Soil Science

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Soil Science By: Ashlyn Haywood [[Begin]] [[Sources Cited]]

Click on one of the topics below to begin learning more about it. [[Soil Ecology]] [[Agriculture]] [[Agricultural Practices]] [[Land Use]]

Soil ecology is the study of the interactions among soil organisms, and between biotic and abiotic aspects of the soil environment. Below are some topics related to soil ecology: [[Types]] [[Composition]] [[Profiles]] [[Properties]] [[Maintenance]] <<back>>

Agriculture is the science or occupation of farming. [[Types of Agriculture]] [[History]] [[Green Revolution]] <<back>>

There are several practices that must be performed to have a successful agricultural endeavor. [[Fertilizers]] [[Pest Management]] [[Crop Rotation Methods]] <<back>>

The world’s land can be used in a variety of fashions, most of which do not have a positive effect on the ecosystems present in the area. [[Different Uses]] [[Food Production]] <<back>>

Scientists have developed a soil classification system that contains twelve soil orders. Below are some of the most common soils alongside other soils that are particularly unique. [[Gelisols]]: Frozen [[Histosols]]: Saturated [[Spodosols]]: Acidic [[Andisols]]: Volcanic [[Oxisols]]: Weathered [[Aridisols]]: Dry [[Mollisols]]: Fertile [[Alfisols]]: Common <<back>>

Soils are often composed of a combination of mineral particles, which are rocks that have been reduced to incredibly small sizes, organic matter, such as the dead remains of plants and animals, water, and air. Among the mineral particles found in soil, the most prominent are often sand, silt, and clay. The varying amounts of these particles determine the soil’s texture, which affects its water retaining properties among others. <<back>>

Mature soils are layered. Each layer is a soil horizon with its own unique texture and composition. The majority of soils have four horizons, which are designated: O, A, B, and C. The O horizon is the top layer at the earth’s surface, often consisting of plant material and animal waste. It protects the underlaying topsoil from erosion and also houses an abundance of microorganisms, such as helpful bacteria and fungi. The A horizon is also known as topsoil and contains organic humus. In certain areas where there is not a surplus of plant material or animal byproducts, this can be topmost horizon. The B horizon, also known as the sub-soil, consists of inorganic rock materials. It is not as fertile as the horizons above it, but deep-rooted plants can utilize all the different water and minerals present in this layer. The C horizon sits above bedrock, which is the source of all inorganic matter found in the soil. Although there is a lack of organic material in this horizon, groundwater can be found there. Different soil types can have different numbers of horizons that vary in thickness and composition. <<back>>

There are various soil properties that affect a plant’s ability to grow. These include both the physical and chemical properties of the soil. Physical Properties: Soil Color Soil Texture Soil Structure Soil Consistence Chemical Properties: Acidity Cation Exchange Capacity <<back>>

There are many different ways that soil can be conserved by minimizing soil degradation during agricultural pursuits. In order to prevent erosion, windbreaks can be placed along the perimeter of farm fields to leave topsoil less exposed. If the amount of tillage, the turning over of the soil, is reduced, erosion will be reduced as well. No-till agriculture is done to achieve the aforementioned at the cost of attracting insects and plant diseases. In order to prevent water runoff, contour farming involves planting crops along the natural contours of the land. Terracing can also control water erosion by using a similar method on steeply sloped hills and mountains. Strip cropping is the planting of different crops on alternating strips of land. If one crop is a ground-covering crop, both water runoff and soil erosion can be reduced. <<back>>

Gelisols are soils that are permanently frozen, meaning they contain permafrost. Permafrost restricts the rooting depth of plants in the areas where it is most prominent. <<back>>

Histosols are mainly composed of organic material, such as leaves, mosses, and grasses, in their upper portion. These soils are found in extremely wet areas and are often saturated throughout the entire year. <<back>>

Spodosols are fascinating because they contain an ashy, gray layer atop a reddish, coffee-colered subsoil horizon. These soils are often very acidic, containing decaying needles from surrounding coniferous trees. <<back>>

