Using parcel level and sub-parcel level data, we analyze Mississippi cropland sales from 2015-2017 and consider how cropland values are affected by their respective characteristics. Such a study has not been conducted in the state of Mississippi. The dataset used is sourced from a private bank in Mississippi and contains information on the unique attributes and amenities of each land parcel sold. Information garnered from the dataset also allows for analysis of the public SSURGO soil characteristics of each land parcel. A hedonic model and spatial error model is used to analyze the impact that the attributes and amenities of each land parcel have on their respective value. It is concluded that physical improvements, soil characteristics, and regional characteristics have a significant impact on the value of cropland.

Carbon dioxide is taken up by crops during production and released back to the atmosphere at different geographical locations through respiration of consumed crop commodities. In this study, spatially distributed county-level US cropland net primary productivity, harvested biomass, changes in soil carbon, and human and livestock consumption data were integrated into the prior terrestrial biosphere flux generated by the Boreal Ecosystem Productivity Simulator (BEPS). A global time-dependent Bayesian synthesis inversion with a nested focus on North America was carried out based on CO2 observations at 210 stations. Overall, the inverted annual North American CO2 sink weakened by 6.5% over the period from 2002 to 2007 compared to simulations disregarding US crop statistical data. The US Midwest is found to be the major sink of 0.36±0.13 PgC yr-1 whereas the large sink in the US Southeast forests weakened to 0.16±0.12 PgC yr-1 partly due to local CO2 sources from crop consumption.

Carbon dioxide is taken up by crops during production and released back to the atmosphere at different geographical locations through respiration of consumed crop commodities. In this study, spatially distributed county-level US cropland net primary productivity, harvested biomass, changes in soil carbon, and human and livestock consumption data were integrated into the prior terrestrial biosphere flux generated by the Boreal Ecosystem Productivity Simulator (BEPS). A global time-dependent Bayesian synthesis inversion with a nested focus on North America was carried out based on CO2 observations at 210 stations. Overall, the inverted annual North American CO2 sink weakened by 6.5% over the period from 2002 to 2007 compared to simulations disregarding US crop statistical data. The US Midwest is found to be the major sink of 0.36±0.13 PgC yr-1 whereas the large sink in the US Southeast forests weakened to 0.16±0.12 PgC yr-1 partly due to local CO2 sources from crop consumption.

Five long-run average cost curves were derived from questionnaire and interview data by connecting points corresponding to the per unit production costs and levels of beef output for four cattle ranch sizes (50, 150, 300, and 500 head of breeding cows). Analysis of the long-run average cost curves in combination with the 1968 weighted Utah beef price revealed that all four ranch sizes studied are capable of meeting cash costs. If the goal of the ranch operator is to meet both cash costs and depreciation, a cattle ranch supporting 105 breeding cows is the minimum size necessary. If provision is made to cover cash costs and depreciation in addition to receiving a fair return for operator and family labor, the ranch must support at least 360 breeding cows. None of the four ranch sizes studied were capable of meeting all production costs including five per cent interest on investment. The minimum ranch size necessary to cover all production costs including 1 . 4 per cent interest on investment is 500 head of breeding cows. Farmer questionnaires and the machine capacity technique provided data from which five long-run average cost curves were derived by connecting points representing average production costs and levels of wheat output for four sizes of wheat farms (500, 1000, 2000, and 3000 acres). The long-run average cost curves were analyzed in combination with the 1968 Utah wheat price. All four wheat farm sizes studied are capable of meeting cash costs. In order to cover both cash costs and depreciation a wheat farm of at least 940 acres is required. The minimum wheat farm size necessary to meet cash costs and depreciation as well as provide a fair return to operator and family labor is 2430 acres. None of the four sizes of wheat farms studied was large enough to cover all costs including interest on investment at five per cent. In order to cover all production costs including 0,64 per cent interest on investment a wheat farm of at least 3000 acres is required, Costs and returns to five management alternatives for marginal Utah cropland ( (1) wheat production by owner-operator, (2) leasing crop.. land to tenants for dryland wheat production, (3) leasing forage on an AUM basis, (4) leasing of forage on a livestock gain basis, and (5) stocker cattle production by the land owner) were compared in the shortrun, in the long-run assuming that all inputs were variable, and in the long-run assuming that land and operator and family labor were fixed, For the marginal cropland owner who also owns wheat production factors, wheat production on an owner-operator basis is the most favorable short-run alternative. Wheat production on a tenant basis is the only short-run alternative open to cropland owners who own neither wheat production factors nor the improvements necessary for grazing enterprises. Leasing forage on a livestock gain basis is the most favorable short-run alternative for cropland owners whose holdings are equipped with grazing improvements. For the long-run situation in which all inputs were considered variable, all five management alternatives yielded negative returns. Under such conditions a rational land owner would refuse to choose from among the five alternatives studied and would instead liquidate his land holdings. When operator and family labor and land were considered fixed, leasing cropland to tenants for dryland wheat production proved to be the most favorable long-run management alternative. Showing the second highest internal rate of return was leasing forage on a livestock gain basis followed ~ stocker cattle production by the land owner. Wheat production ~ the land owner and leasing forage on an AUM basis proved to be the least favorable long-run management alternatives on marginal cropland.

