As the basis for virtually any form of nitrogen fertilizers, ammonia plays a vital role in agriculture; in addition, there has been an increased interest in its use as a carbon-free energy carrier. However, ammonia is also associated with two major environmental concerns: CO₂ emissions from the conventional production process and nitrogen pollution from the excessive use of ammonia-based fertilizers. To mitigate these environmental impacts, we develop an optimization framework for the design of a sustainable ammonia-based agricultural system that synergistically integrates the production of ammonia from renewable resources and effective measures for nitrogen management. The proposed model captures the effect of intermittency by incorporating both design and detailed operational decisions. By applying a multiscale time representation that reduces the problem size and a tailored surrogate model that accurately approximates model nonlinearity, we are able to achieve optimal solutions within reasonable computation times. A computational case study is conducted using real-world data from a local farm in Morris, Minnesota, and the results indicate the trade-off between cost and nitrogen loss. Importantly, we show that practicing effective nitrogen management can significantly reduce the nitrogen loss with only a small increase in net present cost.

Rice production, despite its important role in food security, could bring about environmental problems such as methane emissions and polluting water resources. To decrease such negative environmental impacts, the co-culture of rice with ecologically friendly aquatic animals such as crabs has shown promising results. However, there are still serious concerns about the proper implementation of rice co-culture systems. Having considered rice-crab systems, crab stock density and the amount of crab feed, among others, are two important factors which regulate the performance of the system and the associated environmental pollution. However, their optimal values and their underlying relationship with enviro-economic parameters (e.g. methane emissions, nitrous oxide emissions, ammonia volatilization, yield, N uptake, nitrate in drainage water, and profit) have not been scrutinized yet. Accordingly, a set of farm experiments has been performed to measure enviro-economic parameters under mono- and co-cultivation of rice. Moreover, the attempts were made to explore the underlying correlations between crab stock density and the amount of crab feed as two independent variables and measured parameters such as yield and greenhouse gas emissions. Furthermore, an appropriate optimization model was developed to find the optimal crab density and crab feed in order to minimize the environmental pollution and maximize crab and rice yield as well as net profit. At the end, a farm survey was also conducted to evaluate the shortages in co-culture systems. The results showed that, under optimal rice-crab co-culture system, the improvements in nutrient uptakes ranged from 5.2% to 23.3%, with the lowest for Zn uptake and the highest for N uptake. Under such circumstances, 355% lower global warming impact would be attained compared to rice mono-culture showing a significant contribution to greenhouse gas mitigation. Furthermore, farmers would benefit from 122% higher profit under co-culture systems. The results achieved herein also have policy implications because it would help to decrease national greenhouse gas emissions and avoid deterioration of water resources while help farmers to ensure earning a high profit.

To replace existing high impact ammonia production technologies, a new sustainability-driven waste-based technology producing green ammonia with and without urea was devised using life cycle thinking and sustainable design principles, targeting efficiency, carbon emissions, water, and power use competitiveness. We have used life cycle assessment to determine whether cradle-to-gate, multiple configurations of the core waste-based processes integrating several carbon capture/utilization options can compete environmentally with other available ammonia technologies. Our waste-to-ammonia processes reduce potential impacts from abiotic depletion, human toxicity, and greenhouse gas (GHG) emissions relative to fossil-based and renewable technologies. Among the assessed technologies, coupling dark fermentation with anaerobic digestion and capturing CO₂ for sequestration or later use is most efficient for GHGs, water, and energy, consuming 27% less energy and reducing GHGs by 98% compared to conventional ammonia. Water use is 38% lower than water electrolysis and GHGs are 94% below municipal waste incineration routes per kg NH₃. Additionally, displacing conventional, high impact urea by integrating urea production from process CO₂ decreases life cycle environmental impacts significantly despite increased energy demand. On a fertilizer-N basis, the ammonia + urea configuration without dark fermentation performs best on all categories included. Methane and ammonia leakage cause nearly all life cycle impacts, indicating that failing to prevent leakage undermines the effectiveness of new technologies such as these. Our results show that a green ammonia/ammonia + urea process family as designed here can reduce waste and prevent the release of additional CO₂ from ammonia production while avoiding fossil-based alternatives and decreasing emissions from biogenic waste sources.

