The effect of organic mulch amendments on the physical and chemical properties and revegetation success of a saline-sodic minespoil from central Queensland, Australia

Saline-sodic clay minespoil materials excavated during open-cut coal mining in central Queensland, Australia, pose significant challenges for revegetation, particularly where suitable topsoil capping is not available. We examined the ability of sawdust or straw mulch amendments to ameliorate the adverse properties of these minespoils and improve the success of revegetation efforts. In laboratory studies, mulch application improved infiltration, increased soil moisture retention and reduced surface crust strength. In the field, mulches incorporated to a depth of 0.15 m at application rates of at least 20 t/ha straw or 80 t/ha sawdust were needed to mitigate against capillary rise of salts during drying cycles and support satisfactory vegetation cover. Further research is needed to determine whether improvements are maintained beyond the 4-year trial period reported here.

Sorption characteristics of a nonionic surfactant during remediation of contaminated soil with different organic content

Surfactant enhanced subsurface remediation has gained importance in soil remediation. Since surfactants can be sorbed on soils, the concentration of free surfactant could drop below the critical micelle concentration, CMC, which may reduce the ability of the surfactant to solubilize the contaminants in soils. ^ The main goal of this research was to study the factors affecting the surfactant sorption on soil such as surfactant concentration, soil organic content, and organic contaminants in soil and to determine the organic contaminants removed from soils by surfactant. The results would be served as the basis for the implementation of a future study in the pilot scale and field scale for surfactant enhanced subsurface remediation. ^ This research study investigated the relationship between the organic content of soils and the sorption characteristics of a nonionic surfactant, Triton X-100. The experiments were performed using uncontaminated soils and soil contaminated with naphthalene and decane. The first part of the experiments were conducted in batch mode utilizing surface tension technique to determine the CMC of surfactant Triton X-100 and the effective CMC in the soil/aqueous system. The sorption of Triton X-100 was calculated from the surface tension measurements. The second part of the experiments utilized the SPME/GC/FID technique to determine the concentration of the contaminants solubilized from the soils by the surfactant Triton X-100 at different concentrations. ^ The results indicated that when the concentration of surfactant was lower than the CMC, the amount of surfactant sorbed on soil increased with the increasing surfactant concentration and the surfactant sorption characteristics of the uncontaminated soils could be modeled by the Freundlich isotherm. For the contaminated soils, the amount of surfactant sorbed was higher than those for the uncontaminated soils. The amount of surfactant sorbed on soils also depends on the organic content in the soils. The higher the organic content in the soil, higher is the amount of surfactant sorbed onto the soil. When the concentration of surfactant was higher than the CMC, the amount of surfactant added into the soil/aqueous system will increase the number of micelle and it increase the solubilization of organic contaminant from the soils. The ratio of the moles of organic contaminant solubilized to the moles of surfactant present as micelles is called the molar solubilization ratio (MSR). MSR value for naphthalene was about 0.16 for the soil-water systems. The organic content of soil did not appear to affect MSR for naphthalene. On the other hand, the MSR values for decane were 0.52, 0.39 and 0.38 for soils with 25%, 50% and 75% organic content, respectively. ^

German consumers' attitudes and preferences with regard to organic food and food from different origins

