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Management practices on organic farms in Saskatchewan are largely unstudied, as are their effect on weed populations and soil quality. The objective of this study was to document what management practices are used on organic farms, classify those practices into management systems and determine if those management systems affect weed populations and soil properties. During the 2002 growing season 73 organic fields in the province of Saskatchewan were surveyed. Three components comprised the data set for each field: a management questionnaire, weed counts, and soil samples that were collected and analyzed for various soil properties. Classification of the management practices identified farming systems: the diverse cropping system, the diverse cropping system using green manure, the low diversity cropping system using summerfallow, and the moderately diverse cropping system using perennials in rotation. Ordination of weed data and the four systems was done with redundancy analysis. It determined that the farm management systems only accounted for 5% of the variation in the weed populations. The only system that affected the weed populations was the moderately diverse cropping system using perennials in rotation. Soil properties were compared among the different management systems. Soil properties were not different between the diverse cropping system using green manure, and the low diversity cropping system using summerfallow. The system that included perennials in rotation had significantly lower pH, electrical conductivity, soil organic matter, phosphorous and potassium levels. The nutrient levels in all systems were low, underscoring the importance of nutrient additions to export farming systems.

Management practices on organic farms in Saskatchewan are largely unstudied, as are their effect on weed populations and soil quality. The objective of this study was to document what management practices are used on organic farms, classify those practices into management systems and determine if those management systems affect weed populations and soil properties. During the 2002 growing season 73 organic fields in the province of Saskatchewan were surveyed. Three components comprised the data set for each field: a management questionnaire, weed counts, and soil samples that were collected and analyzed for various soil properties. Classification of the management practices identified farming systems: the diverse cropping system, the diverse cropping system using green manure, the low diversity cropping system using summerfallow, and the moderately diverse cropping system using perennials in rotation. Ordination of weed data and the four systems was done with redundancy analysis. It determined that the farm management systems only accounted for 5% of the variation in the weed populations. The only system that affected the weed populations was the moderately diverse cropping system using perennials in rotation. Soil properties were compared among the different management systems. Soil properties were not different between the diverse cropping system using green manure, and the low diversity cropping system using summerfallow. The system that included perennials in rotation had significantly lower pH, electrical conductivity, soil organic matter, phosphorous and potassium levels. The nutrient levels in all systems were low, underscoring the importance of nutrient additions to export farming systems.

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 137 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 122-128).

A fundamental knowledge gap in understanding land-atmosphere interactions is accurate, high-resolution soil properties. Remote sensing and spatial modeling techniques can bridge the gap between site-specific soil properties and landscape variability, thereby improving predictions of soil attributes. Three studies were completed to advance soil prediction models in semiarid areas. The first study developed a soil pre-mapping technique using automated image segmentation that utilized soil-landscape relationships and surface reflectance to produce an effective map unit design in a 160,000 ha soil survey area. Overall classification accuracy of soil taxonomic units at the suborder was 58 % after including soil temperature regime. Physical soil properties were not significantly different for individual transects; however, properties were significantly different between soil pre-map units when soils from the entire study area were compared. Other studies used a raster approach to predict physical soil properties at a 5 m spatial resolution for a 6,265 ha area using digital soil mapping. The second study utilized remotely-sensed auxiliary data to develop a sampling design and compared three geostatistical techniques for predicting surface soil properties. Ordinary kriging had the smallest prediction error; however, regression kriging preserved landscape features present in the study area and demonstrated the potential of this technique for quantifying variability of soil components within soil map units. The third study applied quantitative data from soil prediction models in study 2 and additional models of subsurface properties to a pedotransfer function for predicting hydraulic soil parameters at the landscape scale. Saturated hydraulic conductivity and water retention parameters were used to predict water residence times for loss to gravity and evapotranspiration across the landscape. High water residence time for gravitational water corresponded to both low drainage density and high clay content, whereas high residence of plant available water was related to increased vegetation response. These studies illustrate the utility of digital soil mapping techniques for improving soil information at landscape scales, while reducing required resources. Resulting soil information is useful for quantifying landscape-scale processes that require constraint of spatial variability and prediction error of soil properties to better model hydrological and ecological responses to climate and land use change.

