The Horse 2020/21

Soil organisms both serve as a source of nutrients for plant growth and drive the transformations of nutrients that make them available to plants. The collective carbon content of all soil bacterial cells is comparable to that of all plants on earth, and their total nitrogen and phosphorous contents are far greater than that of all vegetation, making these microorganisms the primary source of indispensable nutrients for life. Plants fix carbon from the atmosphere, but they require macro and micronutrients that are absorbed from the soil to create biomass and transfer nutrients and energy. Soil microbes and microfauna interact with abiotic factors – temperature, pH, moisture content- and drive these transformation processes. Soil micro, meso and macrofauna play a key role in the physical breakdown of plant residues, allowing the soil microorganisms to liberate the nutrients and energy bound up in the plant material. The role of soil organisms in agriculture has many beneficial effects beyond plant nutrition. For example, soil microbiota such as arbuscular mycorrhizal fungi and nitrogen fixing bacteria can minimise cost and dependence on synthetic nitrogen fertilizers in agriculture, and enhance soil fertility and environmental sustainability, including reducing greenhouse gas emissions from the energy-intensive manufacture of nitrogen fertilizer.

The role of soil biodiversity in addressing global climate change cannot be understated: the soil community’s activities can contribute either to the emission of greenhouse gases or to absorbing carbon into soils from the atmosphere. As part of the natural functions and ecosystem services provided by soils, a healthy soil stores more carbon than that stored in the atmosphere and vegetation combined. Carbon is either fixed or released from soils, depending the activity of the soil organisms and driven by soil conditions. Carbon is fixed into soils through the transformation of plant and animal detritus, and also some bacteria and archaea can fix carbon by using atmospheric CO2 as their energy source. Beyond their direct role in the carbon cycle, soil organisms are also critical for efforts to reduce overall greenhouse gas (GHG) emissions from agriculture. Globally, agricultural ecosystems contribute 10 to 12 percent of all direct anthropogenic GHG emissions each year, with an estimated 38 percent resulting from soil nitrous oxide emissions and 11 percent from methane in rice cultivation. Soil microorganisms are involved in every step of nitrogen and carbon transformations that yield these greenhouse gases, and managing the soil environment to minimise emissions is a key objective in sustainable soil management.

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Sources:
learning.edx.org

http://www.fao.org/

EDX 4.3 Soil Biodiversity Characteristics

Soil biodiversity is the variety of life that exists within the soil, including bacteria, fungi, earthworms, and termites. A teaspoon of topsoil typically contains a vast range of different species and up to 6 billion microorganisms.

The group of large organisms in the soil is visible to the human eye. (Macroscopic)
For example:

• Plants
• soil fauna
• worms (earthworms, pot worms)
• isopods, millipedes, centipedes

The group of small organisms in the soil isn't visible to the human eye. (Microscopic)
For example:

• Soil microbes - bacteria, fungi
• microfauna (nematodes)

If we take a look at an arable field or a grassland then we see, aboveground, a few plant species: one plant species in a monocrop and up to 50 species per square meter in species-rich grassland.

Now if we look at the number of different species or the diversity, we can see the smaller the organisms the more different species there are, ranging from 10 species of earthworms to thousands of species of bacteria and fungi.

Soil life is sensitive to disturbance and compaction of soil because that affects the amount of space and air available for plant roots and other soil biotas.

It is also sensitive to chemicals that end up in the soil water, or pollution like oil spills that block access to food, air, and water. Life in soil is also sensitive to temperature and soil acidity.
Soil organisms feed directly or indirectly on plant inputs and not all species like to eat the same thing. So the type of plant you grow, like the type of crop or green manure that you add to the soil, can all influence the abundance and diversity of the soil life.

A vital part of life on earth is the continuous hydrologic cycle; Water cycles from the atmosphere to and through the earth and back  the atmosphere.

Once water has entered the soil, it will spread out in all directions. The water either gets stored for reusing by plants for example or it drains downward. 
Because of soil water air and nutriens can get in the ground which is very imiportant.

What is soil pollution?

- When the concentration of pollutants on the surface becomes so high that it harms land biodiversity and endangers health (particularly through food)

- Farmers use chemicals, pesticides and fertilisers that pollute the land

- A gobal threat (particularly serious in regions like Europe, Eurasia, Asia and North Africa)

- It's already affecting one third of the world's soil

Causes and types of soil pollution

Erosion, loss of organic carbon, increased salt content, compacting, acidification and chemical pollution are the major causes of current soil degradation

Specific pollution: accounted for by particular causes, occurring in small areas the reasons for which can be easily identified. Land pollution such as this is normally found in cities, old factory sites, around roadways, illegal dumps and sewage treatment stations.