In dieser Studie geht es darum, ein umfassendes Bild bezüglich der Konsumenteneinstellungen, Präferenzen und Zahlungsbereitschaften für ökologisch produzierte Lebensmittel und Lebensmittel verschiedener Herkünfte in Deutschland zu erhalten. Obwohl die regionale Herkunft von Lebensmitteln nicht offiziell und einheitlich geregelt ist und keiner Zertifizierung unterliegt wie die ökologische Produktion von Lebensmitteln, zeigen nationale und internationale Studien gleichermaßen, dass Konsumenten bereit sind, mehr für regionale als für ökologisch produzierte Lebensmittel zu bezahlen. Zur Erreichung des Forschungsziels wurde ein Kaufexperiment in Kombination mit einer Konsumentenbefragung, bestehend aus Fragen zum generellen Einkaufsverhalten, zu Einstellungen gegenüber regionalen und ökologisch produzierten Lebensmitteln und zu soziodemographischen Informationen durchgeführt. Im Kaufexperiment wurden die Attribute Produktherkunft, Produktionsweise und Preis anhand vier verschiedener Produkte (Äpfel, Butter, Mehl und Steaks) untersucht. Die Befragung, einschließlich des Experimentes, war durch Interviewer eines Marktforschungsinstituts initiiert, computergestützt und von den Konsumenten selbständig zu erledigen. Das Ziel war es 80 Konsumenten in jedem der acht Befragungsorte in verschiedenen Regionen Deutschlands zu befragen. Zur Auswertung des Experiments wurden RPL-Modell geschätzt, die die Konsumentenpräferenzen für die zu untersuchenden Produktattribute aufzeigen und die Berechnung von Zahlungsbereitschaften ermöglichen. Für die Gesamtheit der Konsumenten war die regionale Herkunft von Lebensmitteln wichtiger als die ökologische Produktion. Außerdem wurden Produktalternativen, die aus der Region stammen, immer stärker präferiert als Produkte aus Deutschland, aus einem Nachbarland und einem außereuropäischen Land. Weiterhin zeigte die Studie, dass Konsumentenpräferenzen produkt- und regionsspezifisch sind. Folglich wird empfohlen, in zukünftigen Studien unterschiedlich Produkte bzw. Produktgruppen und Konsumenten verschiedener Regionen einzubeziehen. Die zunehmenden Präferenzen und Zahlungsbereitschaften der Konsumenten für regionale Lebensmittel deuteten sowohl in dieser Dissertation als auch in vielen anderen nationalen und internationalen Studien darauf hin, dass es ein großes Potential für einen regionalen Lebensmittelmarkt gibt. Aus diesem Grund wird Produzenten und Vermarktern von ökologischen sowie konventionellen Produkten empfohlen, verstärkt in die Entwicklung von regionalen Versorgungsketten zu investieren.

Analysis of the Market Potential of Syrian Organic Fruit and Vegetables for Exports to Germany

Syria has been a major producer and exporter of fresh fruit and vegetables (FFV) in the Arabic region. Prior to 2011, Syrian FFV were mainly exported to the neighbouring countries, the Gulf States and Northern Africa as well as to Eastern European countries. Although the EU is potentially one of the most profitable markets of high quality FFV (such as organic ones) in the world, Syrian exports of FFV to Western European countries like Germany have been small. It could be a lucrative opportunity for Syrian growers and exporters of FFV to export organic products to markets such as Germany, where national production is limited to a few months due to climatic conditions. Yet, the organic sector in Syria is comparatively young and only a very small area of FFV is certified according to EU organic regulations. Up to the author’s knowledge, little was known about Syrian farmers’ attitudes towards organic FFV production. There was also no study so far that explored and analysed the determining factors for organic FFV adoption among Syrian farmers as well as the exports of these products to the EU markets. The overarching aim of the present dissertation focused on exploring and identifying the market potential of Syrian exports of organic FFV to Germany. The dissertation was therefore concerned with three main objectives: (i) to explore if German importers and wholesalers of organic FFV see market opportunities for Syrian organic products and what requirements in terms of quality and quantity they have, (ii) to determine the obstacles Syrian producers and exporters face when exporting agricultural products to Germany, and (iii) to investigate whether Syrian farmers of FFV can imagine converting their farms to organic production as well as the underlying reasons why they do so or not. A twofold methodological approach with expert interviews and a farmer survey were used in this dissertation to address the abovementioned objectives. While expert interviews were conducted with German and Syrian wholesalers of (organic) FFV in 2011 (9 interviews each), the farmer survey was administrated with 266 Syrian farmers of FFV in the main region for the production of FFV (i.e. the coastal region) from November 2012 till May 2013. For modelling farmers’ decisions to adopt organic farming, the Theory of Planned Behaviour as theoretical framework and Partial Least Squares Structural Equation Modelling as the main method for data analysis were used in this study. The findings of this dissertation yield implications for the different stakeholders (governmental institutions and NGOs, farmers, exporters, wholesalers, etc.) who are interested in prompting the Syrian export of organic products. Based on the empirical results and a literature review, an action plan to promote Syrian production and export of organic products was developed which can help in the post-war period in Syria at improving the organic sector.

