Raw Poultry Litter Research Articles

Characterization of Poultry Litter Biochar and Activated Biochar as a Soil Amendment for Valorization

Biochar applications to soils may enhance soil quality, hydrological properties, and agronomic productivity. Modification of biochar by activation via introduction of heteroatoms at different pyrolysis conditions can alter physical and chemical characteristics, which may enhance soil properties, although the extent of this is unknown. The objective of this study was to investigate the impacts of pyrolysis temperature (400, 500, 600, and 700 °C) on activated (activated with methanesulfonic acid) and unactivated biochar produced from poultry litter to identify optimum production conditions for end use as a soil amendment. Physical, chemical, and surface properties of biochars were determined using wet chemistry and spectroscopic analyses. Results showed that activation with methanesulfonic acid increased biochars’ oxygen content, while decreasing its point of zero charge and electrical conductivity. Conversion of raw poultry litter to activated and unactivated biochar increased concentration of P (3-fold), K (1.8-fold), Ca (3-fold), Mg (2.3-fold), and S (4.8-fold), with concentrations increasing with increasing temperatures (p < 0.05) except for C and N. Activated biochar had lower recovery of C and N, but greater water-holding capacity than unactivated biochar. Concentrations of NH4-N, NO3-N, and water-soluble P were greater in unactivated biochar (p < 0.05). Among all biochars, activated biochar produced at 400 °C had the lowest bulk density, total P, K, Ca, and Mg, and greatest water-holding capacity, water-soluble P, Ca, and Mg concentrations, thereby suggesting improved soil amendment characteristics and subsequent soil health under poultry litter biochars produced under these conditions.

Organomineral Fertilizer Is an Agronomic Efficient Alternative for Poultry Litter Phosphorus Recycling in an Acidic Ferralsol

Brazil is a large phosphate importer due to the high demand for this nutrient for grain cropping on very weathered soils. However, Brazil has an important poultry production that generates ~6.8 million m3 year−1 of organic residue containing phosphorus and other nutrients, increasing the risk of environmental harm. However, if well managed, poultry litter can be a valuable source of P for crop growth in low fertile tropic soils. This article summarizes the long-term agronomic efficiency of organomineral fertilizers in supplying P to soybean and soil P maintenance as a strategy for secondary P recycling. Three fertilizers were used as P source: organomineral based on raw poultry litter, organomineral based on composted poultry litter; and a mineral monoammonium phosphate. Five soybean crop seasons were conducted with annual P doses (20, 40, 60, and 80 kg ha−1 of P2O5) and control without P application. After five crops, one additional soybean crop season was grown without P to evaluate the residual effect. Phosphorus concentration in leaves was evaluated in the first four seasons, and soil P availability in the first, third, and fourth seasons. There was no difference in soybean grain yield, P concentration in leaves, and soil P availability as a function of the P sources in the first crop. Soybean grain yield only varied with the P rate applied after the second season, when the control had the lowest grain yield. After five crops, organomineral resulted in a slight but significant soybean yield gain compared with MAP at higher doses. Over time, the available soil P increased with the highest P dose and decreased in the control treatment. The intermediate dose of 40 kg ha−1 P2O5 was enough to keep soil P level and lead to high soybean grain yield over the time, suggesting that the rate of applied P close to the P exportation by the grains has a long-term sustainable effect even in tropical soils, where residual P stocks are used. It can be concluded that organomineral fertilizer is an efficient farm input that can be used for residue destination and nutrient recycling, especially in acid tropical soils.

Valorization of poultry litter using Acutodesmus obliquus and its integrated application for lipids and fertilizer production

