Lecture 1 - soil Flashcards
soil is a major reservoir of what?
microbial biodiversity with which humans have evolved
what is the global importance of soil?
the essential foundations of sustainable agriculture and ecosystems and the global economy
how does the microbial world influence human wellbeing?
directly, and indirectly via effects on food quality, climate and the environment
what percentage of land is cultivated?
9% of the 30% land surface - little scope for future expansion
why is there little scope for future expansion of land for cultivation?
- A small amount of the earth’s surface is actually suitable for cultivations
the population is increasing but why are yields not?
related to the quality of the soils – not optimal conditions to produce maximum output
what do ecological footprints tell us about the current situation of the worlds resources?
were stamping out the worlds resources -The average ‘ecological footprint’ of a human in high income countries like ours is 5-10 ha but there are only 1.9 ha of productive land per person in the world
what is the growing issue with soil and water management?
- Water management is a big issue and soil management for water is a big issue e.g. filtration and run off
- 97% of available fresh water passes through the soil and into the ground water
- More than 70% of available freshwater is used in agriculture
9 soil ecosystem services
- Food production: crops and livestock
- Fresh water: filtration and storage
- Fibre: cotton, linen, wool
- Wood: construction, paper
- Fuel: wood, peat, straw, biomass
- Carbon and nutrient storage
- Climate regulation
- Waste detoxification and pollution control
- Host biodiversity and support the biodiversity of above-ground ecosystems
what is our biggest household footprint?
- Our consumption of goods and services (individual greenhouse gas emissions)
what is the issue with soil loss?
we are losing a resource that is, for practical purposes and human timespans, essentially non-renewable
how long does it take for 1cm of topsoil to regenerate?
about 200yrs
nearly 33% of the worlds arable topsoil is lost to what?
erosion and pollution (especially with salt) in the last 40 yrs
what does erosion lead too?
preferential removal of organic matter and clay - removing nutrients and releasing CO2
what two things have been added to the revised universal soil loss equation?
c= cropping and management p = soil conservation practices to reduce erosion
what do the terms of the soil loss equation explain?
explain why soil is lost
what is the difference between the factors c and p in the soil loss equation?
factors we can control
4 main anthropogenic causes of soil erosion?
1) cultivation
2) over -grazing
3) deforestation
4) salinization
5 examples of cultivation causing soil erosion
1) tillage
2) bare soil
3) crops with small roots,
4) reduced soil organic matter,
5) compaction
what is salinization?
salt pollution from poor irrigation- leading to very poor vegetation
what 2 things define soil degradation?
- Loss of soil quality - loss of organic matter, salinization, loss of nutrients, infertility.
- Loss of soil quantity - soil erosion and loss of soil volume by oxidation of peat
what does loss of topsoil cause?
soil quality decline- Soil erosion preferentially loses clay, and organic matter that store nutrients. This reduces the capacity of the soil to store nutrients and water.
- More nutrient inputs (fertilizer) are needed to support crop growth.
- A higher proportion of fertilizer is washed out causing pollution.
how can soil effect flood risks?
Eroded soil silts up rivers, and degraded soil stores less water
how is deforestation effecting soil?
Soil is being washed away due to deforestation into rivers -Soil erosion rates may slow down over time once the topsoil has been depleted
how self sufficient is the UK for food?
52% - enough to feed us from 1st January to 10 days into July each year. - rest comes from international sources
It’s easy to blame the farmers but it’s important to know why the farmers are having to manage the soil in unsustainable ways - why?
they arent paid enough to prioritise soils