Previous land use and climate influence differences in soil organic carbon following reforestation of agricultural land with mixed-species plantings

Reforestation of agricultural land with mixed-species environmental plantings (native trees and shrubs) can contribute to mitigation of climate change through sequestration of carbon. Although soil carbon sequestration following reforestation has been investigated at site- and regional-scales, there are few studies across regions where the impact of a broad range of site conditions and management practices can be assessed. We collated new and existing data on soil organic carbon (SOC, 0–30 cm depth, N = 117 sites) and litter (N = 106 sites) under mixed-species plantings and an agricultural pair or baseline across southern and eastern Australia. Sites covered a range of previous land uses, initial SOC stocks, climatic conditions and management types. Differences in total SOC stocks following reforestation were significant at 52% of sites, with a mean rate of increase of 0.57 ± 0.06 Mg C ha−1 y−1. Increases were largely in the particulate fraction, which increased significantly at 46% of sites compared with increases at 27% of sites for the humus fraction. Although relative increase was highest in the particulate fraction, the humus fraction was the largest proportion of total SOC and so absolute differences in both fractions were similar. Accumulation rates of carbon in litter were 0.39 ± 0.02 Mg C ha−1 y−1, increasing the total (soil + litter) annual rate of carbon sequestration by 68%. Previously-cropped sites accumulated more SOC than previously-grazed sites. The explained variance differed widely among empirical models of differences in SOC stocks following reforestation according to SOC fraction and depth for previously-grazed (R2 = 0.18–0.51) and previously-cropped (R2 = 0.14–0.60) sites. For previously-grazed sites, differences in SOC following reforestation were negatively related to total SOC in the pasture. By comparison, for previously-cropped sites, differences in SOC were positively related to mean annual rainfall. This improved broad-scale understanding of the magnitude and predictors of changes in stocks of soil and litter C following reforestation is valuable for the development of policy on carbon markets and the establishment of future mixed-species environmental plantings.

Is land condition a useful indicator of soil organic carbon stock in Australia?

The grazing lands of northern Australia contain a substantial soil organic carbon (SOC) stock due to the large land area. Manipulating SOC stocks through grazing management has been presented as an option to offset national greenhouse gas emissions from agriculture and other industries. However, research into the response of SOC stocks to a range of management activities has variously shown positive, negative or negligible change. This uncertainty in predicting change in SOC stocks represents high project risk for government and industry in relation to SOC sequestration programs. In this paper, we seek to address the uncertainty in SOC stock prediction by assessing relationships between SOC stocks and grazing land condition indicators. We reviewed the literature to identify land condition indicators for analysis and tested relationships between identified land condition indicators and SOC stock using data from a paired-site sampling experiment (10 sites). We subsequently collated SOC stock datasets at two scales (quadrat and paddock) from across northern Australia (329 sites) to compare with the findings of the paired-site sampling experiment with the aim of identifying the land condition indicators that had the strongest relationship with SOC stock. The land condition indicators most closely correlated with SOC stocks across datasets and analysis scales were tree basal area, tree canopy cover, ground cover, pasture biomass and the density of perennial grass tussocks. In combination with soil type, these indicators accounted for up to 42% of the variation in the residuals after climate effects were removed. However, we found that responses often interacted with soil type, adding complexity and increasing the uncertainty associated with predicting SOC stock change at any particular location. We recommend that caution be exercised when considering SOC offset projects in northern Australian grazing lands due to the risk of incorrectly predicting changes in SOC stocks with change in land condition indicators and management activities for a particular paddock or property. Despite the uncertainty for generating SOC sequestration income, undertaking management activities to improve land condition is likely to have desirable complementary benefits such as improving productivity and profitability as well as reducing adverse environmental impact.