Eight multicannulated heifers (average BW 415 +/- 34 kg) were used in a replicated 4 X 4 Latin square to evaluate fluid milk processing wash water solids (WWS) as a dietary N source. Heifers were fed corn/cottonseed hull-based diets containing soybean meal (control, 0% WWS N) or WWS replacing soybean meal at 33, 67, or 100% of supplemental dietary N. Total tract and ruminal DM and OM digestibilities decreased linearly or cubically (P < .05) as dietary WWS N increased. Total ruminal VFA concentration (P < .05) and propionic acid molar proportion (P < .10) were greater in heifers fed 0 vs 100% WWS N. Heifers fed 0% WWS N had the greatest (P < .05) ruminal ammonia concentration at all sampling times. Dietary WWS did not affect (P > .10) ruminal pH, fluid dilution rate, fluid flow, fluid volume, or turnover time. Total tract N digestibility decreased quadratically (P < .10) with increasing WWS N in the diet. Supplemental WWS N did not affect (P > .10) flow of duodenal ammonia N or bacterial N, or efficiency of microbial N synthesis. Diets containing WWS N resulted in a cubic increase (P < .10) in duodenal flow of essential amino acids compared with 0% WWS N; however, there were no differences in small intestinal amino acid disappearance. Data indicate that WWS can replace 33% of the soybean meal N in a corn/cottonseed hull-based diet without decreasing ruminal fermentation, fluid digesta kinetics, microbial efficiency, or small intestinal amino acid utilization.

The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (60:40, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2–3 mg kg⁻¹, 0.14 mg kg⁻¹ and 38, respectively, measuring red species for milk, cheese and beer (4.9–5.5% error; 4.8–6.3% RSD; n = 5); and 5–400 µg L⁻¹, 0.4 µg L⁻¹ and 137, respectively, measuring blue species for water samples (3.3–5.7% error; 3.6–6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.

Twelve ruminally, duodenally, and ileally cannulated (average initial BW 313 +/- 20 kg) and 27 intact Hereford heifers (average initial BW 256 +/- 17 kg) were used in two experiments to evaluate dairy food wash water solids (WWS) as a protein source in medium-quality hay diets. Heifers received a basal diet of orchardgrass hay (7.4% CP) and were assigned to one of three supplement treatments: control (C;.9% CP), WWS (18.8% CP)-, and soybean meal (SBM 19.1% Cp)-based supplements (fed at 1.5 kg of DM/d). Supplements were formulated to have similar ME concentrations. Ruminal ammonia concentrations were greater (P <.10) for WWS- and SBM-supplemented heifers than for C heifers at most sampling times. Moreover, WWS and SBM increased (P < .10) total VFA (mM) and acetate (mol/100 mol) and lowered propionate (mol/100 mol) at several sampling times. Ruminal fluid volume (liters) was unchanged (P > .10) by treatment; however, fluid dilution and flow rate (liters/h) were less (P < .10) in C heifers than in heifers fed SBM or WWS supplements. Wash water solids and SBM supplementation increased (P < .10) OM, NDF, and ADF digestibilities compared with C heifers. Feeding WWS and SBM supplements increased BW at 84 d (P < .10) compared with C-supplemented heifers. Forage intake at 54 and 84 d by heifers supplemented with SBM or WWS was greater (P < .10) than by C heifers. Control-supplemented heifers had the least, WWS intermediate, and SBM the greatest ADG at 84 d (P < .10; .14 vs .35 vs .48 kg/d, respectively). These data indicate that WWS may be used as a protein source without serious adverse effects in heifers consuming medium-quality hay for 84 d.