Microalgae are recognized as potential candidates for resource recovery from wastewater and projected for biorefinery models. This study was undertaken to evaluate the potential of poultry litter and municipal wastewater as nutrient and water sources, for the cultivation of Acutodesmus obliquus for lipids production for biodiesel application. The efficacy of lipid extracted biomass (LEA) as fertilizer for mung bean crops was also assessed in microcosm. A. obliquus cultivation in acid pre-treated poultry litter extract (PPLE) showed maximum biomass production of 1.90 g L−1, which was 74.67% and 12.61% higher than the raw poultry litter extract (RPPE) and BG11 respectively. Higher NO3-N, NH3-N, and PO4-P removal of 79.51%, 81.82%, and 80.52% respectively were observed in PPLE as compared to RPLE treatment. The highest biomass (140.36 mg L−1 d−1), lipids (38.49 mg L−1 d−1), and carbohydrates (49.55 mg L−1 d−1) productivities were observed in the PPLE medium. The application of LEA as a fertilizer for mung bean crops showed improvement in plant growth and soil microbial activity. A maximum increase in organic carbon (59.5%) and dehydrogenase activity (130.8%) was observed in LEA amended soil which was significantly higher than chemical fertilizer (CF) control in 30 days. Whilst plant fresh weight and leaf chlorophyll in the LEA amended soil was comparable to whole algal biomass (WA) and CF control. The strategy developed could be a basis for sustainable biorefinery for the valorization of wastewater for the production of microalgae-derived biofuel and byproducts for agricultural application.

Decomposition of poultry litter organic matter co-applied with industrial and agricultural products/by-products.

Increasing soil organic matter (SOM) is one purpose of applying manures to soils, but soil-applied manures decompose and disappear in a short time, leaving very little trace as SOM. The objective of this study was to test and identify agricultural and industrial products and by-products (PBPs) that reduce the speed of manure decomposition and, potentially, increase SOM. Raw poultry litter (PL) was amended with selected PBPs (15% fresh weight) and incubated for 1-3 mo. Unamended PL lost an average of 19% of its dry weight after 1 mo incubation and 24% of its dry weight after 3 mo. Monitoring the CO2 release during a 1-mo incubation revealed that decomposition and weight loss of unamended PL is greatest in the first 2 d. Amending PL with Al2 (SO4 )3 · 18H2 O and CaO reduced cumulative CO2 release and final dry biomass loss during the incubation period of 1-3 mo. Amending PL with Al2 (SO4 )3 · 18H2 O reduced PL temperature by up to 14°C and pH by ∼4.0, whereas CaO elevated its temperature by up to 24°C and pH by ∼4.0. Both products suppressed total culturable bacteria and reduced dehydrogenase activity soon after mixing. Amending PL with flue gas desulfurization gypsum, CaCO3 , cement kiln dust, or biochar either enhanced or had no effect on suppressing litter decomposition. Our results overall show that the decomposition of PL and possibly other manures may be slowed and that the soil-residence life of manure C may be increased using PBPs that raise or lower manure pH and temperature.

On station maggot production using poultry litter as substrate: assessment on the quantity and the chemical quality of the litter before and after maggot production in Burkina Faso

The maximization of organic substrates production for land sustainable management is a major challenge for agricultural production in countries like Burkina Faso. The objective of this study was to assess the quantity and the quality of organic substrates produced by poultry activity on station. Therefore, 54 local chickens at eighteen months old were allocated to 3 batches (boxes), with 18 chickens per batch. Rice husk was spread on the floor of the 3 boxes as litter for the chickens. The chickens were reared on the litter for 6 months in semi-confinement. Then, the poultry litter (PL) was used as substrate for maggots’ production. The quantities and the chemical characteristics of the raw PL as well as the residues of the litter after maggots’ production (RMP) were determined, and, simulations were done to estimate the quantities of organic substrates and the chemical nutrients that poultry farms can produce. The results show a production of 226.06 kg DM of PL after 6 months of semi- confinement, with a decrease of 30.33% when the PL was used to produce maggots. Carbon and nitrogen contents also registered a decreased of 8.83 and 8.39% respectively when PL was used to produce maggots. However, with phosphorus and potassium contents, an increase of 49.12 and 34.21% were noted, respectively. It was concluded that small poultry farmers with 30 to 100 adult chickens, could produce the equivalence of 100 to 300 kg of fertilizer (NPK (15-15-15)) in semi-confinement condition.Keywords: local poultry, litter, organics substrates, maggot production, fertilizer, small farm.

