Doctor of Philosophy / Department of Agronomy / Charles W. Rice / Variable N fertilizer application recommendations would benefit from crediting the N that will be mineralized and available to the crop during the growing season. During the 1994 and 1995 growing season, the spatial and temporal pattern of N mineralization was assessed on two central Kansas corn fields. Net N mineralization was measured in the field using a buried bag and a resin core method. A 60 m sampling grid was established on the field and the N mineralization was measured at each grid point. The field N mineralization measured was then compared to three lab incubation (14 day anaerobic incubation, CO₂ evolved 1 day after rewetting, and N released on autoclaving) measurements to determine if the field N mineralization could be predicted by a laboratory test. Nitrogen mineralization in the field was highest in May and declined during the growing seasons. Patches of high N mineralization appeared and disappeared during the season, areas of high and low mineralization were not found in the same areas month after month. The semivariance of the laboratory incubations tended to be smoother near the origin than the field incubations, indicating that the field incubations were subject to more sources of variability (such as microclimatic variations) than the laboratory incubations. Crop yields were not correlated with N mineralization in these fields. Soil moisture appeared to be more important to crop yields than the N contributed by mineralization. In these fields N mineralization does not need to be included in N fertilization recommendations unless the amount of fertilizer applied is much lower than in this study. Finally, a method to estimate the initial δ¹³ C content of a soil is proposed. This method can be used if a location can be found that has had a continuous C₃, a continuous C₄crop and a C₃/ C₄rotation treatment.

Agricultural intensification to increase food, feed, and fibre production has also resulted in environmental degradation, including poorer soil quality and high emissions of greenhouse gases (GHGs) like nitrous oxide (N2O). Intercropping, an agroecosystem management practice where more than one crop is planted on the same plot of land at the same time, promotes the complementary use of soil nutrients, and may improve soil quality and increase the retention of inorganic nitrogen (N) in the soil, thereby reducing N2O emissions. An experiment was conducted in Balcarce, Argentina to determine the impact of intercropping maize (Zea mays L.) and soybean (Glycine max (L.) Merr.), (either 1:2 or 2:3 rows of maize to soybean) on soil quality and soil N transformations after six cropping seasons. It was found that intercropping significantly improved soil quality over a six year period, as indicated by the soil organic carbon (SOC), soil total nitrogen (TN), soil light fraction organic matter (LF), and soil microbial biomass carbon (SMB-C). However, the soil quality also significantly improved in the sole crops over this time, and in 2012, only SMB-C was significantly (p<0.05) greater in the 2:3 intercrop than in the sole crops. Intercropping resulted in higher rates of gross nitrogen (N) mineralization than the sole crops, and the 2:3 intercrop resulted in higher rates of gross N immobilization than in the other treatments. However, the high rate of gross N mineralization resulted in a low relative NH4+ immobilization in both intercrops, signifying a lower potential for reducing soil NH4+ concentrations than in the sole crop treatments. Net N immobilization occurred in all treatment plots, which was desired at the end of the fallow period to reduce N losses from the soil. The 2:3 intercrop appeared to perform better than the 1:2 intercrop. However, further research needs to be conducted to determine the seasonal variations in N mineralization and immobilization, and to further examine the intercrop spatial arrangements to increase crop residue yield.