Andisols are typically composed of weathered volcanic materials, such as volcanic ash. These soils have an unusually high capacity to hold both nutrients and water, but they are also one of the world’s most uncommon soil types. <<back>>

Oxisols are very weathered, having a high concentration of iron oxides, quartz, and clay minerals. These soils are often not very fertile because they are naturally nutrient poor. <<back>>

Aridisols are among the driest of the soil types. With high concentrations of salt, these soils are found in both hot and cold deserts around the world. <<back>>

Mollisols are soils found in prairie environments that are considered highly fertile and nutrient rich. This richness can be attributed to the yearly addition of organic matter to the soil from the roots of grassland plants. <<back>>

As one of the most common soil types, alfisols are moderately weathered. With the nutrient amounts reliant on decaying leaves, their fertility can vary on an almost seasonal basis. <<back>>

Sustainable Agriculture Sustainable agriculture refers to the ability of a farm to produce food indefinitely without causing sever damage to an ecosystem’s health. Urban Agriculture Urban agriculture is the practice of cultivating food around a town or city. It is generally done for as a means of earning income. Organic Agriculture Organic agriculture is a system that relies on ecological processes rather than other inputs to sustain the health of soils, ecosystems, and people. Conservation Agriculture Conservation agriculture is done to achieve high profits without sacrificing an ecosystem’s health. This is often done through no-till methods, topsoil management, and crop rotation. Industrial Agriculture Industrial agriculture is a form of modern farming that refers to the industrialized production of crops. The methods of industrial agriculture are often take into consideration economic and political factors over environmental ones. Slash and Burn Agriculture Slash and burn agriculture consists of cutting and burning of forests or woodlands to create fields for agriculture. The use of fire serves as a rudimentary technique of fertilization. <<back>>

Agriculture began thousands of years ago and allowed humankind to abandon their nomadic ways in favor of a more structured lifestyle. As great cities began to form across the ancient world, more and more fields began to be deprived of nutrients. This led to slash and burn practices, which allowed for the creation of new fields where forests once stood. Fallow fields had also become a common site. These were acres of land set aside in hopes that they would one day become fertile once again. More than a thousand years after agriculture began, irrigation allowed for crops to grow in arid areas. Irrigation systems were used in some of the world’s most impressive empires to provide fresh water to all who dwelled within them. Today, some of the techniques of the past can still be seen in today’s agricultural pursuits. <<back>>

The term Green Revolution refers to the renovation of agricultural practices that spread throughout the world in an effort to increase the amount of calories produced per acre. In the 1940s, Norman Borlaug began conducting research in Mexico and developed new disease resistant high-yield varieties of wheat. When these crops were combined with new mechanized agricultural technologies, the country was producing a great surplus of wheat. The practices that were adopted by Mexico quickly became more commonplace throughout the world. More countries were using high-yield plant varieties that respond better to fertilizer and are more resistant to disease. New agriculture technologies were also being used more often, helping increasing the amount of food produced worldwide. <<back>>

There are two main varieties of fertilizers used by those attempting to grow crops, organic and inorganic. [[Organic Fertilizers]] [[Inorganic Fertilizers]] From an entirely environmental standpoint, it is clear that organic fertilizers are more beneficial to the plants being grown and the environment surrounding them. <<back>>

In most modern agricultural endeavors, there are a large variety of different ways one can eliminate pests present on farmland. Biological Control One method of controlling pests is to either introduce competitors, pathogens, and predators or introduce plants modified to be resistant to pests. Introducing new organisms to the environment can have a negative effect on the surrounding ecosystems. There are also laws that one needs to consider when purchasing different types of genetically modified foods. Chemical Control Another, more infamous, method of controlling pests is the use of pesticides, toxic chemicals that are often sprayed atop a stretch of land to kill pests. Especially in recent years, the use of pesticides has been looked down upon because of the often detrimental impact they can have on a environment. There are still pesticides in use, but they have been modified to minimize harm dealt to people and the ecosystems that surround them. Overview There are other methods of controlling pests, such as changing irrigation practices or using sun screens, but the practices listed above are the one’s most commonly associated with pest elimination. <<back>>