Influence of Poultry Litter Amendment Type and Irrigation Events on Survival and Persistence of Salmonella Newport

Salmonella enterica subsp. enterica serovar Newport is a bacterial foodborne pathogen isolated from several environmental reservoirs on the Delmarva Peninsula and has been associated with several produce-related outbreaks. However, little is known about specific interactions between Salmonella Newport and soil amendments used as fertilizers. The purpose of this study was to determine Salmonella Newport persistence and resuscitation in raw poultry litter (PLR), a common biological soil amendment, and in soils containing poultry litter-based (heat-treated poultry pellets [HTPP]) or chemical fertilizer (urea [U]) amendments to provide equivalent levels of nitrogen to the soil. Inoculated samples were stored in a growth chamber and irrigated regularly over 4 weeks. Soil samples were collected every week for 4 weeks to determine moisture content and surviving Salmonella Newport populations (log CFU per gram dry weight). Data were analyzed by using a one-way analysis of variance and Student's t test. The PLR supported significantly higher (5.07 log CFU/g dry weight [gdw]) populations of Salmonella Newport than HTPP only (1.70 log CFU/gdw). However, PLR-amended (PRLA) soil (2.5 log CFU/gdw) samples had significantly (P < 0.05) lower Salmonella Newport populations compared with HTPP-amended (4.5 log CFU/gdw) and U-amended (4.0 log CFU/gdw) soil samples. The effect of irrigation on Salmonella Newport population levels in PRLA soils was significant, and in a comparative study, the overall increase in the pathogen levels in U-amended soil (mean = 1.12 log CFU/gdw) was significantly greater than that in PLRA soil (mean = 0.54 log CFU/gdw), whereas that in HTPP-amended soil (0.80 log CFU/gdw) was not significantly different from PLRA soil.

Speciation Transformation of Phosphorus in Poultry Litter during Pyrolysis: Insights from X-ray Diffraction, Fourier Transform Infrared, and Solid-State NMR Spectroscopy.

Converting poultry litter (PL) into biochar by slow pyrolysis is a promising approach for recycling organic waste with enhanced phosphorus (P) utilization efficiency, which needs fundamental knowledge of in situ P speciation transformation for optimizing the biochar conversion conditions. In this study, solid-state NMR spectroscopy was employed to characterize solid-state P and C speciation of raw PL and PL-derived biochars prepared at various pyrolysis temperatures. The NMR analysis indicated that phytates were decomposed while hydroxyapatite (Ca10(PO4)6(OH)2) formed during conversion of PL to PL-derived biochar at a pyrolysis temperature above 300 °C. With increasing pyrolysis temperature to above 500 °C, farringtonite (Mg3(PO4)2) formed. The higher pyrolysis temperature also favored the formation of calcite and provided deeper carbonization (i.e., greater dominance of thermally stable aromatic structures) in the biochar products. Water extractable P decreased significantly from 2.9 g/kg in PL to less than 0.3 g/kg in the PL-derived biochars prepared above 300 °C, indicating the inhibition effect of pyrolysis on the P lability mainly through transformation of labile phosphates in PL into less soluble forms. Overall, this study suggested that different pyrolysis temperatures should be considered for selective conversion of PL to biochar products with distinct agricultural and environmental applications that demand special P release patterns.

Combustion and Co-Combustion characteristics of torrefied poultry litter with lignite

This study investigated the thermal properties and activation energies of raw and torrefied poultry litter samples in the range of 250–300 °C by using thermogravimetric analysis (TGA). Four heating rates, 5 °C/min, 10 °C/min, 20 °C/min, and 30 °C/min were applied during the thermogravimetric analysis. Furthermore, co-combustion of raw and torrefied poultry litter samples with low-rank Turkish lignite was studied and the effect of the blending ratio on thermal reactivity of poultry litter was also investigated.Raw poultry litter has the highest fuel reactivity with the lowest ignition and burnout temperature as compared to both torrefied poultry litter samples and their blends. Torrefaction had a serious effect on the decomposition temperatures of the samples (i.e. the temperature at the maximum derivative thermogravimetric curve, ignition, and burnout temperatures). Decomposition temperatures increased with torrefaction temperature and derivative thermogravimetric curves shifted towards higher temperatures. The combustion performances of all lignite blended samples were also found to be better than lignite. Furthermore, as blends contain more poultry litter which is torrefied at a higher temperature, the fuel properties of blends improve and get closer to lignite.