Initial soil surveys are incomplete for large tracts of public land in the western USA. Digital soil mapping offers a quantitative approach as an alternative to traditional soil mapping. I sought to predict soil classes across an arid to semiarid watershed of western Utah by applying random forests (RF) and using environmental covariates derived from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and digital elevation models (DEM). Random forests are similar to classification and regression trees (CART). However, RF is doubly random. Many (e.g., 500) weak trees are grown (trained) independently because each tree is trained with a new randomly selected bootstrap sample, and a random subset of variables is used to split each node. To train and validate the RF trees, 561 soil descriptions were made in the field. An additional 111 points were added by case-based reasoning using aerial photo interpretation. As RF makes classification decisions from the mode of many independently grown trees, model uncertainty can be derived. The overall out of the bag (OOB) error was lower without weighting of classes; weighting increased the overall OOB error and the resulting output did not reflect soil-landscape relationships observed in the field. The final RF model had an OOB error of 55.2% and predicted soils on landforms consistent with soil-landscape relationships. The OOB error for individual classes typically decreased with increasing class size. In addition to the final classification, I determined the second and third most likely classification, model confidence, and the hypothetical extent of individual classes. Pixels that had high possibility of belonging to multiple soil classes were aggregated using a minimum confidence value based on limiting soil features, which is an effective and objective method of determining membership in soil map unit associations and complexes mapped at the 1:24,000 scale. Variables derived from both DEM and Landsat 7 ETM+ sources were important for predicting soil classes based on Gini and standard measures of variable importance and OOB errors from groves grown with exclusively DEM- or Landsat-derived data. Random forests was a powerful predictor of soil classes and produced outputs that facilitated further understanding of soil-landscape relationships.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-08T12:44:50Z No. of bitstreams: 1 PGCS17MA159.pdf: 5049867 bytes, checksum: 6d34f91f61e1e07b1998c6ac3f8d5b62 (MD5) / Made available in DSpace on 2018-03-08T12:44:50Z (GMT). No. of bitstreams: 1 PGCS17MA159.pdf: 5049867 bytes, checksum: 6d34f91f61e1e07b1998c6ac3f8d5b62 (MD5) Previous issue date: 2017-02-17 / Capes / In the municipality of Vacaria/RS most of the soils are developed from basalt, with predominance of the Latossolos and to a lesser extent the Nitossolos, which have a clayey texture to a very clayey throughout the profile. However, in the western part of the municipality, there is an expressive area where soils with superficial horizons with high sand contents predominate, being an unusual feature, since there is no indication in the literature of the presence of sandstones, nor of Holocene sandy deposits in the region. The aim of this study was to identify, physical and chemical characterization, classification and mapping of sandy soils occurrence areas in Vacaria/RS, using spectroradiometry tools and geoprocessing software. The study area was delimited based on observation points obtained in the field and corresponded to an area of 540 Km². From this, one hundred collection points were selected for physical, chemical, spectral and morphological analyzes in the superficial horizons, in addition to six representative profiles for complete description and classification. The collects were concentrated in areas where soils presented higher sand contents, and also in areas bordering them where soils have a clayey texture. The spectral analyzes were efficient to distinguish the soils based on the sand and iron contents extracted by dithionite-citrate-sodium bicarbonate, it demonstrates that spectroradiometry is a tool that can be used in a complementary way in soil survey and reduces operating costs. The predominance of Latossolos Brunos occurred in most of the area where soils presented texture with greater amount of sand. In the vicinity of these predominate Latossolos Vermelhos and Vermelho-Amarelos with brownish superficial horizons. Based on the survey carried out, the area that presents soils with textured