Widespread pollution: covers extensive areas and has several causes the reasons for which are difficult to identify. Cases such as these involve the spreading of pollutants by air-ground-water systems and seriously affect human health and the environment.

Consequences of soil pollution

Damage to health

Soil pollutants enter our body through the food chain, causing illnesses to appear. Moreover, the spread of antibiotics in the environment increases the pathogens' resistance to these drugs.

Poorer harvests

Soil pollution agents jeopardise world food security by reducing the amount and quality of harvests.

Climate change

In the first decade of the 21st century, soil degradation released between 3.6 and 4.4 billion tonnes of CO₂ into the atmosphere.

Water and air pollution

Soil degradation affects the quality of air and water, particularly in developing countries.

Population displacement

Soil degradation and climate change will have driven between 50 and 700 million people to emigrate by 2050.

Species extinction

Soil contamination is one of the main causes that could trigger the sixth mass extinction event in history — the population of land vertebrates fell by 38 % between 1970 and 2012 —.

Desertification

The number of inhabitants in the most arid areas of the earth could account for 45 % of the world's population in 2050, while world wetland areas have decreased in size by 87 % over the last three centuries.

Economic impact

Global economic losses caused by soil degradation are expected to exceed 10 % of the world's annual Gross Domestic Product (GDP).

Solutions to reduce soil pollution

- Eat sustainable foodstuffs, properly recycle batteries, produce homemade compost and dispose of drugs in the places authorised for this purpose.

- Encourage a more eco-friendly model for industry, farming and stock breeding, among other economic activities

- Improve urban planning and transport planning and waste water treatment.

- Improve the management of mining waste, restore the landscape and conserve topsoil.

- Involve local communities and indigenous peoples in the design, implementation and assessment of sustainable land and soil management.

Source
[1] What is soil pollution?
[2] Introduction soil pollution

Were you aware that:

• China and India are losing soil 30 to 40 times faster than the natural soil replenishment rate allows it
• 400 billion Dollars per year is the estimated damage of soil erosion worldwide
• 30% of the world's arable land has become unproductive due to soil erosion over the past 40 years
• About 60% of soil that is washed away ends up in rivers, streams and lakes
  • This increases the danger of waterways overflooding

Together, wind and water erosion account for 84% of all land degradation making them the biggest danger for future food planting.

[in progress]

In Wädenswil there is the Rietliau sewage treatment plant, which purifies the water for the municipality of Wädenswil. It was put into operation in 1947 and has since been renovated again in 2005. The treatment plant is one of the medium-sized ones in the canton of Zurich, with a population equivalent of 44,000. The purified water flows back into Lake Zurich. There is a small recycling station for glass, plastic, etc. right in front of the treatment plant.

Sources (PDF) : https://www.hw.zh.ch/ara/Waedenswil.pdf

The ARA Mönchaltorf is built for 4000 people. It was installed in the year 1971. The last extension was 2003. The water is drawn from the Aabach and the Greifensee.
In Mönchaltorf, the following steps are processed:
1. Preliminary sedimentation
2. Activated sludge plant with deep aeration
3. Nitrification / denitrification
4. Chemical phosphate elimination
5. Wastewater filtration

Source:
moenchaltorf.ch
zh.ch

For my waste water, the ARA Bubikon / Wolfhausen is responsible. It covers 3558 people from Bubikon and Wolfhausen (2018). The size of the sewer is actually for 5000 inhabitants. 

In Bubikon there is also a second ARA called Weidli, this one covers also some people from Bubikon but also the people from Dürnten. It was founded in 1972 and the ARA Bubikon / Wolfhausen in 1951. 

The waters the ARA's use is the lake of Zurich and the Klausbauch.
 

ARA Bubikon (PDF, zh.ch)

Survey about diseases of trees and foreign plants in the city of Zurich

Hi everyone

I'm a student from the WKVW in Switzerland and I'm making a project with Kevin about diseases of trees and foreign plants in the city of Zurich.
We made a survey to learn about this topic from different countries and we would really appreciate it if your students could fill out this survey!

The survey you can find here: https://www.umfrageonline.ch/s/acf71bf

We are at your disposal for any questions and uncertainties.

Best regards,
Kevin and Tamara