Master of Science / Department of Agronomy / Peter J. Tomlinson / Growing cover crops (CCs) in rotation with cash crops has become popular in recent years for their many agroecosystem benefits, such as influencing nutrient cycling and reducing nutrient losses. This study aimed to (i) determine the long-term effects of no-till with CCs and varying nitrogen (N) rates on subsequent sorghum [Sorghum bicolor (L.) Moench] yield and yield components, (ii) assess how CCs affect the N dynamic in the soil-crop relationship during the growing season and N use efficiency (NUE) of sorghum, and (iii) define and evaluate important periods of nitrous oxide (N₂O) losses throughout the cropping system. Field experiments were conducted during the 2014-15 and 2015-16 growing season in a three-year no-till winter wheat (Triticum aestivum L.) – sorghum – soybean [Glycine max (L.) Merr] rotation. Fallow management consisted of a chemical fallow (CF) control plus four CCs and a double-crop soybean (DSB) grown after wheat harvest. Nitrogen fertilizer was subsurface banded at five rates (0, 45, 90, 135, and 180 kg ha⁻¹) after sorghum planting. On average, DSB and late-maturing soybean (LMS) provided one-third and one-half of the N required for optimum economic grain yield (90 kg N ha⁻¹), respectively; resulting in increased grain yield when compared to the other CCs and CF with 0-N application. Crimson clover (Trifolium incarnatum L.) and daikon radish (Raphanus sativus L.) had no or negative effects on sorghum yield and N uptake relative to CF across all N rates. Sorghum-sudangrass (SS) (Sorghum bicolor var. sudanese) significantly reduced N uptake and grain yield, even at higher N rates. Sorghum following CF had the lowest NUE at optimum grain yield when compared to all CC treatments, suggesting that CCs have a tendency to improve NUE. Cover crops reduced N₂O emissions by 65% during the fallow period when compared to CF; however, DSB and SS increased emissions when N was applied during the sorghum phase, indicating that N fertilization might be the overriding factor. Moreover, about 50% of the total N₂O emissions occurred within 3 weeks after N application, regardless of the cover crop treatment, indicating the importance of implementing N management strategies to reduce N₂O emissions early in the growing season. Overall, these results show that CC selection and N fertilizer management can have significant impacts on sorghum productivity and N₂O emissions in no-till cropping systems.

This thesis is concerned with the UK agro-food system, and in particular the emergence of 'alternative strategies' ('AS') that seek to overcome, or at least circumvent, some of the problems associated with the globalised and industrialised practices on which it is based. Underlying the emergence of these 'AS' is the intention to reconnect the processes of food production and consumption in various ways, and to reconfigure the relationship between producers and consumers. Commercial imperatives remain important within 'AS', but they are overlain with social, cultural and ethical constructs that can significantly influence the motives of those involved, as illustrated by Fair Trade produce which seeks to introduce a sense of equity within the exchange process. This research focuses on the relationship between producers and consumers within the context of Farmers' Markets (FMs). FMs have been used as the portal for this purpose because they are considered to be an exemplar of how producer-consumer relations are being reconfigured within a concrete exchange context. FMs aim to re-locate production within specific localities and specific personal relationships, in an attempt to facilitate produce traceability and give food a sense of identity. In order to examine these emerging relationships, data were drawn from a questionnaire survey of FM managers across the UK, semi-structured interviews with producers and focus group discussions with consumers at five FMs in England. In the first instance the data were interpreted through the notion of 'embeddedness', which established that the exchange process at FMs is modified by social interaction within a localised setting. As this did not permit an explanation of aspects of the relationship that were clearly of value to the participants, but extraneous to their commercial evaluations, the data were also analysed within the notion of 'regard', which established that there were additional benefits to the producers and consumers at FMs, intrinsic to the human-level interaction between them. For example, producers sometimes felt personally valued for the effort they make to produce high-quality food produce. On this basis, it was possible to establish what distinguishes FMs as a retail outlet, in terms of how the producers and consumers relate to each other and to the produce available. In order to better understand the significance of these results within the wider agro-food system, they were subsequently assessed within Conventions Theory (CT). CT is based upon a number of conventions, of which the 'civic' and 'domestic' conventions are of particular relevance in this instance as they I are concerned, respectively, with the general societal benefits of a product, and the development of trust in a product on the basis of attachments to specific places or people. The concept of conventions enables an understanding of how the participants at a FM define the quality of the products to be exchanged between them. However, CT does not specifically address the benefits of regard and so this thesis proposes that a regard convention should be considered, which can specifically incorporate this aspect of quality evaluation. Each of the conventions of quality identified for FMs is the subject of ongoing negotiation, and the concept of a bubble of FM alterity is suggested as a means of understanding the durability of FMs as an 'AS', before their underlying integrity is breached and they cease to have a distinctive identity. In this context, the term bubble is used to convey flexibility and elasticity, whereas alterity means 'otherness' which implies an intention to produce change within the agro-food system.