The use of blasted rock overburden as a topsoil substitute during surface-mined land reclamation is practiced in areas with thin, unrecoverable topsoil. The long-term productivity of topsoil substitutes has often been difficult to maintain under forage and row crops. The objective of this project was to evaluate the effectiveness of an unamended topsoil substitute as a tree growth medium compared to both topsoil- and organic matteramended minesoils based on the accumulation and mineralization of carbon and nitrogen pools. A factorial experiment was established in 1987; treatments (5 cm of a Jefferson series topsoil, 8 cm of whole-tree woodchips, and an unamended control) were assigned to lysimeters filled with blasted overburden. All lysimeters were planted with a treecompatible ground cover of grasses and legumes and 10 pitch pine x loblolly pine hybrid seedlings (Pinus rigida L. x P. taeda L.). The control treatment was designed based on principles hypothesized as necessary for the success of reclamation forestry; i.e., the selection of a suitable spoil material (slightly acid, low salt concentration), placing that material in an uncompacted (rough-graded) condition, and planting a tree-compatible ground cover of grasses and legumes. It was hypothesized that, under these conditions, C and N accumulation and N supply would be comparable to topsoil- and organic matteramended minesoils. Two years after treatment, net accumulated total organic C in the fine-earth fraction was 4.4, 3.7, and 9.2 g kg⁻¹ for the control, topsoil, and woodchip treatments, respectively; after 8 years, concentrations were 12.7, 16.0, and 18.2 g kg⁻¹. Net accumulated total Kjeldahl N after 8 years was 784, 1132, and 679 kg ha⁻¹! for the control, topsoil, and woodchip treatments, respectively, but amended minesoils were not significantly different from the control. Total Kjeldahl N accumulation rates were 103, 149, and 89 kg N ha⁻¹ yr⁻¹. Aerobic N mineralization potential after 1 year was 31, 63, and 56 mg kg⁻¹ for the control, topsoil, and woodchip treatments and increased to 112, 157, and 118 mg kg⁻¹ after 8 years. The woodchip treatment seemed to confer no additional benefits, relative to N accumulation and cycling, compared to the control. The topsoil treatment increased the amount of N and the N mineralization capacity of the minesoil, but did not affect the N accumulation rate or the N mineralization rate relative to the control. While maximum plant productivity would probably be realized in a topsoil-amended minesoil, pine tree volume between the control and topsoil treatments was not significantly different after 5 years. / Master of Science

<p>The main project Dry preservation of source-separated organic household wastes involves a new technique for treatment of biowaste through drying. Investigations are going on to determine how the dried biowaste best can be used to close the natural circular flow of nutrients. The objective of this degree project is to determine if the dried biowaste can be used as a soil conditioner. By restoring the nutrients in the material to the ground, the natural circular flow is closed. A declaration of contents, including the nutrient levels, C/N ratio, pH and the electrical conductivity of the dried biowaste, was constructed and a germination test was done to make sure that the material did not inhibit sprouting. Further on a method was developed to study the decomposition process, and in particular the nitrogen mineralization of the dried biowaste. This method was then used practically.</p><p>The results of this degree project indicate that the decomposition capacity of the dried biowaste is very good. The germination test showed that the material in a diluted form (up to 50 % dried biowaste) did not inhibit sprouting. The examination of the nitrogen mineralization showed a fast liberalisation of nutrients available to plants, with only a shorter period of nitrogen immobilization. Together these results imply that the dried material could function well as a soil conditioner.