Anaerobic digestion (AD) is a sustainable waste management technology that primarily generates two products: biogas and digestate. The technology relies on the microorganisms' activity, which depends on several operational factors, such as pH, temperature, solid contents, and ammonia levels. Ammonia is an inorganic form of nitrogen resulting from the biodegradation of organic nitrogen. It is considered one of the major concerns for AD operations due to its inhibitory effects on some microorganisms, particularly methanogens. A common feedstock characterized by high nitrogen content is poultry manure (PM). PM is often avoided in anaerobic digesters due to the anticipated inhibition resulting from its high ammonia levels. However, since poultry manure is one of the most widely available organic wastes, researchers have extensively investigated ways to include PM as a primary feedstock for AD. One possible way to treat high ammonia levels in digestate is ammonia stripping, the physio-chemical separation of ammonia from a solution by introducing a stripping (carrier) gas. There are a few approaches to performing ammonia stripping in AD applications; the most commonly discussed in the literature are pre-hydrolysis and side-stream ammonia stripping. Pre-hydrolysis ammonia stripping is performed on raw feedstock after increasing pH and temperature and is usually not restricted in selecting the gas carrier. On the other hand, side-stream ammonia stripping is when a portion of the digester's working volume is filtered, and the filtrate is sent to a unit where pH and temperature are increased. The carrier gas in these systems is often limited to anaerobic gases such as biogas or steam. The third and most novel approach is post-hydrolysis ammonia stripping, conducted at an intermediate stage between hydrolysis and methanogenesis in a two-stage AD process. This configuration would address the shortcomings of the other two systems. However, there is minimal information on the feasibility and potential of this approach in the literature. This study aims to comprehensively investigate the post-hydrolysis ammonia stripping approach through the following four phases: Phase I) Proof of Concept; Phase II) Optimization; Phase III) Assessment of Alternative Carrier Gases; and Phase IV: Comparison of Different Ammonia Stripping Configurations. Phase I provided the proof of concept under the batch mode and compared the performance of post-hydrolysis ammonia stripping with two-stage AD and co-digestion to improve poultry manure's methane potential as the primary substrate. It was observed that ammonia stripping successfully improved methane potential by up to 150%, whereas improvements due to two-stage AD and co-digestion were limited to 41 and 9%, respectively. Phase II provided more insight into optimizing the ammonia stripping process. Different stripping conditions were tested (pH 7.8 (unadjusted), 9 and 10, temperature 25 (unadjusted), 40 and 55 °C, and flow rate 300 L/L/hour). The results showed that higher pH and temperature lead to higher removal efficiency. However, it was concluded that optimal conditions ultimately depend on the initial and target ammonia levels. Moreover, Analysis of Variance showed that pH and temperature were significant factors affecting the ammonia removal efficiency. In addition, it was observed that higher stripping temperatures (55 °C) enhanced the digestibility of PM and increased its methane potential more than stripping at 40 °C. It was concluded that the optimum stripping conditions were pH 9.5, temperature 40 or 55 °C, and flowrate of 100 L/L/hour to collectively increase ammonia removal while reducing the associated costs and material handling. In Phase III, renewable natural gas (RNG) was evaluated as a stripping medium in batch testing as a potential replacement for biogas and air. Ammonia stripping with RNG yielded promising results comparable to the application of air in terms of ammonia removal and enhancing biogas production from PM (60 and 69% ammonia removal for RNG and air, respectively). In addition, a metagenomic shotgun analysis showed that most biogas production was conducted through hydrogenotrophic methanogens instead of acetoclastic methanogens, which are more susceptible to high ammonia levels. Phase IV assessed the semi-continuous flow two-stage operation of mesophilic AD reactors coupled with different ammonia stripping configurations. Post-hydrolysis ammonia stripping successfully achieved a stable operation of PM mono-digestion at ammonia levels of 1700 and 2400 mg NH₃-N/L in the cases of stripping with air and RNG, respectively. In addition, post-hydrolysis ammonia stripping in semi-continuous flow mode may have promoted acetoclastic methanogens growth since volatile fatty acid concentrations were reduced in the digesters. Phase IV also proved that the performance of post-hydrolysis ammonia stripping is superior over pre-hydrolysis and side-stream ammonia stripping. In the semi-continuous flow reactors, post-hydrolysis ammonia stripping with air achieved on average 831 L biogas/ kg VS at an organic loading rate (OLR) of 2.6 g VS/L/day, whereas side-stream ammonia stripping resulted in average of 700 L biogas/ kg VS at OLR of 1.8 g VS/L/day and higher ammonia stripping requirements. Having said that, the base scenario (no ammonia stripping) was inhibited, indicating that both ammonia stripping configurations were considered successful in alleviating inhibitory effects of ammonia from poultry manure. Phase IV results also proved that air stripping repeatedly outperformed RNG as stripping mediums by having higher ammonia removal efficiencies resulting in higher methane production. However, stripping with RNG is believed to have more practical advantages than air due to avoiding the risk of oxygen infiltration into the reactor. Moreover, renewable natural gas has proven to be an efficient stripping medium that is available on-site. The final stage of Phase IV tested pre-hydrolysis ammonia stripping using air in batch mode and compared it with post-hydrolysis ammonia stripping. Pre-hydrolysis ammonia stripping provided little to no improvement to the methane potential of PM in batch mode and therefore was excluded from the semi-continuous flow experiment. The four phases of this study demonstrated the flexibility and the superiority of post-hydrolysis ammonia stripping over the other pre-hydrolysis and side-stream ammonia stripping. In addition, post-hydrolysis ammonia stripping was proven efficient and feasible for ammonia removal and enabling the mono- or co-digestion of poultry manure. The study also showed that using RNG instead of biogas can significantly reduce the operational costs of the treatment.