Increases in agricultural intensification over the past century have resulted in significant alterations to the rural landscape across the Midwest. Pollinators are essential to sustain natural and managed ecosystems. They are vital for food production and their declines have been linked, in part, to a rise in intensive agricultural practices. There is a recognized need among numerous stakeholders to build sustainability into the management of agroecosystems to protect both the biotic and abiotic resources of these systems. The use of cover crops is gaining interest among agricultural producers for benefits such as improving water quality and soil health. Cover cropping systems have the potential to provide floral resources to pollinators and suppress problematic driver weeds. The overall objective of this study was to quantify the effects of cover crops on plant and pollinator biodiversity within agricultural systems. This study aimed to characterize the pollinator diversity indicative of the patchwork mosaic forest-agroecosystem of Crab Orchard National Wildlife Refuge; evaluate the roles cover crop treatments play in supporting pollinator diversity and weed suppression benefits in a conventionally managed system; and provide the basis of recommendations for sustainable weed suppression tactics and for enhancing the quality of pollinator habitat within agricultural systems.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. November 2016, Johannesburg. / Drought stress is one of the major limitations to crop production worldwide and has been predicted to become more severe in the future due to global climate change. Research has often been focused on genetic engineering to improve the tolerance of plants to abiotic and biotic stresses. Plant growth-promoting rhizobacteria (PGPR) are an alternative mechanism to improve the tolerance of plants to many stresses and is crucial for developing and third world countries. In this study, Helianthus annuus was inoculated with Pseudomonas koreensis and subjected to drought stress. The germination and growth characteristics, leaf water content, leaf electrolyte leakage and leaf area, substrate water content, phenolic compounds and proline concentration, root bacterial counts, as well as recovery and regrowth, were compared between uninoculated and inoculated plants. In addition, the phosphatase activity, siderophore and indole-3-acetic acid (IAA) production, as well as growth at -0.73 MPa was compared between P. koreensis and P. fluorescens. It was found that inoculated plants were significantly taller plants and had a larger leaf area; and had significantly higher phenolic and proline concentration and a higher colonised root surface under drought stress. However, inoculation negatively affected germination and chlorophyll fluorescence. These plants also had a lower substrate water content under drought stress. P. koreensis outperformed P. fluorescens in all parameters studied, except for growth under osmotic stress. It can be concluded that P. koreensis generally improves the drought stress tolerance of H. annuus, however, further investigations are needed to determine the reasons for some of the negative effects. / LG2017

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science, Johannesburg, South Africa 2017. / Fuelwood is still heavily relied upon by rural communities as a source of energy. The current levels of wood harvesting have been deemed unsustainable, with models predicting the local exhaustion of wood resources in most cases. However, wood depletion has generally not happened to the level of severity predicted by the models. This may partially due to under-accounting for coppice regeneration. Many savanna species that are harvested for fuelwood demonstrate strong coppicing ability, which allows for regrowth after a disturbance. This ability to regrow or coppice is a key functional trait which allows species to persist and survive in frequently disturbed environments. There is surprisingly limited knowledge about coppice dynamics in savanna trees and how managerial actions might influence the coppice response and production of savanna species. To address this problem, this study investigated the influence of four post-harvest treatments on various aspects of the coppice response of Terminalia sericea and Dichrostachys cinerea – two important savanna fuelwood species – in a field experiment. A total of 108 felled trees per species were exposed to one of four treatments, which were applied monthly for 12 months. The treatments were (1) Control – no coppice shoots were removed for 12 months, (2) Harvest – all coppice shots were removed monthly, (3) Single