Use of raw and composted poultry litter in lettuce produced under field conditions: microbiological quality and safety assessment

Lettuce (Lactuca sativa L.) constitutes one the most important vegetable crops worldwide. Poultry litter is being applied as an economically suitable alternative to nitrogen fertilizers in lettuce cultivation. However, little is known about the effects of this practice over this fresh product safety that is usually consumed as a salad. The aim of this work was to determine the microbiological quality and the nitrate content in lettuce produced, under field conditions, using either raw or composted poultry litter, coming from the same original batch. Two experiments were conducted in the experimental field of Facultad de Ciencias Agrarias (UNL, Santa Fe, Argentina) to assess the effects of recently extracted poultry litter that consisted of broiler chicken manure plus rice husk, or composted for 12 mo. The application amounts were: 20 T ha-1 (T1); 40 T ha-1 (T2); and no application of manure (T). Increasing the applied quantities had also increased the health risk associated with lettuce consumption, due to higher nitrate levels and microbial contamination. However, these risks were reduced by composting the material. Even when lettuce contamination with faecal bacteria was mainly due to the use of poultry litter, the number and incidence of pathogens were reduced when properly composted manure was applied instead of raw one. Increasing the dose of poultry litter applied also increases the health risk in lettuce. Though, when the material is properly composted, its fertilizing capacity is maintained, giving proper yields with lower nitrate levels and microbial contamination by enterobacteria.

Reducing of oxytetracycline in poultry manure by using the composting technique

The composted poultry litter was taken for the quantitative analysis of Tetracyclines. In this work the relative antibiotic compound included Oxytetracycline and their traces were encountered in the initial poultry litter and in their respective 30 days interval composted samples and the quantification is done by HPLC optimized by the method followed by Feng et al., 2016. From the quantification method the oxytetracycline compound were detected quantitatively to the tune of 216.67 mg kg-1 as against 33.97 mg kg-1 respectively in the raw poultry litter and composted poultry litter, respectively. It indicated that composting of animal manures is capable of reducing the antibiotic concentration drastically from the raw manures.

Agricultural Practices Influence Salmonella Contamination and Survival in Pre-harvest Tomato Production.

Between 2000 and 2010 the Eastern Shore of Virginia was implicated in four Salmonella outbreaks associated with tomato. Therefore, a multi-year study (2012–2015) was performed to investigate presumptive factors associated with the contamination of Salmonella within tomato fields at Virginia Tech’s Eastern Shore Agricultural Research and Extension Center. Factors including irrigation water sources (pond and well), type of soil amendment: fresh poultry litter (PL), PL ash, and a conventional fertilizer (triple superphosphate – TSP), and production practices: staked with plastic mulch (SP), staked without plastic mulch (SW), and non-staked without plastic mulch (NW), were evaluated by split-plot or complete-block design. All field experiments relied on naturally occurring Salmonella contamination, except one follow up experiment (worst-case scenario) which examined the potential for contamination in tomato fruits when Salmonella was applied through drip irrigation. Samples were collected from pond and well water; PL, PL ash, and TSP; and the rhizosphere, leaves, and fruits of tomato plants. Salmonella was quantified using a most probable number method and contamination ratios were calculated for each treatment. Salmonella serovar was determined by molecular serotyping. Salmonella populations varied significantly by year; however, similar trends were evident each year. Findings showed use of untreated pond water and raw PL amendment increased the likelihood of Salmonella detection in tomato plots. Salmonella Newport and Typhimurium were the most frequently detected serovars in pond water and PL amendment samples, respectively. Interestingly, while these factors increased the likelihood of Salmonella detection in tomato plots (rhizosphere and leaves), all tomato fruits sampled (n = 4800) from these plots were Salmonella negative. Contamination of tomato fruits was extremely low (< 1%) even when tomato plots were artificially inoculated with an attenuated Salmonella Newport strain (104 CFU/mL). Furthermore, Salmonella was not detected in tomato plots irrigated using well water and amended with PL ash or TSP. Production practices also influenced the likelihood of Salmonella detection in tomato plots. Salmonella detection was higher in tomato leaf samples for NW plots, compared to SP and SW plots. This study provides evidence that attention to agricultural inputs and production practices may help reduce the likelihood of Salmonella contamination in tomato fields.

