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Soil regeneration, as a particular form of ecological regeneration within the field of restoration ecology, is creating new soil and rejuvenating soil health by: minimizing the loss of topsoil, retaining more carbon than is depleted, boosting biodiversity, and maintaining proper water and nutrient cycling. [1] This has many benefits, such as: soil sequestration of carbon in response to a growing threat of climate change, [2] [3] a reduced risk of soil erosion, [3] and increased overall soil resilience. [1]
Soil quality means the ability of the soil to "perform its functions." [4] Soil is integral to a variety of ecosystem services. These services include food, animal feed, and fiber production, climate moderation, waste disposal, water filtration, elemental cycling, [1] and much more. Soil is composed of organic matter (decomposing plants, animals, and microbes), biomass (living plants, animals, and microbes), water, air, minerals (sand, silt, and clay), and nutrients (nitrogen, carbon, phosphorus). [4] For optimal plant growth, a proper carbon to nitrogen ratio of 20–30:1 must be maintained. [3] Promoting biodiversity is key to maintaining healthy soil. [5] This can be done by growing a variety of plants, always keeping soil covered, maintaining a living root system, and minimizing soil disturbance. [5] Macro and micro organisms assist with processes such as decomposition, nutrient cycling, disease suppression, and moderating CO2 in the atmosphere. [1] Plants have a particularly symbiotic relationship with microbes in the rhizosphere of the soil. [5] The rhizosphere is an "area of concentrated microbial activity close to the root" and where water and nutrients are readily available. [5] Plants exchange carbohydrates for nutrients excreted by the microbes, different carbohydrates support different microbes. [5] Dead plants and other organic matter also feed the variety of organisms in the soil. [5] Organisms like earthworms and termites are examples of macro organisms in the soil. [1] A good indication that you have quality soil is a lack of pests and diseases. [1] Low biodiversity increases the risk of pests and diseases. [5]
Having too much or too little of any of the components of soil can cause soil degradation. For example, having a high clay content reduces aeration and water permeability. [3] Another example is that, though phosphorus and nitrogen are essential for plant growth, they are toxic in high amounts. [3] Soil degradation means that soil quality has diminished, which causes ecosystem functions to decline. [1] One third of the globe's land has degraded soil; [1] especially the tropics and subtropics with around 500 million hectares. [1] Soil degradation occurs due to physical, chemical, and biological forces. [5] These forces can be natural and anthropogenic. [5] [1] Tilling is a physical example which causes erosion, compaction, and decreased microbial activity. [5] Erosion is “one of the most serious problems facing urban soil quality", [4] and the problem is exacerbated by uncovered soil. [4] Compaction occurs when soil is pushed together and becomes harder, so the ability to retain air and water is diminished. [4] This increases erosion and flooding, diminishes the ability of plants to grow good root systems, and reduces biological diversity. [4] Overgrazing is another example in which the root system beneath the soil is damaged, reducing water permeability. [5] Acidification, salinization, nutrient leaching, and toxin contamination are a few types of chemical degradation. [1] Toxins can accumulate in the soil from industrial processes like mining and waste management. [3] Some biological examples include biodiversity loss, emitting greenhouse gasses, reduced carbon content, and a reduced capacity to sequester carbon. [1] One of the most predictable ways to determine whether soil degradation has occurred is to measure its organic carbon content. [1] The soil organic carbon pool is extremely important for soil fertility. [1]
There is a significant connection between the carbon cycle and climate change. [6] Most greenhouse gases are primarily composed of carbon and they produce an effect where warmer air that is heated by the sun is kept from leaving the atmosphere by forming a barrier in the troposphere. According to the Intergovernmental Panel on Climate Change, greenhouse gasses produced by human activity are the most significant cause of global climate change since the 1950s. [7] Without human interaction, carbon is removed from and reintroduced to soil through a variety of ecosystem processes known as the carbon cycle. Humans have been significantly influencing the global carbon cycle since the Industrial Revolution through various means, such as transportation and agriculture. Through these actions, most of this carbon has moved in one direction, from the lithosphere and biospheres to the atmosphere. By means of fossil fuels and intensive farming, much of the natural carbon in the Earth's pedosphere has been released into the atmosphere, contributing to greenhouse gasses.
