Organically certified farms using compost to improve or maintain fertility rarely consider compost carryover and its impact on the determination of economically optimal application rates. Compost carryover is comprised of nutrient and non-nutrient elements. Both affect crop growth, yet carryover is typically described primarily in terms of nitrogen (N)-carryover only. This study tested a new method for estimating compost carryover on organically certified land and expressed carryover in units that capture both the nutrient and non-nutrient components. Compost carryover for five treatment rates was estimated over four years in an organically certified field trial in a corn and squash rotation. Nitrate (NO3-), phosphorus (P), soil organic matter (SOM) were investigated to determine the residual effect of a one-time compost application. Implications for fertility management and farm profitability were considered. The new method successfully modeled carryover, determining that compost had a persistent and positive effect on crop yields, evident even three years after an initial one-time application. No NO3- carryover was observed in any year, suggesting that yield responses were due primarily to non-N carryover. Compositional changes in SOM corresponding to compost input three years earlier suggested that compost was able to influence non-nutritive soil properties many years after incorporation. High value cash-crops are necessary in organic rotations to offset the high input cost of compost use. In organic fertility management, compost is an important and economical source of non-N fertility, which benefits crop yield many years after incorporation. When used with a dedicated N-fixing cover crop in a rotation that includes a high value cash-crop, complete fertility goals could be met in a sustainable manner. (153 pages)

No description available.

Land application of poultry litter has been successfully practiced for centuries to maintain and improve soil fertility, although over application may promote loss of nutrients through runoff or leaching. To decrease the potential for adverse environmental impacts of N and P in groundwater, a new approach developed in this research was to use a composted mixture of poultry litter (PL) and yard waste (YW) as a soil amendment for corn (Zea mays L.) production. Objectives of this research were to evaluate effects of pre-compost C:N substrate ratios for poultry litter-yard waste compost (PYC) on the availability of soil P, to determine the P response of corn plants to inorganic P, PL and PYC application, and to study relationships between P availability and both inorganic P and PYC application. Langmuir isotherms were used in this research to select soils with relatively high P fixation capacities. Phosphorus sorption maximum for soils evaluated were as follows: 304 and 449 micrograms of P per gram for A horizon Coastal Plain soils (Series: Kempsville and Myatt, respectively); 487 micrograms of P per gram for an A horizon Ridge and Valley soil (Series: Frederick); 918 and 603 micrograms of P per gram for A horizon Piedmont soils (Series: Elioak and Vance, respectively); 1099 microgram of P per gram for mine tailings (Series: Emporia located in the Coastal Plain); and 1524 microgram of P per gram for A and upper mixed horizon soil (Series: Starr from Piedmont region). Based on intermediate to high P sorption maxima, soil from the Vance and Starr series and mine tailing from Emporia series were selected for greenhouse research to evaluate P availability of PYC . Treatments applied to the soil in the greenhouse and field studies consisted of various levels of P as Ca(H₂PO₄)₂.H₂O, PL and PYC from 15:1, 20:1, and 25:1 C:N ratio substrates. Each P source increased dry weight of corn plants grown in the greenhouse by alleviation of P deficiency. Phosphorus uptake from PYC and PL application was either equal to or higher than P uptake from an equal level of P application as Ca(H₂PO₄)₂.H₂O. Application of 87.2 kg of P per ha increased corn grain yields in a field experiment on Vance sandy loam from 6340 kg per ha on the control to a range of 10,170 to 11,350 kg ha for PYC digested from the three C:N ratio substrates. The yields on PYC treatments were attributed to a combination of factors including slow mineralization of P with less fixation during the growing season. The low P fixing capacity results from the blockage of H₂PO₄⁻ sorption by competition of negative charge from organic material and from the displacement of H₂PO₄⁻ in soil solution by OH⁻ from application of the alkaline composts. It would be desirable from the standpoint of more PL utilization to prepare composts from low substrate ratio substrates. Hence, in this research composts were prepared from 15:1, 20:1, and 25:1 C:N substrates, which consisted of PL and YW. The composting process was complete after only four months for the PYC from the 20:1 and 25:1 C:N ratio substrates. Yard waste compost without PL may require somewhere between two to three years for complete composting as opposed to four months with PL addition. The composting was incomplete in four months (presence of undigested leaves and NH₃) for the PYC from the 15:1 C:N ratio substrate. The latter compost resembled poultry manure rather than a high quality compost after the 4-month composting period. / Ph. D.