</p> / <p>Projektet Torrkonservering av matavfall från hushåll innefattar en helt ny teknik för behandling av bioavfall genom torkning. Undersökningar pågår angående hur det torkade bioavfallet bäst kan användas för att sluta det naturliga kretsloppet. Examensarbetets huvudsyfte var, som ett led i dessa undersökningar, att utreda om det torkade bioavfallet kan användas som ett jordförbättringsmedel. Genom att tillföra bioavfallet till jord så återförs näringen i materialet till marken och kretsloppet sluts. En varudeklaration, med materialets näringshalter, C/N-kvot, pH och elektrisk konduktivitet, togs fram och ett groningstest utfördes för att kontrollera att bioavfallet inte var groningshämmande. Vidare utvecklades en metod för att studera det torkade bioavfallets nedbrytningsegenskaper i form av dess kvävemineralisering. Denna metod användes därefter praktiskt.</p><p>Resultatet av detta examensarbete tyder på att torkat bioavfall har mycket goda nedbrytningsegenskaper. Groningsförsöket visade att materialet i utspädd form (upp till 50 % torkat bioavfall) inte är groningshämmande, och mineraliseringsförsöket visade på en snabb frigörelse av växttillgängligt kväve, och en immobiliseringsperiod på ett par veckor. Tillsammans indikerar dessa resultat att det torkade materialet kan fungera väl som ett jordförbättringsmedel.</p>

The main project Dry preservation of source-separated organic household wastes involves a new technique for treatment of biowaste through drying. Investigations are going on to determine how the dried biowaste best can be used to close the natural circular flow of nutrients. The objective of this degree project is to determine if the dried biowaste can be used as a soil conditioner. By restoring the nutrients in the material to the ground, the natural circular flow is closed. A declaration of contents, including the nutrient levels, C/N ratio, pH and the electrical conductivity of the dried biowaste, was constructed and a germination test was done to make sure that the material did not inhibit sprouting. Further on a method was developed to study the decomposition process, and in particular the nitrogen mineralization of the dried biowaste. This method was then used practically. The results of this degree project indicate that the decomposition capacity of the dried biowaste is very good. The germination test showed that the material in a diluted form (up to 50 % dried biowaste) did not inhibit sprouting. The examination of the nitrogen mineralization showed a fast liberalisation of nutrients available to plants, with only a shorter period of nitrogen immobilization. Together these results imply that the dried material could function well as a soil conditioner. / Projektet Torrkonservering av matavfall från hushåll innefattar en helt ny teknik för behandling av bioavfall genom torkning. Undersökningar pågår angående hur det torkade bioavfallet bäst kan användas för att sluta det naturliga kretsloppet. Examensarbetets huvudsyfte var, som ett led i dessa undersökningar, att utreda om det torkade bioavfallet kan användas som ett jordförbättringsmedel. Genom att tillföra bioavfallet till jord så återförs näringen i materialet till marken och kretsloppet sluts. En varudeklaration, med materialets näringshalter, C/N-kvot, pH och elektrisk konduktivitet, togs fram och ett groningstest utfördes för att kontrollera att bioavfallet inte var groningshämmande. Vidare utvecklades en metod för att studera det torkade bioavfallets nedbrytningsegenskaper i form av dess kvävemineralisering. Denna metod användes därefter praktiskt. Resultatet av detta examensarbete tyder på att torkat bioavfall har mycket goda nedbrytningsegenskaper. Groningsförsöket visade att materialet i utspädd form (upp till 50 % torkat bioavfall) inte är groningshämmande, och mineraliseringsförsöket visade på en snabb frigörelse av växttillgängligt kväve, och en immobiliseringsperiod på ett par veckor. Tillsammans indikerar dessa resultat att det torkade materialet kan fungera väl som ett jordförbättringsmedel.