Dirt or soil is incredibly important for supporting life on earth. It allows us to grow crops, which allowed ancient nations to put down roots and build cities and civilizations. For dirt to grow healthy plants, the soil needs important nutrients that help feed growth. Water, healthy soil, and soil quality play important roles in successful crop growth. Today, we know more about soil than ever before, and that allows us to make soil fertile and conserve it so that it can continue to nourish us.
History of Agriculture
Humans first started growing crops roughly 13,000 years ago, including things like wheat, barley, pistachios, almonds, flax, rice, chickpeas and lentils. Early humans were forced to rely on rivers and lakes to provide fertile soil and water. That's why locations like the Nile River are home to some of the oldest known civilizations. Every year, the Nile floods, so the people could plant and then harvest their crops. This consistency led to the development of early cities, and then early nations. Volcanic valleys also had very fertile ground, which led to civilizations springing up around them. Pompeii is the most famous of these because it was tragically destroyed when the volcano erupted. As we learn more about crops and soil, we have developed more efficient ways to care for crops, gardens, and flowers.
Beginnings of Soil Science
Without fertile soil, plants can't grow well. Although people observed that different plants grew better in different areas, it wasn't until the early 1900s that scientists really started to understand soil. Before that, they only considered the topmost layers important, because they assumed that's where the plant's nutrients came from. Today, soil science takes a closer at the climate where the soil is found, the specific plants growing in that region, the soil age, and even the minerals it contains. All this allows scientists to classify soil and learn more about it.
Soil Fertility and Crop Growth
Soil is full of rich nutrients that feed trees, plants, crops, and the animals (including humans) that eat them. Scientists have identified 17 elements that are important for the best crop growth, including elements like carbon, hydrogen and oxygen, and macronutrients like potassium, calcium, magnesium, iron and nickel. Healthy soil allows air and water to move through it, stores water so plants can grow, and is strong enough for people and animals to walk on. In a garden, the best soil holds all 17 nutrients, has a healthy pH range, it drains well and it can clump together. It's important to test the soil fertility every few years to make sure it's healthy, but be careful not to over-fertilize it. Too many nutrients can be more devastating for flowers and crop growth than too few. Today we know that only about 11% of the soil on earth is fit for growing food and we also know that soil isn't all the same, so it's more important than ever that we take steps to care for it.
Soil Types
Soil varies by color, texture, and depth. The most common soil types are sand, silt, clay and organic matter. Organic matter comes from living organisms, like mushrooms, straw, sawdust and leaves that have been broken down to fertilize the soil. The balance of the different types of soil is what allows plants to grow and air and water to move through the soil easily. So, sand allows water to flow through easily, but it's not firm enough for most plants. It also erodes easily because it's lightweight and doesn't bond well. Clay clumps easily, but it's difficult for water to flow through it, so it tends to form puddles. If you've ever tried to plant or dig a hole to bury a plant in clay soil, you know it's also hard to work with, particularly if it's been raining. Silt is a mixture of sand and clay, which allows it to bond well together while still allowing water and air to flow through it. Loamy soil is the best of all because it contains calcium and other nutrients from organic matter, plus it's easy to work with. It's exactly what you want if you're farming or gardening.
Soil Conservation
Soil conservation is an extremely important process that protects soil from breaking down. Every year, we lose soil from damage caused by people and nature. If we don't make changes, we will continue to lose healthy soil, which will lead to fewer crops and more hunger. Erosion from wind and water are two of the major causes of destruction to soil. When the wind blows, it can move rocks and dirt, causing the earth to erode. Similarly, heavy rainfalls can displace soil and cause lakes and rivers to flood, leading to more erosion. All over the planet, strong waves striking shores have slowly eroded the coastline and caused it to change. Humans have sped up this process. Farming, allowing livestock to destroy plant cover, clearing trees, and constructing buildings have all led to soil loss and soil erosion. Without deeps roots to hold soil in place, it's easier for it to get washed away. Conserving soil could decrease food prices, increase the amount of food available, improve water quality, and help animal habitats. Farmers can improve soil conservation by rotating crops, using buffer strips and planting cover crops. You can even do simple things to preserve soil when you're gardening at home, like rotating crops and flowers so different things grow in different locations year after year. You can also:
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Encourage your parents and local farmers to use organic pesticides
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Help local groups stabilize rivers and lakes during times of flooding so the bank doesn't erode into the water
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Keep storm drains in your neighborhood free of litter and debris
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Start a compost pile of leftover food
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Plant shrubs and small plants around your house
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Volunteer at a gardening center to learn how to care for soil and plants
Soil is an important, but often overlooked resource. When we take steps to conserve it, it ensures that it will be healthy for future generations. Learning more about soil and soil conservation is always a good step. The more we know about something, the more we value it.
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Types of Soil (PDF)
The article was created by Chad Kremp
