RESOURCES FOR AGRICULTURE + CONSERVATION Flashcards
what factors drive plant production
- available water
- radiation (temp, sunlight)
- soil properties
what are some models to estimate productivity?
- French and Schulz - yield = (water use - 110mm) x 20 (yield vs water use)
- APSIM = using past measurements
- online tools
what aspects of rainfall impact ag
- amount
- seasonal distribution
- long-term variations
- extremes
- climate change
define evapotranspiration, evaporation, transpiration
evapotranspiration = ET, evaporation combined with transpiration and interception
Evaporation = vaporisation and loss of water from wet surfaces
Transpiration = direct water use by plants; extraction of water from depth
evaporation so important
- water balance
- related to plant growth rates
- irrigation requirements measured
how is irrigation requirement estimate
NWR = ETc - Reff
NWR = net water requirement
ETc = crop evapotranspiration
Reff = effective rainfall (50% rain)
What are ways of dealing with temperature limits
- seasonal planting
- variety of crop
- planting dates
- site selection
- disease control
- sheep shearing and wind chill changes
what are the main components of soils
- particle size
- particle composition
- water holding capacity
- nutrients
- stability
how can soils impact plant productivity
- waterlogging
- salinity
- nutrient deficiencies
- pH
- hardsetting
- non wetting
compaction
what are the central challenges to soil and water
- eutrophication
- wind erosion
- salinization
- biodiversity loss (moncultures)
- soil contamination
how is salinity increased in ag?
- land clearing causes release of built up salt in soils
- this is an issue because water is required to dilute and move salt away
explain the case study “saltland at Wickepin”
- salt catchments were cleared and salinized
how does land clearing impact salinity
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Solutions to increased salinity
- drainage
- salt tolerant crops
- reforestation
- complete revegetation
what is sequestration?
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