Pastures and soils Flashcards
Describe the family Poaceae?
Grasses eg spikelets with bristles eg buffel grass, open panical, guinea grass
monocotyledons
most effective with shallow water
often dormant during drought or the dry season
estimated to comprise 20% of the worlds pasture
ecologically important, prevent land erosion
Ephemerals - short lived growing only during favourable conditions
Highly adaptable
Describe the family leguminosae, and the three subfamilies Fabaceae, Mimosaceae and Caesalpiniacecae?
The range of uses for legumes is much broader than that of grasses.
The fruit is a pod
symbiotic nitrogen fixation
Fabaceae = Pea type flowering legumes centro, butterfly pea
Mimosaceae = rounded inflorescence type of flowers (Mimosa, Leucaena)
Caesalpiniacecae = yellow or open top flowers (Wyn Cassia, Senna sp).
Describe the family Apocynaceae ?
Propella shaped petals
Name the plant?
Black spear grass
native pasture
Name the plant?
Mitchell grass
Native species
Name the plant?
Buffel grass
- Introduced species which is now naturalised as a pasture and rehabilitation plant
Describe the plant?
Kangaroo grass
native species
Describe the plant?
Butterfly pea
legume
Describe the plant ?
while clover
more common in Sourthern Australia where rainfall is more reliable
Describe the plant ?
Cavalacade centro.
Name the constraints on livestock production in Northern Australia?
- Infertile soils low in phosphorous and nitrogen
- tropical grasses have low digestability, and low feed value once mature
- total rainfall and its variability
- animal disease, ticks, buffalo fly, botulism and infectious diseases
- some properties less than 50% Bos indicus
- Large propertys (sometimes to large for a single family to manage)
- Woody weeds eg rubbervine, prickly acacia
- sometimes cattle in such poor condition by October, they can not be mustered
- Owner/ manager lacks financial skills
- Remoteness, cost of inputs, marketing and information
Describe the problems associated with tropical soils?
Most soils in the tropics are of poor quality, as the high quality soils are used for crop production
- Soil PH 6-7.5 (wet tropics acidic 4.5, Western Qld PH )
- Soil organic Carbon is low 1-2%
- Soil total N is 0.06 to 0.02 % (1 is very low and 30 is good, North QLD around 4-12 ppm)
- Low phosphorus causes botulism (bone chewing country) during the dry season soils become P deficient cattle look for P and protein, chew bones carcase.
Describe native pasture quality throughout the dry and wet season in QLD what affect dose this have on stock?
Tropical grasses have low disgestability and low feed value once matured.
- During the dry season / drought the grass becomes stalky stops growing (rank) and is of low nutritional value.
- Grass quality drops quickly post flowering.
- Nitrogen and phosphorus also decrease throughout the wet season going into the dry.
- In addition tropical grasses have lower digestability (58%), compared to temperate grasses (73%)
- Sometimes cattle are in such a poor nutritional state by October they can not be mustered, poor fertility = poor pregnancy rate
- see saw pattern growth pattern on native pasture
At the begining of the rainy season, the new expanding leaves provide the best fodder. As the wet season progresses the quantity and quality of native pastures decrease.
With an increased amount of silica and hardened tissues in the fodder.
Describe the advantages of Bos indicus over Bos taurus when keeping cattle in the trophics ?
- Good foragers
- tick resistance
- heat resistance
- good walkers
- good mothers
- high survival
Note prior to 1977 mostly Bos taurus cattle which had poor disease resistance and survival rates in the tropics.
After 1987 mostly Bos indicusbecame the dominant breed in the tropics.
What affects could woody weeds have on cattle production ?
Picture prickly acacia below
Woody weeds such as rubber vine below could shade out pastures lowering pasture and animal production.
What is El Nino and El Nina, and tropical cyclones ?
El Nino
Refers to the extensive warming of the central and Eastern Pacific that leads to a major shift in weather patterns across the Pacific = events associated with an increased probability of dryer conditions.
El nina
Is associated with cooler than normal water temperatures in the Equatorial Pacific ocean that leads to a major shift in weather patterns = generally associated with wetter conditions.
Tropical cyclones
These are low pressure systems which form over warm tropical waters. They derive their eneergy from the warm tropical oceans > 26.5 degrees at surface. Cyclone season is Nov - April
What is a sown pasture ?
A sown pasture is a native grass and a introduced grass or legume.
Native kangaroe grass, black spear grass
introduced legume stylo
introduced grass while clover, sabi grass
Define a savanna?