Phosphorus (P) released in overland flow is related to P form, soil solution P concentration and the release rate of P from soil. Models relating soil test P (STP) to water soluble P (WSP) and the degree of P saturation (DPS) to STP are used in Virginia to estimate P loss potential. Typically the reservoir of biologically available P in eastern soils has been attributed to P sorbed onto surface sites of non-crystalline aluminum (Al) and iron (Fe) oxides, extractable in ammonium oxalate. More recently, soils with a long-term history of manure application have exhibited properties that indicate calcium (Ca) may also be limiting P, especially in soils impacted by poultry manure. Accurate estimation of P loss potential is critical for justification of long-term management approaches. To evaluate the accuracy of model estimation of P loss potential and P source, we evaluated the (i) soil chemical properties, (ii) soil solution equilibria, (iii) inorganic speciation, and (iv) P desorption capacity of soils impacted over a long period of time by poultry litter (broiler and layer), dairy manure and commercial fertilizer applications. Soil chemical properties were measured with various extractions, while soil solution was measured in samples equilibrated at field capacity. Inorganic material was analyzed using scanning electron microscopy with electron dispersive capacities. Phosphorus desorption capacity was determined by calculating the rate of P release into a 0.01 M NaCl batch reactor. Out of the said analysis, we found that Al and Ca were the primary soil chemical elements limiting soil test P extractability and release. Soils with a high P sorbing capacity (PSC), that were not yet saturated, retained the most total soil P over a 60 hr. batch release experiment. Phase diagrams show that all soils were supersaturated with respect to common Al-, and Fe â P minerals. Saturation indices calculated with Visual Minteq were correlated with the degree of P saturation, and suggested that as the DPS increased, formation of less soluble Ca -P minerals occurs. The soils found to be supersaturated with respect to tri-calcium phosphate (TCP) and octa-calcium (OCP) had the highest P release rate coefficients for both the first (k1) and second (k2) phases of release. Scanning electron microscopy with electron dispersive analysis (SEM-EDS) found that for some manure impacted soils, Al formed associations with P that are stable over a large soil to solution ratio. Additionally, it appears that as non-crystalline Al becomes saturated with P, Ca-P forms may act as an additional reservoir of P in soils with a long-term history of poultry manure application. / Master of Science

MSCAGR (Soil Science) / Department of Soil Science / Poultry manure (PM) is an inexpensive source of fertilizer but it decomposes quickly and releases carbon and greenhouse gases. Biochar (BC) could be an alternative source of carbon to improve soil quality and reduce greenhouse gas emission. This study investigated the effect of co-application of BC and PM on selected soil physical and chemical properties and performance of maize. A field experiment was conducted at the University of Venda experimental farm during 2015/2016 and 2016/2017 seasons. The experiment was a 4 x 3 factorial arrangement consisting of four rates of BC (0, 5, 10 and 20 t ha-1) and three rates of PM (0, 2, and 4 t ha-1) in a RCBD arrangement replicated three times. Maize was planted in both seasons. After harvest, soil bulk density was determined at four soil depths (0-5, 5-10, 10-15, and 15-20 cm), while aggregate stability and selected soil chemical properties were determined at two soil depths (0-15 cm and 15-30 cm). Data were subjected to ANOVA using Genstat 17th edition. The least significant difference was used to compare the treatment means at P < 0.05. Soil aggregate stability, organic carbon, Ca2+, Mg2+, K+, maize dry matter and maize grain yield increased with increasing rates of BC and PM application at 0 - 15 cm depth in both seasons. The combination of BC at 20 t ha-1 and PM at 4 t ha-1 significantly (P < 0.05) decreased soil bulk density at 5 - 10 cm depth but increased soil available P and total N at the two depths in both seasons. The results of this study suggested that BC and PM improved soil ability to retain and supply nutrients through improved soil aggregate stability and reduced bulk density thereby improving maize dry matter and grain yield. Combining BC with PM proved to enhance the ability of soil to function by improving selected soil physical and chemical properties thereby improving maize dry matter and grain yield. / NRF

No description available.

Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-03-15T15:04:04Z No. of bitstreams: 2 arquivototal.pdf: 509626 bytes, checksum: 30e4f0c026fa899a21a33f324f18a271 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-03-15T15:04:04Z (GMT). No. of bitstreams: 2 arquivototal.pdf: 509626 bytes, checksum: 30e4f0c026fa899a21a33f324f18a271 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2010-12-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The aim of this study was to evaluate the behavior of peanut (Arachis hypogaea L.) variety BR-1 under different periods of application of organic sources. The experiment was conducted in a greenhouse without temperature control, at the headquarters of EMBRAPA /CNPA, Campina Grande, from October 2009 to March 2010. The treatments were distributed in 4 x 3 factorial arrangement, consisting of four periods of manure application (0, 15, 30 and 45 days before sowing) and three organic sources (manure cattle, goat and poultry) with four replications in completely randomized design. Peanuts have a significant effect on age assessment in main stem length, leaf area and number of branches, was also significant in interaction between age assessment with organic sources applied to the last variable. Regarding of the peg not reach the ground, number of pods produced and root dry matter were influenced significantly by the organic sources applied, while the number of normal pods and shoot dry matter showed a significant effect for treatments, both in times of application and organic sources. The use of poultry manure as organic source provided higher biomass of peanut. The peanut has benefited from fertilization with poultry manure to produce more normal pods and, consequently, increased production of pods. The peanut production was negatively influenced by the use of poultry manure, goat manure and cattle manure before sowing. / O objetivo do presente estudo foi avaliar o comportamento do amendoim (Arachis hypogaea L.) var. BR-1 quando submetida a diferentes épocas de aplicação de fontes orgânicas. O experimento foi conduzido em casa de vegetação, sem controle de temperatura, nas dependências da EMBRAPA/CNPA, em Campina Grande, no período de outubro 2009 a março de 2010. Os tratamentos foram distribuídos em arranjo fatorial 4 x 3, constituídos de quatro épocas de aplicação de esterco ( 0, 15, 30 e 45 dias antes da semeadura) e três fontes orgânicas (estercos bovino, caprino e de galinha) com quatro repetições, em delineamento inteiramento casualizado. O amendoim mostrou efeito significativo sob idade de avaliação em comprimento da haste principal, a área foliar e número de ramos, também foi significativo na interação entre idade de avaliação com fontes orgânicas aplicadas para o ultimo variável. No que tange ginóforos que não atingiram o solo, número de vagens produzidas e a matéria seca de raiz, foram influenciadas significativamente pelas fontes orgânicas aplicadas, enquanto o número de vagens normais e matéria seca da parte aérea mostraram efeito significativo aos tratamentos, tanto nas épocas de aplicação como fontes orgânicas. A utilização de esterco de galinha como fonte orgânica proporcionou plantas de amendoim com maior acúmulo de biomassa. A cultura do amendoim beneficiou-se da adubação com esterco de galinha para produzir mais vagens normais e, consequentemente, maior produção de vagens. A produção do amendoim foi influenciada negativamente pela utilização dos estercos de galinha, caprino e bovino, antes da semeadura.

