This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
Oats and the other small grains have been “rediscovered” with the drive towards intensifying agricultural production, integrating crops and livestock into diversified systems, and increasing environmental stewardship. Globally, oats and other winter annual small grains such as wheat, cereal rye, triticale, and barley, have been used primarily for grain production. The secondary market following grain production has been restricted to straw, used mainly as livestock bedding. In regions where livestock are economically important, oats and the other annual small grain crops can be used as a grazed forage or fodder crop, hay, or silage. There are several characteristics that make oats and other small grains suitable for multiple agricultural uses. All the small grains are fairly easy to establish, have rapid growth, can be productive, and have a high nutritional value for livestock. Recent improvements in cultivar development have allowed oats and wheat to be grown across a broader range of stressful environmental conditions. Similarly, cultivar development in oats and wheat has improved grazing tolerance, which is important in dual-purpose systems that emphasize both grazing and grain production. On a worldwide scale, oats and other annual small grains are economically and environmentally important forage crops, especially when used as focused components within intensified agricultural systems. Challenges include development of improved cultivars of oats and other small grains for use in intensified agricultural systems, including both grazing and no grazing, that serve as short rotation crops, dual-purpose crops, or are designed to mitigate a specific environmental issue.
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
Oil crops play a critical role in global food and energy systems. Major oil crops include rapeseed, soybean, oil palm, and sunflower. Since these crops have high oil content, they provide cooking oils for human consumption, biofuels for energy, feed for animals, and ingredients in beauty products and industrial processes. In 2014, oil crops occupied approximately 20% of crop-harvested area worldwide. While small-scale oil crop production for subsistence or local consumption continues in certain world regions, global demand for these versatile crops has led to substantial expansion of oil seed agriculture destined for export or urban markets. In particular, development of oil palm in Southeast Asia and soybeans in South America has been identified as major proximate causes of tropical deforestation. This expansion has diverse effects on the environment, including: loss of forests, savannas, and grasslands; greenhouse gas emissions; biodiversity decline; fire; altered water quality and hydrology; homogenization of agroecosystems; and regional climate change. While yield increases are touted as a solution to reducing rates of oil crop expansion into natural ecosystems, the higher profits that often accompany greater yields may actually encourage expansion. Moreover, oil crops are frequently good substitutes for one another and are therefore interlinked in today’s global markets. As a result, changes in oil seed production in one region may have substantial impacts on other crops and regions. Ensuring a sustainable supply of oil seed products to meet global demand remains a major challenge for agricultural companies, farmers, governments, and civil society.
In recent years, a number of food safety incidents in Europe and East Asia have led to concerns about threats to the environment and human health. In this context, the significance of a re-evaluation of risks with regards to food safety is essential, which includes re-visiting Western risk theories advanced by Ulrich Beck and Anthony Giddens. The dimensions of risks and food safety are four-fold.
First, major incidents, such as the disaster at the Fukushima nuclear plant in Japan in 2011 and the melamine crisis in China in 2008, have impacted the perception of food safety among consumers. These incidents led to fears of an increase of food safety incidents and to a collapse of trust in established brand products and technologies in post-industrial societies. It is necessary, therefore, to re-assess the risks of utilizing future-oriented technologies and mass food production systems.
Second, the use of genetically modified organisms in food products and the consumption of food additives have produced new food-related risks. This underlines the significance of risk assessment, in particular, as “reflexive modernization” requires individuals to familiarize themselves with new and possibly harmful food technologies and to assess, manage, and avoid risks on their own responsibility and on a highly personalized basis.
Third, various food-related incidents, such as the case of imported poisoned dumplings in Japan in 2008, have triggered the emergence of civil engagement in the form of consumer education initiatives. Both governmental and non-governmental initiatives stress the significance of locality, providence, and food heritage preservation as a way to ensure and maintain food safety and balanced nutritional habits. In other words, the notion of locality is linked to the desire to minimize the risk.
Fourth, poor individual eating habits, as self-imposed risks, have attracted scholarly attention. Food education initiatives in European and Asian nations seek to strengthen the culinary competence of individuals and embrace national staple foods and local food specialties at the same time. Efforts to provide adequate information about nutrition and to counter the rise of health conditions such as obesity and diabetes often coincide with a return to conservative gender perceptions and family values. This calls for new forms of culinary education that take the demands of working parents, individualized work schedules, and dining outside the home into consideration.
