14-1 How is Food Produced?
What Systems Provide Us with Food? The Challenges Ahead
Historically, humans have depended on three systems for their food supply. Croplands mostly produce grains, and provide about 77% of the world’s food. Rangelands produce meat, mostly from grazing livestock, and supply about 16% of the world’s food. Ocean fisheries supply about 7% of the world’s food.
We face important challenges in increasing food production without causing serious environmental harm. To feed the world’s 8.9 billion people projected to exist in 2050, we must produce and equitably dis- tribute more food than has been produced since agriculture began about 10 000 years ago, and do it in an environmentally sustainable manner.
We also face the challenge of sharply reducing poverty because about one out of five people do not have enough land to grow their own food or enough money to buy sufficient food—regardless of how much is available.
How Do Our Food Production Systems Compare with Natural Ecosystems? Simpler and Less Sustainable
Our food production systems—agroecosystems—are remarkably different from natural ecosystems. Our knowledge of the ecological principles underlying natural ecosystems is relatively recent, and is often poorly applied to our agroecosystems. Some of the differences between agroecosystems and natural ecosystems include the following:
Natural Ecosystems | Agroecosystems | |
|---|---|---|
Effect on soil | Natural ecosystems tend to stabilize the soil under plant cover. Soil moisture is protected from the drying effect of sunlight and air, and roots hold the soil in place preventing erosion by wind or water. | Agroecosystems that involve plowing expose the soil to erosion and lose soil moisture that would normally be protected by plant cover. Major nutrients can be replaced artificially using chemical fertilizers, but trace nutrients and organic matter are depleted by these methods. |
Effect on surrounding ecosystems | Natural ecosystems tend to evolve over time, with adaptations promoting the survival and reproduction of the many organisms involved. This results in resilient ecosystems attuned to current and changing conditions. | Agroecosystems are designed to promote human choices such as crops of a particular colour or shape or flavour. These choices are typically focused on developing traits other than survival and reproduction, leaving these systems vulnerable to disruptions and reliant on humans for protection and propagation. |
Driving force | Natural systems are driven by solar energy. | Agroecosystems are often driven by large investments of fossil fuels, mechanization, and human intervention. |
Succession | Natural ecosystems are typically undergoing a process of succession as pioneer organisms capitalize on an opportunity to colonize a freshly disturbed area and are gradually replaced by species typical of a mature ecosystem. | In contrast, many methods of food production devote much time and energy to holding succession at a desired stage. |
Structural Diversity | Natural ecosystems involve a great deal of structural diversity. Differences in physical spaces among plants, and among canopies of leaves, allow for a great variety of microhabitats that can be colonized by organisms that feed on potential pests. | Agroecosystems tend to have uniform spacing among plants, leaving relatively few options for pest-predators requiring shelter. |
Biological Diversity | Natural ecosystems typically contain a great deal of biological diversity, including rich communities of genetically diverse organisms, and complex food webs with many predators and competitors that tend to keep potential prey species in check. | Most agroecosystems tend to be simple monocultures of a single species of crop-plant, or perhaps even one specific genetically similar variety of a crop-plant. Such ecosystems are vulnerable to diseases and |
pests that can overwhelm the defences of the crop, particularly in the absence of the natural pest control exerted by diverse ecosystems. |
What Plants and Animals Feed the World? Our Three Most Important Crops
Today only 14 plant and 8 terrestrial animal species supply an estimated 90% of our global intake of calories. Just three grain crops—wheat, rice, and corn—provide more than half the calories people consume. These three grains, and most other food crops, are annuals, whose seeds must be replanted each year.
Two-thirds of the world’s people survive primarily on traditional grains (mainly rice, wheat, and corn), mostly because they cannot afford meat. As incomes rise, most people consume more meat and other products of domesticated livestock, which in turn means more grain consumption by those animals.
What Are the Major Types of Food Production? High-Input and Low-Input Agriculture
There are two major types of agricultural systems:
Industrialized agriculture, or high-input agriculture, uses large amounts of fossil fuel energy, water, commercial fertilizers, and pesticides to produce single crops (monocultures) or livestock animals for sale.
Plantation agriculture is a form of industrialized agriculture used primarily in tropical developing countries. It involves growing cash crops (such as bananas, coffee, soybeans, sugarcane, cocoa, and vegetables) on large monoculture plantations, mostly for sale in developed countries.
Traditional agriculture consists of two main types:
Additional subsistence agriculture typically uses mostly human labour and draft animals to produce only enough crops or livestock for a farm family’s survival.
In traditional intensive agriculture, farmers increase their inputs of human and draft labour, fertilizer, and water to get a higher yield per area of cultivated land. They produce enough food to feed their families and to sell for income.