prune – the coppice shoot with the widest diameter was left on the stump, and (4) Usable – coppice shoots that reached a diameter of 2 cm were removed. The effect that these treatments had on the average diameter, length and cumulative number of coppice shoots produced per stump was compared. The measurements of diameter and length were used in developing allometric equations for the prediction of coppice shoot biomass. The predicted biomass produced through the study was compared across treatments to gain an understanding of how productivity could be influenced by management of coppice shoots. The mean shoot diameter, length, as well as cumulative number of coppice shoots produced per stump was higher in the single prune treatment for both species while the harvest treatment resulted in high numbers of coppice shoots but with low average diameter and length. Applying the growth rates of coppice shoots found in this study it can be assumed that unmanaged coppice shoots will take approximately 5.5 years to reach a preferred harvestable diameter of 4 cm, while single prune coppice shoots would take 3.3 years to reach the preferred harvestable diameter. Diameter had more of an influence on the predicted coppice biomass production of T. sericea while D. cinerea biomass prediction was more influenced by shoot length. However, only diameter was used to compare the prediction of coppice biomass with previously developed equations as these equations did not consider length for predicting biomass of different components of trees. From the derived models, the calculated biomass at the end of the study period as well as the calculated biomass produced through the year was greatest for the control treatment. The predicted dry shoot stem biomass at the harvestable diameter of 4 cm was 114.60 g for T. sericea and 95.88 g for D. cinerea. From the findings of this study it is clear that post-harvest management can be utilised to manipulate coppice response and biomass production. Keywords: Fuelwood; Coppice shoot; Post-harvest treatment; Diameter; Length; Biomass / LG2018

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2018. / The use of egusi melon in soup has been domesticated and egusi has predominantly been regarded as a secondary crop. The aim of this study was to evaluate the functional characteristics of egusi seed (Citrullus lanatus subsp mucosospermus) hydrocolloid and oil in instant egusi soup. An instant production of egusi soup by adding boiling water to an instant soup mix will promote the availability of this nutritious seed as a healthy meal option. Egusi oil was successfully extracted from egusi seed using supercritical carbon dioxide method. The percentage oil yield which measures the amount of oil derivable from egusi seed ranged from 46-53% w/w. There was a significant difference in the oil yield as pressure and temperature are increased at a constant CO2 flow rate of 30 g/h. The proximate composition of egusi oil was determined using standard AOAC method. The moisture contents were 1.3, 2.0 and 1.9% w/w, respectively for EO1 (60oC and 450 bar), EO2 (55oC and 600 bar) and EO3 (75oC and 600 bar). EO1 was significantly (p ≤ 0.05) lower in moisture content compared to EO2 and EO3. The fat content was 99.1% w/w (EO1), 98.3% w/w (EO2) and 98.9% w/w (EO3), with no significant difference in the three oil samples. The fatty acid composition was analyzed using gas chromatography. The fatty acid content of egusi oil was high in polyunsaturated and monounsaturated fatty acids, which was identified as linoleic (62%) and oleic (15%) acids. The saturated fatty acid (undecylic, myristic, palmitic and stearic) composition of egusi oil differed significantly (p ≤ 0.05) with EO1, having the lowest compared to EO2 and EO3. The index of atherogenicity (IA %) were significantly low 0.35, 0.38 and 0.38% w/w for EO1, EO2, and EO3, respectively. The thrombogenicity index (IT %) were 0.08, 0.09 and 0.09% w/w for EO1, EO2, and EO3, respectively with no significant difference. Peroxide Value (PV) measured using auto titrate Titrino plus, ranging from 11.60 for EO1 milliequivalents peroxide/kg to 12.60 for EO2 and 11.89 milliequivalents peroxide/kg for EO3. The oxidative stability index (OSI) was measured using Methrohm Rancimat at 120°C, expressed as the induction time of oxidation was 10.2, 11.5 and 5.3 h for EO1, EO2, and EO3, respectively, with E03 significantly higher than EO1 and EO2 (p ≤ 0.05). The iodine number, determined by AOAC direct titration method was high and ranged from 95 g/100 g for EO1 to 129 g/100 g for EO3, with EO3 being significantly high (p ≤ 0.05). The nutritional and functional properties of