Jean-François Bissonnette and Rodolphe De Koninck
Plantation farming emerged as a large-scale system of specialized agriculture in the tropics under European colonialism, in opposition to smallholding subsistence agriculture. Despite large-scale plantations in the tropics, smallholdings have consistently formed the backbone of rural economies, to the extent that they have become the main producers of some of the former plantation crops. In the early 21st century, oil palm has become the third most important cash crop in the world in terms of area cultivated, largely due to the expansion of this crop in Malaysia and Indonesia. Although in these countries, oil palm is primarily cultivated in large plantations, smallholders cultivate a large share of the territory devoted to this crop. This is related to the programs set up by governments of Malaysia and Indonesia during the second half of the 20th century, to provide smallholders with land plots in capital intensive large-scale oil palm schemes. Despite the relative success encountered by these programs in both countries, policymakers have continued to insist on the development of private centrally managed large-scale plantations. Yet, smallholding family farming has remained the most resilient economic activity in rural areas of the tropics. This system has proven adaptive to environmental change and, given proper access to markets and capital, particularly responsive to market signals. Today, many small-holdings are still characterized by the diversity of crops cultivated, low use of chemical inputs, reliance on family labor, and high levels of ecological knowledge. These are some of the main factors explaining why small family farms have proven more efficient than large plantations and, in the long term, more economically and ecologically resilient. Yet, large-scale land acquisitions for monocrop production remain a current issue, highlighting the paradox of the latest stage of agrarian capitalism and of its persistent built-in disregard for environmental deterioration.
Soils, the Earth’s skin, are at the intersection of lithosphere, hydrosphere, atmosphere, and biosphere. The persistence of life on our planet depends on the maintenance of soils, as they constitute the biological engines of Earth. Human population has increased exponentially in recent decades, along with the demand for food, materials, and energy. These needs have caused a shift from a low-yield and improvised agriculture to a more productive, high-cost, and intensive one. However, soils are fragile ecosystems and require centuries to develop; thus, within the human timescale, they are not renewable. Modern agriculture, ever more intensive, suggests serious concern about the conservation of soil as living organism, of its capacity to perform the vast number of biochemical processes needed to complete the biogeochemical cycles of plant nutrients, such as nitrogen and phosphorus, crucial for crop primary production. Most practices related to intensive agriculture determine an over-exploitation of soils as living organisms, with deterioration even in the short-middle term of their biological properties, which cumulatively can be called “soil quality.” Recent trends turn towards styles of agriculture management that are more sustainable or conservative for soil quality.
In general, any anthropogenic exploitation of soils tends to disturb or divert them from a more “natural” development that, by definition, represents the best comparison term for measuring the relative shift from soil sustainability. The continuous degradation of soil health and quality due to abuse of land potentiality or intensive management has been occurring for decades. Soil microbiota, being “the biological engine of the Earth” provide pivotal services in the functioning of the soil ecosystem. Hence, management practices protecting soil microbial diversity and resilience should be pursued. Besides, any abnormal change in rate of innumerable biochemical soil processes, as mediated by microbial communities, may constitute an early and sensitive warning of soil homeostasis alteration and, therefore, may diagnose a possible risk for soil sustainability. Among the vast number of soil biochemical processes and related attributes (bioindicators) potentially able to assess the sustainable use of soils, those related to the mineralization or immobilization of major nutrients (C and N), including enzyme activity (functioning) and composition (community diversity) of microbial biomass, have paramount importance due to their centrality in soil metabolism. Comparing, in various pedoclimates, the impact of different agricultural factors (fertilization, tillage, etc.), under intensive and sustainable managements of soil microbial community, diversity and functioning by both classical and molecular soil quality indicators allow us to outline the most reliable biochemical soil attributes for assessing risky shifts from soil sustainability.
