Land Use and Agriculture

Soil is not just dirt. It is the loose layer of minerals and organic matter on Earth's surface that plants grow in, and it is shaped over time by climate, living things, the land's shape and the rock beneath. The USDA Natural Resources Conservation Service (NRCS) notes that soil sustains plant and animal life, regulates the flow of water, filters pollutants and cycles nutrients.

NRCS lists five soil-forming factors:

• Climate: rain and temperature control how fast rock weathers and how fast organic matter breaks down.
• Organisms: plants, animals, fungi and microbes add organic matter and mix the soil.
• Relief: the shape of the land. Steep slopes shed water and soil, while low spots collect them.
• Parent material: the rock or loose sediment that the soil forms from.
• Time: soil forms slowly, so its layers take a long time to develop.

Over time these factors sort soil into layers called horizons. A vertical cut through all of them is a soil profile. Soil scientists label the master horizons with capital letters. NRCS notes that most soils have at least an A, a B and a C horizon; some also have an O horizon on top or an E horizon below the A.

Erosion is the detachment and movement of soil. On farmland, the two main forces are water and wind.

• Water erosion begins when raindrops splash bare soil loose. Thin sheets of runoff carry it off (sheet erosion), then the flow cuts small channels (rills) and, if nothing stops it, deep gullies. The soil that leaves a field becomes sediment in streams and lakes, often carrying nutrients and pesticides with it.
• Wind erosion lifts dry, loose, bare soil, especially on flat, open land in dry years.

Erosion is natural, but farming can speed it up. The IPCC estimates that soil erosion from agricultural fields is now 10 to 20 times the rate at which new soil forms on fields with no tillage, and more than 100 times on conventionally tilled fields. The IPCC also estimates that about a quarter of Earth's ice-free land is affected by human-induced degradation.

NRCS sums up soil health with four ideas: reduce disturbance, keep the soil covered, grow a variety of plants, and keep living roots in the ground as long as possible. Healthy soils absorb more water, so less runs off and less soil erodes. Here are common practices that apply those ideas.

How common are these practices? USDA ERS found that conservation tillage (no-till, strip-till or mulch-till) was used on roughly 70% of U.S. soybean acres (2012), 65% of corn acres (2016), 67% of wheat acres (2017) and 40% of cotton acres (2015).

The Food and Agriculture Organization of the United Nations (FAO) reports in its Global Forest Resources Assessment 2025 that forests cover more than 4 billion hectares, about 32% of Earth's land. The tropics hold 45% of them, and five countries (Russia, Brazil, Canada, the United States and China) hold more than half.

Deforestation means converting forest to another land use, such as cropland, pasture, mines or towns. The main driver is agriculture. Global Forest Watch data show that agricultural expansion, both large commodity farms and small farms growing food for families, was the leading cause of tree cover loss across the tropics in 2025. In Brazil, permanent agriculture such as soy and cattle accounted for 73% of primary forest loss from 2002 to 2025. Wildfire and logging are also leading causes of tree cover loss, but after logging, Global Forest Watch often sees trees regrow or get replanted in later years.

The trends are mixed:

• FAO estimates that 489 million hectares of forest have been lost to deforestation since 1990. The deforestation rate fell from 17.6 million hectares a year in 1990–2000 to 13.6 million in 2000–2015 and 10.9 million in 2015–2025.
• Forests also expand, through reforestation (replanting or natural regrowth) and new forest on other land. Counting gains, FAO's net forest loss fell from 10.7 million hectares a year in 1990–2000 to 4.12 million in 2015–2025.
• About 92% of the world's forests regenerate naturally, and 8% are planted. Planted forests have grown by 120 million hectares since 1990.
• Global Forest Watch reported that the tropics lost 4.3 million hectares of primary (old-growth) rainforest in 2025, more than 11 soccer fields a minute. That was 36% less than the record set in 2024, a year of extreme fires, but 46% more than a decade earlier.

“Industrial” and “sustainable” are not two separate boxes. Most farms mix practices, and each one has benefits and costs. The evidence below shows both sides.

Yields have soared. According to USDA's National Agricultural Statistics Service, U.S. corn yields rose from 20.5 bushels per acre in 1930 to a record 186.5 in 2025, about nine times as much, thanks to better seeds, fertilizer, pest control and machinery. Higher yields mean less land is needed for the same harvest: U.S. cropland in 2022 was 377 million acres, the lowest since the USDA series began in 1945.

A food system includes everything from farm to fork: growing, processing, shipping, selling, cooking, eating and throwing away. The IPCC estimates that the whole food system accounts for 21–37% of human-caused greenhouse gas emissions, and that agriculture uses about 70% of the world's freshwater.

Land per food. According to Our World in Data, about half of the world's habitable land is used for agriculture, and most of that land feeds livestock. A large study by Joseph Poore and Thomas Nemecek, using data from about 38,700 farms in 119 countries, found that beef and lamb take roughly 50 to 100 times as much land per gram of protein as peas or tofu. There is important nuance, though: livestock can graze grasslands and steep hills where crops can’t grow (one study estimates that 65% of the grassland grazed by cattle isn’t suitable for crops), and animal foods provide high-quality protein and micronutrients.

Food loss and waste. Not all food that is grown gets eaten. The IPCC estimates that 25–30% of all food produced is lost or wasted.

• Food loss happens between harvest and the store, for example when food spoils in storage or is damaged during transport. FAO estimates that 13.3% of food was lost this way in 2023, about the same as in 2015. Losses were highest for fruits and vegetables (25.4%) and in sub-Saharan Africa (23.0%), where cold storage and good roads can be scarce.
• Food waste happens in stores, restaurants and homes. The UN Environment Programme estimated that 1.05 billion tonnes of food were wasted in 2022, about 19% of the food available to consumers. Households wasted 60% of it, about 79 kilograms per person per year.

In the United States, EPA reports that more than one-third of the food produced is never eaten. Growing that uneaten food takes an area of farmland equal to California and New York combined. Ways to cut loss and waste include better storage and cooling along supply chains (the steps that move food from farm to consumer), buying and cooking only what will be eaten, donating extra food and composting scraps.

The 2020 Census counted 2,611 urban areas in the United States, home to 80.0% of the population. As towns grow, they often spread onto nearby farmland and natural land. Low-density, car-dependent growth on a city's edge is called urban sprawl. USDA ERS notes that land can switch back and forth between forest, grassland and cropland, but conversion to urban use is typically permanent.

American Farmland Trust estimates that from 2001 to 2016, the United States lost or compromised 2,000 acres of farmland and ranchland every day to development. If those trends continue, it projects that another 18.4 million acres, nearly the size of South Carolina, could be converted between 2016 and 2040. Its report also models other futures: faster rural sprawl could raise the total to 24.4 million acres, while more compact development could keep up to 13.5 million acres in farming.

Sprawl brings tradeoffs too. New homes on the edge of town can be cheaper and roomier, but they can mean longer drives, less farmland and more paved surfaces. Pavement and roofs stop rain from soaking in, so more stormwater runs into streams.