Elemental Composition of Swine Manure from 1997 to 2017: Changes Relevant to Environmental Consequences

Impacts of utilizing swine lagoon sludge as a composting ingredient

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.

Additions of optimum water, spent mushroom compost and wood biochar to improve the growth performance of Althaea rosea in drought-prone coal-mined spoils

Ecosystem degradation as a result of coal mining is a common phenomenon in various regions of the world, especially in arid and semi-arid zones. The implementation of appropriate revegetation techniques can be considered crucial to restore these degraded areas. In this regard, the additions of spent mushroom compost (SMC) and wood biochar (WB) to infertile and degraded soils have been reported to enhance soil fertility and plant growth under water (W) deficit conditions. However, the combined application of W, SMC and WB to coal mine degraded soils, to promote Althaea rosea growth and facilitate subsequent restoration, has not been explored yet. Hence, in the current study a pot experiment was carried out by growing A. rosea on coal mine spoils to assess the influence of different doses of W, SMC and WB on its morpho-physiological and biochemical growth responses. The results indicated that several plant growth traits like plant height, root length and dry biomass significantly improved with moderate W-SMC-WB doses. In addition, the simultaneous application of W-SMC-WB caused a significant decrease in hydrogen peroxide (H₂O₂) (by 7-56%), superoxide anion (O₂^●‒) (by 14-51%), malondialdehyde (MDA) (by 23-46%) and proline (Pro) contents (by 23-66%), as well as an increase in relative water content (by 10-27%), membrane stability index (by 2-24%), net photosynthesis rate (by 40-99%), total chlorophylls (by 43-113%) and carotenoids (by 31-115%), as compared to the control treatment. The addition of SMC and WB under low-W regime enhanced leaf water use efficiency, and soluble sugar content, also boosting the activity of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase in leaf tissues, thus reducing the oxidative stress, as proved by low levels of H₂O₂, O₂^●‒, MDA and Pro contents. Finest growth performance under optimum doses of W (60% field capacity), SMC (1.4%) and WB (0.8%) suggest that revegetation of A. rosea with the recommended W-SMC-WB doses would be a suitable and eco-friendly approach for ecological restoration in arid degraded areas.

Second-Generation Phosphorus: Recovery from Wastes towards the Sustainability of Production Chains

Phosphorus (P) is essential for life and has a fundamental role in industry and the world food production system. The present work describes different technologies adopted for what is called the second-generation P recovery framework, that encompass the P obtained from residues and wastes. The second-generation P has a high potential to substitute the first-generation P comprising that originally mined from rock phosphates for agricultural production. Several physical, chemical, and biological processes are available for use in second-generation P recovery. They include both concentrating and recovery technologies: (1) chemical extraction using magnesium and calcium precipitating compounds yielding struvite, newberyite and calcium phosphates; (2) thermal treatments like combustion, hydrothermal carbonization, and pyrolysis; (3) nanofiltration and ion exchange methods; (4) electrochemical processes; and (5) biological processes such as composting, algae uptake, and phosphate accumulating microorganisms (PAOs). However, the best technology to use depends on the characteristic of the waste, the purpose of the process, the cost, and the availability of land. The exhaustion of deposits (economic problem) and the accumulation of P (environmental problem) are the main drivers to incentivize the P’s recovery from various wastes. Besides promoting the resource’s safety, the recovery of P introduces the residues as raw materials, closing the productive systems loop and reducing their environmental damage.

Interactive effects of drought, organic fertilizer, and zinc oxide nanoscale and bulk particles on wheat performance and grain nutrient accumulation

Drought (40% field moisture capacity), organic fertilizer (O-F; 10%), and nano vs. bulk-ZnO particles (1.7 vs. 3.5 mg Zn/kg) were assessed in soil to determine their interactive effects on wheat performance and nutrient acquisition. Drought significantly reduced (6%) chlorophyll levels, whereas nano and bulk-ZnO alleviated some stress, thereby increasing (14-16%) chlorophyll levels, compared to the control. O-F increased (29%) chlorophyll levels and counteracted Zn's effect. Drought delayed (3-days) panicle emergence; O-F, nano and bulk-ZnO each accelerated (5-days) panicle emergence under drought, relative to the control and absence of O-F. Drought reduced (51%) grain yield, while O-F increased (130%) yield under drought. Grain yield was unaffected by Zn treatment under drought but increased (88%) under non-drought condition with bulk-ZnO, relative to the control. Drought lowered (43%) shoot Zn uptake. Compared to the control, nano and bulk-ZnO increased (39 and 23%, respectively) shoot Zn in the absence of O-F, whereas O-F amendment enhanced (94%) shoot Zn. Drought increased (48%) grain Zn concentration; nano and bulk-ZnO increased (29 and 18%, respectively) grain Zn, relative to the control, and O-F increased (85%) grain Zn. Zn recovery efficiency was in the order O-F > nano-ZnO > bulk-ZnO, regardless of the water status. Grain Fe concentration was unaffected by drought, under which O-F significantly reduced grain Fe, and nano-ZnO significantly reduced grain Fe, in the absence of O-F. Nano and bulk-ZnO also significantly reduced grain Fe, with O-F amendment under drought. Drought can have dire consequences for food and nutrition security, with implications for human health. This study demonstrated that drought-induced effects in food crops can be partially or wholly alleviated by ZnO particles and Zn-rich O-F. Understanding the interactions of drought and potential mitigation strategies such as fertilization with Zn-rich organic manure and ZnO can increase options for sustaining food production and quality under adverse conditions.

Assessing modified aluminum-based water treatment residuals as a plant-available phosphorus source

Inorganic phosphorus (P) fertilizers are a finite resource; alternative means of creating P fertilizers from current municipal and agricultural waste sources may reduce our reliance on phosphate rock mining, and improve waste disposal and nutrient cycling. Previous research demonstrated that organic aluminum water treatment residual composites (Al/O-WTR), created by mixing aluminum water treatment residuals (Al-WTR) with swine wastewater, have the potential to be a source of plant-available P. A greenhouse study was conducted to compare spring wheat (Triticum aestivum L.) growth with increasing application rates of swine wastewater-derived Al/O-WTR and commercial P fertilizer (both applied at 34, 67, and 135 kg P₂O₅ ha^-1) in either sandy loam or sandy clay loam soil. Spring wheat straw and grain P uptake were comparable across all treatments in the sandy loam, while straw and grain P uptake were lower with Al/O-WTR in the sandy clay loam. The Al/O-WTR did not affect soil organic P concentrations, but did increase phosphatase activity in both soils. Increased phosphatase activity suggests that Al/O-WTR application stimulated microorganisms and enhanced the extent to which microbial communities mineralized Al/O-WTR-bound organic P. Overall, these results suggest that Al-WTR can be used to make P fertilizer, combining two "waste" products to create a useful product. Phosphorus harvesting via Al/O-WTR may be a feasible future alternative to mining phosphate rock, while avoiding unnecessary waste disposal and improving agricultural nutrient cycling.