Chapter 12, Problem 9CR

To determine

The key concept for this Section 12.6. Define soil conservation. Describe six ways to reduce topsoil erosion. Definition of hydroponics, and the way in which it can be used to deal with soil degradation. Distinguish among organic fertilizer, synthetic inorganic fertilizer, animal manure, green manure, and compost. The way in which crop rotation helps to restore topsoil fertility. Some ways to prevent and some ways to clean up soil salinization. The way in which one can reduce desertification. Describe three ways to make aquaculture more sustainable. Describe two ways to make meat production and consumption more sustainable. Summarize three important aspects of making a shift to more sustainable food production. Describe the role of organic farming in making this shift. List the advantages of relying more on organic polyculture and perennial crops. The five strategies that could help farmers and consumers to shift to more sustainable agriculture. The three important ways in which individual consumers can help to promote more sustainable food production.

Answer to Problem 9CR

The sustainable production of food is the key concept of the section. Soil conservation includes decreasing soil erosion and restoring soil fertility. The methods for reducing topsoil erosion include terracing, contour planting and strip cropping, alley cropping, and windbreaks and cover crops, conservation tillage farming, no-till, and minimum-tillage farming. The method of raising crops in greenhouses is hydroponics. Fertilizers made from organic materials are known as organic fertilizers, and they include animal manure, green manure, and compost. Crop rotation is the method of planting a series of different crops in the same area from season to season. Soil salinization is prevented by reducing irrigation switches to salt-tolerant crops and by using more efficient irrigation methods. The methods for reducing desertification include population growth, overgrazing, deforestation, and destructive forms of planting, irrigation, and mining. Shifting from less grain-efficient forms of animal protein into more grain-efficient forms is the method in which meat production and consumption can be made more sustainable. The use of polyculture and perennial would help in increasing the growth of organic farming. The use of organic fertilizers, biological pest control methods, and efficient irrigation methods are the three important ways in which individual consumers can help to promote more sustainable food production.

Explanation of Solution

The key concept of Section 12.5 is the method in which food can be produced in a more sustainable manner. More sustainable production of food is possible by conserving topsoil, efficiently producing more meat, decreasing the harmful effects of aquaculture, and abolishing government subsidies that promote the types of agriculture that are harmful to the environment.

A variety of methods for decreasing soil erosion and restoring the fertility of soil are included in soil conservation. They are generally done by keeping the soil covered with vegetation.

The six methods to reduce topsoil erosion include the following:

(i) Terracing involves the conversion of steep slope land into a series of level terraces. Each terrace can retain water, which reduces soil erosion.

(ii) Contour planting includes plowing and planting the crops in rows. The rows act as a dam that holds water and prevents soil erosion.

(iii) Strip cropping includes planting the crops in alternative series (such as cotton and corn). In this, one crop would act as a cover crop that traps the topsoil and prevents soil erosion.

(iv) Alley cropping involves planting leguminous crops between the orchard trees. The trees would provide shade to the crops and prevent evaporative loss of water. Therefore, alley cropping also helps in reducing soil erosion.

(v) Windbreaks include the planting of trees around the crops. The planted trees would reduce soil erosion by the wind.

(vi) Conservation tillage farming includes the use of special machines that directly inject the seed in the soil without disturbing the topsoil.

Hydroponics is a method in which some producers raise crops in greenhouses.

Nutrients can be completely restored to topsoil using both inorganic and organic fertilizers. Organic fertilizers are from plant and animal materials and commercial inorganic fertilizers are produced from various minerals. There are different types of organic fertilizers. One is animal manure, which is the dung and urine of cattle, horses, poultry, and other farm animals. It enriches organic nitrogen and encourages the growth of beneficial soil bacteria and fungi. Another type is known as green manure that consists of freshly cut or growing green vegetation that is ploughed into the topsoil for increasing the organic matter and humus available to the next crop. A third type is the compost formed due to the breakdown of organic matter such as leaves, crop residues, food wastes, paper, and wood in the presence of oxygen by the microorganisms in soil.

Planting crops such as corn and cotton on the same land, several years in a row, can lead to the depletion of nutrients. One method that can be applied to reduce soil degradation is crop rotation in which farmers plant a series of different crops in the same area from season to season.

The methods that can be applied to resist soil salinization include reduce irrigation, switch to salt-tolerant crops, and use of more efficient irrigation methods. Three methods for the irrigation of crops are gravity flow, central pivot, and drip irrigation. In gravity flow, water is generally derived from an aqueduct system or a nearby river. In the central pivot, water is usually pumped from underground and sprayed from a mobile boom with sprinklers. In drip irrigation, water is transferred to individual plant roots above- or below-ground pipes or tubes. Decreasing the amount of water that is put onto crop fields will help to reduce soil salinization. Drip or trickle irrigation, which is also known as micro irrigation, is an efficient method for delivering small amounts of freshwater to crops accurately.

Reducing desertification is not an easy method. It is not possible to control the timing and location of prolonged droughts caused by changes in weather patterns. However, population growth, overgrazing, deforestation, and destructive forms of planting, irrigation, and mining have left much land vulnerable to topsoil erosion and thus desertification can be reduced. It is also possible to reduce the contribution of human to projected climate change, which results in an increase in severe and prolonged droughts in larger areas of the world during this century. The land suffering from desertification can be restored by planting trees and other species of plants that anchor topsoil, holding water by growing trees and crops together, and by establishing windbreaks.

A more sustainable method of meat production and consumption involves shifting from less grain-efficient forms of animal protein, such as beef, pork, and carnivorous fish produced by aquaculture into more grain-efficient forms, such as poultry and herbivorous farmed fish.

The methods that can be applied to make aquaculture more sustainable include the following:

1.    Limit locations of fish farms to decrease the losses of mangrove forests and estuaries.

2.    Advance management of aquaculture wastes.

3.    Decrease the escape of aquaculture species into the wild.

The benefits of organic farming include the following:

1.    Fertility of soil increases.

2.    Soil erosion reduces.

3.    Holds more water in soil during drought years.

4.    Reduces the emission of carbon dioxide.

5.    Decreases water pollution by recycling livestock wastes.

6.    Reduces pollution from pesticides.

7.    Increase in biodiversity above and below the ground.

8.    Uses about 30% less energy per unit of yield.

Four important components of a more sustainable food production system include high-yield polyculture, organic fertilizers, biological pest control, integrated pest management, efficient irrigation, perennial crops, crop rotation, water-efficient crops, soil conservation, and subsidies for sustainable farming and fishing.

A significant factor of more sustainable agriculture is to depend less on single-crop organic agriculture and more on organic polyculture. For instance, on one piece of land, a diversified organic vegetable farm may grow forty or more different crops. Some scientists propose that larger dependence on polycultures of perennial crops is a component of more sustainable agriculture. Such crops can live for many years without having to be replanted and are adapted better to regional soil and climate conditions than most of the annual crops.

More sustainable food production can be promoted by the following methods:

a.    Use of organic fertilizers.

b.    Biological pest control methods.

c.    Efficient irrigation methods.

d.    Crop rotation.