Daycent is a biogeochemical model of agroecosystems, simulating fluxes of carbon and nitrogen between the atmosphere, vegetation, and soil. [1] It is a daily time series version of the CENTURY biogeochemical model.
The United States Environmental Protection Agency, United States Department of Agriculture/ARS and the Colorado State University Natural Resource Ecology Lab are currently using the Daycent model to develop a national inventory of N2O emissions from U.S. agricultural soils. This inventory will be compared and contrasted with the existing Intergovernmental Panel on Climate Change (IPCC) agricultural N2O emissions inventory for the United States. [2] [3] Having more accurate data to account for nutrient cycling could have significant implications for public policy associated with the United Nations Framework Convention on Climate Change (UNFCCC) and potential future mitigation efforts in the United States. [4]
Model inputs include daily minimum and maximum air temperature and precipitation, surface soil texture class, and land cover/use data. Model outputs include daily fluxes of various N-gas species (e.g., N2O, NOx, N2); daily CO2 flux from heterotrophic soil respiration; soil organic C and N; net primary productivity; daily water and nitrate (NO3) leaching, and other ecosystem parameters. Daycent has been tested using data from various native and managed systems. [5] [6] [7] [8] In similar studies, comparisons between Daycent simulated data and measured values for annual crop yields, N2O emissions, and NO3 leaching produced r2 values of 0.72, 0.68, and 0.61 respectively. [9]
Other models used for simulating carbon and nitrogen biogeochemistry in agricultural systems include
Global warming potential (GWP) is an index to measure how much infrared thermal radiation a greenhouse gas would absorb over a given time frame after it has been added to the atmosphere. The GWP makes different greenhouse gases comparable with regard to their "effectiveness in causing radiative forcing". It is expressed as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide, which is taken as a reference gas. Therefore, the GWP has a value of 1 for CO2. For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered.
Nitrous oxide, commonly known as laughing gas, nitrous, factitious air, among others, is a chemical compound, an oxide of nitrogen with the formula N
2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen.
Miscanthus × giganteus, also known as the giant miscanthus, is a sterile hybrid of Miscanthus sinensis and Miscanthus sacchariflorus. It is a perennial grass with bamboo-like stems that can grow to heights of 3–4 metres (13 ft) in one season. Just like Pennisetum purpureum, Arundo donax and Saccharum ravennae, it is also called elephant grass.
Livestock's Long Shadow: Environmental Issues and Options is a United Nations report, released by the Food and Agriculture Organization (FAO) of the United Nations on 29 November 2006, that "aims to assess the full impact of the livestock sector on environmental problems, along with potential technical and policy approaches to mitigation". It stated that livestock accounts for 18% of anthropogenic greenhouse gas emissions, a figure which FAO changed to 14.5% in its 2013 study Tackling climate change through livestock.
In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss. Leaching may also refer to the practice of applying a small amount of excess irrigation where the water has a high salt content to avoid salts from building up in the soil. Where this is practiced, drainage must also usually be employed, to carry away the excess water.
The environmental impact of agriculture is the effect that different farming practices have on the ecosystems around them, and how those effects can be traced back to those practices. The environmental impact of agriculture varies widely based on practices employed by farmers and by the scale of practice. Farming communities that try to reduce environmental impacts through modifying their practices will adopt sustainable agriculture practices. The negative impact of agriculture is an old issue that remains a concern even as experts design innovative means to reduce destruction and enhance eco-efficiency. Animal agriculture practices tend to be more environmentally destructive than agricultural practices focused on fruits, vegetables and other biomass. The emissions of ammonia from cattle waste continue to raise concerns over environmental pollution.
Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.
Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance. It includes soil conservation, soil amendment, and optimal soil health. In agriculture, some amount of soil management is needed both in nonorganic and organic types to prevent agricultural land from becoming poorly productive over decades. Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control.
Greenhouse gas emissions from wetlands of concern consist primarily of methane and nitrous oxide emissions. Wetlands are the largest natural source of atmospheric methane in the world, and are therefore a major area of concern with respect to climate change. Wetlands account for approximately 20–30% of atmospheric methane through emissions from soils and plants, and contribute an approximate average of 161 Tg of methane to the atmosphere per year.
