Topic: The main causes of soil degradation

Target group

2nd‑grade student of high school or technical school (basic programme).

Core curriculum

General requirements

II. Skills and application of knowledge in practice.

6) Anticipation of the effects of human economic activity in a geographical environment.

Specific requirements

XIII. Man and the geographical environment - conflicts of interest: the impact of human activities on the atmosphere on the example of smog, hydrological investments on the geographical environment, agriculture, mining and tourism on the geographical environment, transport to living conditions and degradation of the natural environment, urban and rural development on the cultural landscape, conflict human interests - environment, revitalization processes and pro‑ecological activities.

Student:

3). analyzes, on examples from the world and Poland, the impact of agricultural activity, including crop rotation and agricultural monoculture, chemization and mechanization of agriculture, drainage and excessive grazing of animals on the natural environment;

Purpose of the lesson:

To explain to students the main causes of soil degradation.

Criteria for success:

• you mention the main causes of soil degradation on Earth;

• provide examples of human activities that cause soil degradation;

• on the chosen example, you will discuss the relationship between human activities and soil degradation.

Skills acquired and improved:

• computer support;

• using the e‑textbook;

• independent learning;

• group work;

• information processing;

• communication.

Teaching aids:

• computers with internet access, or tablets;

• multimedia resources contained in the lesson „Main causes of soil degradation”;

• interactive whiteboard / blackboard, marker / chalk.

Teaching methods and techniques:

• exhibiting: presentation;

• problematic: targeted conversation, brainstorming, didactic discussion;

• giving: mini‑lecture;

• programmed: using a computer, using an e‑manual;

• practical: subject exercises.

Forms of work:

• individual work;

• work in groups;

• collective work.

Course of classes

Before classes

1. Before classes, the instructor recommends students to familiarize themselves with the entire material from the lesson „Main causes of soil degradation” in the e‑textbook.

Initial phase

1. In class, the teacher determines the purpose of the lesson, informing students about its planned course. Then he writes the topic of classes on the blackboard or interactive whiteboard. Students write it in notebooks.

2. The teacher designates a student who will discuss the main causes of soil degradation in the world. If necessary, the facilitator completes the student's statement.

3. The teacher divides the class into groups. Working with the expert tables method, students try to systematize the knowledge of lessons on the mechanisms of soil degradation as a result of human activity. Each expert table deals with one of the following issues:

• overgrazing and deforestation;

• overexploitation of soil;

• fertilization and errors in the use of chemical plant protection products;

• incorrect irrigation;

• use of heavy agricultural machinery.

4. The group indicated by the teacher presents the results of the joint work, referring the material from the lesson. The teacher complements the students' statement. He also explains that in addition to the discussed factors contributing to the degradation of soils on a global scale, there are also others that can only be relevant locally. As an example, he gives the method of plowing on slopes with a strong slope and presents a gallery devoted to this issue. The trainer explains that in the case of a plowed field along the slope, soil degradation occurs much faster as a result of washing away the humus out of it than in the case of a plowed field along contour lines.

5. The teacher asks students to use the brainstorming method to present arguments for or against the ban on breeding in areas affected by soil degradation, as a solution limiting their further destruction. All arguments are kept on the current table and discussed in the class forum.

6. Working individually, students solve interactive exercises from the abstract.

Summary

1. The teacher goes on to summarize the lesson, during which the students can discuss any unclear issues and complete the notes.

Homework

1. Listen to the abstract recordings at home. Very important is the pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

The main causes of soil degradation

There are many causes of land degradation, which often overlap. The most common cause of land degradation is overgrazing, that is, when the animals eat plants so fast that vegetation has no chance to grow back. This leaves the soil bare, especially its humus layer. Wind and rainwater easily remove humus, which makes the soil lose its qualities. This is especially characteristic of arid and semi‑arid areas, such as the Sahel region of Africa. The effects of reckless deforestation are similar, only they can be seen much sooner.

Improper agricultural practices also contribute to the deterioration of soil quality. Prolonged overexploitation of land leads to a reduction of the amount of humus. As a result, the soil becomes poorer in nutrients and its structure deteriorates, causing reduced water absorption, inhibiting the activity of soil‑dwelling organisms and weakening its chemical stability.

An obvious solution would seem to be to use fertilisers. Natural ones are the best, but unfortunately they are usually hard to come by in sufficient amounts. Synthetic fertilisers, on the other hand, can be counterproductive when used improperly. For instance, too much can poison the soil, killing soil micro‑organisms, activating heavy‑metal compounds and changing the pH (increasing acidity) of the soil, which makes it more difficult for plants to absorb nutrients. Over‑fertilisation is typical of developed countries where intensive farming is popular.

Soil degradation may also derive from incorrect use of chemical plant protection products. When such substances, toxic by their very nature, penetrate the soil, they kill soil‑dwelling organisms, disturbing, as a result, soil formation processes.

Even improper irrigation can have grave consequences. Water used in farming is often rich in salts. In the process of evaporation, only water particles enter the atmosphere, whereas mineral compounds remain in the soil. The amount of the latter grows with time, leading to soil degradation due to increased salinity. Soil salinity is a characteristic feature of arid areas in both developing and developed countries.

Soil degradation can be also caused by some types of agricultural machinery. Machines used for harvesting crops are usually large and heavy, so they compact the soil. This, in turn, hinders gas exchange, water absorption, movement of animals living in the soil, but also makes it easier for water to run over the soil instead of entering it. All these factors combined impair the quality of the land or, in other words, lead to its degradation. Owing to the costliness of agricultural machinery, this type of degradation is typical of developed countries.

In addition to factors contributing to the degradation of soils on a global scale, there are also others that can only be relevant locally, for example, plowing on the steep slopes. In the case of a field plowed along the slope, soil degradation occurs much faster as a result of washing out the humus out of it than in the case of a contour plowing.