Rotating one’s crops in an agricultural endeavor has never been more important. Crop rotation is the systematic approach to deciding what should be planted from one year to the next. Alternating between different varieties of crops can aid in maintaining soil fertility and preventing the spread of pests and disease. <<back>>

Organic fertilizers are usually made from organic waste products or powdered minerals. Advantages of Organic Fertilizers Organic fertilizers gradually increase the soils ability to hold water and nutrients. There’s little risk of chemicals and salts that can be harmful to plants. Organic fertilizers are renewable, biodegradable, and environmentally friendly. Disadvantages of Organic Fertilizers The effectiveness of organic fertilizers is limited seasonally because they need warmth and moisture. It takes organic fertilizer’s a long time to provide nutrients to plants in desperate need. <<back>>

Inorganic fertilizers have been refined to extract nutrients and bind them in specific ratios with other chemical fillers. Advantages of Inorganic Fertilizers Since nutrients are available to plants immediately, improvement can occur in days. They produce the exact ratio of nutrients desired with ratios and chemical sources that are relatively easy to understand. They’re inexpensive Disadvantages of Inorganic Fertilizers Inorganic fertilizers are primarily made from nonrenewable sources, including fossil fuels. They grow plants, but can do long-term damage to the soil, upsetting the entire ecosystem. Repeated applications of the fertilizer may result in a toxic buildup of chemicals that can kill the plants that are exposed. <<back>>

The most common uses of the land are listed below. Crop Land used primarily for the production and harvest of some kind of vegetation. Pasture Lands composed of domesticated foraging species that are primarily used as livestock. Range Land used primarily for the production of grazing animals that could be used in rotation with crops. Forest Land on which the primary vegetation is tree cover and used primarily for the production of wood products and related materials. Rural Land Land that is barren, sandy, rocky or that is impacted by a lack of natural resources. Developed Land Land occupied by buildings and related facilities used for residences, commercial sites, public highways, and other places associated with towns and cities. As is made clear by the categories listed above, an incredible thirty-seven percent of the earth’s landmass is used for food production. <<back>>

Despite all the land in the world used to produce food, there are still people that are malnourished in some of the world’s most impoverished places. Even worse, as the population continues to grow, more sixty-nine percent more food calories will need to be produced before the end of the century. This will be even harder to accomplish when one factors in the effects of climate change and the economic costs of rapidly expanding the food production industry. Although hope may seem lost, if efforts are taken to reduce the rate of climate change and control overpopulation occurring in developing countries, it is possible that the human race may continue to thrive in the coming centuries. <<back>>

Sources Cited "AP Environmental: Chapter Fifteen Summary." Parkway Schools. Parkway Schools, 2012. Web. 10 Dec. 2015. "All You Wanted to Know about the Green Revolution." About.com Education. About.com, 2014. Web. 10 Dec. 2015. "Pros and Cons of Organic vs. Chemical Fertilizers | Today's Homeowner." Today's Homeowner. Danny Lipford Media, 2012. Web. 10 Dec. 2015. Saundry, Peter. "AP Environmental Science: Chapter Eleven- Soils." Encyclopedia of Earth. Boston University, 25 Nov. 2008. Web. 10 Dec. 2015. "Soil Physical and Chemical Properties." Natural Resources Conservation Service. Natural Resources Conservation Service, 2014. Web. 10 Dec. 2015. "Soil Physical and Chemical Properties." Natural Resources Conservation Service. Natural Resources Conservation Service, 2014. Web. 10 Dec. 2015. "The Global Food Challenge Explained in 18 Graphics." World Resources Institute. World Resources Institute, 2013. Web. 10 Dec. 2015. "The Key To Keeping A Rich Vegetable Patch." Rodale's Organic Life. Rodale Inc., 2010. Web. 10 Dec. 2015. <<back>>