Over the last century, much of the United State prairie pothole region has been converted to cultivated cropland. Concerns have been raised on government subsidized crop insurance effect on grassland to cropland conversion in the United States. Most grassland in the United State prairie pothole region are privately owned making a vivid understanding of landowners’ response to crop insurance subsidies important to facilitate effective design of prairie pothole conservation programs. The purpose of this study was to determine the extent of land use conversion with the removal of crop insurance subsidies in the United States prairie pothole region. Government subsidies on crop insurance was determined to have a measurable impact on Conservation Reserve Program land acreage within the United States. It was estimated that a 15% reduction in the net returns to cropland resulted in about 274,000 increase in the land acreage of the Conservation Reserve Program. In Conclusion, the removal of crop insurance subsidies was predicted to slow down but not stop the conversion of grassland to cropland in the United States prairie pothole region.

Cropland management practices have traditionally focused on maximising the production of food, feed and fibre. However, croplands also provide valuable regulating ecosystem services, including carbon (C) storage in soil and biomass. Consequently, management impacts the extents to which croplands act as sources or sinks of atmospheric carbon dioxide (CO2). And so, reliable information on cropland ecosystem C fluxes and yields are essential for policy-makers concerned with climate change mitigation and food security. Eddy-covariance (EC) flux towers can provide observations of net ecosystem exchanges (NEE) of CO2 within croplands, however the tower sites are temporally and spatially sparse. Process-based crop models simulate the key biophysical mechanisms within cropland ecosystems, including the management impacts, crop cultivar, soil and climate on crop C dynamics. The models are therefore a powerful tool for diagnosing and forecasting C fluxes and yield. However, crop model spatial upscaling is often limited by input data (including meteorological drivers and management), parameter uncertainty and model complexity. Earth observation (EO) sensors can provide regular estimates of crop condition over large extents. Therefore, EO data can be used within data assimilation (DA) schemes to parameterise and constrain models. Research presented in this thesis explores the key challenges associated with crop model upscaling. First, fine-scale (20-50 m) EO-derived data, from optical and radar sensors, is assimilated into the Soil-Plant-Atmosphere crop (SPAc) model. Assimilating all EO data enhanced the simulation of daily C exchanges at multiple European crop sites. However, the individually assimilation of radar EO data (as opposed to combined with optical data) resulted in larger improvements in the C fluxes simulation. Second, the impacts of reduced model complexity and driver resolution on crop photosynthesis estimates are investigated. The simplified Aggregated Canopy Model (ACM) – estimating daily photosynthesis using coarse-scale (daily) drivers – was calibrated using the detailed SPAc model, which simulates leaf to canopy processes at half-hourly time-steps. The calibrated ACM photosynthesis had a high agreement with SPAc and local EC estimates. Third, a model-data fusion framework was evaluated for multi-annual and regional-scale estimation of UK wheat yields. Aggregated model yield estimates were negatively biased when compared to official statistics. Coarse-scale (1 km) EO data was also used to constrain the model simulation of canopy development, which was successful in reducing the biases in the yield estimates. And fourth, EO spatial and temporal resolution requirements for crop growth monitoring at UK field-scales was investigated. Errors due to spatial resolution are quantified by sampling aggregated fine scale EO data on a per-field basis; whereas temporal resolution error analysis involved re-sampling model estimates to mimic the observational frequencies of current EO sensors and likely cloud cover. A minimum EO spatial resolution of around 165 m is required to resolve the field-scale detail. Monitoring crop growth using EO sensors with a 26-day temporal resolution results in a mean error of 5%; however, accounting for likely cloud cover increases this error to 63%.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24244号 / 農博第2523号 / 新制||農||1094(附属図書館) / 学位論文||R4||N5415(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 舟川 晋也, 教授 樋口 浩和, 真常 仁志 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Grain sorghum provides energy-rich seeds for waterfowl. I conducted experiments in 22 sorghum fields in Arkansas, Mississippi, and Louisiana during falls 2006 – 2007 to evaluate abundance of ratoon grain (i.e., second crop after harvest), waste grain, and natural seeds. I also conducted surveys of wintering waterfowl in flooded croplands and moist-soil wetlands to evaluate if ducks and geese differentially used habitats. Fertilized plots in 2007 produced >4 times more ratoon grain (x = 219.57 ± 39.65 [SE] kg/ha) than other treatments. Fertilized plots in southern regions of my study area produced ~5 times more ratoon grain (x = 262.93 ± 50.28 kg/ha) than others. Mallards and other ducks used moist-soil wetlands (x >65 ducks/ha) more than other habitats. I did not observe geese using flooded sorghum. I recommend not manipulating sorghum stubble after harvest, fertilizing, and flooding it after ratoon grain has matured, and integrating moist-soil wetlands into agricultural lands.