In apple (Malus domestica Borkh.) orchards, rootstock genotype, and soil fertility management practices impact soil fertility, plant associated soil microbial communities, and orchard productivity. Apple growers select rootstocks to confer beneficial traits, including size control, precocity, and pest and disease resistance. Rootstock genotype may also influence microbial communities, resulting in changes that affect tree health and productivity. Many apple growers apply synthetic nitrogen fertilizers to improve fruit yield and quality. In excess of tree requirements, nitrogen fertilizers may reduce crop yield and quality, as well as contribute to water pollution. The addition of carbon-based amendments, such as yardwaste, chicken litter composts, and biochar, may potentially reduce nitrogen and water loss, while improving soil structure and mineral nutrient availability. Orchard and pot-in-pot experiments were designed to study the following objectives: 1) determine the effects of integrated carbon-based fertilizer amendments on tree growth, productivity, and orchard soil fertility, 2) assess the effects of biochar on tree growth, leaf mineral nutrition, soil physiochemistry, and microbial community structure and activity, and 3) understand how rootstocks and fertilizers alter soil microbial communities. Applications of composts, integrated compost-calcium nitrate fertilizers, and biochar increased soil carbon, organic matter, cation exchange capacity and microbial respiration. In the orchard study, nitrogen fertilizer application did not increase tree growth, fruit quality, or leaf nitrogen concentration. Biochar applied at high rates with nitrogen fertigation increased tree growth and leaf nitrogen concentration similar to nitrogen fertigation. In the pot-in-pot compost study, chicken litter compost increased tree growth, and integrated compost-calcium nitrate fertilizer applications increased leaf N concentration. Analysis of the microbial community structure of bulk soil samples from the biochar and compost pot-in-pot experiments determined that the community structure was similar for all treatments during the three-year study. Metagenomic sequencing of the rhizosphere bacterial community indicated that compost applications altered community diversity and evenness, and that compost treatments were more similar to each other than to the calcium nitrate treatment. Data from my dissertation research suggests that compost can be used to increase orchard soil fertility, tree growth, and leaf nutrition, and that compost applications increase soil microbial community diversity and activity. / Ph. D.

Exposure of bare soil for long periods and onsite compaction create soil and water problems in asparagus production. This project aims to develop a cost effective and practical runoff and soil erosion management system. Two field trials (Phase 1 running from April - July 2012 and Phase 2 running from May - November 2013) tested different combinations of shallow soil disturbance (SSD) and mulch (straw and compost) application for soil erosion control. Cranfield University’s soil bin was used to test the effect of different tine configurations on soil disturbance. The results of this research corroborated observations that asparagus production can result in levels of unsustainable soil loss that will contribute to the degradation of the existing soil resource. The field trials demonstrated that a straw mulch applied at 6 t ha- 1 significantly improved key performance indicators (KPIs, i.e. runoff initiation, volume and rate; total soil loss; sediment concentration; total oxides of nitrogen; orthophosphate-P; and sediment-bound P) as compared with the Non-SSD Control. In general, SSD (irrespective of tine configuration) was ineffective at improving key performance indicators as compared with the Non-SSD Control. In the soil bin work, different tine configurations generated varying degrees and extent of SSD, with the modified para-plough giving the greatest soil disturbance for the least draught force. However, the differences in SSD observed in the soil bin had no effect on the KPI’s tested in the Phase 2 field trial. The effective treatments observed in the field trials only yielded cost savings to the farmer/grower when a high level of soil loss occurred. This research highlights the need to develop erosion control measures in asparagus fields, with wider implications to other row crops. However caution is needed, given the observed variation in effectiveness and reliability of in-field mitigation measures, especially during ‘extreme’ rainfall events.