Mineral and organic pollution in river Sabor (Northeastern Portugal): ecotoxicological effects on freshwater fauna

Aquatic ecosystems are final collectors of all kinds of pollution as an outcome of anthropogenic inputs, such us untreated industrial and municipal sewage and agricultural pollutants. There are several aquatic ecosystems that are threatened by mineral and organic pollution. In Northeastern Portugal, near Bragança, different watercourses are suffering negative impacts of human activities. It has been developed several studies in the monitoring of environmental impacts in these river basins, namely in Rio Fervença, affected by organic pollution, and in Portelo stream, affected, since 2009, by the collapse and continuous input of mining deposits. In this sense, the present study aimed to continue the monitoring study of ecological status of freshwater ecosystems of Northeastern Portugal, namely the following objectives: a) mineral pollution effects of mining deposits sudden incorporated into Portelo stream; b) organic pollution due to domestic and industrial inputs in River Fervença. Also, since fish are useful experimental models to evaluate toxicological mechanisms of contaminants, c) acute toxicity tests with Cu were conducted in laboratory conditions. During 2015/2016, it was made abiotic and biotic characterization of 16 sampling sites distributed by both Portelo and Fervença rivers, tributaries of main River Sabor (Douro Basin). Several physicochemical parameters were determined and Riparian Quality (QBR Index) and Channel Quality (GQC) Indexes were determined for habitat evaluation. Fish and invertebrate communities were sampled, according to protocols of Water Framework Directive (WFD). Several metrics were determined, with particular emphasis on the Biotic Index IBMWP and the Northern Portuguese Invertebrate Index (IPtIN). Acute toxicity tests were conducted with an Iberian fish species, common barbel (Luciobarbus bocagei) and some plasmatic electrolytes levels were evaluated, to assess their contribution to mitigate osmoregulatory adverse effects of Cu. Also, same electrolytes were measured after changing to clean water, in attempt to assess fish capacity to reverse this situation. Results obtained for both rivers showed a significant level of disturbance that affected decisively water, habitat and biological quality of aquatic ecosystems. Mineral and Organic Pollution in River Sabor (NE Portugal): Ecotoxicological Effects on Freshwater Fauna Due to this change of environmental conditions in Portelo stream (extreme pH values, high conductivity and presence of heavy metals), several biological metrics (e.g. taxonomic richness, abundance, diversity, evenness) confirmed, comparatively with reference sites, a substantial decrease on ecological integrity status. The same pattern was found for Fervença River; however other water parameters, namely the content of most limiting nutrients (e.g. N and P) seemed to have more influence in the composition and structure of macroinvertebrate and fish communities. In fact, despite the operation of the Sewage Treatment Plant of Bragança, Fervença River presented significant levels of disturbance that affected decisively the quality and ecological integrity of the aquatic ecosystem. The synergic effect of domestic and industrial pollution, intensive agriculture, regulation and degradation of aquatic and riparian habitats contributed to the decrease of ecological condition, namely in the downstream zones (after Bragança). The results for acute toxicity, showed that fish can change Na+ and K+ levels face to Cu exposition and, depending of Cu concentration tested, can also return to normal levels, providing some insights to that are believed to occurred in fish population, near the Portelo mines. The low ecological integrity status detected in the lotic ecosystems in NE Portugal as a result of mineral and organic pollution deserves the development of several measures for rehabilitation and improving of water quality. On the other hand, environmental education actions are needed to contribute to improvement of ecological integrity of the river and its conservation.