defatted egusi flour and hydrocolloid extracted using supercritical carbon dioxide extraction was also successfully achieved. Proximate analysis of defatted egusi (DEF) flour after supercritical extraction was carried out according to standard AOAC procedures. The moisture content of DEF ranged from 5.3 to 10.1% w/w, crude protein 48.3 to 60.4% w/w, crude fibre 3.4 to 4.5% w/w) and ash 5.3 to 6.8 % w/w). The protein content of defatted egusi flour differed significantly (p ≤ 0.05) between samples. The amino acid compositions of DEF showed glutamic acid had the highest concentration of 12.9, 11.8 and 9.8 mg/100 g for DEF1, DEF2, and DEF3, respectively with a significant difference (p ≤ 0.05) across the samples. In functionality, the water absorption and solubility index at a low temperature of 50oC ranged between 52.5 to 57.6% w/w and 68.0 to 73.3% w/w respectively for DEF1 to DEF3, which significantly differed between samples. The final viscosity of defatted egusi flour ranged from 126.7 to 126.3 cP, which differed significantly (p ≤ 0.05) between samples. Egusi flour is high in protein 60% w/w and carbohydrate 25% w/w was treated with hot water to extract its hydrocolloid. Functional properties of egusi hydrocolloid for the three defatted flour shows a stable emulsifier as the breakdown viscosity remained constant at (8.00 cP). Breakdown viscosity of egusi hydrocolloid confirmed its stability.

Esta dissertação de mestrado analisa as evidências de transformações sobre o uso do solo na região sudoeste do Estado do Rio Grande do Sul, especificamente na rodovia RSC-377 que conecta os municípios de São Francisco de Assis e Manoel Viana, a partir da categoria de análise da paisagem. Buscou-se compreender o aumento expressivo de áreas destinadas a lavoura de grãos em detrimento às da pecuária. Para o caminho metodológico foi realizado o levantamento histórico sobre a inserção da lavoura de grãos nos municípios, a partir de dados secundários, e entrevistas diretas com proprietários do trecho da RSC-377. As entrevistas buscavam identificar as percepções na paisagem sobre o avanço da lavoura e os consequentes efeitos desse processo no Pampa. As entrevistas foram realizadas mediante um questionário e buscavam elementos de marca e matriz, além da geração de ambiências com os produtores para conceber as novas intencionalidades existentes sobre esse tipo de produção. Concebe-se em trabalhos anteriores que o aumento das áreas de lavoura de grãos, especialmente da soja, é resultado da migração de produtores oriundos de outras regiões do estado do Rio Grande do Sul na região da Campanha, além também da aplicação do sistema de plantio direto. Os resultados foram obtidos através da percepção e das ambiências sobre a paisagem transformada. Constatou-se a necessidade de retomar a paisagem como conceito-chave para leituras do espaço geográfico, assim como na elaboração de documentos que visem aprimorar melhoramentos no modo como exploramos os recursos disponíveis no espaço. Superando a barreira de conceber a paisagem apenas como a forma que é visível. / This research analyzes the evidence of the changes about the use of the soil in the southwestern region of the Rio Grande do Sul state, specifically in RSC-377 highway that connects the cities of São Francisco de Assis and Manoel Viana, from the analysis category of landscape. It sought to understand the significant increase of areas for grain crops to the detriment of livestock. For the methodological approach was performed historical survey on the inclusion of grain crops in the municipalities, based on secondary data, and direct interviews with the owners of the stretch of RSC-377. The interviews sought to identify the perceptions in the landscape about the progress of agriculture and the resulting effects of this process in Pampa. The interviews were conducted through a questionnaire and sought elements of “marca” and “matriz”, besides the “geração de ambiências” with the producers to conceive the new intentions that exist about this type of production. It is conceived in previous studies that the increase of grain crop areas, especially soy, is a result of migration of producers from other regions of Rio Grande do Sul state in Campaign region, and also the application of no-tillage system. The results were obtained through the perception and the “ambiências” of the transformed landscape. It was found the need to resume the landscape as a key concept to perusal the geographical space, as well as on documents aiming to improve improvements in the way we explore the available resources in space. Overcoming the barrier of conceive the landscape only as the shape that is visible.