Beyond damage to rainfed agricultural and forestry ecosystems, soil erosion due to water affects surrounding environments. Large amounts of eroded soil are deposited in streams, lakes, and other ecosystems. The most costly off-site damages occur when eroded particles, transported along the hillslopes of a basin, arrive at the river network or are deposited in lakes. The negative effects of soil erosion include water pollution and siltation, organic matter loss, nutrient loss, and reduction in water storage capacity. Sediment deposition raises the bottom of waterways, making them more prone to overflowing and flooding. Sediments contaminate water ecosystems with soil particles and the fertilizer and pesticide chemicals they contain. Siltation of reservoirs and dams reduces water storage, increases the maintenance cost of dams, and shortens the lifetime of reservoirs. Sediment yield is the quantity of transported sediments, in a given time interval, from eroding sources through the hillslopes and river network to a basin outlet. Chemicals can also be transported together with the eroded sediments. Sediment deposition inside a reservoir reduces the water storage of a dam.
The prediction of sediment yield can be carried out by coupling an erosion model with a mathematical operator which expresses the sediment transport efficiency of the hillslopes and the channel network. The sediment lag between sediment yield and erosion can be simply represented by the sediment delivery ratio, which can be calculated at the outlet of the considered basin, or by using a distributed approach. The former procedure couples the evaluation of basin soil loss with an estimate of the sediment delivery ratio SDRW for the whole watershed. The latter procedure requires that the watershed be discretized into morphological units, areas having a constant steepness and a clearly defined length, for which the corresponding sediment delivery ratio is calculated. When rainfall reaches the surface horizon of the soil, some pollutants are desorbed and go into solution while others remain adsorbed and move with soil particles. The spatial distribution of the loading of nitrogen, phosphorous, and total organic carbon can be deduced using the spatial distribution of sediment yield and the pollutant content measured on soil samples. The enrichment concept is applied to clay, organic matter, and all pollutants adsorbed by soil particles, such as nitrogen and phosphorous. Knowledge of both the rate and pattern of sediment deposition in a reservoir is required to establish the remedial strategies which may be practicable. Repeated reservoir capacity surveys are used to determine the total volume occupied by sediment, the sedimentation pattern, and the shift in the stage-area and stage-storage curves. By converting the sedimentation volume to sediment mass, on the basis of estimated or measured bulk density, and correcting for trap efficiency, the sediment yield from the basin can be computed.
Soils are the complex, dynamic, spatially diverse, living, and environmentally sensitive foundations of terrestrial ecosystems as well as human civilizations. The modern, environmental study of soil is a truly young scientific discipline that emerged only in the late 19th century from foundations in agricultural chemistry, land resource mapping, and geology. Today, little more than a century later, soil science is a rigorously interdisciplinary field with a wide range of exciting applications in agronomy, ecology, environmental policy, geology, public health, and many other environmentally relevant disciplines. Soils form slowly, in response to five inter-related factors: climate, organisms, topography, parent material, and time. Consequently, many soils are chemically, biologically, and/or geologically unique. The profound importance of soil, combined with the threats of erosion, urban development, pollution, climate change, and other factors, are now prompting soil scientists to consider the application of endangered species concepts to rare or threatened soil around the world.
Gary Sands, Srinivasulu Ale, Laura Christianson, and Nathan Utt
Agricultural (tile) drainage enables agricultural production on millions of hectares of arable lands worldwide. Lands where drainage or irrigation (and sometimes both) are implemented, generate a disproportionately large share of global agricultural production compared to dry land or rain-fed agricultural lands and thus, these water management tools are vital for meeting the food demands of today and the future. Future food demands will likely require irrigation and drainage to be practiced on an even greater share of the world’s agricultural lands. The practice of agricultural drainage finds its roots in ancient societies and has evolved greatly to incorporate modern technologies and materials, including the modern drainage plow, plastic drainage pipe and tubing, laser and GPS-guided installation equipment, and computer-aided design tools. Although drainage brings important agricultural production and environmental benefits to poorly drained and salt-affected arable lands, it can also give rise to the transport of nutrients and other constituents to downstream waters. Other unwanted ecological and hydrologic environmental effects may also be associated with the practice. The goal of this article is to familiarize the reader with the practice of subsurface agricultural drainage, the history and extent of its application, and the benefits commonly associated with it. In addition, environmental effects associated with subsurface drainage including hydrologic and water quality effects are presented, and conservation practices for mitigating these unwanted effects are described. These conservation practices are categorized by whether they are implemented in-field (such as controlled drainage) versus edge-of-field (such as bioreactors). The literature cited and reviewed herein is not meant to be exhaustive, but seminal and key literary works are identified where possible.