FERTILISER CREDIT AND AGROECOLOGICAL USE OF ORGANIC SOIL AMENDMENTS IN NORTHERN GHANA

Contemporary African agricultural policy embodies the African Green Revolution’s drive towards modernisation and commercialisation. Agroecologists have criticised this movement on ecological, social and political grounds. Northern Ghanaian fertiliser credit schemes provide a good example through which these critiques can be examined in a context where agricultural policy reflects the African Green Revolution’s ideals. This study aimed to determine the relationship of such credit schemes to farmers’ use of organic amendments, elucidate other factors related to organic amendment use, and comment on the relevance of this modernisation policy and its relationship to agroecology. A first research phase employed semi-structured key informant interviews. Qualitative data from these informed construction of a semi-structured questionnaire that was used in a survey of 205 farmers. Multistage sampling purposively identified five villages and selected farmers within who had joined government and donor-funded fertiliser credit schemes. The use of organic and inorganic amendments was compared to that of peers who had not taken part in such schemes. Quantitative data were used in binomial logistic regression, inferential and descriptive statistics. Qualitative data were content analysed. Credit group membership was associated with higher fertiliser application and yield, but had little influence on the extent of commercialisation. Farmers who applied organic amendments were 40% less likely to belong to a fertiliser credit scheme than not, indicating substitution between organic and inorganic fertilisers. Organic amendments were 40% more likely to be applied to compound farms than outfields and six times more likely to be applied by household heads than other household members. However, household heads also preferentially joined credit groups. This was part of an agroecological soil fertility management strategy. Household heads appreciated the soil moisture retention properties of organic amendments, and applied them to compound farms to reduce risk to their household food supply in a semi-arid environment. They simultaneously accessed fertiliser to enhance this household provisioning strategy. They appreciated the increased yields this achieved, yet complained that the repayment terms of credit schemes were unfair, fertiliser did not enhance yields in dry conditions and fertilisers were supplied late. Farmers’ use of credited fertiliser alongside their existing agroecological strategy is helpful to the extent that it raises yields, yet is problematic in that it conflicts with risk-reduction strategies based on organics. There is some potential for modernised and agroecological management paradigms to coexist. For fertiliser credit to play a role in this, schemes must use fairer repayment terms and involve a focus on simultaneous use of organic amendments.

INFLUENCE OF A NATIVE INSECTARY PLANT, CHAMAECRISTA FASCICULATA (MICHX.) ON ORGANIC FIELD CORN AND ARTHROPOD COMMUNITIES

Increasing plant diversity in conventionally monoculture agrosystems has been promoted as a method to enhance beneficial arthropod density and efficacy, suppress herbivory and provide a range of ecosystem services. I investigated the pest suppressive potential and economic impact of plant diversification in organic field corn. The experiment consisted of two treatments, corn grown in monoculture (C) and bordered by strips of partridge pea (PP). Pest and natural enemy populations, corn damage, yield, and profits were compared among treatments. Natural enemy and herbivore arthropod populations were affected by treatment and distance from plot border. Corn damage due to pests was also affected by treatment and location, but did not significantly affect yield. Yield in monoculture plots was generally greater than in PP but did not result in greater profit. Pest and natural enemy arthropod abundances were elevated in partridge pea treatment borders, but these populations did not consistently diffuse into plot interiors. The potential causes and implications of findings are discussed.

Production Diseases in European Organic Dairy Farms – Current Status and Identification of Drivers for Improvement by Means of a Systemic Approach

The aims of this thesis were to determine the animal health status in organic dairy farms in Europe and to identify drivers for improving the current situation by means of a systemic approach. Prevalences of production diseases were determined in 192 herds in Germany, France, Spain, and Sweden (Paper I), and stakeholder consultations were performed to investigate potential drivers to improve animal health on the sector level (ibid.). Interactions between farm variables were assessed through impact analysis and evaluated to identify general system behaviour and classify components according to their outgoing and incoming impacts (Paper II-III). The mean values and variances of prevalences indicate that the common rules of organic dairy farming in Europe do not result in consistently low levels of production diseases. Stakeholders deemed it necessary to improve the current status and were generally in favour of establishing thresholds for the prevalence of production diseases in organic dairy herds as well as taking actions to improve farms below that threshold. In order to close the gap between the organic principle of health and the organic farming practice, there is the need to formulate a common objective of good animal health and to install instruments to ensure and prove that the aim is followed by all dairy farmers in Europe who sell their products under the organic label. Regular monitoring and evaluation of herd health performance based on reference values are considered preconditions for identifying farms not reaching the target and thus in need of improvement. Graph-based impact analysis was shown to be a suitable method for modeling and evaluating the manifold interactions between farm factors and for identifying the most influential components on the farm level taking into account direct and indirect impacts as well as impact strengths. Variables likely to affect the system as a whole, and the prevalence of production diseases in particular, varied largely between farms despite some general tendencies. This finding reflects the diversity of farm systems and underlines the importance of applying systemic approaches in health management. Reducing the complexity of farm systems and indicating farm-specific drivers, i.e. areas in a farm, where changes will have a large impact, the presented approach has the potential to complement and enrich current advisory practice and to support farmers’ decision-making in terms of animal health.

