<p> Soil moisture sensor use in crop production systems has the potential to give inference on plant water status for the purpose of irrigation scheduling and site-drought characterization. These processed measurements could serve as the framework on which to compile trial results across locations, thereby more accurately defining varietal yield response to drought. Still, the ability to characterize drought within a given field or initiate irrigations from these data hinge upon the ability of the instrument to characterize soil moisture at the sampled point and extrapolate that information across the landscape and time. Therefore, the objectives of this research were to: (1) test the response of the Watermark 200SS (Irrometer Company, Inc., Riverside, CA) and Decagon 10HS (Decagon Devices, Inc., Pullman, WA) to changes in water content of three dissimilar soils representing common soils in row-crop production under variable environmental conditions; (2) develop a soil moisture-based index to quantify drought stress in dryland cotton cultivar trials; and (3) determine if a limited number of soil moisture sensors deployed into a dryland cultivar trial could accurately characterize the VWC at a given point within the field and if this measurement could be extrapolated out to the field scale from the very small sphere of influence characterizing the utilized soil moisture sensors. During the 2012 and 2013 growing seasons soil moisture sensors were deployed into over 14 cotton cultivar trials across the U.S. Cotton Belt and into a water-input controlled container study. Tested sensors' inability to accurately predict container VWC emphasized the relatively small quantity of soil on which these sensors rely and the variability in soil moisture within a very limited volume. Results from the drought-index studies suggested both the Accumulated Soil Moisture Stress Index (ASMSI) and the relative reduction in evapotranspiration (1-(ET_{c adj}/ET_c)) appear to have potential in characterizing the amount of stress experienced within dryland cultivar trials. Analysis of spatial and temporal stability suggested trends between sensors were consistent, but absolute node readings varied. Optimism concerning the potential of these measurements/approaches for increasing water use efficiency is coupled with a call for more arbitrary, universal methods of measurement analysis.</p>

Thesis (M.Sc. Earth and Ocean Sciences)--University of Waikato, 2008. / Title from PDF cover (viewed September 16, 2008) Includes bibliographical references (p. 163-169)

Thesis (M.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 48-50). Also available in electronic format on the Internet.

Made available in DSpace on 2014-06-11T19:33:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-01-09Bitstream added on 2014-06-13T21:06:41Z : No. of bitstreams: 1 deluca_hbjf_dr_jabo.pdf: 1271148 bytes, checksum: 60d1c5bc98b36ac556c0af43141173bc (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se verificar se a época de semeadura, o grau de compactação do solo e o conteúdo de água no solo influenciam o comportamento de duas cultivares de soja (CAC-1, classificada como resistente e FT-Cristalina, como suscetível), em relação a severidade da podridão vermelha da raiz (PVR). Os experimentos foram desenvolvidos na FCAV/UNESP/Jaboticabal, envolvendo etapas de casa de vegetação e de campo. No campo, as cultivares FT-Cristalina e CAC-1 apresentaram níveis de doença variáveis conforme a época de semeadura, sendo que no outono/inverno 2009, na cultivar CAC-1 foi observado maior número de plantas com sintomas da PVR na parte aérea. Na primavera/verão 2009/10, a cultivar FT-Cristalina apresentou maior número de plantas com sintomas. Graus mais elevados de compactação e de umidade do solo (-0,001 MPa) favoreceram a ocorrência da PVR, e reduziram o desenvolvimento e produtividade da soja. Houve maior desenvolvimento radicular na camada superficial (0,0-0,10 m) onde a compactação foi menor comparada a camada de 0,10-0,20 m. Tanto na cultivar resistente quanto na suscetível à PVR, observaram-se maiores áreas, comprimentos, densidades e massas seca de raízes nas plantas inoculadas. Em casa de vegetação, na primavera/verão de 2009/10, o maior grau de compactação (resistência a penetração = 0,602 MPa) foi o qual proporcionou menor desenvolvimento radicular. No outono/inverno de 2010, a PVR foi influenciada pela irrigação, sendo que nas menores tensões de água observaram-se maiores severidades dos sintomas na parte aérea em ambas cultivares. Os tratamentos infestados, nesta época, tiveram a altura de plantas reduzida em relação aos não infestados. A infestação do solo com F. tucumaniae promoveu redução significativa do desenvolvimento do sistema radicular / The objective of this experiment was to assess the influence of sowing time, soil compaction level, and soil water content on the severity level of sudden death syndrome (SDS) in two soybean cultivars – one (CAC-1), classified as resistant and another (FT-Cristalina) as susceptible. Experiments were carried out in Jaboticabal, a campus of the Paulista State University, in Jaboticabal, state of São Paulo, Brazil. The experiments were conducted both in the field and under green house conditions. In the field both cultivars showed variable levels of SDS, depending on sowing time. When sowing was made during the 2009 Fall/Winter period, CAC-1 cultivar showed the highest number of plants with the sudden death syndrome. When sowing took place during the 2009/10 Spring/Summer period, FT-Cristalina was the cultivar with the highest number of plants exhibiting the symptoms. High soil compaction and moisture (-0.001 MPa) degrees favored the occurrence of SDS and this resulted in plant growth and yield reductions. Plant root system, due to soil compaction, was more developed at the depth of 0.0 – 0.10 m than at 0.10 – 0.20. Plants of both cultivars showed root larger areas, lengths, densities, and dry matter when they had been previously inoculated. Under green house conditions, during the 2009/10 Spring/Summer period, the highest degree of soil compaction (penetration resistance of 0.602 MPa) was the factor causing the lowest root development. During the 2010 Fall/Winter period, SDS was influenced by irrigation – the lower soil water´s tensions (high irrigation level), the more severe the symptoms in both cultivars. Infected plants were shorter than the non infected ones. Soil infection with F. tucumaniae caused significant reductions in root system development