Luis Santos Pereira
Surface irrigation is the oldest and most-used irrigation method and is used on more than 83% of the world's irrigated area. It comprises traditional systems, developed over millennia, and modern systems with mechanized and often-automated water application, adopting precise land leveling. It adapts well to non-sloping conditions, low- to medium-soil infiltration characteristics, most crops and crop mechanization, as well as environmental conditions. Modern methods provide for water and energy saving, control of environmental impacts, labor saving, and cropping economic success—thus competing with pressurized irrigation methods. Surface irrigation refers to a variety of gravity applications of the irrigation water that infiltrates into the soil while flowing over the field surface. The ways and timings of how water flows over the field and is infiltrating the soil determines the irrigation phases—advance, maintenance, or ponding; depletion and recession—which vary with the irrigation method, namely, paddy basin, leveled basin, border, and furrow irrigation generally used for field crops; and wild flooding and water spreading from contour ditches, yet used for pasture lands. System performance is commonly assessed using the distribution uniformity indicator while management performance is assessed with the application efficiency or the beneficial water use fraction. The factors influencing system performance are multiple and interacting—inflow rate, field length and shape, soil hydraulics roughness, field slope, soil infiltration rate, and cutoff time—while management performance, in addition to these factors, highly depends upon the soil water deficit at time of irrigation, thus on the way that farmers are able to manage irrigation. The process of surface irrigation is complex to describe because it combines the surface flow process with the process of infiltration into the soil profile. Numerous mathematical computer models, therefore, have been developed for its simulation aimed at both design adopting a target performance and field evaluation of actual performance. The use of models in design allows the consideration of the factors referred to before and, when adopting any type of decision support system or multi-criteria analysis, to also take into consideration economic and environmental constraints and issues.
There are various aspects favoring and limiting the adoption of surface irrigation. Favorable aspects include the simplicity of its adoption at farm in flat lands with low infiltration rates, namely, when water conveyance and distribution are performed with canal and low-pressure pipe systems, low-capital investment, and low-energy consumption. Most significant limitations include high-soil infiltration and high variability of infiltration throughout the field, land leveling requirements, need for control of a constant inflow rate, difficulties in matching irrigation time duration with soil water deficit at time of irrigation, and difficult access to equipment for mechanized and automated water application and distribution. The modernization of surface irrigation systems and design models, as well as models and instruments usable to support surface irrigation management, have significantly impacted water use and productivity, and thus the competitiveness of surface irrigation.
Coffee is an extremely important agricultural commodity, produced in about 80 tropical countries, with an estimated 125 million people depending on it for their livelihoods in Latin America, Africa, and Asia, with an annual production of about nine million tons of green beans. Consisting of at least 125 species, the genus Coffea L. (Rubiaceae, Ixoroideae, Coffeeae) is distributed in Africa, Madagascar, the Comoros Islands, the Mascarene Islands (La Réunion and Mauritius), tropical Asia, and Australia. Two species are economically important for the production of the beverage coffee, C. arabica L. (Arabica coffee) and C. canephora A. Froehner (robusta coffee). Higher beverage quality is associated with C. arabica. Coffea arabica is a self-fertile tetraploid, which has resulted in very low genetic diversity of this significant crop. Coffee genetic resources are being lost at a rapid pace due to varied threats, such as human population pressures, leading to conversion of land to agriculture, deforestation, and land degradation; low coffee prices, leading to abandoning of coffee trees in forests and gardens and shifting of cultivation to other more remunerative crops; and climate change, leading to increased incidence of pests and diseases, higher incidence of drought, and unpredictable rainfall patterns. All these factors threaten livelihoods in many coffee-growing countries.
The economics of coffee production has changed in recent years, with prices on the international market declining and the cost of inputs increasing. At the same time, the demand for specialty coffee is at an all-time high. In order to make coffee production sustainable, attention should be paid to improving the quality of coffee by engaging in sustainable, environmentally friendly cultivation practices, which ultimately can claim higher net returns.