Background: Climate-smart agriculture (CSA) addresses the challenge of meeting the growing demand for food, fibre and fuel, despite the changing climate and fewer opportunities for agricultural expansion on additional lands. CSA focuses on contributing to economic development, poverty reduction and food security; maintaining and enhancing the productivity and resilience of natural and agricultural ecosystem functions, thus building natural capital; and reducing trade-offs involved in meeting these goals. Current gaps in knowledge, work within CSA, and agendas for interdisciplinary research and science-based actions identified at the 2013 Global Science Conference on Climate-Smart Agriculture (Davis, CA, USA) are described here within three themes: (1) farm and food systems, (2) landscape and regional issues and (3) institutional and policy aspects. The first two themes comprise crop physiology and genetics, mitigation and adaptation for livestock and agriculture, barriers to adoption of CSA practices, climate risk management and energy and biofuels (theme 1); and modelling adaptation and uncertainty, achieving multifunctionality, food and fishery systems, forest biodiversity and ecosystem services, rural migration from climate change and metrics (theme 2). Theme 3 comprises designing research that bridges disciplines, integrating stakeholder input to directly link science, action and governance.
The slow reaction of phosphate with aggregated particles of ferrihydrite, after initial rapid phosphate sorption, was investigated by measuring the changes, with time and temperature, in the amount of phosphate sorbed, and the extractability of the sorbed phosphate. The ferrihydrite was, subsequently, recovered and examined by infra-red spectrometry (IR) and electron probe micro-analysis.Phosphate continued to react with ferrihydrite for at least 90d at 2 5 T , but was completely recovered by extraction with 0.1 M NaOH. The IR spectra of sorbed phosphate was insensitive to the temperature and duration of the reaction. Electron probe microanalysis of the aggregates showed that phosphate migrated to surface sorption sites within the aggregated particles of ferrihydrite.There was no evidence for the formation of surface coatings of ferric phosphate, for changes in the type of bonding, or for penetration of phosphate into the crystal lattice. The slow reaction was attributed to the migration of phosphate to surface sorption sites of decreasing accessibility within aggregates.
The effects of fire on the cryptogam cover and physical and micromorphological properties of a massive red earth soil were studied in a semi-arid eucalypt woodland, heavily invaded by shrubs, near Coolabah, N.S.W. Fire reduced the cryptogam cover and concomitantly increased the depositional material produced by erosion and the area of bare surface. Annual fires for 7 years completely destroyed the cryptogamic crusts, but they recovered slowly in the absence of fire to reach the same cover as unburnt areas after about 4 years. A single fire also caused a major decline in aggregate stability of the 0-1 cm horizon, possibly because of alteration of organic cementing materials which consist of gels secreted by algae. Micromorphological observations of surface crusts showed that, as the frequency of fire increased, there was more depositional material produced by erosion coupled with the presence of thin laminated deposits. There was also less surface irregularity, fewer algal gels and less evidence of soil mixing by soil fauna. There was a significant negative relationship between the saturated infiltration rate and the number of fires (r2 = 0.63, P = 0.05). However, there was no effect of fire treatment on the unsaturated infiltration rate measured at a supply pressure of -40 mm, at which pores >0.75 mm diameter are excluded from water flow. In our burned plots, the rate of recolonization by cryptogams was relatively fast and, with approximately 4 years recovery, cryptogam cover reached the level of unburned controls. This cryptogam cover is critical in maintaining the physical properties of the soil. It is concluded, therefore, that irregular fires in this land system will not result in a permanent decline in the physical properties of the soil.
