003 - Agricultural Opportunities and Challenges in Arid Environments
Geographic Knowledge and Understanding
Agricultural opportunities and challenges in arid areas, including the distinction between aridity and infertility, irrigation access, salinization risk and land ownership.
There are possibilities for agricultural development in arid places. The demand for certain crops creates power over the approaches used to farm and these have environmental and social impacts.
- To be able to describe and explain the opportunities and challenges in arid areas for agriculture.
- To be able to explain the distinction between aridity and infertility.
- To be able to describe and explain irrigation access and link it to salinization risk.
- To be able to explain how land ownership presents opportunities and challenges for agriculture.
Define the words above by using the useful links below and your Freshwater textbook by Codrington.
Activity One - Read
There is a difference between aridity and infertility and if often comes down to the amount of rainfall an area receives. When travelling down the Draa Valley in Morocco that area was technically classified as hyper arid but dates were being grown.
- Read the text in the first box below and write down five of the most important facts about aridity.
- What is the difference between aridity and infertility when focusing on soils?
- Write a summary of the three key forms of irrigation.
- Of the total land area of the world, the hyper-arid zone covers 4.2 percent, the arid zone 14.6 percent, and the semiarid zone 12.2 percent. Therefore, almost one-third of the total area of the world is arid land.
- The hyper-arid zone comprises dryland areas without vegetation, with the exception of a few scattered shrubs. True nomadic pastoralism is frequently practiced. Annual rainfall is low, rarely exceeding 100 millimetres. The rains are infrequent and irregular, sometimes with no rain during long periods of several years.
- The arid zone is characterized by pastoralism and no farming except with irrigation. For the most part, the native vegetation is sparse, being comprised of annual and perennial grasses and other herbaceous vegetation, and shrubs and small trees. There is high rainfall variability, with annual amounts ranging between 100 and 300 millimetres.
- The semi-arid zone can support rain-fed agriculture with more or less sustained levels of production. Sedentary livestock production also occurs. Native vegetation is represented by a variety of species, such as grasses and grass-like plants, fortes and half-shrubs, and shrubs and trees. Annual precipitation varies from 300-600 to 700-800 millimetres, with summer rains, and from 200-250 to 450-500 millimetres with winter rains.
- Soil fertility is the ability of a soil to provide nutrients for plant growth. Not all soils in arid environments lack the necessary nutrients to be productive but the lack of available water limits plant growth and agricultural potential.
- Flood irrigation
- Results in a large surface area of water since furrows between crops will be filled with water. It is simple, relatively cheap, requires little energy and can use lower quality water than other systems. Conventional furrow systems are only 60% efficient in water absorption by the plants.
- Sprinkler irrigation
- Sprinkler systems use spray nozzles and pressurized water and can either be movable (such as center-pivot) or fixed. The most efficient systems are Low Energy Precision Application (95%) and Low Elevation Spray Application (88%) sprinklers. They are an adaptation of center-pivot irrigation in which the nozzles extend right down to the ground so the water is supplied only and exactly where it is needed and can be applied at low pressure. This saves water as less is lost to wind or evaporation from the foliage and energy as well as preventing soil erosion caused by runoff of excess water. On the down side sprinkler systems are expensive to install and may become less efficient when it is dry or windy, and they may damage crops by frequently wetting non-root areas.
- Drip irrigation
- This is where water is supplied at very low pressure, very slowly, directly to a plant's roots from plastic tubing. It is the most efficient form of irrigation at 97%, results in very little erosion. However it is also the most expensive form of irrigation
Adapted from - Mission 2012
Activity Two - Watch
One of the key ways to bring the desert back to life is to bring water to the desert. The traditional method of doing this was flood irrigation which was first used 3500BC in Mesopotamia. Fortunately are technology has advanced since then but not everyone has access to it due to cost. While the syllabus point doesn't ask for an example it is good to discuss irrigation using specific examples.
- Collect a piece of A4 paper and a set of coloured pens.
- You are going to use a different colour for each of the examples used in the clips below.
- For each examples write down the causes and consequences of the irrigation techniques.
Activity Three - Comprehension
Answer the following questions on salinisation using the text book in the 'Useful Resource' box below.
- How does salinisation occur?
- How can salinisation be reduced?
- Create a detailed example for an area in the world that suffers from salinisation.
Activity Four - Draa Valley, Morocco
We visited Morocco for a reason and the key one was to be able to use it to create detailed examples of the different opportunities and challenges that arid environments provide. You are now going to record enough notes to be able to write an essay on farming in the desert using the Draa Valley, Morocco as your detailed example. Below are a variety of resources that will help you to develop your detailed example - don't be scared of the number of pages in one of the resources! For you detailed example you will need to include the following things:
- Description of the location
- Amount of precipitation that falls and the type of arid environment the Draa Valley is - Page 19 IMPETUS article.
- Types of crops that are grown in the Draa Valley - Page 67 IMPETUS article
- Why dates are such an important crop - Pages 4-5 IMPETUS article
- What the opportunities and challenges are for growing water melons in the region.
Image Three - The Draa Valley
Activity Five - Land Ownership
For areas that rely on farming for their main source of income land ownership is critical for a families success. In the past it has been men who have owned the land in Morocco and women have little say about it. This is slowly changing. Read the article in the 'Useful Resource' box and write notes on the revolutionary changes that are currently taking place in Morocco.
Exam Style Question
“Agriculture in hot, arid areas is difficult.” Discuss this statement. [10 marks]