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nitrification inhibitors can reduce the potential for environmental contamination of animal wastes, relatively to nitrate (NO3 -) leaching and nitrous oxide (N2O) emission. However, this strategy has not yet been sufficiently evaluated by research, especially with poultry litter (PL). Therefore, the objective of this study was to evaluate the effect of the product "Agrotain Plus" (AP), containing 81% of dicyandiamide (DCD), on the nitrification inhibition, ammonia (NH3) volatilization and carbon (C) and nitrogen (N) PL mineralization. Two laboratory experiments were conducted, using a Hapludalf soil collected in the 0-10 cm layer. In one experiment, conducted for 54 days, the treatments consisted of PL (4.7 Mg ha-1, dry basis) incorporated in the soil, without and with AP doses (3.5, 7.0 and 14 kg ha-1), and without PL or AP (control). In the other experiment, conducted for 69 days had all these treatments plus two additional treatments of CA on the soil surface, without and with AP (7 kg ha-1). The AP delayed NO3 - production in soil, and this inhibitory effect was more intense at the highest dose of AP (14 kg ha-1). NH3 volatilization occurred only when PL remained on the soil surface and was favored by the addition of AP. The AP addition increased PL C- and Nmineralization by 4 and 28%, respectively. The results of this study indicated that dicyandiamide (DCD), contained in the product Agrotain Plus, reduces the nitrification rate of PL ammonia in soil and could be a strategy to preserve the N of this organic material and reduce potential pollution of the environment. / Inibidores de nitrificação podem reduzir o potencial de contaminação ambiental de dejetos de animais, relativamente à lixiviação de nitrato (NO3 -) e à emissão de óxido nitroso (N2O). Todavia, essa estratégia não tem sido suficientemente avaliada pela pesquisa, especialmente com a cama de aviário (CA). Por isso, o objetivo do presente trabalho foi o de avaliar o efeito do produto Agrotain Plus (AP), o qual contém 81% de dicianodiamida (DCD), sobre a inibição da nitrificação, a volatilização de amônia (NH3) e a mineralização do carbono (C) e do nitrogênio (N) da CA. Foram conduzidos dois experimentos em laboratório, em solo da camada 0-10 cm de um Argissolo Vermelho Distrófico arênico. Num experimento, conduzido durante 54 dias, os tratamentos constaram da incorporação ao solo de CA (4,7 Mg ha-1, massa seca), sem AP e juntamente com as doses de 3,5, 7,0 e 14 kg ha-1 de AP, além de um tratamento sem CA e sem AP (testemunha). No outro experimento, conduzido durante 69 dias, além desses tratamentos havia dois com adição da CA na superfície do solo, com e sem adição de AP (7 kg ha-1). O AP, contendo DCD como inibidor da nitrificação, retardou o aparecimento de NO3 - no solo, sendo que esse efeito inibitório da nitrificação foi mais intenso na maior dose de AP (14 kg ha-1). A volatilização de NH3 ocorreu apenas quando a CA permaneceu na superfície do solo e foi favorecida pela adição de AP. A adição do AP aumentou a mineralização do C e do N da CA em 4 e 28%, respectivamente. Os resultados deste trabalho indicam que a dicianodiamida (DCD), contida no produto Agrotain Plus, reduz a taxa de nitrificação do N amoniacal da cama de aviário no solo e poderá constituir uma estratégia para preservar o N deste material orgânico, além de reduzir o seu potencial poluidor do ambiente.

Broiler litter (BL) is a high value manure available to Kentucky crop producers to utilize as a fertilizer. The rate of BL application, timing of application, and method of application are all important factors to take into account when utilizing BL. A laboratory incubation was conducted to observe nitrogen (N) mineralization rates of BL amended soils over time under different conditions. Different application methods, application rates, watering frequencies, and bedding materials were used to determine their influence on N mineralization. Broiler litter applied on the soil surface, at lower rates, at lower watering frequency resulted in lower mineralization rates than BL that was incorporated, at higher rates and higher watering frequency. The rice hull bedding BL treatments had a significantly higher initial amount of NH4+-N than the wood-based bedding materials. The increased NH4+-N content produced a lower pH due to higher rates of nitrification. The difference in NH4+-N resulted in the rice hull BL treatments containing more inorganic N throughout the incubation. The wood-based BL contained significantly more carbon (C), zinc (Zn), and potassium (K). The results collected will help improve current nutrient recommendations and provide information that will help utilize BL more efficiently and economically.