characteristics differentiated from those typical of the studied region. The results obtained complement the existing knowledge about the soils of the region and the delimitation of the area of occurrence seeks to support future works related to the genesis, use, management and conservation of the soils with sandy surface horizon in Vacaria/RS / No município de Vacaria/RS a maioria dos solos são desenvolvidos de basalto, com predomínio dos Latossolos e em menor extensão os Nitossolos, com textura argilosa a muita argilosa em todo o perfil. Entretanto, na região oeste do município ocorrem solos com horizontes superficiais com altos teores de areia, sendo esta uma característica incomum, uma vez que não consta na literatura indicações da presença de arenitos, e tampouco de depósitos arenosos holocênicos na região. Com este estudo objetivou-se identificar, caracterizar física e quimicamente, classificar taxonomicamente e mapear a área de ocorrência de solos com altos teores de areia em Vacaria/RS, utilizando ferramentas de espectrorradiometria e softwares de geoprocessamento. A área de estudo foi delimitada com base em pontos de observação obtidos a campo e correspondeu a uma área de 540 km2. A partir disso foram selecionados cem pontos de coleta para análises físicas, químicas, espectrais e morfológicas, nos horizontes superficiais, além de seis perfis representativos para descrição completa e classificação. As coletas concentraram-se na região de solos com os maiores teores de areia e em zonas limítrofes a estes onde os solos apresentam textura argilosa. As análises espectrais foram eficientes para distinguir os solos com base nos teores de areia e ferro extraído por ditionito-citrato-bicarbonato de sódio, demonstrando que a radiometria pode ser utilizada em levantamento de solos para reduzir os custos operacionais. Nas áreas onde os solos apresentam os maiores teores de areia na camada superficial predominaram os Latossolos Bruno, enquanto nas adjacências, predominam os Latossolos Vermelhos e Vermelho-Amarelo com horizontes superficiais mais brunados. Com base no levantamento realizado, a área avaliada apresenta solos com características texturais diferenciadas daqueles característicos da região estudada. Os resultados obtidos complementam o conhecimento existente sobre os solos da região e a delimitação da área de ocorrência deve apoiar futuros trabalhos relacionados à gênese, uso, manejo e conservação dos solos com altos teores de areia em Vacaria/RS

Made available in DSpace on 2015-03-26T13:53:06Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4545101 bytes, checksum: 4fdc84bcbb07d778489d34cab40f90c4 (MD5) Previous issue date: 2008-07-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Because the demand for arable areas has turned very intense in the last years, soils then considered as not appropriate to agricultural use are now being revalued and studied in order to use them for forest plantings, to example of Cambisols developed from pellitic rocks of Bambui Group. In reason of the expressiveness of these soils, usually associated Latossols, it was selected the areas of Farm Olhos d`Água and Cachoeira, Minas Gerais State, whose objectives were: study the physical characteristics, chemistries and mineralogical of the soils; understand the processes of soil genesis; show the space distribution of the soils through semi-detailed mapping, in the scale 1:20.000. The samples of soils were submitted to the physical and chemical analyses of routine, retention of water, total and sulfuric digestion, and mineralogical analyses. It was verified in Cambisols medium tenor of silt of 47%. Some characteristics observed in these soils, as horizontal direction of the origin material, high silt tenors and of density of the soil, kaolinite and illite prevalence in the fraction clay, consistence hard or very hard when dry, and structure in blocks faintly developed contribute to low quality of the forest planting. The smaller capacity of water retention of Cambisols, associated to the low hydraulic conductivity, to the little thickness of the solum and larger difficulty of infiltration of water, in reason of topography and of superficial stamp, seems to be indicative of smaller capacity of water recharge in the areas where they appear, could contribute to the depreciation in the quality of the forest planting. Results of Ki around 2,0 for Cambisols indicate smaller soil genesis and larger kaolinite proportion and illite in the fraction clay, comparatively to Latosols. In