Soil quality assessment in conservation agriculture systems

Soil is a key resource that provides the basis of food production and sustains and delivers several ecosystems services including regulating and supporting services such as water and climate regulation, soil formation and the cycling of nutrients carbon and water. During the last decades, population growth, dietary changes and the subsequent pressure on food production, have caused severe damages on soil quality as a consequence of intensive, high input-based agriculture. While agriculture is supposed to maintain and steward its most important resource base, it compromises soil quality and fertility through its impact on erosion, soil organic matter and biodiversity decline, compaction, etc., and thus the necessary yield increases for the next decades. New or improved cropping systems and agricultural practices are needed to ensure a sustainable use of this resource and to fully take the advantages of its associated ecosystem services. Also, new and better soil quality indicators are crucial for fast and in-field soil diagnosis to help farmers decide on the best management practices to adopt under specific pedo-climatic conditions. Conservation Agriculture and its fundamental principles: minimum (or no) soil disturbance, permanent organic soil cover and crop rotation /intercropping certainly figure among the possibilities capable to guarantee sustainable soil management. The iSQAPER project – Interactive Soil Quality Assessment in Europe and China for Agricultural Productivity and Environmental Resilience – is tackling this problem with the development of a Soil Quality application (SQAPP) that links soil and agricultural management practices to soil quality indicators and will provide an easy-to-use tool for farmers and land managers to judge their soil status. The University of Évora is the leader of WP6 - Evaluating and demonstrating measures to improve Soil Quality. In this work package, several promising soil and agricultural management practices will be tested at selected sites and evaluated using the set of soil quality indicators defined for the SQAPP tool. The project as a whole and WP6 in specific can contribute to proof and demonstrate under different pedoclimatic conditions the impact of Conservation Agriculture practices on soil quality and function as was named the call under which this project was submitted.

Local Understandings of Soil Fertility, Rainfall and Conservation Agriculture in Laikipia, Kenya: A Qualitative Analysis.

Conservation Agriculture (CA) is mostly referred to in the literature as having three principles at the core of its identity: minimum soil disturbance, permanent organic soil cover and crop diversity. This farming package has been described as suitable to improve yields and livelihoods of smallholders in semi-arid regions of Kenya, which since the colonial period have been heavily subjected to tillage. Our study is based on a qualitative approach that followed local meanings and understandings of soil fertility, rainfall and CA in Ethi and Umande located in the semi-arid region of Laikipia, Kenya. Farm visits, 53 semistructured interviews, informal talks were carried out from April to June 2015. Ethi and Umande locations were part of a resettlement programme after the independence of Kenya that joined together people coming from different farming contexts. Since the 1970–80s, state and NGOs have been promoting several approaches to control erosion and boost soil fertility. In this context, CA has also been promoted preferentially since 2007. Interviewees were well acquainted with soil erosion and the methods to control it. Today, rainfall amount and distribution are identified as major constraints to crop performance. Soil fertility is understood as being under control since farmers use several methods to boost it (inorganic fertilisers, manure, terraces, agroforestry, vegetation barriers). CA is recognised to deliver better yields but it is not able to perform well under severe drought and does not provide yields as high as ‘promised’ in promotion campaigns. Moreover, CA is mainly understood as “cultivating with chemicals”, “kulima na dawa”, in kiswahili. A dominant view is that CA is about minimum tillage and use of pre-emergence herbicides. It is relevant to reflect about what kind of CA is being promoted and if elements like soil cover and crop rotation are given due attention. CA based on these two ideas, minimum tillage and use of herbicides, is hard to stand as a programme to be promoted and up-scaled. Therefore CA appears not to be recognised as a convincing approach to improve the livelihoods in Laikipia.