Biosolids have been used as soil conditioners and fertilizers in agriculture and mine land reclamation, but application of Exceptional Quality (EQ) biosolids to rehabilitate anthropogenic soils for urban agriculture is recent and requires greater study to ensure their appropriate use. The objectives were: 1) to quantify plant available nitrogen (PAN) of new EQ biosolids in a greenhouse bioassay; 2) to quantify PAN of EQ biosolids applied to an urban degraded subsoil via tall fescue N fertilizer equivalency, and compare field results to laboratory tests; 3) to investigate EQ biosolids and inorganic fertilizer effects on urban soil properties, vegetable yields, and potential N and phosphorus (P) loss. Biosolids evaluated were products of thermal hydrolysis plus anaerobic digestion (BLOOM), blending with woody mulch (BM) and sand/sawdust (BSS), composting (LBC), and heat-drying (OCB). Organic N mineralization of new blended biosolids products ranged between 20-25% in the greenhouse bioassay. Products BLOOM, BM, and OCB had the highest organic N mineralization as estimated by the 7-day anaerobic incubation, and this test and soil nitrate-N had the highest correlations with tall fescue N uptake (r=0.49 and r=0.505, respectively). We conducted a two-year field study with four growing seasons (fall 2016-2017 and summer 2017-2018) in an urban disturbed subsoil where EQ biosolids were applied seasonally at agronomic N rates, and yearly at reclamation rates (5x agronomic N). Cabbage yields were greater with reclamation rates (~3.0 kg m-2) and bell pepper yields were greater with BLOOM reclamation rate (~1.0 kg m-2) than with the inorganic fertilizer (1.0 kg m-2 and 0.2 kg m-2, respectively) during second year growing seasons. Soil carbon (C) accumulation (%C remaining in the soil) two years after biosolids additions ranged between 37 to 84%. Soil N availability and mineralization were limited most likely due to lack of residual soil C and N, and high clay content. Nitrogen leaching losses from reclamation rates were not greater than agronomic N rates. Leachate P was below detection during most of the experiment. Despite limiting soil conditions, biosolids amendment at reclamation rates showed greatest potential to increase vegetable yield and improve soil properties after two years of application, while not impairing water quality. / Doctor of Philosophy / Exceptional Quality (EQ) biosolids are by-products of wastewater treatment plants that have been processed to destroy pathogens, reduce attraction by disease-spreading organisms (e.g. flies, mosquitoes, rodents, etc.), and limit heavy metal concentrations. These characteristics make EQ biosolids safe for use by home gardeners for growing food crops. There is limited information on optimal recommended rates at which these products should be applied to urban gardens. The purpose of our research was to determine optimum application rates of EQ biosolids to urban gardens based on their essential plant nutrient (esp., nitrogen and phosphorus) availability. We learned that the EQ biosolids we studied are less concentrated in plant available nitrogen and phosphorus than biosolids applied to conventional agricultural fields. This is because we diluted our biosolids with sawdust, sand, and woody mulch to facilitate their storage, handling, and ease of application. We learned that high EQ biosolids application rates reduce soil compaction and increase essential plant nutrient availability and crop yields for agriculture practiced in urban soils. The high application rates of EQ biosolids accomplished such soil-improving and yield-increasing benefits without impairing local water quality.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22130号 / 農博第2376号 / 新制||農||1073(附属図書館) / 学位論文||R1||N5238(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 德地 直子, 教授 北島 薫, 准教授 舘野 隆之輔 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Climate change resulting from emissions of fossil fuel combustion has sparked considerable interest in renewable energy and fuel production research, particularly energy derived from cellulosic ethanol, which is derived from biomass such as wood and grass. Cellulosic ethanol demonstrates a more promising future as a global energy source than corn-derived ethanol because it does not displace food crops, irrigation is not required, and chemical application rates are much lower than for annual crops, such as corn. Growing cellulosic biomass for energy can help reduce greenhouse gas emissions via carbon (C) sequestration and by reducing demand for fossil fuel production. The objective of this study was to investigate how land use change affects soil properties and selected soil C and nitrogen (N) dynamics among alternative cellulosic biofuel treatments at the Weyerhaeuser Alabama Cellulosic Biofuel Research site in west-central Alabama. Composite soils for characterization, along with forest floor, were collected at year 1 and year 2 after treatment establishment at 0-15cm and 15-30cm depths at six locations along three hillslope-riparian transects in five experimental watershed treatments. Decomposition of loblolly pine needles was assessed in each watershed using an in situ litter bag method. Seasonal in situ net nitrogen mineralization was measured using a sequential core method, and an anaerobic incubation for N mineralization potential of composite soils was performed in the laboratory. Results revealed high variability of soil properties and processes within these watersheds, along with no consistent treatment effects. This study provides baseline data for these watershed treatments for future studies. / Master of Science