Considering extreme events of climate change and declining availability of appropriate quality water and/or highly productive soil resources for agriculture in dryland regions, the need to produce more food, forage and fibre will necessitate the effective utilization of marginal‐quality water and soil resources. Recent research and practices have demonstrated that effective utilization of these natural resources in dry areas can improve agricultural productivity per unit area and per unit water applied. This paper focuses on the following three case studies as examples: (1) low productivity soils affected by high levels of magnesium in soil solution and on the cation exchange complex; (2) degraded sandy soils under rainfed conditions characterized by low water‐holding capacity, organic matter and clay content and (3) abandoned irrigated soils with elevated levels of salts inhibiting growth of income generating crops. The results of these studies demonstrate that application of calcium‐supplying phosphogypsum to high‐magnesium soils, addition of clays to light textured degraded soils and phytoremediation of abandoned salt‐affected soils significantly improved productivity of these soils. Furthermore, under most circumstances, these interventions were economically viable, revealing that the efficient use of marginal‐quality water and soil resources has the potential to improve livelihoods amid growing populations in dry areas while reversing the natural resource degradation trend. However, considerably more investment and policy‐level interventions are needed to tackle soil degradation/remediation issues across both irrigated and dryland agricultural environments if the major challenge of producing enough food, forage and fibre is to be met. Copyright © 2011 John Wiley & Sons, Ltd.
Feeding over 9 billion people by the second half of this century will require a major paradigm shift in agricultural systems. Agriculture uses approximately 40 % of the terrestrial surface, is the major user of fresh water resources and contributes 17%of greenhouse gas emissions. In turn, agriculture will be detrimentally affected by climate change in many climatic regions. Impacts of agriculture on ecosystem services include land clearing, loss of forest cover and biodiversity, significant soil degradation and water quality decline. Agricultural production will have to increase, even if we can reduce the rate of increase in demand for food. Given the current pressures on natural resources, this will have to be achieved by some form of agricultural intensification that causes less environmental impact. Therefore, it is not just intensification of agriculture, but ‘sustainable intensification’ that must be at the forefront of the paradigmshift. There is also a need to assess the situation holistically, taking into account population growth and resource intensive consumption patterns, improved systems of governance, changing diets and reducing waste. We review how and where natural resources are being placed under increasing pressure and examine the Becological footprint^ of agriculture. Suggested solutions include the application of existing scientific knowledge, implementation of emerging principles for sustainable land and water management and reclamation of salinized land. Encouragement of community action and private sector supply chain and production codes, backed up by improved national and regional governance and regulation also need to be encouraged if we are to see agricultural production become truly sustainable
Conventional soil mapping is limited in its capabilities in that it presents a summary of the soil surveyor's conceptual view of soil variation. As such, the method conveys little regarding what is known about the variation of individual soil properties, or the quantitative nature of their variation. We developed a new method for soil mapping, based on the concepts employed in the PROSPECTOR mineral exploration system, which builds on existing soil surveyor knowledge to construct quantitative statements about individual soil properties via the development of a network of rules. These rules operate within a system of Bayesian inference to assign the varying probability of occurrence of a soil property of interest within an area, given evidence that relates to it in a known way. Permissible evidence includes the range of attributes normally used by a soil surveyor, such as landform, vegetation, land use, or parent material, and can also include remotely sensed digital data. Evidence is weighted according to the uncertainty associated with it, and combined to produce a single estimate of probability of a given attribute. The relationship between the evidence and prediction is stated explicitly at each stage of the procedure and is thus repeatable in a consistent manner. The system has the advantage that while it does not discard the evidence and knowledge used in conventional soil survey, it produces quantitative estimates of the distribution of soil properties, which can be used for a wide range of applications. The data produced is amenable to storage in geographic information systems and related data bases. As such, it can be updated or enhanced as new information or knowledge becomes available.
The effect of treatment with either gypsum or sodium chloride on the saturated hydraulic conductivity (K,) of repacked soil columns and modulus of rupture (MOR) was studied on surface samples of two red-brown earth soils from SE wheat belt in Australia.When the exchangeable sodium percentage (ESP) of the two soils was increased to > 80, K, was substantially reduced and MOR increased relative to the untreated soil; the values of the parameters were nearly equal for these pairs of high ESP soils. However, after treatment with gypsum the Raywood soil had a K, twice, and a MOR less than half, the corresponding values for the Glenloth soil.Micromorphological and scanning electron microscope (SEM) observations suggest that the increase in K, following gypsum treatment is associated with an increase in visible macropores and reduced clay dispersion; Na treatment increased dispersion at the soil surface, with the clay particles forming an impermeable surface seal and illuviation argillans.
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