Doctor of Philosophy / Environmental Design and Planning / Timothy D. Keane / Kenya has been adversely affected by soil erosion due to population growth, changes in land use and land cover, and unsustainable agricultural practices. Issues related to land degradation cost the Kenyan government approximately $390 million or 3 percent of the country’s GDP yearly (Government of Kenya, 2013). Despite extensive land degradation, many attempts to encourage the use of soil and water conservation (SWC) practices have been unsuccessful. The study focuses on Merigi Ward, Kenya. Merigi Ward lies within the Mara River Basin (MRB), an ecologically and economically important river basin that has experienced extensive erosion problems. Increased agricultural activities driven by population growth in the area and changes in land use and land cover have degraded the landscape. SWC practices are greatly needed to mitigate the effects of erosion and conserve the natural resources within the MRB. Past studies suggest that social capital may increase the adoption of SWC practices (Knowler & Bradshaw, 2007; Nyangena, 2008). This study defines social capital as the groups and networks, trust and reciprocity, formal and informal rules, and information that informs the interactions among persons that lead to collective action. Twenty-five smallholder farmers within Merigi Ward were interviewed and the relationship between the adoption of SWC practices and social capital was explored through a qualitative analysis. Additionally, the MRB is home to the Mau Mara Serengeti Sustainable Water Initiative (MaMaSe). The MaMaSe initiative is a public private partnership (P3) with the goal to promote sustainable water use, economic growth, and environmental conservation within the basin. The effect the MaMaSe initiative had on the level of social capital amongst the study participants was also investigated. Findings suggest that social capital is an important aspect of SWC adoption in Merigi Ward. Groups and networks provide farmers with implementation support and information. Particularly, the local farmers’ cooperative provides farmers with implementation assistance and links (bridging capital) to experts at the MaMaSe initiative and the Ministry of Agriculture. Strong bonding capital works in the favor of this community allowing for high levels of trust. Thus, farmers collaborate to help one another implement practices and exchange information, materials, and experiences. In general, social capital has helped facilitate better environmental conservation awareness and the use of SWC practices. The largest impact the MaMaSe initiative had on the community’s social capital was expanding networks (particularly bridging and linking capital) and providing in depth information and guidelines for SWC practice use. The P3 has also helped the farmers integrate environmental conservation into their daily lives and has helped promote a shared understanding of the importance of conservation. The findings of this study will help environmental conservation professionals understand how to use social capital to strengthen natural resource management.