Measures aimed at mitigating environmental impacts, especially the anthropic ones, are being progressively studied. Increasing greenhouse gases (GHG) emissions are among the biggest environmental problems in the world, with agriculture one of the major contributors to this impact. Water eutrophication from land misuse and agricultural systems also fits into such a scenario of concern. Biochar, the product of the pyrolysis of organic materials, appears as a recover of a list of environmental problems, among them the mitigation of GHG and the recovery of eutrophic or wastewater. In this sense, biochars of sugarcane straw (BCS) and poultry manure (BPM) were used in GHG emission tests in soils with contrasting textures. To do so, two pyrolysis temperatures (350 and 650 °C), three doses (12.5, 25 and 50 Mg ha-1), two texture classes (sandy and clayey) and two pH values (original pH and pH 5.5) were used. These same biochars were submitted to doping processes pre-pyrolysis with Mg2+ and post-pyrolysis with Al3+ for the adsorption of phosphorus (P). Desorption and adsorption experiments in competition with other anions by the exchange sites were done. The potential GHG mitigation of both biochars has been proven in the gas emission tests. The increase of the pyrolysis temperature (350 to 650 °C) further increases the gas mitigation, and the acidification of the original pH of the biochar causes a similar effect. The benefits of pyrolyzing such organic materials are best seen in sandy soil, with the production of biochar from these residues being an environmentally safe way of depositing these materials, at least with regard to the emission of GHG. Both biochars do not have P adsorption capacity without passing through chemical modification, and the doping process, with Mg or Al, granted this ability. The pre-doping process with Mg2+ generated a P maximum adsorption capacity (PMAC) of 250.8; 163.6; 17.7; 17.57 mg g-1 for the pyrolyzed BPM at 350 and 650 °C and for the BCS also pyrolysed at 350 and 650 °C, respectively. The post-doping process with Al3+ generated a PMAC of 701.6 and 758.9 mg g-1 for BPM and BCS, both of which were pyrolysed at 350 °C, respectively. The superior PMAC of the Al doped biochars was attributed to the fact that the cation that makes the bridge (Al3+) is trivalent, with high affinity for P. The high adsorption of Al by the biochars corroborates with such a statement. Both biochars, produced by the two doping processes, had a desorption of P around 80 % of the adsorbed value, allowing the inference that these products have the capacity to be used in nutrient reuse, mitigating another environmental problem: the use of the finite reserves of P. With the positive results coming from the pyrolysis of the materials in this thesis, we certify the biochar potential as a GHG mitigator, recovery for waters and a potential slow release fertilizer in P reuse. / Medidas que visam a mitigação de impactos ambientais, especialmente os antrópicos, estão sendo cada vez mais estudadas. A crescente emissão de gases de efeito estufa (GEE) está entre os maiores problemas mundiais, sendo a agricultura um dos grandes contribuintes para este impacto. A eutrofização de águas, ocasionada pelo mau uso do solo e dos sistemas agrícolas, também se encaixa em tal cenário de preocupação. O biocarvão, produto da pirólise de materiais orgânicos, aparece como recuperador de uma lista de problemas ambientais, dentre eles a mitigação de GEE e a recuperação de águas eutrofizadas ou residuárias. Neste sentido, biocarvões de palha de cana-de-açúcar (BPC) e de dejeto de galinha (BDG), foram utilizados em ensaios de emissão de GEE em solos com texturas contrastantes. Para tal, duas temperaturas de pirólise (350 e 650 °C), três doses (12,5; 25 e 50 Mg ha-1), duas classes texturais (arenoso e argiloso) e dois pHs (pH original e pH 5.5), foram utilizados. Estes mesmos biocarvões foram submetidos a processos de dopagem pré-pirólise com Mg2+ e pós-pirólise com Al3+ para a adsorção de fósforo (P). Ensaios de dessorção e de adsorção em competição com outros ânions pelo sítio de troca foram feitos. O potencial mitigador de GEE de ambos os biocarvões foi comprovado nos ensaios de emissão de gases. O aumento da temperatura de pirólise (350 para 650 °C) eleva ainda mais a mitigação dos gases, sendo que a acidificação do pH original do biocarvão causa efeito semelhante. Os benefício de se pirolisar tais materiais orgânicos são melhores vistos no solo arenoso, sendo a produção de biocarvão a partir destes resíduos uma forma ambientalmente segura de deposição destes materiais, ao menos no que se diz respeito a emissão de GEE. Ambos os biocarvões não possuem capacidade de adsorção de P sem passar por modificação química, sendo que o processo de dopagem, seja ele com Mg ou Al, concedeu tal habilidade. O processo de pré-dopagem com Mg2+ gerou uma capacidade máxima de adsorção de P (CMAP) de 250,8; 163,6; 17,7; 17,6 mg g-1 para o BDG pirolisado a 350 e 650 °C e para o BPC também pirolisado a 350 e 650 °C, respectivamente. O processo de dopagem por pós-pirólise com Al3+ gerou uma CMAP de 701,6 e 758,9 mg g-1 para o BDG e BPC, ambos pirolisados a 350 °C, respectivamente. A superior CMAP dos biocarvões dopados com Al foi atribuída ao fato de o cátion que faz a ponte (Al3+) ser trivalente, com elevada afinidade pelo P. A elevada adsorção de Al pelos biocarvões corrobora com tal afirmação. Ambos os biocarvões, produzidos pelos dois processos de dopagem, tiveram uma dessorção de P em torno de 80 % do valor adsorvido, permitindo a inferência de que estes produtos possuem a capacidade de serem utilizados no reuso de nutrientes, mitigando outro problema ambiental: o uso das reservas finitas de P. Com os resultados positivos advindos da pirolisação dos materiais nesta tese, constatamos o potencial do biocarvão como mitigador de GEE e recuperador de águas.