Memoria para optar al título profesional de Ingeniero Agrónomo / Considerando la relevancia de la uva de mesa en el norte del país y las restricciones asociadas a los suelos con bajo contenido de materia orgánica, se hace necesario el uso de enmiendas orgánicas para mejorar las condiciones físicas del suelo, con el propósito de aumentar o mantener los rendimientos en el tiempo. En el presente trabajo se evaluó la acción sinérgica del compost con un cultivo de cobertura, sobre las propiedades físicas del suelo y algunas variables de desarrollo de la vid. El estudio se realizó en Vicuña, Región de Coquimbo, sobre un suelo Typic Haplocambid cultivado con un parrón de uva de mesa variedad Queen Rose. Considerando unidades experimentales de 7 plantas en la hilera en un diseño en bloques al azar, en noviembre de 2014 se realizaron las aplicaciones de compost (5,7 ton ha-1) y en mayo de 2015 se realizó la siembra de haba (500.000 plantas ha- 1). Se generaron así los tratamientos testigo (T0), suelo acondicionado con compost (T1) y suelo acondicionado con compost más cultivo de cobertura (T2). Al cabo de seis meses (septiembre de 2015) se evaluó por horizonte genético la densidad aparente, distribución de tamaño de poros, resistencia mecánica, estabilidad de los micro agregados y conductividad hidráulica, además del rendimiento y crecimiento de raíces. Los manejos generaron una tendencia a incrementar el agua aprovechable del suelo, alcanzando en el rango de 0-60 cm de profundidad, niveles de 61,8; 70,3 y 67,4 mm en los tratamientos T0, T1 y T2, respectivamente. Junto con esto, se mejoró la porosidad gruesa en superficie, especialmente con compost, aunque sin diferencias estadísticas significativas. Por otra parte, la mayor continuidad porosa se generó en el tratamiento de compost con haba (T2), el cual logró los mayores niveles de conductividad hidráulica, la que alcanzó niveles de 2,3; 3,5 y 6,9 cm h-1 en T0, T1 y T2, respectivamente. En cuanto a la resistencia mecánica, en general los valores se encontraron por debajo del valor crítico de 80 N. Finalmente, hubo un aumento en el peso promedio de racimo en T1 de un 5,9% con respecto al testigo, aunque sin lograr diferencias estadísticas significativas, por lo que es necesario continuar estudiando las alternativas de cultivos de cobertura para potenciar el efecto del compost sobre las propiedades físicas del suelo.

by Chu Lee Man. / Bibliography: leaves 176-204 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