Nutrient enrichment, which can be detrimental to the health of aquatic systems, is one of the leading causes of impairment of our Nations? waters. Development and initial calibration of a hydrologic, hydrodynamic, and water quality model of dissolved oxygen and nutrient concentration for the St. Louis Bay watershed in coastal Mississippi is documented herein. The model was developed using the USEPA BASINS 3.0 analysis system and WinHSPF, a comprehensive watershed loading and transport modeling software. The resulting model simulates significant watershed and instream physical, chemical and biological processes including rainfall runoff and associated water quality from a variety of land use categories. Extensive data describing the study area, land use practices, hydrology and water quality are presented, analyzed and discussed relative to model development and adequacy to support future modeling projects. Integration of this data into a valuable water quality assessment model and preliminary model calibration is also presented.

Ancestral Pueblo communities of the central Mesa Verde region (CMVR) became increasingly reliant on agriculture for their subsistence needs during Basketmaker III (BMIII) through Terminal Pueblo III (TPIII) (AD 600–1300) periods. Researchers have been studying the Ancestral Pueblo people for over a century using a variety of methods to understand the relationships between climate, agriculture, population, and settlement patterns. While these methods and research have produced a well-developed cultural history of the region, studies at a smaller scale are still needed to understand the changes in farming behavior and the distribution of individual sites across the CMVR. Soil moisture is the limiting factor for crop growth in the semi-arid region of the Goodman Watershed in the CMVR. Thus, I constructed the soil moisture proxy model (SMPM) that is on a local scale and focuses on variables relevant to soil moisture – soil particle-size, soil depth, slope, and aspect. From the SMPM output, the areas of very high soil moisture are assumed to represent desirable farmland locations. I describe the relationship between very high soil moisture and site locations, then I infer the relevance of that relationship to settlement patterns and how those patterns changed over time (BMIII – TPIII). The results of the model and its application help to clarify how Ancestral Pueblo people changed as local farming communities. The results of this study indicates that farmers shifted away from use of preferred farmland during Terminal Pueblo III, which may have been caused by other cultural factors. The general outcome of this thesis is an improved understanding of human-environmental relationships on the local landscape in the CMVR.