · 2023-10-16 · 1 citations

  articleOpen accessSenior author

  Concrete is an essential aspect of modern infrastructure, and is a much-preferred construction material as it is a highly resistant and requires low maintenance. Concrete is produced through the creation of a paste comprised of cement and water that is mixed with aggregates such as sand and gravel. However, the concrete industry is one of the largest consumers of natural resources globally, and the emissions associated with its production are very high. Cement, one of the primary constituents of concrete, emits 0.93 pounds of CO2 for every pound produced. Thus, concrete production is a major source of CO2 emissions and accounts for approximately 8% of global carbon emissions. As the global demand for concrete continues to increase, it is evident that efforts must be made to reduce emissions associated with its production to mitigate climate change. This research proposes that the cultivation of algae can be integrated into the process of cement production so as to reduce the emissions associated with concrete. Algae uptake CO2 through photosynthesis, having a CO2 bio-fixation efficiency of 10-50 times higher than terrestrial plants. Algae have the ability to capture 1.8 kg of CO2 per kilogram of algal biomass. Therefore, we hypothesize that, through the integration of algae cultivation and cement production, CO2 can be effectively recycled through a closed-loop system. Algal biomass can be cultivated using the CO2 emitted from cement flue gas. The cultivated algae can be harvested and used to produce methane gas (CH4) via anaerobic digestion, which can in turn be used to power the cement plant, which will in turn produce more CO2 to be captured through further algal cultivation.

  PublisherOA PDFDOI

• Start-up of the mesophilic anaerobic co-digestion of two-phase olive-mill waste and cattle manure using volatile fatty acids as process control parameter

  Fuel · 2022-06-16 · 26 citations

  articleOpen access

  In this work, the start-up and stabilization stages of mesophilic anaerobic co-digestion of 2POMW and CM in a semi-continuously fed stirred tank reactor (SSTR) were analyzed. Volatile fatty acids (VFAs) were monitored and used as the main control parameter for the start-up and stabilization stages, as well as to evaluate the potential inhibition episodes. The results showed that accumulation of propionic acid was the key factor in the inhibition of the methanogenic phase, leading to process imbalance. To avoid the problems associated with inhibition by high VFA concentrations, several reinoculations were performed using a suitable inoculum adapted to VFA degradation. The start-up phase was carried out in batch conditions for 97 days, reaching a final concentration of propionic acid of 12.77 mg/L. From that moment, the reactor was fed in a semi-continuous mode with a hydraulic retention time (HRT) of 40 days. A total period of 140 days was required to achieve a stable performance of the reactor with a methane productivity of 0.34 LCH4/LRd.

  PublisherDOI

• Compost Composition and Application Rate Have a Greater Impact on Spinach Yield and Soil Fertility Benefits Than Feedstock Origin

  Horticulturae · 2022-07-29 · 14 citations

  articleOpen access

  Rapid urbanization results in the accumulation of food wastes that can be composted and diverted from landfills. Previous lab incubations demonstrated that food-based composts can increase soil N relative to manure-based composts, but these benefits were not tested within a crop system. We assessed soil fertility and yield of spinach (Spinacia oleracea L.) grown in two different soils in a greenhouse, comparing two food- and two manure-based composts added at the recommended N rate (101 kg N ha−1). We quantified soil N mineralization and resin-extractable phosphorus, spinach biomass (root and shoot), and crop nutrient concentrations and accumulation. Nitrogen mineralization generally peaked four weeks after application, and one food-based compost (but no manure-based composts) increased soil phosphorus at harvest compared to an unamended control. One manure-based compost and one food-based compost produced a higher yield and greater nitrogen, phosphorus, and potassium accumulation than the unamended control, whereas only the food-based compost increased spinach phosphorus and potassium concentrations. There was a positive relationship between yield and compost inputs of potassium and plant-available nitrogen (especially nitrate), suggesting that potassium inputs may also explain differences observed among composts. Our results suggest that food-based compost provides more nutrients than composts made from cow manure fiber.

  PublisherOA PDFDOI

• Co-digestion of two-phase olive-mill waste and cattle manure: Influence of solids content on process performance

  Fuel · 2022-04-13 · 14 citations

  articleOpen access

  The solids content is a key parameter in the development of anaerobic digestion as it can determine the proper operation and performance of the process. The influence of the total solids content on the mesophilic anaerobic co-digestion of two-phase olive-mill waste (2POMW) and cattle manure (CM) was investigated. Four different total solids (TS) concentrations, in a 75:25 mixture of 2POMW:CM, were studied in batch reactors of 2 L capacity: 10%TS (R10), 15%TS (R15), 20%TS (R20) and 28.6%TS (Reactor non-diluted). The methane yields and the organic matter removal efficiency for the reactor with 10 and 15% TS were significantly higher than in the reactors with a higher solids content (R20 and Rnd). The hydrolytic and acidogenic phases were not adversely affected by the total solid content since the concentration of volatile fatty acids (VFAs) increased as TS percentage increased. However, a clear effect on the methanogenic phase was observed, which led to the accumulation of VFAs in the reactors R15, R20 and Rnd. Experimental results have shown that the best conditions correspond to the reactor containing 10% TS. The volatile solids and VFA removal in reactor R10 were 57.5% and 93.7% respectively. Moreover, the methane yield and the specific methane production were 35.80 LCH4/kgVSadded and 82.51 LCH4/kgVSremoved respectively.

  PublisherDOI

• Mesophilic anaerobic co-digestion of two-phase olive-mill waste and cattle manure: Optimization of semi-continuous process

  Fuel · 2022-07-22 · 14 citations

  articleOpen access

  Anaerobic co-digestion of organic wastes is an effective technology for the management of two or more substrates with different characteristics. In this context, the main objective of this work was the optimization of biogas production for the treatment of a mixture of two-phase olive-mill waste (2POMW) and cattle manure (CM) (60:40 w/w) at mesophilic temperature range (35 °C). The effect of hydraulic retention time (HRT) on the performance and stability of the digestion process was studied. A decreasing series of HRTs in the range of 40–12 days was analyzed. The corresponding organic loading rates (OLR) were in the range 2.01–6.07 gVS/LR·d. Pseudo steady-state operation of the reactor was established for HRTs between 40 and 15 days. For 15-days HRT, the maximum values of methane productivity (0.94 LCH4/LR·d) and specific methane yield (0.52 LCH4/gVSremoved) were obtained while total acidity (measured as acetic acid) in the effluent were<150 mg/L, verifying process stability. In addition, the removal efficiencies of volatile solids (VS) and dissolved organic carbon (DOC) were 38 and 67 %, respectively. At 12-days HRT, decreases in methane production and organic matter removal efficiencies were observed, with values of 27 and 47 % for VS and DOC removal, respectively. Therefore, 12-days HRT was considered as inadequate for the anaerobic co-digestion of 2POMW and CM because a clear increase in volatile fatty acids was observed at the end of this period, leading to process destabilization and a decrease in biogas production.

  PublisherDOI

Frequent coauthors

• Q. Lena

  Zhejiang University

  14 shared

• Evandro B. da Silva

  Technical Solutions (United States)

  13 shared

• Paul Smith

  8 shared

• Emer Colleran

  6 shared

• Henry C. Aldrich

  6 shared

• Wendy Mussoline

  University of Florida

  6 shared

• Cheryl L. Mackowiak

  6 shared

• R. A. Nordstedt

  University of Florida

  6 shared