this fraction also verified gibbsite and VHE. The silt fraction revealed the presence mainly of mica and quartz and the sand fraction, basically quartz, confirming the low reserve of nutrients in the larger fractions. In the fraction clay of Latosols, kaolinite, illite, gibbsite, and VHE were verified. The gibbsite presence is larger than verified in the fraction clay of Cambisols, to infer for the results of Ki, around 1,4. The low tenors of CaO, MnO, MgO and, mainly P2O5, obtained by the total digestion, revealed the low capacity of reserve of these nutrients in all the studied soils. As for total K2O, the largest tenors in Cambisols indicate larger presence of micas in relation to Latosols. / Em virtude da demanda por áreas cultiváveis tornar-se muito grande nos últimos anos, áreas ocupadas por solos até então tidos como marginais ao aproveitamento agrícola estão sendo reavaliadas e estudadas visando seu aproveitamento com plantios florestais, a exemplo dos Cambissolos desenvolvidos de rochas pelíticas do Grupo Bambuí. Em razão da expressividade destes solos, normalmente associados a Latossolos, selecionou-se as áreas das Fazendas Olhos d`Água e Cachoeira, pertencentes à empresa V&M Florestal (Curvelo - MG), cujos principais objetivos foram: estudar as características físicas, químicas e mineralógicas dos solos; compreender os processos pedogenéticos atuantes; mostrar a distribuição espacial dos solos por meio de mapeamento semi- detalhado na escala 1:20.000. As amostras de solos (LVA, LV e CX) foram submetidas às análises físicas e químicas de rotina, retenção de água, digestão total e sulfúrica, e análises mineralógicas. De acordo com os resultados, constatou-se que os CX das Fazendas Olhos d Água e Cachoeira apresentaram teores médios de silte de 40 e 54 %, respectivamente, com textura variando de argilo-siltosa a franco-argilo-siltosa. São ácidos, distróficos e álicos. Podem apresentar linhas de pedra em diferentes profundidades e estão normalmente associados a topografias mais movimentadas. Algumas características observadas nos CX, como direção horizontalizada do material de origem, elevados teores de silte e de densidade do solo, predomínio de caulinita e ilita na fração argila, consistência dura ou muito dura quando secos, e estrutura em blocos subangulares fracamente desenvolvida, estimulam a formação de selamento superficial e erosão laminar acentuada, contribuindo para a queda de qualidade dos sítios florestais nas áreas de ocorrência destes solos. A menor capacidade de retenção de água pelos materiais dos horizontes A e Bi dos CX, associada à baixa condutividade hidráulica, à pouca espessura do solum e maior dificuldade de infiltração de água em razão da topografia e do selamento superficial, parece ser indicativo de menor capacidade de recarga hídrica nas áreas onde ocorrem (CX), podendo contribuir para a depreciação na qualidade dos sítios florestais. Resultados de Ki em torno de 2,0 para os CX indicam menor pedogênese e maior proporção de caulinita e ilita na fração argila, comparativamente aos Latossolos. Nesta fração, foram constatadas também gibbsita e VHE. A fração silte revelou a presença principalmente de mica e quartzo e a fração areia, basicamente quartzo, confirmando a baixa reserva de nutrientes nas frações grosseiras. Todos os LVA e LV são ácidos, distróficos, na maioria álicos, e de textura argilosa ou muito argilosa. Apresentam estrutura geralmente do tipo blocos subangulares e consistência variando de ligeiramente dura a dura quando secos. Os LV apresentaram menores teores de silte do que os LVA, 23 e 31%, respectivamente, indicando maior intemperização, ainda que os resultados de Ki sejam semelhantes entre estas duas subordens. São profundos, podendo apresentar linha de pedra, em geral, abaixo de 150 cm. Na fração argila dos Latossolos foram constatadas caulinita, ilita, gibbsita, e VHE. A presença de gibbsita parece ser maior do que a constatada na fração argila dos CX, a inferir-se pelos resultados do Ki, em torno de 1,4. A fração silte revelou a presença principalmente de quartzo e mica e a fração areia, basicamente quartzo. Ainda que não existam diferenciações químicas e físicas marcantes entre os Latossolos, constatou-se nos perfis P8 e P10, ambos LV, magnetização considerável na fração areia, cuja difratometria de raios-X confirmou a presença de magnetita. Diferentemente de todos os LV do presente estudo, o P10 se destacou pela ocorrência de teores de Fe2O3 da digestão sulfúrica de 22 dag kg-1 para os horizontes A e Bw.