An industrial soil collected from a recycling factory was contaminated by DEHP and spilled diesel. The soils were divided into two batches for off-site ex situ bioremediation by SMC. This industrial soil was contaminated with 5.4-6.9 g/kg total petroleum hydrocarbons (TPH), 14.5--19.0 g/kg oil and grease and 95-99 mg/kg DEHP. The removal by 3% SMC amendment applied twice accounted for 56-64%, 31--33% and 51--54% disappearance of the TPH, oil and grease and DEHP contaminants, respectively. Beside chemical analysis, six bacteria and six fungi were inoculated into the sterilized soil samples for ecotoxicity tests. The original soil samples containing residual oil and DEHP contents were found to be more toxic than the SMC-treated soil. Thus SMC simultaneously degrades organic pollutants and reduces toxicity in less than a month. / An underground water sample contaminated with dibutyl phthalate (DBP, 127.5+/-20.7 mu1/1) and DEHP (67.0+/-7.7 mu1/1) was tested. One percent SMC could remove 94.2+/-3.6% and 100% for DBP and DEHP, respectively, within 1 h at room temperature. DBP and DEHP were degraded completely by SMCE except 0.2% SMCE for DBP after 24-h treatment. SMC had higher removal efficiencies than SMCE, because SMC had an integrated system of biosorption and biodegradation to remove DBP and DEHP. The sorption kinetics of DBP and DEHP by SMC could be described by the Freundlich monolayer model. Even after eight cycles of the sorption-desorption of DEHP SMC maintained the 100% removal efficiency. Thus SMC is a good biosorbent for DEHP. / Besides, DEHP-contaminated sediment was collected from Kai Tak Approach Channel, Kowloon. This sediment contained 44.4-128.0 mg/kg DEHP and heavy metals 21.3-23.4 mg/kg Cd, 24.9-43.5 mg/kg Ni, 128.5-198.5 mg/kg Pb, 144.6-329.2 mg/kg Zn and 164.5-230.0 mg/kg Cu, and bore an unpleasant sewer smell. SMC and SMCE as strong oxidizing agents could decrease the S content of sediment significantly as well as calcium nitrate, and consequently lowered the evolution of nuisance gas hydrogen sulfide. With the treatment of the optimized combination of 2.25% SMCE and 0.25% nitrate, the malodor could be removed completely and the contents of H2S and NH3 in the air were decreased significantly. For the degradation of organic pollutants, the target pollutant DEHP showed a sharp decrease in the first week in the time effect experiment after the treatment with the combination of 2.25% SMCE and 0.25% nitrate, while the decrease of DEHP slowed down in the second week. The results may be attributed to the immediate degradation of DEHP by enzymes in SMCE. When raw sediment and nitrate-treated sediment were bioremediated with SMCE, larger fluctuation in DEHP removal was observed with the nitrate-treated sediment. It supports that nitrate and SMCE would act in optimum at a certain combination. The effect on mobilization of sediment heavy metals by SMC or SMCE was also examined. Although some laboratory results suggested reduction of copper and lead, other results using different environmental samples of the sediment did not reproduce the results. Further investigation is needed. / Plasticizers are additives used in the manufacture of plastics, and high residual plasticizer levels are encountered in the environment. Bis(2-ethylhexyl) phthalate (DEHP), being the most common plasticizer, is a suspected human carcinogen and an endocrine disruptor. Therefore, DEHP-contaminated soil, sediment and water samples were collected, and the bioremediation capacities of the spent compost of mushroom Pleurotus pulmonarius (SMC) were determined. / This study reveals the potential in applying SMC of P. pulmonarius in bioremediation of DEHP from the soil, sediment and water environments. More investigation and field studies would be appropriate for developing spent P. pulmonarius compost in environmental cleanup. / Using artificially spiked garden soil with DEHP and ultra-low sulphur diesel, the removal efficiencies of SMC were 41.7+/-9.8% and 36.1+/-8.4% for TP11 and DEHP, respectively. SMCE which contained the water-soluble nutrients, SMC enzymes and micro-organisms had about half removal efficiency of SMC on the same pollutant. The enriched SMC microorganisms also showed biodegradation of DEHP and diesel, so did the filtrate containing enzymes and nutrients of SMC. Thus SMC acted in multiple ways in bioremediation of DEHP: biostimulation and bioaugmentation. Besides, the immobilized lignolytic enzymes of the mushroom P. pulmonarius played a major role in biodegradation. / Gao, Ting. / "October 2009." / Adviser: S.W. Chiu. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 204-237). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Improving housing for dairy cattle is of interest because hoof and udder health, which are associated with the housing environment, are important economic and welfare issues. The objectives were: 1) to assess the influence of housing––conventional cubicle (CCD) vs compost bedded pack (CBP),––and management (grazing vs semi-grazing) on the performance and welfare in dairy cows 2) describe the performance of the CBP under a grazing or semi-grazing system, and 3) to assess viability of CBP housing in a pasture-based system. This study mixes three research approaches, an analysis of existing and secondary data; an experiment, and a case-study. If taken out of context and used in isolation, this mix of methods would lead to ambiguity and confusion. But in the context of the Malawi dairy industry, it is by mixing these methods that we can best inform farmer’s decisions about the type of structures that best serve them individually and the Malawian dairy industry as a whole. Cows were evaluated weekly for udder, hock, and hoof health, under a grazing (cows kept at pasture for 33 to 42% of the day) and semi-grazing system (cows kept at pasture for 16.67% of the day). No difference was observed between grazing and semi-grazing system regarding milk yield, hoof, hock, and udder health. Sub-clinical high SCC and SCC were 22% and 48% lower in the CBP barn than in the CCD barn. Cows in the CBP produced 1.2 kg per cow/day more milk than cows in CCD. No difference in CBP performance was observed under a grazing or semi-grazing system. Partial budget analysis showed that CBP was viable with net returns of $881. The benefits of the CBP over CCD are $ 1425 per year, but it would take an investment of $5368. The farmer would be expected to pay back the investment in 3.77 years.

Organic wheat grown under dryland conditions encounters challenges such as limited nutrients and water. Maintaining organic wheat production requires solutions to these problems in order to retain economic sustainability for the farmers. Research on biochar and compost have been conducted globally. Despite well known benefits of compost on soil and crop production, few organic farmers apply compost to their fields. Research on biochar is still new. Biochar is charcoal created from pyrolyzing agricultural material under conditions of low oxygen and high heat. Many studies claim that biochar is a valuable soil amendment for improving organic production and reducing environmental pollution (such as greenhouse gas emission, water pollution, or nutrient leaching). It may hold more moisture in the soil and retain nutrients. We conducted a study on the interactions between biochar and compost in organic winter wheat production and soil quality under dryland conditions. We analyzed the response to biochar and compost, and investigated individual and combined effects on wheat yield, wheat quality, and soil quality. This study revealed that compost had significant impacts on increasing wheat yield and had slight impacts on soil quality while biochar had none to slight impacts on soil and wheat production. We validated the usefulness of compost for organic wheat production in dryland condition, but found no real benefit for biochar in this first year.