Climate-friendly gardening is a form of gardening that can reduce emissions of greenhouse gases from gardens and encourage the absorption of carbon dioxide by soils and plants in order to aid the reduction of global warming. To be a climate-friendly gardener means considering both what happens in a garden and the materials brought into it as well as the impact they have on land use and climate. It can also include garden features or activities in the garden that help to reduce greenhouse gas emissions through processes not directly related to gardening.
Soil compaction, also known as soil structure degradation, is the increase of bulk density or decrease in porosity of soil due to externally or internally applied loads. Compaction can adversely affect nearly all physical, chemical and biological properties and functions of soil. Together with soil erosion, it is regarded as the "costliest and most serious environmental problem caused by conventional agriculture."
Dr. C. Vernon Cole was a soil scientist known primarily for his work on nutrient cycling in agroecosystems. He was a member of Working Group II of the Intergovernmental Panel on Climate Change (IPCC) Second Assessment report, and the lead author of Chapter 23 “Agricultural Options for Mitigation of Greenhouse Gas Emissions”. The IPCC was awarded the Nobel Peace Prize in 2007.
Elizabeth Pattey is a principal research scientist at Agriculture and Agri-Food Canada (AAFC) and the leader of the micrometeorology laboratory at the Ottawa Research and Development Centre. Her research supports nationwide improvement in the environmental performance of agriculture, in support of the United Nations' Framework Convention on Climate Change and Canada’s Clean Air Act. She is the co-author for over 80 peer-reviewed scientific publications, and her areas of expertise include trace gas flux measurement techniques, process-based models, and remote-sensing applications.
Urine patches in cattle pastures generate large concentrations of the greenhouse gas nitrous oxide through nitrification and denitrification processes in urine-contaminated soils. Over the past few decades, the cattle population has increased more rapidly than the human population. Between the years 2000 and 2050, the cattle population is expected to increase from 1.5 billion to 2.6 billion. When large populations of cattle are packed into pastures, excessive amounts of urine soak into soils. This increases the rate at which nitrification and denitrification occur and produce nitrous oxide. Currently, nitrous oxide is one of the single most important ozone-depleting emissions and is expected to remain the largest throughout the 21st century.
Carbon farming is a set of agricultural methods that aim to store carbon in the soil, crop roots, wood and leaves. The technical term for this is carbon sequestration. The overall goal of carbon farming is to create a net loss of carbon from the atmosphere. This is done by increasing the rate at which carbon is sequestered into soil and plant material. One option is to increase the soil's organic matter content. This can also aid plant growth, improve soil water retention capacity and reduce fertilizer use. Sustainable forest management is another tool that is used in carbon farming. Carbon farming is one component of climate-smart agriculture. It is also one way to remove carbon dioxide from the atmosphere.
Raymond L. Desjardins is a senior research scientist at Agriculture and Agri-Food Canada (AAFC) in the Agrienvironment Division of the Ottawa Research and Development Centre. His areas of expertise include agricultural meteorology, micrometeorology, air quality, and climate change. He is a Fellow of the Royal Society of Canada, was co-recipient of the Nobel Peace Prize awarded to the Intergovernmental Panel on Climate Change (IPCC) in 2007, and in 2018 was appointed as Member of the Order of Canada for his research in agrometeorology and for his innovative devices to quantify greenhouse gas (GHG) emissions.
Climate-smart agriculture (CSA) is a set of farming methods that has three main objectives with regards to climate change. Firstly, they use adaptation methods to respond to the effects of climate change on agriculture. Secondly, they aim to increase agricultural productivity and to ensure food security for a growing world population. Thirdly, they try to reduce greenhouse gas emissions from agriculture as much as possible. Climate-smart agriculture works as an integrated approach to managing land. This approach helps farmers to adapt their agricultural methods to the effects of climate change.
The amount of greenhouse gas emissions from agriculture is significant: The agriculture, forestry and land use sectors contribute between 13% and 21% of global greenhouse gas emissions. Emissions come from direct greenhouse gas emissions. And from indirect emissions. With regards to direct emissions, nitrous oxide and methane makeup over half of total greenhouse gas emissions from agriculture. Indirect emissions on the other hand come from the conversion of non-agricultural land such as forests into agricultural land. Furthermore, there is also fossil fuel consumption for transport and fertilizer production. For example, the manufacture and use of nitrogen fertilizer contributes around 5% of all global greenhouse gas emissions. Livestock farming is a major source of greenhouse gas emissions. At the same time, livestock farming is affected by climate change.