Kinetic modelling of augmenting biomethane yield from poultry litter by mitigating ammonia

ABSTRACTIn this study, the kinetics of biogas production was studied by performing a series of the laboratory experiment with air stripped poultry litter. Four kilograms of Raw Poultry Litter is mixed with water in the ratio 1:3, respectively, and loaded inside the digesters and the samples are compared with Air stripped Poultry Litter for a retention time of 21 days. The modified Gompertz equation suitably construes the cumulative biogas produced as a function of time. From the kinetics of the system, it is inferred that the biogas production potential (A), maximum biogas production rate , and lag phase period (λ) of Raw Poultry litter is 18.77 (l/kg of VS); 1.08 (l/kg of VS/day); 1.5 days, respectively, comparing with Air stripped Poultry Litter of 22.05 (l/kg of VS); 1.30 (l/kg of VS/day); 1 day, respectively. These results show that biogas production can be enhanced efficiently by means of ammonia removal pre-treatment process.

Transformation of Phosphorus in Speciation and Bioavailability During Converting Poultry Litter to Biochar

Converting poultry litter (PL) to biochar and applying the biochar to cropland as a soil amendment may be a best approach for recovering nutrients from solid biowastes while minimizing the nutrient runoff losses from the treated field. To evaluate the potential of PL-derived biochar as a slow-release phosphorus (P) fertilizer, the speciation, mobilitylability, and bioavailability of P in PL and the derived biochars were examined and compared. Raw PL and its derived biochars through 300–600°C slow pyrolysis were analyzed for total P (TP), inorganic P (IP), and organic P (OP) contents. The TP was fractionated into readily, generally, moderately, low, and non-labile pools by sequential extraction with different solutions. The TP was further assessed for bioavailability using batch extraction by water, Olsen, Bray-1, Mehlich-3, and 1 M HCl extractants. The P species in biochars were characterized using solid-state 31P nuclear magnetic resonance (NMR) techniques. The results indicate that during pyrolysis OP in PL was transformed to IP and water-soluble P to low labile forms such as hydroxyapatite and oxyapatite especially during pyrolysis, initially to polyphosphate-P and subsequently to orthophosphate-P at higher temperature. Orthophosphate-P was the predominant form in biochar, with products from higher pyrolysis temperature demonstrating reduced labile P pools yet enlarged low to non-labile fractions. Bray-1 and Mehlich-3 were appropriate extractants for evaluating the immediate to medium-term available and the long-term available P in biochar, respectively. Converting PL to biochar through 450°C pyrolysis significantly reduced the water-soluble proportion and the lability of P but did not compromise the long-term P bioavailability, resulting in a P-enriched, slow release soil amendment that would minimize the P runoff risks following field application. The promising results need to be further validated in soil-biochar-plant systems.

Biochar lowers ammonia emission and improves nitrogen retention in poultry litter composting

The poultry industry produces abundant quantities of nutrient-rich litter, much of which is composted before use as a soil amendment. However, a large proportion of nitrogen (N) in poultry litter is lost via volatilisation during composting, with negative environmental and economic consequences. This study examined the effect of incorporating biochar during composting of poultry litter on ammonia (NH3) volatilisation and N retention. Biochars produced at 550°C from greenwaste (GWB) and poultry litter (PLB) feedstocks were co-composted with a mixture of raw poultry litter and sugarcane straw [carbon (C):N ratio 10:1] in compost bins. Ammonia emissions accounted for 17% of the total N (TN) lost from the control and 12–14% from the biochar-amended compost. The TN emitted as NH3, as a percentage of initial TN, was significantly lower (P<0.05) i.e. by 60% and 55% in the compost amended with GWB and PLB, respectively, relative to the control. The proportion of N retained in the finished compost, as a percentage of initial TN, was 84%, 78% and 67% for the GWB, PLB and nil biochar control, respectively. Lower concentration of dissolved organic C (DOC) together with higher activity of beta-glucosidase and leucine-aminopeptidase were found in the GWB-amended compost (cf. control). It is hypothesized that lower NH3 emission in the GWB-amended compost was caused not just by the higher surface area of this biochar but could also be related to greater incorporation of ammonium (NH4+) in organic compounds during microbial utilisation of DOC. Furthermore, the GWB-amended compost retained more NH4+ at the end of composting than the PLB-amended compost. Results showed that addition of biochar, especially GWB, generated multiple benefits in composting of poultry litter: decrease of NH3 volatilisation, decrease in NH3 toxicity towards microorganisms, and improved N retention, thus enhancing the fertiliser value of the composted litter. It is suggested that the latter benefit is linked to a beneficial modification of the microbial environment.