There are many ways to regenerate soil and improve soil quality, such as land management by conservation agriculture. Agriculture is one of the main factors in the depletion of soil richness. [8] As one historical review put it, "Accelerated soil erosion has plagued the earth since the dawn of settled agriculture, and has been a major issue in the rise and fall of early civilization." [9] Certain agricultural practices can deplete the soil of carbon, such as monoculture, [10] where only one type of crop is harvested in a field season after season. This depletes nutrients from the soil because each type of plant has a specific set of nutrients that it requires to grow or that it can fix back into the soil. With a lack of plant diversity, only certain nutrients will be absorbed. Over time, these nutrients will be depleted from the soil. Agroecology is an overarching category of approaches to creating a more sustainable agricultural system and increasing soil health. These conservation agricultural practices utilize many techniques and resources to maintain healthy soil. Some examples are cover cropping, crop rotation, reducing soil disturbance, retaining mulch, and integrated nutrient management. [1] These practices have many benefits, including increased carbon sequestration and reducing the use of fossil fuels. [1]
Permaculture (from "permanent" and "agriculture") is a type of conservation agriculture, which is a systems thinking approach that seeks to increase the carbon content of soil by utilizing natural patterns and processes. There is a strong emphasis on knowledge of plants, animals, and natural cycles to promote high-efficiency food production, decrease reliance on human involvement, and create a sustainable and resilient ecosystem. This can be accomplished through intentional landscaping to increase the efficiency of capturing rainfall into the system or by placing nitrogen-fixing plants near nitrogen-demanding plants, such as legumes. [3] Utilizing the interconnections of various plants, animals, and processes is a key practice in permaculture. Native plants should be used whenever possible, [3] their roots help water infiltrate deep into the soil. [4]
holistic management stems from the work of Allan Savory, who observes that planned grazing can improve soil health and reverse the effects of desertification by increasing biomass. Researchers dispute the desertification claim. [11] [12]
There are also many kinds of soil amendments, both organic and inorganic. [3] They promote soil quality in a variety of ways, such as sequestering toxins, balancing the pH of the soil, adding nutrients, and promoting the activity of organisms. [3] The current conditions of the soil will determine which type of amendment and how much to use. [3] Inorganic amendments are generally used for things like improving the texture and structure of the soil, balancing the pH, and limiting the bioavailability of heavy metal toxins. [3] There are two types of inorganic amendments: alkaline and mineral. Some examples of inorganic amendments include wood ash, ground limestone, and red mud. [13] Mineral amendments include gypsum and dredged materials. [3] Organic amendments improve biological activity, water permeability, and soil structure. [4] Mulch, for example, reduces erosion and helps to maintain the temperature of the soil. [3] Compost is rich in organic matter, [4] it is composed of decomposed matter such as food, vegetation, and animal wastes. [3] Adding compost increases the moisture and nutrient content of the soil and promotes biological activity. Creating compost requires careful management of temperature, the carbon to nitrogen ratio, water, and air. [3] Biochar is an amendment that is full of carbon and is created by pyrolysis, a high-temperature decomposition process. [1] Wastes from animals are common soil amendments, usually their manure. The moisture and nutrient content will vary depending on the animal from which it came. [3] Human wastes can also be used, like the byproduct biosolids from wastewater facilities. Biosolids can be high in nutrient content, so should be used sparingly. [3]
An ecosystem is a system that environments and their organisms form through their interaction. The biotic and abiotic components are linked together through nutrient cycles and energy flows.
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain the required amount of nutrients causes malnutrition. Nutritional science is the study of nutrition, though it typically emphasizes human nutrition.
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the probability of developing resistant pests and weeds.
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms that may deplete the water of oxygen. Eutrophication may occur naturally or as a result of human actions. Manmade, or cultural, eutrophication occurs when sewage, industrial wastewater, fertilizer runoff, and other nutrient sources are released into the environment. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in water and causing substantial environmental degradation.
Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state. Degradation is an evolution, different from natural evolution, related to the local climate and vegetation. It is due to the replacement of primary plant communities by the secondary communities. This replacement modifies the humus composition and amount, and affects the formation of the soil. It is directly related to human activity. Soil degradation may also be viewed as any change or ecological disturbance to the soil perceived to be deleterious or undesirable.
Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.
Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. It also refers to the soil's ability to supply plant/crop nutrients in the right quantities and qualities over a sustained period of time. A fertile soil has the following properties:
Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. Organic refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.
Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors. In the early 1870s a consulting chemist to the Royal Agricultural Society in England, named J. Thomas Way, performed many experiments on how soils exchange ions, and is considered the father of soil chemistry. Other scientists who contributed to this branch of ecology include Edmund Ruffin, and Linus Pauling.
Bulk soil is soil outside the rhizosphere that is not penetrated by plant roots. The bulk soil is like an ecosystem, it is made up of many things such as: nutrients, ions, soil particles, and root exudates. There are many different interactions that occur between all the members of the bulk soil. Natural organic compounds are much lower in bulk soil than in the rhizosphere. Furthermore, bulk soil inhabitants are generally smaller than identical species in the rhizosphere. The main two aspects of bulk soil are its chemistry and microbial community composition.
The phosphorus cycle is the biogeochemical cycle that involves the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based materials do not enter the gaseous phase readily, as the main source of gaseous phosphorus, phosphine, is only produced in isolated and specific conditions. Therefore, the phosphorus cycle is primarily examined studying the movement of orthophosphate (PO4)3-, the form of phosphorus that is most commonly seen in the environment, through terrestrial and aquatic ecosystems.
Soil respiration refers to the production of carbon dioxide when soil organisms respire. This includes respiration of plant roots, the rhizosphere, microbes and fauna.
Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous benefits to soil's physical and chemical properties and its capacity to provide regulatory ecosystem services. SOM is especially critical for soil functions and quality.
Soil biodiversity refers to the relationship of soil to biodiversity and to aspects of the soil that can be managed in relative to biodiversity. Soil biodiversity relates to some catchment management considerations.
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.
Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nutrients, such as nitrogen, that are utilised by bacteria, fungi and other organisms in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web.
Soil microbiology is the study of microorganisms in soil, their functions, and how they affect soil properties. It is believed that between two and four billion years ago, the first ancient bacteria and microorganisms came about on Earth's oceans. These bacteria could fix nitrogen, in time multiplied, and as a result released oxygen into the atmosphere. This led to more advanced microorganisms, which are important because they affect soil structure and fertility. Soil microorganisms can be classified as bacteria, actinomycetes, fungi, algae and protozoa. Each of these groups has characteristics that define them and their functions in soil.