Measures aimed at mitigating environmental impacts, especially the anthropic ones, are being progressively studied. Increasing greenhouse gases (GHG) emissions are among the biggest environmental problems in the world, with agriculture one of the major contributors to this impact. Water eutrophication from land misuse and agricultural systems also fits into such a scenario of concern. Biochar, the product of the pyrolysis of organic materials, appears as a recover of a list of environmental problems, among them the mitigation of GHG and the recovery of eutrophic or wastewater. In this sense, biochars of sugarcane straw (BCS) and poultry manure (BPM) were used in GHG emission tests in soils with contrasting textures. To do so, two pyrolysis temperatures (350 and 650 °C), three doses (12.5, 25 and 50 Mg ha-1), two texture classes (sandy and clayey) and two pH values (original pH and pH 5.5) were used. These same biochars were submitted to doping processes pre-pyrolysis with Mg2+ and post-pyrolysis with Al3+ for the adsorption of phosphorus (P). Desorption and adsorption experiments in competition with other anions by the exchange sites were done. The potential GHG mitigation of both biochars has been proven in the gas emission tests. The increase of the pyrolysis temperature (350 to 650 °C) further increases the gas mitigation, and the acidification of the original pH of the biochar causes a similar effect. The benefits of pyrolyzing such organic materials are best seen in sandy soil, with the production of biochar from these residues being an environmentally safe way of depositing these materials, at least with regard to the emission of GHG. Both biochars do not have P adsorption capacity without passing through chemical modification, and the doping process, with Mg or Al, granted this ability. The pre-doping process with Mg2+ generated a P maximum adsorption capacity (PMAC) of 250.8; 163.6; 17.7; 17.57 mg g-1 for the pyrolyzed BPM at 350 and 650 °C and for the BCS also pyrolysed at 350 and 650 °C, respectively. The post-doping process with Al3+ generated a PMAC of 701.6 and 758.9 mg g-1 for BPM and BCS, both of which were pyrolysed at 350 °C, respectively. The superior PMAC of the Al doped biochars was attributed to the fact that the cation that makes the bridge (Al3+) is trivalent, with high affinity for P. The high adsorption of Al by the biochars corroborates with such a statement. Both biochars, produced by the two doping processes, had a desorption of P around 80 % of the adsorbed value, allowing the inference that these products have the capacity to be used in nutrient reuse, mitigating another environmental problem: the use of the finite reserves of P. With the positive results coming from the pyrolysis of the materials in this thesis, we certify the biochar potential as a GHG mitigator, recovery for waters and a potential slow release fertilizer in P reuse. / Medidas que visam a mitigação de impactos ambientais, especialmente os antrópicos, estão sendo cada vez mais estudadas. A crescente emissão de gases de efeito estufa (GEE) está entre os maiores problemas mundiais, sendo a agricultura um dos grandes contribuintes para este impacto. A eutrofização de águas, ocasionada pelo mau uso do solo e dos sistemas agrícolas, também se encaixa em tal cenário de preocupação. O biocarvão, produto da pirólise de materiais orgânicos, aparece como recuperador de uma lista de problemas ambientais, dentre eles a mitigação de GEE e a recuperação de águas eutrofizadas ou residuárias. Neste sentido, biocarvões de palha de cana-de-açúcar (BPC) e de dejeto de galinha (BDG), foram utilizados em ensaios de emissão de GEE em solos com texturas contrastantes. Para tal, duas temperaturas de pirólise (350 e 650 °C), três doses (12,5; 25 e 50 Mg ha-1), duas classes texturais (arenoso e argiloso) e dois pHs (pH original e pH 5.5), foram utilizados. Estes mesmos biocarvões foram submetidos a processos de dopagem pré-pirólise com Mg2+ e pós-pirólise com Al3+ para a adsorção de fósforo (P). Ensaios de dessorção e de adsorção em competição com outros ânions pelo sítio de troca foram feitos. O potencial mitigador de GEE de ambos os biocarvões foi comprovado nos ensaios de emissão de gases. O aumento