Applying raw poultry litter leachate for the cultivation of Arthrospira platensis and Chlorella vulgaris

In the present paper, the use of raw poultry litter (PL) as a nutrient source for the cultivation of Arthrospira platensis and Chlorella vulgaris was investigated. PL was added to acid solution (62.5mM H2SO4) for the extraction of nutrients contained in PL. After settling, the supernatant, called PL leachate (PLL) was diluted 25×, 20×, 15×, and 10× and used as a medium for the cultivation of A. platensis and C. vulgaris. A. platensis could not survive in 15× and 10× diluted leachate and while in 20× and 25× dilutions the biomass production was only half of that in a control medium (Zarrouk). The biomass composition had a high carbohydrate content (37–44%), which suggests that A. platensis was stressed due to nutrient limitation. C. vulgaris grew well in PLL-based media and the biomass production was higher than in the control medium (BG-11). Biomass composition of C. vulgaris in PLL-based media had lower protein content and higher carbohydrate and lipid content than in the control medium. The overall process for producing microalgal biomass from PL that we propose includes: (i) acid extraction of nutrients through the generation of PL leachate (PLL), (ii) indoor PL composting and recovery of stripped ammonia and CO2, and (iii) use of recovered ammonia and CO2 along with the PLL for the cultivation of microalgae and cyanobacteria for the production of biomass.

English

Poultry litter constitutes one of the animal wastes that are produced in large quantity. Information on the quantity generated may enhance planning for its utilisation. Quantification of poultry litter (PL) generated and its utilisation is rare in Nigeria. This study was designed to investigate PL management in Lagos, Nigeria and possible utilisation potential. Questionnaires were distributed to poultry farmers in Lagos to evaluate poultry waste generation and management practices. Additionally, PL was also quantified from selected farms. Greenhouse experiments were conducted to evaluate the agronomic effects of raw and composted PL (each applied at 0, 5, 10 t/ha and replicated four times) on the growth and heavy metals uptake of Abelmoschus esculentus (okra). Poultry farms were situated in the residential, non-residential and industrial areas with non-residential areas housing a larger percentage. About 53% of the farms were located near rivers or streams. A few of the poultry farmers treated and utilised PL using chemical and physical methods before disposal. Also, no record of waste utilization was found in 72.3% of the farms. About 87.4% of the farmers quantified the PL generated. About 89.3% of the farmers disposed PL in open dumpsites. Mean poultry litter generated from four farms per bird/day was 0.11 ± 0.001 kg. The HMs contents in plants grown on the poultry treated soils were below the permissible levels in soil. The heavy metals concentrations in the leaves and fruits (which are usually the edible parts of okra plants) for all the treatments fall within WHO/FAO permissible levels. Overall, soil amended with 5 t/ha composted poultry litter performed best in terms of fruit production and reduction in HMs uptake. The use of composted poultry litter as fertiliser at calculated quantity will increase PL management. Key words: Poultry litter management, heavy metals, Lagos, Abelmoschus esculentus.

Improved anaerobic digestion performance and biogas production from poultry litter after lowering its nitrogen content

Poultry litter (PL) was pre-treated in order to reduce its nitrogen content and to increase the C/N ratio. The pre-treatment consisted of a first anaerobiosis phase of about 60days in order to accumulate ammonia nitrogen, followed by an ammonia stripping phase by heating the substrate at 80°C for 24h. The digestion was performed with PL and pre-treated PL (TPL) after ammonia stripping as mono-substrate under four total solids loads, i.e. 5%, 10%, 15% and 20%. The TPL after ammonia stripping displayed lower ammonia (62–73%) and VFA (41–65%) concentrations compared to digesters with raw PL, while bio-methane yield increased about 8–124%. Bio-methane yields in the series with TPL after ammonia stripping were about 193, 196, 215 and 147 LCH4/kgCOD, based on the COD added, for 5%, 10%, 15% and 20% TS load, respectively. The results indicate that lowering nitrogen content using the suggested process improves bio-methane yields significantly.

