Presentation on theme: "Land and Soil Conservation By: Alexandra Hulvalchick"— Presentation transcript:
1 Land and Soil Conservation By: Alexandra Hulvalchick
2 3 main land usesAgriculture- less than 1/3 of land on earth can be used for farming. The rest is too dry, salty, wet, or mountainous.To have more room we clean forests, drain wetlands, and irrigate deserts. When we make the changes organisms must leave.The land is usually used for grazing or pastures.Development – the construction of buildings, roads, dams, and other structures.People first settled near good soil and water. As the pop. grew they turned into cities. More structures were built.In the us an area ½ the size of New Jersey is developed each year.It destroys farmland and habitats.
3 3 Main uses of landMining – the removal of nonrenewable resources like iron, copper, and coal from the land.Strip Mining – is when you remove a strip of land to get to minerals and replacing the strip. It exposes soil which can be blown or washed away. It stays free of vegetation for yearsUnderground mining – the process of digging shafts or tunnels to mine minerals deep underground.
4 How land is Used in the Usa We use land in the usa for forests, woodland, cropland, rangeland, grassland, cities, wilderness parks, wildlife refuges, wetlands, tundra, and deserts.
5 What layers make up fertile soil? The 1st layer of soil from the top is called litter. It is a mixture of dead leaves and grass.The 2nd layer of soil is called the topsoil. It is a mixture of rock fragments, nutrients, water, air, and decaying animal and plant matter. Most water absorbed by plants is in this layer.The 3rd layer of soil is called subsoil. It contains rock fragments, water, air, but less decaying matter than topsoil.The final layer is bedrock. It is the rock that makes up the Earth’s crust. Freezing and thawing gradually break apart the bedrock.
6 Why is it important?It takes hundreds of years to form a few centimeters of soil.Poor soil management can result in three problems: erosion, nutrient depletion, and desertification.
7 What is erosion?Erosion- the process by which water, wind or ice moves particles of rocks or soil.Mostly plant roots hold the soil in place but when exposed to wind it erodes rapidly.Logging, mining, and farming expose soil and helps cause erosion.Some types of farming reduce erosion.
8 Nutrient DepletionNutrient Depletion – the situation that arises when more soil nutrients are used than the decomposers can replace.Plants need nitrogen, phosphorus, potassium and other nutrients to grow. The get them from the soil.Decomposers make these nutrients from the remains of dead organisms.Farmers that plant the same crops over and over uses up the nutrients and causes nutrient depletion.A way to prevent it is to fallow, or leave clear of crops. You can also leave the what is left of the plants so the can decompose.You can also rotate the crops by planting different crops each year. It helps because different plants absorb different nutrients. Corn absorbs lots of nutrients but not oats. If you alternate the planting of these crops it helps control the amount of nutrients in the soil.
9 DesertificationDesertification – the advance to desert like conditions into areas previously fertileIn the past 50 years 5 billion hectares of land have turned to deserts.One cause is the climate. When drought happens crops fail and without cover the soil easily blows away.Another cause is overgrazing of cattle and sheep or cutting down trees.It is a serious problem. Plants can’t grow and livestock and people have no food.
10 Land ReclamationLand reclamation – the process of restoring an area of land to a more natural, productive state.It can be used to restore it for wildlife as well as agriculture.It is currently happening all over the world but is very expensive and difficult so it is easier to protect in from the beginning.