Orientador: José Eduardo Corá / Banca: Rogério Peres Soratto / Banca: Luís Reynaldo Ferraciú Alleoni / Banca: José Carlos Barbosa / Banca: Carlos Eduardo Angeli Furlani / Resumo: Em sistema de semeadura direta, os resíduos das culturas de entressafra são utilizados para protegerem a superfície do solo dos agentes erosivos e promoverem a ciclagem de nutrientes. O objetivo desse trabalho foi avaliar o efeito de sequências de culturas na quantidade, qualidade, decomposição e liberação de nutrientes dos resíduos vegetais de culturas de entressafra, bem como a cobertura do solo proporcionada pelos resíduos, na fertilidade do solo, nas frações particulada e associada aos minerais de C, nas substâncias húmicas do solo e na produtividade de milho e soja cultivados no verão, em região de clima tropical. O experimento foi conduzido em Jaboticabal, SP (48°15'22'' W e 21°18'58'' S), em um Latossolo Vermelho eutrófico. O delineamento experimental foi em faixas, com três repetições. Os tratamentos foram constituídos pela combinação de três sequências de culturas de verão (rotação soja-milho, monocultura de milho e monocultura de soja) com sete culturas de entressafra (milho, sorgo, girassol, crotalária, guandu, nabo forrageiro e milheto). O experimento foi iniciado em 2002 e o presente estudo se refere aos anos agrícolas 2008/2009 e 2009/2010. Avaliaram-se as quantidades de matéria seca e acúmulo de N, P, K, Ca, Mg e S pelas culturas de entressafra, bem como a dinâmica de decomposição e liberação dos nutrientes, por meio da utilização de sacolas de decomposição, com os seguintes períodos de avaliação: 15, 30, 60, 120 e 180 dias. A cobertura do solo foi avaliada após o manejo e ao final de cada ano agrícola. Amostras de solo foram coletadas nas camadas 0-10, 10-20 e 20-30 cm de profundidade em duas ocasiões, antes da semeadura das culturas de entressafra, em março, e de verão, em outubro, nos anos de 2008 e 2009. As amostras de solo foram submetidas às análises químicas para determinação dos teores... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In no-tillage system, the offseason crops residues are expected to maintain the soil covered in order to control soil erosion and to promote the nutrients cycling. The objective of this study was to evaluate the offseason crops dry matter quality and production, soil cover, residues decomposition and nutrient release and their effects on soil fertility, C content of humic substances, particulate and mineral associated organic matter fractions and summer maize and soybean yield. A field experiment has been carried out on a Rhodic Eutrudox at Jaboticabal, SP, Brazil (48°15'22'' W and 21°18'58'' S). A randomized split-block design with three replications was used. The treatments were the combination of three summer crops sequences (soybean-corn rotation, monoculture of corn and monoculture of soybean) with seven offseason crops (maize, grain sorghum, sunflower, sunn hemp, pigeon pea, oilseed radish and pearl millet). The cultivations started in 2002 and this study is related to 2008/2009 and 2009/2010 growing seasons. The offseason crops dry matter production and N, P, K, Ca, Mg and S accumulations were evaluated at management moment. The period of time to measure the residue decomposition and the nutrient release was 15, 30, 60, 120 and 180 days, using litter bags. The soil cover was evaluated after the offseason crops management and at the end of each growing season. The soil was sampled at 0-10, 10-20 and 20-30 cm soil depths in two occasions, before the offseason crops sowing, at March, and before the summer crops sowing, at October, in 2008 and 2009. Total organic C, pH, P, K, Ca, Mg and H+Al were determined in each soil samples. The soil samples obtained on October at 0-10 cm were submitted for physical and chemical organic matter fractionation, for particulate, mineral-associated, humic acid, fulvic acid and humin C content determination. The summer monoculture... (Complete abstract click electronic access below) / Doutor

Typescript (photocopy). / Digitized by Kansas Correctional Industries

