W10, Soil amendments Flashcards

1
Q

What benefits do organic fertilisers possess over inorganic ones?

A

→ 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

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2
Q

True or False?

A majority of farmers worldwide rely on inorganic inputs to support production.

A

False.

Most of the world’s farmers rely on biologically regulated nutrient supply systems to support production.

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3
Q

List some examples of organic amendments

A
  • Animal manure
  • Crop stubble
  • Cover crops
  • Vermicast
  • Humanure
  • Industrial food waste
  • Compost
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4
Q

What are common application rates of compost in broadacre agriculture?

A

Can be anywhere from 2-30 t/ha

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5
Q

What are common application rates of compost in horticultural systems?

A

Often exceed 30 t/ha due to the higher value and nutrient demand of the crop.

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6
Q

What issues can there be when using compost as an organic amendment?

A

→ 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)
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7
Q

How does [P] differ in organic amendments?

A

The amount, availability, and composition of P differs depending on the source.

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8
Q

True or False?

Mixing organic and inorganic fertilisers isn’t as good as using one or the other

A

False. Using a combination almost has a hybrid-vigour-like effect.

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9
Q

How long does it take for worms to turn organic waste into casts?

A

Depends on the quantity, but generally 22-32 days

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10
Q

What is the ideal stocking density of worms (worms/L waste)?

A

150 worms / L of waste

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11
Q

How much do earthworms generally eat per day?

A

Around 75% of their body weight / day.

A 200 mg worm can eat 150 mg/day

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12
Q

What are some typical application rates for vermicast and vermitea?

A

Casts: 2-50 t/ha

Liquid: 10-100 L/ha

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13
Q

What are fish hydrolysates?

A

Basically ground up feral fish species (e.g. carp) that are digested with enzymes and turned into a liquid.

Rich source of nutrients.

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14
Q

What are some typical application rates for fish hydrolysate?

A

Foliar spray: 10-30 L/ha

Soil drench: 20-60 L/ha

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15
Q

What has biochar been shown to achieve in terms of soil and agricultural production?

A
  • Enhance the efficiency of synthetic N ferts
  • Enhance biological N fixation potential of rhizobium-legume systems
  • Improve soil structure
  • Increase SOC
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16
Q

What’s the problem with our understanding of biochar at the moment?

A

Results on the effectiveness of biochar are highly variable. Some show positive results, some show negative.