nÃo hà / This study evaluates the indicators of soil and water and its implications for the public supply of Juazeiro system pollution from interactions between aquifers and soils that makes up part of the drainage area of the stream of the Apes. For this, a characterization of the soils of the area as the physical, chemical and biological aspects was conducted through qualitative indicators of total organic carbon, total nitrogen, basal respiration and C / N ratio. Surface waters were also characterized in terms of COD and BOD parameters and groundwater for the parameters of Ammonia, Nitrite, Nitrate and chloride. The data obtained in the characterization of the soils of the study area were analyzed using multivariate statistical methods Principal Component Analysis and Cluster Analysis Hierarchical Agglomerative; and those obtained in the characterization of surface water were contrasted with the framework set out by the CONAMA Resolution No. 357 for classes of freshwaters. Data from qualitative monitoring of groundwater, provided by CAGECE, were analyzed regarding the classification according to the predominant uses, by Resolution No. 396 of CONAMA and how to meet potability standards, by Ordinance No. 9214 MS. It was found that the soils of the drainage area of &#8203;&#8203;the stream of the Apes are degraded by human interference in the area, standing surface water polluted by sewage to the fullest extent analyzed, not fitting into any of the classes of freshwater, based the parameters analyzed. Of groundwater supply wells included in the study area meet the required legal standards, but already show signs of pollution by domestic sewage. / Este trabalho procura avaliar os indicadores de poluiÃÃo de solos e Ãguas e suas implicaÃÃes no sistema de abastecimento pÃblico de Juazeiro do Norte, a partir das interaÃÃes entre os aquÃferos e os solos que compÃe parte da zona de drenagem do riacho dos Macacos. Para isso, foi realizada uma caracterizaÃÃo dos solos da Ãrea quanto os aspectos fÃsicos, quÃmicos e biolÃgicos, atravÃs dos indicadores qualitativos de carbono orgÃnico total, nitrogÃnio total, respiraÃÃo basal e relaÃÃo C/N. Foram caracterizadas tambÃm as Ãguas superficiais quanto aos parÃmetros de DQO e DBO e as Ãguas subterrÃneas quanto aos parÃmetros de AmÃnia, Nitrito, Nitrato e Cloreto. Os dados obtidos na caracterizaÃÃo dos solos da Ãrea de estudo foram analisados atravÃs dos mÃtodos de estatÃstica multivariada AnÃlise de Componentes Principais e AnÃlise de Cluster Aglomerativa HierÃrquica; e os obtidos na caracterizaÃÃo das Ãguas superficiais foram contrastados com o enquadramento previsto pela ResoluÃÃo n 357 do CONAMA para classes de Ãguas doces. Os dados de monitoramento qualitativo das Ãguas subterrÃneas, fornecidos pela CAGECE, foram analisados, quanto ao enquadramento segundo os usos preponderantes, pela ResoluÃÃo n 396 do CONAMA e quanto ao atendimento aos padrÃes de potabilidade, pela Portaria MS n 9.214. Constatou-se que os solos da Ãrea de drenagem do riacho dos Macacos encontram-se degradados pelas interferÃncias antrÃpicas na Ãrea, estando as Ãguas superficiais poluÃdas por esgotos em toda a extensÃo analisada, nÃo se enquadrando em nenhuma das classes de Ãgua doce, com base nos parÃmetros analisados. As Ãguas subterrÃneas dos poÃos de abastecimento inseridos na Ãrea de estudo atendem aos padrÃes legais exigidos, mas jà apresentam indÃcios de poluiÃÃo por esgotos domÃsticos.

Federal and state programs have encouraged farmers in the Mississippi Delta region to implement best management practices (BMPs) to promote soil and water conservation. An onarm water storage (OFWS) system is a structural BMP that has several potential benefits, namely, the ability to capture and reuse rainwater and tailwater runoff, provide supplemental water for irrigation, reduce groundwater withdrawals, and improve downstream water quality. However, research demonstrating these benefits and providing new insights for downstream water quality improvement and nutrient-rich runoff management is limited. This dissertation addresses these research gaps by examining the ability of OFWS systems to mitigate off-site nutrient movement, analyzing the impacts of rainfall characteristics on the ability of OFWS systems to reduce NO3-N, studying the hydrological and physical-chemical characteristics of the volume of water exiting an OFWS system, and using the AnnAGNPS model to simulate runoff, nutrient, and sediment loads entering a tailwater recovery ditch and identify the critical contributing areas of non-point source pollution. Significant seasonal water quality improvements were observed at different locations throughout the OFWS system, and more importantly, highlight downstream nutrient reduction, particularly during winter and spring. However, recurrent and high intensity rainfall events can minimize the system’s effectiveness in reducing downstream nutrient pollution. The NO3-N concentrations observed in the ditch were strongly dependent on antecedent hydrological conditions with characteristics of next-to-last rainfall events playing a more influential role. The nutrient load was greater in winter, as this season produced the highest effluent discharge. Agricultural fields draining to the outlet of the system produced 7.1 kg NO3-N ha-1yr-1 and 2.3 kg TP ha-1yr-1 that was discharged with outflow events. AnnAGNPS simulations showed that larger fields coupled with poorly drained soils resulted in higher runoff, and this condition mirrored the annual rainfall patterns. High nitrogen loss was due to fertilization of corn and winter wheat. TP and sediment loss patterns were similar and influenced by the hydrological condition. This study can be used by stakeholders and agencies to better identify where these systems can be implemented to improve water quality and offer a supplemental source of surface water.