da temperatura de pirólise (350 para 650 °C) eleva ainda mais a mitigação dos gases, sendo que a acidificação do pH original do biocarvão causa efeito semelhante. Os benefício de se pirolisar tais materiais orgânicos são melhores vistos no solo arenoso, sendo a produção de biocarvão a partir destes resíduos uma forma ambientalmente segura de deposição destes materiais, ao menos no que se diz respeito a emissão de GEE. Ambos os biocarvões não possuem capacidade de adsorção de P sem passar por modificação química, sendo que o processo de dopagem, seja ele com Mg ou Al, concedeu tal habilidade. O processo de pré-dopagem com Mg2+ gerou uma capacidade máxima de adsorção de P (CMAP) de 250,8; 163,6; 17,7; 17,6 mg g-1 para o BDG pirolisado a 350 e 650 °C e para o BPC também pirolisado a 350 e 650 °C, respectivamente. O processo de dopagem por pós-pirólise com Al3+ gerou uma CMAP de 701,6 e 758,9 mg g-1 para o BDG e BPC, ambos pirolisados a 350 °C, respectivamente. A superior CMAP dos biocarvões dopados com Al foi atribuída ao fato de o cátion que faz a ponte (Al3+) ser trivalente, com elevada afinidade pelo P. A elevada adsorção de Al pelos biocarvões corrobora com tal afirmação. Ambos os biocarvões, produzidos pelos dois processos de dopagem, tiveram uma dessorção de P em torno de 80 % do valor adsorvido, permitindo a inferência de que estes produtos possuem a capacidade de serem utilizados no reuso de nutrientes, mitigando outro problema ambiental: o uso das reservas finitas de P. Com os resultados positivos advindos da pirolisação dos materiais nesta tese, constatamos o potencial do biocarvão como mitigador de GEE e recuperador de águas.

Many producers in North America are finding it profitable to make the transition from conventional farming to organic agriculture. Organic fertilisers may affect crop production and soil quality differently than inorganic fertilisers. The objectives of this study conducted in Ste.-Anne-de-Bellevue. Quebec were to examine crop yield, grain quality, soil fertility and microbial community parameters in wheat and corn agroecosystems receiving poultry manure or inorganic fertiliser. Wheat grain yield declined and corn grain yield did not increase with higher N rates, suggesting that increased N supply did not encourage grain production. Soil analyses demonstrated high inherent soil fertility at the study site, and fertilisation led to an environmentally undesirable increase in residual soil NO3 concentrations. Microbial biomass and respiration in corn agroecosystems were greater with poultry manure amendments than inorganic fertiliser, but not in wheat agroecosystems due to significant variation among field replicates. Phospholipid fatty acid analysis revealed significant differences between wheat and corn soil microbial community composition, but differences due to fertilisation were less evident. Further work is needed to uncover the relationships among N fertilisation, crop nutrition and soil microbiology in organic agroecosystems.

No description available.

Two experiments were conducted with caged layer waste. In the first experiment fresh waste was treated with: no additive, 2% formaldehyde, 3% sodium metabisulfite, 1% formaldehyde and 2% propionic acid, 3% formic and 2% propionic acids and stored in polyethylene lined 208 liter metal drums. In experiment II waste treated with 2% formaldehyde, 1 % formaldehyde and 2% prop ionic, 3 % formic and 2% propionic (w/w), stored for at least 42 d, used in a metabolism trial as N supplements to a basal diet fed to sheep. The formaldehyde, formaldehyde/propionic and formic/propionic treatments eliminated the bacterial decomposition of the waste and no undesirable fermentation was observed on the stored material. Waste treated with no additive or sodium metabisulfite underwent putrefaction. Nitrogen supplementation of a basal diet with treated caged layer wastes improved apparent digestibility of crude protein and N retention in sheep fed these diets. Supplementation of a basal diet with chemically treated caged layer waste improves the nutritional value of the diet which suggests that caged layer waste is efficiently utilized as a N source by ruminants when used as a protein supplement. / Master of Science