GHG SOIL CONSERVATION & RESTORATION Flashcards
what is REDD+?
what is their aim?
what does the + signify?
Reducing Emissions from Deforestation and Forest Degradation
- stop deforestation 1.1 GtC/y
- remove CO2 by restoring forest capacity over next 50 years at average rates that allow current 2nd growth forests to reach maturity 2 GtC/y; restore degraded forests 1 GtC/y; reforest recently deforested lands 1 GtC/y
+ signifies:
- conservation of forests
- sustainable management of forests
- enhancement of forest carbon stocks
what is the 4 per mille initiative?
- amount of C stock increase needed to offset CO2 emissions
- a growing international coalition of nation-states, international organisations, NGOs, research centres, universities, farmers organisations, and businesses
what are some practices that increase soil organic carbon?
- conservation, tillage, residue management and mulch farming
- apply organic wastes to soil
- use N and other nutrient sources more efficiently
- convert marginal and degraded lands to restorative land uses
- eliminate summer (bare) fallow and incorporate legumes and other appropriate cover crops in rotations
- agroforestry (combo of trees)
What is the most efficient and safest climate mitigation strategy? what other benefit would it have?
- restore soils to sequester carbon back where it belongs, in the soils and in the plants
- enhances food security; +1 tonne of soil carbon per hectare per year increases crop yield by 20-70 kg/hectare of wheat, 10-50 for rice, 30-300 for maize
- would lead to an increase of 24-40 million metric tonnes in grain production at the global level
what are the limiting factors for if regenerating soils is feasible?
- depends on how much C is there already; if already a lot of C in the soil, can’t get much more into it as near saturation
- depends how long improved management has been practiced on the site; more years means lower sequestration rate
what is the benefit and limitation for incorporating rice straw to stimulate rice growth?
- improves plant growth and waterlogged conditions; slow decomposition
- but leads to very high CH4 emissions from rice fields
biochar is the product of … of biomass, which is the … of biomass in … oxygen environments
pyrolysis
heating
low
what is the process of biochar, which is a negative emission technology used to improve soil fertility?
- carbon captured by photosynthesis (biomass) from the atmosphere is locked into biochar
- preventing degradation and return of carbon into the air
- biochar is then applied into the soil
biochar so partly burnt, so some of it comes back out as CO2, but left with biochar which tends to be very resistant to decomposition. it’s very stable and is degraded over centuries/millenia.
what is pyrolysis? what are the products of it?
thermal decomposition in the absence of oxygen
- gas, bio-oil and a solid char
what is pyrolysis and gasification (part of biochar section)? what are the products of it?
the conversion of biomass into carbon monoxide, carbon dioxide, hydrogen, methane and nitrogen with a limited supply of oxygen and/or steam
- syngas (mixture of gases CO, CH4, H2) and char
what are the benefits and risks of biochar amendment?
benefits:
- increased C stabilisation/sequestration
- increased persistence of nutrients bound into biochars which are slowly released, improving growth over time when used with fertilisers
risks:
- produce toxic compounds too, which can be added to agricultural soils/food we eat
- might increase persistence of pollutants
what is bioremediation?
a branch of biotechnology that employs the use of living organisms, like microbes and bacteria, to decontaminate affected areas.
- removes contaminating pollutants from the soil e.g. heavy metals like mercury and arsenic as a result of pesticides/herbicides
- think polyaromatic hydrocarbons
what are polyaromatic hydrocarbons?
a class of chemicals that occur naturally in coal, crude oil and gasoline, resulting from burning them. they can bind to or form small particles in the air.
what can be used to break down polyaromatic hydrocarbons by stimulating the growth of microbes? what are they mainly produced by?
lignolytic enzymes
- it’s a biostimulant to boost the growth of organisms that break down lignin
- lignin added to soil to stimulate growth of microbes
- mainly produced by fungi, but also some bacteria
what is phytoremediation? how does it enhance PAH dissipation from soil? what plant is commonly used due to its extensive root system? under what concentration of contaminants does it work best under?
- uses plants to clean up contaminated environments
- can enhance PAH dissipation from soil by plant uptake (phytoextraction), or stimulating microbe activity through root exudates (rhizoremediation)
- ryegrass commonly used due to its extensive root system
- low; high conc’s may limit plant growth and take too long to take up
