Mahmoud Sharara’s research while affiliated with North Carolina State University and other places

This study investigates Miscanthus biochar’s potential to reduce ammonia (NH3) emissions in poultry production. Biochar from lignocellulosic biomass has proven a versatile tool in environmental remediation for water, soil, and air quality applications with ample opportunity for inclusion in agricultural systems. Ammonia emissions present a concern for animal/human health and the environment. The impacts of biochar production temperature (400 and 700 °C), organic acid activation (acetic acid, citric acid), and application rate (0.24 and 0.49 kg m−2) on broiler litter NH3 emissions were evaluated. Biochar production parameters, i.e., temperature, and acid type were found to significantly impact its performance as an NH3 control measure. The following factors, ranked by magnitude of impact, were found to statistically impact the NH3 emission rate: biochar application rate (p < 0.001), biochar production temperature (p = 0.003), and lastly acid type (p = 0.007). The best performing biochar was produced at 400 °C, activated with acetic acid, and applied at a high addition rate (0.49 kg m−2). This treatment reduced cumulative NH3 volatilization after 2 weeks by 19.7%.

Manure relocation strategies are needed to mitigate excessive phosphorus (P) application to agricultural land in areas of intensive animal agricultural production. This requires conceptual frameworks such as the manureshed, which categorizes agricultural areas according to the potential to export or receive manure for P fertilization. To further understand how the manureshed concept could be utilized, assessments of the potential implementation and necessity of the manureshed model are needed. With North Carolina at the center of the largest manureshed in the United States, North Carolina is an ideal test case to identify areas of concern for manure relocation under the manureshed framework. Swine and poultry dominate North Carolina's agricultural production, and because the vast majority of North Carolina producers are not required to limit manure applications to a P‐based rate, P accumulates. Therefore, soil test data from samples submitted to the North Carolina Department of Agriculture and Consumer Services (NCDA&CS) from 2017 to 2019 were used to determine how manureshed classes defined by Spiegal et al. correspond to current soil test P levels. It was determined that 36% of counties experience very high (>100 mg P kg⁻¹; N = 36) median P concentrations in soil. Furthermore, fields cultivated with warm‐season forages had the highest mean P concentration (188 mg kg⁻¹) and high median P trended toward counties with high animal production. Lastly, while mean soil P for all manureshed classifications fell into the very high category, manure source counties had the highest mean soil P concentrations (188 mg kg⁻¹), which was 39%–52% higher than the other classifications. This suggests that, in addition to manuresheds classification, soil test data are needed to design and promote manure redistribution strategies.

Nutrient cycling in crop–animal production is impacted by changes in both systems, with imbalance hotspots in concentrated animal production regions severely impacting water quality. This study assesses manure–crop nutrient balances in five river basins in North Carolina and demonstrates a new approach for partial nutrient balances along hydrological boundaries. County‐level crop production data were combined with crop‐type spatial distribution data to derive spatially referenced nutrient uptake and removal. Similarly, spatially referred animal production inventory data were used to derive excreted and recovered manure nutrients. Partial nutrient balances were developed for both N and P in basins and hydrologic units. Excreted manure N and P were 139% and 159% of respective plant N and P removal at harvest across the five basins. Finer geographical scales revealed hotspots for manure surplus, particularly within the Cape Fear basin (up to 96% N and 97% P). Despite N hotspots, plant‐available manure N met only 38% of crop N demand due to significant losses during storage. Plant‐available manure P exceeded crop P removal by 54% over the entire area. Cape Fear showed the greatest P excess, 76% greater than crop removal. This study contributes to nutrient cycling improvements by connecting crop–animal nutrient budgets to hydrologic resources. Furthermore, we show the value of finer spatial scales to identify hotspots that play a significant role in nutrient losses. We conclude that nutrient‐surplus basins require, in addition to manure nutrient conservation, a basin‐wide redistribution and export strategies to address nutrient excesses and water quality impacts.

Lagoon sludge, a byproduct of swine operations in the Southeast United States, poses a management challenge due to its high mineral and metal content. Composting is a low-cost, scalable technology for manure management. However, limited information is available on composting swine lagoon sludge in terms of recipes, greenhouse gas emissions and end-product quality. Moreover, due to its high Zn and Cu content, high inclusion of sludge in composting recipes can potentially inhibit the process. To address these knowledge gaps, in-vessel aerated composting (0.4 m3each) was carried out to evaluate impacts of sludge inclusion, at 10% (Low Sludge, LS-Recipe) and 20% (High sludge, HS-Recipe) wet mass-basis, on composting process and end-product quality. Comparable maximum temperatures (74 ± 2.7 °C, 74.9 ± 2.9 °C), and organic matter loss were observed in both recipes. Similarly, sludge inclusion ratio had no significant impact on cumulative GHG emissions. The global warming potential (20-year GWP) for swine lagoon sludge composting using LS and HS recipes was observed to be 241.9 (±13.3) and 229.9 (±8.7) kg CO2-e/tDM respectively. Both recipes lost 24–28% of initial carbon (C) and 4–15% of nitrogen (N) respectively. Composting and curing did not change water-extractable (WE) phosphorus (P) concentrations while WE Zn and Cu concentrations decreased by 67–74% and 55–59% respectively in both recipes. End compost was stable (respiration rates <2 mgCO2-C/g OM/day) with germination index >93 for both recipes.