Soil organic carbon represents the largest constituent of the global C pool and carbon budgets are studied by researchers and modelers in C cycling, global climate change, and soil quality studies. Pedon and soil interpretation record databases are used with soil and ecological maps to estimate regional SOC even though these databases are rarely complete for surface litter and mineral subsurface horizons. The first main objective of the project is to improve the ability to produce soil organic carbon estimates from existing spatial soils datasets, such as STATSGO. All records in the STATSGO Layer table that were incomplete or appeared to be incorrectly filled with a null or zero value were considered invalid. Data sorting procedures and texture lookup tables were used to identify exiting correct (valid) data entries that were used to substitute invalid records. STATSGO soil property data were grouped by soil order, MLRA, layer number, and texture to produce replacement values for all invalid data used to calculate mass SOC. Grouping criteria was specific to each variable and was based on texture designations. The resulting filled and unfilled tables were used with procedures assuming Normal and Lognormal distribution of parameters in order to analyze variation of mass SOC estimates caused by using different computation techniques. We estimated mass SOC to 2 m in Maine and Minnesota using filled and unfilled STATSGO data tables. Up to 54% of the records in Maine and up to 80% of the records in Minnesota contained null or zero values (mostly in fields related to rock fragments) that were replaced. After filling, the database resulted in 1.5 times higher area-weighted SOC. SOC calculated using the Normal distribution assumption were 1.2 to 1.5 times higher than those using the Lognormal transformation. SOC maps using the filled tables had more logical geographic SOC distribution than those using unfilled tables. The USDA Forest Service collects and maintains detailed inventory data for the condition and trends of all forested lands in the United States. A wide range of researchers and landowners use the resulting Forest Inventory and Analysis (FIA) database for analytical and decision making tasks. FIA data is available to the public in transformed or aggregate format in order to ensure confidentiality of data suppliers. The second main objective of this project was to compute SOC (kg m-2) results by FIA forest type and forest type group for three depth categories (25 cm, 1 m, and 2 m) at a regional scale for the 48 contiguous United States. There were four sets of results derived from the filled STATSGO and FIA datasets for each depth class by region: (1) SOC computed by the Lognormal distribution approach for (1a) all soil orders, (1b) without Histosols; and (2) SOC computed by the Normal distribution approach for (2a) all soil orders, (2b) without Histosols. Two spatial forest cover datasets were relevant to this project, FIA and AVHRR. We investigated the effects of FIA inventory data masking for Maine and Minnesota, such as plot coordinates rounding to the nearest 100 arc-second, and the use of 1 km resolution satellite-derived forest cover classes from AVHRR data, on SOC estimates to 2 m by forest type group. SOC estimates by soil mapping unit were derived from fixed STATSGO database tables and were computed by the Lognormal distribution approach including all soil orders. The methods in this study can be used for a variety of ecological and resource inventory assessments and the automated procedures can be easily updated and improved for future uses. The procedures in this study point out areas that could benefit the most during future revisions of STATSGO. The resulting SOC maps are dynamic and can be rapidly redrawn using GIS whenever STATSGO spatial or tabular data undergo updating. Use of pedon data to define representative values for all properties in all STATSGO layers and correlation of STATSGO layers to soil horizons will lead to vast improvement of the STATSGO Layer table and promote its use for mass SOC estimation over large regions. / Master of Science