Vombsjön är en av de viktigaste dricksvattentäkterna i södra Skåne som förser bland annat Malmö och delar av Lund med dricksvatten. Sjön lider av övergödning och återkommande algblomningar som komplicerar dricksvattenproduktionen. Fosfor från sjöns bottensediment (intern belastning) och fosfor från det jordbruksdominerade avrinningsområdet (extern belastning) behöver kartläggas för att råda bukt på övergödningsproblematiken i sjön och trygga produktionen av ett säkert dricksvatten. Inom ramen för detta examensarbete har den externa fosforbelastningen kartlagts genom modellering av Vombsjöns avrinningsområde med den hydrologiska modellen Soil and Water Assessment Tool (SWAT+). Resultaten från modelleringen visar att det nära 45 000 ha stora avrinningsområdet i genomsnitt tillför 25 ton totalfosfor per år via de tre huvudvattendragen som mynnar ut i Vombsjön. Medelvärdet är beräknat på simuleringar gjorda för åren 2011 – 2022 och belastningen varierar mellan 14–37 ton totalfosfor för de undersökta åren. 79 % av totalfosforn tillförs sjön via det största vattendraget Björkaån, 11 % via Torpsbäcken och 10 % via Borstbäcken. Den månatliga vattenföringen har manuellt kalibrerats och validerats mot en mätpunkt i avrinningsområdet. Miljöövervakning från ett jordbruksdominerat typområde i samma läckageregion som Vombsjöns avrinningsområde till största del ligger inom användes för att jämföra storleksordningen på den arealspecifika fosfortransporten. De arealspecifika månads- och årstransporterna låg inom samma storleksordning men variationerna mellan de två områdena var stora somliga år och månader. Den hydrologiska modellen behöver vidareutvecklas för att bättre simulera vattenföringen under höst och vinter, när vattenföringen generellt är som störst. Vidare behöver modellen kalibreras och valideras mot fler vattenföringsstationer och uppmätta fosforhalter i avrinningsområdet för att avgöra hur väl modellen simulerar fosfortransporten. / Vombsjön is one of the most important drinking water sources in southern Skåne, supplying drinking water to Malmö and parts of Lund. The lake suffers from eutrophication and reoccurring algal blooms which are complicating the drinking water production. Phosphorus leaching from the bottom sediment of the lake (internal load) and phosphorus coming from the agriculture- dominated catchment (external load) needs to be investigated to address the eutrophication issues and ensure a safe drinking water production. As part of this thesis, the external phosphorus load has been investigated through hydrological modeling of the catchment area, using Soil and Water Assessment Tool (SWAT+). The modeling results show that the approximately 45 000 hektar big catchment area contributes to an average of 25 tons of total phosphorus per year via the three main watercourses that flows into Vombsjön. The average load is based on simulations between 2011 and 2022, and the load varies between 14–37 tons of total phosphorus for the examined years. 79 % of the total phosphorus load is supplied to the lake via the largest watercourse, Björkaån, 11 % via Torpsbäcken and 10 % via Borstbäcken. The monthly water flow has been manually calibrated and validated against flow measurements at one point in the catchment area. Environmental monitoring data from an agriculture- dominated catchment area, located in the same leakage region as most of the Vombsjöns catchment area, was used to compare the magnitude of the area-specific phosphorus transport. The area-specific monthly and annual transports of total phosphorus were within the same order of magnitude, but there were significant variations between some years and months. The hydrological model needs further development to better simulate water flow during autumn and winter, when the flow is generally highest. Furthermore, the model needs to be calibrated and validated against more flow stations and measured phosphorus concentrations within the catchment area to determine how well the model simulates phosphorus transport.

A greenhouse experiment was conducted at the University of Arizona, Tucson, Arizona, to study the effects of liquid sewage sludge loading rates on the vegetative growth, yield, and quality of barley grain and straw. Vegetative growth, grain yields, and straw yields were similar whether barley was grown with inorganic N or equivalent amounts of plant-available N from sewage sludge. Sewage sludge loading rates higher than three times the recommended plant-available N rate decreased barley stands in the seedling stage. The loss of stand was compensated for by higher tillering later in the season. High sludge loading rates tended to delay maturity, increase tillering and increase straw yield; however, they did not affect grain yield. Concentrations of cadmium (Cd), copper, (Cu), lead (Pb), nickel (Ni), and zinc (Zn) in barley grain and straw and the amounts of heavy metals recovered in the soil following each harvest were similar to the control for all sewage sludge treatments.

Attempts to characterize nitrogen (N) status of irrigated spring wheat by using basal stem nitrate - N (NO₃⁻N) tissue tests have shown contradictory results, due to the wide range of agronomic conditions existing in Arizona. Seven N fertility trials were conducted at the Maricopa and Safford Agricultural Centers over the 1985-88 crop years to examine the effects of N rate, N fertilizer form, residual soil N, soil texture and contrasting varieties on basal stem NO₃⁻N concentrations, yield and quality of irrigated durum wheat. Fertilizer N treatments were broadcast at planting then at the 5-6 leaf, boot and anthesis growth stages to simulate fertigation in conjunction with the first four basin irrigation events. Stem tissue samples were taken from all plots at the 3-4 leaf 5-6 leaf joint, boot and anthesis growth stages for NO₃⁻N analysis with a nitrate electrode. Diagnostic levels for durum wheat basal stem tissue NO₃⁻N tests at these growth stages are presented.