Phosphorus release behaviors of poultry litter biochar as a soil amendment

Phosphorus (P) may be immobilized and consequently the runoff loss risks be reduced if poultry litter (PL) is converted into biochar prior to land application. Laboratory studies were conducted to examine the water extractability of P in PL biochar and its release kinetics in amended soils. Raw PL and its biochar produced through 400°C pyrolysis were extracted with deionized water under various programs and measured for water extractable P species and contents. The materials were further incubated with a sandy loam at 20gkg−1 soil and intermittently leached with water for 30days. The P release kinetics were determined from the P recovery patterns in the water phase. Pyrolysis elevated the total P content from 13.7gkg−1 in raw PL to 27.1gkg−1 in PL biochar while reduced the water-soluble P level from 2.95gkg−1 in the former to 0.17gkg−1 in the latter. The thermal treatment transformed labile P in raw PL to putatively Mg/Ca phosphate minerals in biochar that were water-unextractable yet proton-releasable. Orthophosphate was the predominant form of water-soluble P in PL biochar, with condensed phosphate (e.g., pyrophosphate) as a minor form and organic phosphate in null. Release of P from PL biochar in both water and neutral soils was at a slower and steadier rate over a longer time period than from raw PL. Nevertheless, release of P from biochar was acid-driven and could be greatly promoted by the media acidity. Land application of PL biochar at soil pH-incorporated rates and frequency will potentially reduce P losses to runoffs and minimize the adverse impact of waste application on aquatic environments.

Pyrolysing poultry litter reduces N2O and CO2 fluxes

Application of poultry litter (PL) to soil can lead to substantial nitrous oxide (N2O) emissions due to the co-application of labile carbon (C) and nitrogen (N). Slow pyrolysis of PL to produce biochar may mitigate N2O emissions from this source, whilst still providing agronomic benefits. In a corn crop on ferrosol with similarly matched available N inputs of ca. 116kgN/ha, PL-biochar plus urea emitted significantly less N2O (1.5kgN2O–N/ha) compared to raw PL at 4.9kgN2O–N/ha. Urea amendment without the PL-biochar emitted 1.2kgN2O–N/ha, and the PL-biochar alone emitted only 0.35kgN2O–N/ha. Both PL and PL-biochar resulted in similar corn yields and total N uptake which was significantly greater than for urea alone. Using stable isotope methodology, the majority (~80%) of N2O emissions were shown to be from non-urea sources. Amendment with raw PL significantly increased C mineralisation and the quantity of permanganate oxidisable organic C. The low molar H/C (0.49) and O/C (0.16) ratios of the PL-biochar suggest its higher stability in soil than raw PL. The PL-biochar also had higher P and K fertiliser value than raw PL. This study suggests that PL-biochar is a valuable soil amendment with the potential to significantly reduce emissions of soil greenhouse gases compared to the raw product. Contrary to other studies, PL-biochar incorporated to 100mm did not reduce N2O emissions from surface applied urea, which suggests that further field evaluation of biochar impacts, and methods of application of both biochar and fertiliser, are needed.

Thermochemical pre- and biological co-treatments to improve hydrolysis and methane production from poultry litter

The biochemical methane potential (BMP) of raw poultry litter waste was assessed in batch assays. Biological co-treatment with Clostridium cellulolyticum, Caldicellulosiruptor saccharolyticum and Clostridium thermocellum as bioaugmentation strains, and thermochemical pre-treatments with lime and sodium hydroxide performed at different temperatures and pressures were applied as strategies to improve the BMP by favouring the hydrolysis of the cellulolytic material in the waste. Anaerobic digestion of the raw waste allowed a specific methane production of 145±14LCH4kg−1VS, with 1% total solids and 0.72gVSinoculumg−1VSwaste. The pre- and co-treatments contributed to a significant increase (up to 74%) in the waste solubilisation when using C. saccharolyticum, but methane production did not improve considerably. Therefore, the conversion of soluble organic matter to methane was the limiting step of the anaerobic digestion process of poultry litter waste.