W10, Soil amendments Flashcards
What benefits do organic fertilisers possess over inorganic ones?
→ Improve soil structure
= ↓ erosion
= ↑ water and nutrient holding capacity
= ↑ pH buffering capacity
= ↑ water infiltration
= ↓ penetration resistance
→ Provides nutrients at a rate more in line with crop growth
→ Promotes biological diversity and activity
= ↑ aggregation
= ↑ nutrient cycling
= ↑ nutrient uptake (AM enhance P uptake)
= ↑ disease resistance
= ↑ ecosystem resilience
→ Not as polluting to the environment
→ Less energy intensive
→ Part of a healthy agroecological system
True or False?
A majority of farmers worldwide rely on inorganic inputs to support production.
False.
Most of the world’s farmers rely on biologically regulated nutrient supply systems to support production.
List some examples of organic amendments
- Animal manure
- Crop stubble
- Cover crops
- Vermicast
- Humanure
- Industrial food waste
- Compost
What are common application rates of compost in broadacre agriculture?
Can be anywhere from 2-30 t/ha
What are common application rates of compost in horticultural systems?
Often exceed 30 t/ha due to the higher value and nutrient demand of the crop.
What issues can there be when using compost as an organic amendment?
→ Possibility of contamination
- weed seeds
- heavy metals (esp. in green waste)
- salts (esp. in green waste)
- pathogens
→ Inconsistent composition
- different input materials in diff seasons (lots of grass in spring, lots of leaves in autumn)
How does [P] differ in organic amendments?
The amount, availability, and composition of P differs depending on the source.
True or False?
Mixing organic and inorganic fertilisers isn’t as good as using one or the other
False. Using a combination almost has a hybrid-vigour-like effect.
How long does it take for worms to turn organic waste into casts?
Depends on the quantity, but generally 22-32 days
What is the ideal stocking density of worms (worms/L waste)?
150 worms / L of waste
How much do earthworms generally eat per day?
Around 75% of their body weight / day.
A 200 mg worm can eat 150 mg/day
What are some typical application rates for vermicast and vermitea?
Casts: 2-50 t/ha
Liquid: 10-100 L/ha
What are fish hydrolysates?
Basically ground up feral fish species (e.g. carp) that are digested with enzymes and turned into a liquid.
Rich source of nutrients.
What are some typical application rates for fish hydrolysate?
Foliar spray: 10-30 L/ha
Soil drench: 20-60 L/ha
What has biochar been shown to achieve in terms of soil and agricultural production?
- Enhance the efficiency of synthetic N ferts
- Enhance biological N fixation potential of rhizobium-legume systems
- Improve soil structure
- Increase SOC
