APES chapter 9

Agriculture

the deliberate practice of raising plants and livestock for human use and consumption (food, fiber, fuel, and medicine). It is divided into two primary land uses:

Cropland

Land used specifically to raise plants for human use (such as grains, vegetables, and fruit orchards).

Rangeland

Land used primarily for grazing livestock (such as cattle, sheep, and goats) on grasses and shrubs.

Traditional Agriculture

Human and animal muscle power, hand tools, and simple machinery.

Industrial Agriculture

Heavy machinery, fossil fuels, synthetic fertilizers, chemical pesticides, and large-scale irrigation.

Sustainable Agriculture

Ecological principles, crop rotation, cover crops, integrated pest management, and minimal synthetic inputs.

Monocultures

• The practice of planting a single, genetically uniform crop species over a massive area (e.g., vast fields of only corn or soybeans).

• Pros: Highly efficient for industrial harvesting and planting.

• Cons: Highly vulnerable to disease and pest outbreaks (since a single pest can wipe out an entire crop) and reduces local biodiversity.

Polycultures

• A traditional method where multiple different crops are planted together in the same space (e.g., the Native American "Three Sisters" method: corn, beans, and squash grown together).

• Pros: Enhances biodiversity, naturally deters pests, improves soil nutrient cycling, and provides varied yields.

Leaching

Leaching is the process where solid particles—either suspended or dissolved in liquid—are transported downward through the soil profile.

• As rainwater or irrigation water seeps down through the topsoil, it dissolves water-soluble minerals and carries them deep into the subsoil or out of reach of plant roots.

• While natural, excessive leaching can strip topsoil of vital nutrients like nitrogen and calcium, reducing soil fertility.

Overirrigation

Applying more water than plants can use or soil can hold.

Waterlogging

Severe overirrigation saturates the soil completely, filling all pore spaces with water. This cuts off oxygen supply, suffocating plant roots and hindering their ability to respire and absorb gases.

Salinization

The buildup of salts in surface soil layers. When irrigation water is applied in arid or semi-arid regions, the water evaporates quickly, leaving behind dissolved salts that eventually accumulate to toxic levels for plants, rendering the land barren.

Inorganic (Synthetic) Fertilizers

Synthetically manufactured mineral supplements (created in factories using fossil fuels).

• Pros: Highly concentrated, fast-acting, and precisely formulated. • Cons: Easily leached into waterways causing eutrophication (algal blooms); energy-intensive to produce.

Organic Fertilizers

The natural remains, wastes, and residues of organisms (e.g., livestock manure, crop residue, compost, bone meal).

• Pros: Improves soil structure, adds organic matter, and releases nutrients slowly. • Cons: Bulky, harder to apply on a massive industrial scale, and nutrient ratios are less precise.

Pollination

is the essential ecological process by which the male sex cells of a flowering plant (pollen) are transferred to the female sex cells (eggs) to fertilize them and produce seeds and fruit.

Abiotic

Plants like grasses, corn, and most conifers rely on the wind to randomly scatter massive clouds of pollen.

Biotic

Roughly 75% of global crop species depend on animal pollinators (such as bees, butterflies, moths, bats, birds, and beetles) to move pollen efficiently.

The Decline of Pollinators:

• Insect populations are facing steep global declines due to habitat loss, climate change, and agricultural chemicals.

• Pesticides—particularly systemic insecticides like neonicotinoids—are a major driver, often indirectly killing pollinators by contaminating nectar and pollen, weakening their immune systems, and disrupting their navigation and reproductive behaviors.

Insect Diversity

A rich variety of pollinators ensures high crop fertilization rates and resilient agricultural yields.