Lecture 14 - components of agricultural sustainability Flashcards
what are the 9 components of agricultural sustainability?
- Soil and land
- Nutrients
- Water use
- Organic matter
- Biota
- Energy and agrochemicals
- Crop productivity- food supply
- People
- Climate and ecosystems
describe the effect of climate change on crop production
- rising sea levels are damaging soils from salinization
- when crops are stressed they are more vulnerable to disease and pests
- Estimated 200-400 million more at risk of hunger by 2080 due to climate change
how is climate change affecting soil?
- extreme weather- drought / high rainfall erosion events
- Warming – increased decomposition of soil organic matter.
- Sea level rise - thermal expansion and melting ice caps and glaciers - flooding- Hundreds of millions of people live on fertile land just above sea level and these are areas important for food production
- risk of salinization of soil groundwaters as the sea levels rise
what are soil conservation technologies?
No-till cultivation, strip-cropping, contour planting, terracing, mulches, cover crops, leys, agro-forestry, and wind-breaks. Water management- to store water in soil (mulches, organic matter, terracing)
- Many techniques try to mimic natural ecosystems: complete vegetation cover gives very low soil losses - protect from wind and erosion
what are techniques used to enhance the nutrients in the soil?
- Legumes and green-manures in rotations to build and retain fertility.
Agro-forestry especially with legume trees - Phosphorus mobilizing plants, mycorrhizas and bacteria- use of cultivation techniques and inoculants to achieve these goals.
- Use of rock-dust fertilization from abundant rock sources like basalt- especially using rock dust waste as a by-product of mining for other uses such as roadstone.
- Waste recycling, composting and manures
- organic matter nutrient storage, and ion exchange capacity
example of how you can change the availability of nutrients already in the soil
rich Phosphorus sources already In our soils – In some environments adding silicate rock dusts can change the availability of P - by changing the soil chemistry
what are added cobenefits of adding silicate rock dusts?
additional environmental benefits such as getting more calcium/ base cations and alkalinity into oceans e.g. great barrier reef to counteract ocean acidification
what is a global key constraint on crop production?
water availability
describe how increased water irrigation of wheat (during critical growth stages) in the UK could affect yield?
Under irrigation UK wheat growing can yield 11.5-14.8 Tonnes per hectareAt 13 tonnes per hectare we can produce enough wheat to feed over 150 people per hectare at current consumption.
At 13 tonnes per ha UK land allocated to wheat could support 346 million people at current UK consumption.
what is the issue with increased irrigation?
needs infrastructure - e.g. capture of rainwater in the west and move it to the east
- Irrigation often requires pumping- frequently using groundwater resources at rates that are unsustainable- energy and water supply implications
what is an issue with using groundwater?
it usually contains salt and when the water evaporates it leaves salt behind in the soil - Salt accumulation in soils where irrigation practices are poor- destroys soil
describe a process to remove the salt from water?
DESALINATION - carry out using reverse osmosis, and solar power to replace fossil fuels - could also then use sea water for crop irrigation - can use this technology in areas which are currently deserts! However costs are high and you would have to pay more for food
what are the advantages of increased organic matter in the soil? (5)
- reduces erosion,
- increases water and nutrient storage,
- helps reduce atmospheric CO2 concentrations,
- increases soil aggregate size and stability,
- increases crop yields
what is the productivity of land largely determined by?
to a large extent determined by the fertility of the soil, which is turn is mostly determined by its organic matter content and stored nutrients
What are the optimal strategies to rapidly accumulate soil organic carbon?
- Agroforestry
- Leys
- Legumes
describe the issue with pests and disease on agriculture
Resistance to chemicals and banning of use of some chemicals presents increasing problems for crop production
what are techniques used to battle pests and diseases?
Diverse cropping systems and rotations to reduce build-up of diseases and pests. Inducible defences (e.g. by mycorrhiza-induced systemic resistance).
what was the issue with the neonicotinoid insecticide?
seed coating with a neonicotinoid insecticide negatively affects wild bees
- underground these neonicotinoids were also toxic to earthworms - didn’t break down as quickly in soils - so accumulated in high concentrations - especially in field margins where the organic matter is high
describe the use of biological control agents and its efficiency
Facilitating or adding natural enemies of pests - not always a solution in simplified agricultural systems - relevant to the ‘land sparing land sharing’ debate - suggests that actually converting whole areas uniformly to agriculture is probably a bad thing in terms of building up natural organisms – pushes you more down the chemical pathway which has lots of problems
what can help to improve Soil structure, aggegation, drainage and C sequestration?
Earthworms
Mycorrhizas
Leys and legumes, cover crops, agro-forestry.
what it intercropping?
- Growing crops for protection and enhancing nutrients via legumes etc
describe the findings of Liu et al for dual cropping
found the optimal planting for dual cropping was maize row distance of 0.4 m, soybean row distance 0.4 m, and distance between maize and soybean rows of 0.6m
in terms of energy what does our economy and food supply depend on?
cheap oil
If we are going to have sustainable agriculture we most have sustainable energy systems - what is a possible solution to this?
- Possible use of non-edible plant oils as new sources for biodiesel production