The El Niño Southern Oscillation (ENSO), which refers to a coupling between equatorial Pacific Ocean and atmosphere anomalies, is a major source of interannual climate variability. Although it is fundamentally a tropical Pacific phenomena, both warm (El Niño) and cold (La Niña) events alter atmospheric circulations -- and subsequently temperature and precipitation patterns -- well into the mid- latitudes. Furthermore, both El Niño and La Niña have characteristic multi-year life cycles of sea surface temperature and zonal wind anomalies. The research in this thesis focuses on understanding whether the global teleconnections and multi-year evolution of El Niño and La Niña imposes a risk of synchronous or sequential crop failures relevant to global food production. In the first chapter, which focuses on maize, wheat and soy in the Americas, we analyze the dynamics underlying ENSO life cycles to illustrate which aspects of the system are most important for agriculture. In North America, the same-season teleconnections affecting soybean and maize have been well studied, but we demonstrate the importance of lagged soil moisture teleconnections for wheat in the southern Great Plains. In South America, peak ENSO sea surface temperature (SST) teleconnections are concurrent with, and therefore critical for, wheat and maize growing seasons while soil moisture memory in Argentina plays an important role during the soybean growing season In the second chapter we show how the teleconnections from chapter one lead to correlated crop production anomalies in North and South America. We estimate the magnitude of ENSO-induced Pan-American production anomalies and discuss how increasing crop harvesting frequency may affect Pan-American production variability. We find that ENSO-induced production anomalies are greatest for maize, with median anomalies of about 5% of Pan-American production. After broadly characterizing ENSO-induced production anomalies, we demonstrate that they are not static in time. Increasing crop harvesting frequency in Brazil has affected the correlated risks posed by ENSO to soybeans and maize. In the third chapter we expand our analysis of agriculturally relevant teleconnections to the greater Pacific Basin region, and move beyond observations into model simulations. In this chapter we propose a coherent framework for understanding how trans-Pacific ENSO teleconnections pose a correlated risk to crop yields in major agricultural belts of the Americas, Australia and China over the course of an ENSO life cycle. The potential for consecutive ENSO-induced yield anomalies is of particular interest in these major food producing areas, where modest changes in yield have significant effects on global markets. We demonstrate that ENSO teleconnections relevant for crop flowering seasons are the result of a single trans-Pacific circulation anomaly that develops in boreal summer and persists through the following spring. These trans-Pacific ENSO teleconnections are often (but not always) offsetting between major producing regions in the Americas and those in northern China or Australia. Multi-year La Niñas, however, only tend to force multi-year growing season anomalies in Argentina and Australia. In our final chapter we estimate of the relative contribution of major modes of climate variability to crop yield variability at the global scale. We consider the influence of not only ENSO, but also the Indian Ocean Dipole (IOD), tropical Atlantic variability (TAV) and the North Atlantic Oscillation (NAO). We find that modes of climate variability account for 18.4%, 7.4% and 5.4% of globally aggregated maize, soy and wheat production variability, respectively. All modes of variability are important in at least one region studied, but only ENSO has a significant influence on global production. The low fractions of global-scale soy and wheat production variability attributable to climate is a result of significant but offsetting ENSO-induced yield anomalies in major production regions. Our findings represent an observationally-derived limit on the importance of climate variability to crop production stability that is not dependent on the fidelity of present generation of climate or crop models. In terms of synchronous crop failures within a single harvest year, we find that ENSO poses a significant correlated risk to maize yields but that it has a much smaller effect on global wheat and soy production. ENSO-forced maize production anomalies offset less than wheat and soy at the global scale because production is concentrated in regions with same-sign yield anomalies, notably the United States and Southeast Africa. To illustrate this point, we show that ENSO is largely responsible for the largest synchronous maize failure in the post-1960 historical record. These results demonstrate how the distribution of global cropland in relation to ENSO teleconnections contributes significantly to the presence for maize or absence for wheat and soy of synchronous global crop failures