A savanna is defined as a continuous stratum of grasses, sedges and herbs that may contain shrub or tree species at varying densities, but suuficiently dispersed so not to influence grass growth to any major extent.
Savannas are among the areas of the world with the greatest potential for increasing agriculture and animal production.
Define a rangeland ?
The definition overlaps with savanna
A rangeland is a semi natural ecosystem in which man seeks to obtain a productive output by simple adding stock to a natural landscape.
- no ploughing or fertilizing
- the natural plant communities form the basis of the enterprise
What is a 3P plant ?
3P
- perenial, lives for atleast a year
- productive, high Kg DM/Ha/mm rainfall
- palatable, animals like to eat it
good nutritive value during the wet season
can be deficient in protein and energy during the dry season
eg. Mitchel, Kangaroo, Queensland blue, Buffel, Sabi and Guinea grass.
Name and describe the grass pictured below ?
Flinders grass
- short lived perennial grass
- can be nutritious for short periods to fatten stock
What supplements could be implemented during the dry season to prevent feed deficiencies ?
Examples what they provide
- Urea = protein not very palatable and can be toxic
- the aim is to have stock consume about 60g of urea per head per day
- Molasses = energy or to make other feeds more palatable
- P, Na, N (protein), grain and minerals
During the dry season a shortage of energy and protein are common
The pastures are initially deficient in phosphorous and sulphur, with a subsequent decline in protein and digestability as the season goes on.
The difference between temperate and tropical grasses ?
In general temperate and pasture grasses are more palatable and nutritious, than those of arid or tropical regions.
Why
- better quality soils and less severe climate
- different biochemical pathways
C3 and C4 plants.
Temperate grasses and all legumes + most shrubs are C3 plants.
C4 grasses in Northern tropical Australia
What is tillering ?
Many grasses reproduce vegetatively by the production of large numbers of tillers (stolons or rhizomes).
Tillering can result in dense tufts, often large tussocks and/ or a network of shoots connected by stems that are just above or below the ground.
Describe three different survival strategies of rangeland plant types ?
1) Perennial drought resistant plants
dormant during drought and resume growth with the onset of the wet season.
woody species tress and shrubs and include sclerophyllous evergreen grasses spinifex.
2) Perennial or drought-evading plants
aerial parts of the plant die when moisture is exhausted - restarts growth with rain
eg medium sized tussock grasses (Mitchell grass).
3)Short lived drought evading plants
Survive long dry periods as seeds.
This group comprises a large number of short grasses and seeds (Flinders grass)
Describe meristems on grass Poaceae?
Apical meristems are located at a low point on grass protected by the cylindrical leaf base.
The meristem is the point from which the plant grows.
Being low down protects the meristem from grazing, fire or being destroyed by hoofed animals.
Meristems may be stimulated to grow by removal.
Describe legumes and nitrogen fixation ?
All living things need nitrogen an essential component of DNA and protein. Nitrogen gas is not useable by most organisms due to it being fairly inert.
We need biologically useable nitrogen -
Bacteria in the root nodules of legumes produce biologically usable nitrogen (mainly ammonia) from the nitrogen gas in the air.
This process is called nitrogen fixation.
Bacteria = Rhizobium
The bacteria (rhizobium infect the roots of legumes causing the formation of nodules in which the bacteria live. The bacteria act to fix N from the air into the soil.
As a result the plant becomes rich in N and some may diffuse into the soil benefiting other plants.
Describe a few adaptations of poaceae ?
- meristem located low to the ground and suurounded by cylindrical base of the leaf for protection
- Large variety of breeding systems self pollination, cross pollination, cloning maintaining a large gene pool enable them to adapt rapidly
- Produce large numbers of seeds with a large of number of methods for dispersion
- Tillering
- 90% of grassland biomass thus usually dominating the community
- coevevolved with herbivore species
These adaptations allow grass species to thrive under conditions which would discourage most other plant species.
Describe and name this grass?
Rye grass
- introduced high feed quality and digestability
- usually grown in temperate and semi arid areas south inland Australia
- important for the dairy industry in QLD eg Atherton Tablelands
- winter feed in the subtropics
Describe and name this plant?
Sorghum
- native species
- can be sown for grain, pasture, forage crop or silage
- monsoonal
- prennial species of native sorghum tend to have low fodder value in the monsoon area especially low in the dry season.
Identify this plant ?
couch grass
Toxicity of Legumes ?
Due to legumes being fixing nitrogen they have a high protein quantity, they evolved to protect this great energy source.
Many legumes are toxic particually through the production of alkaloids a type of chemical defence.
Many but not all legumes are toxic.
The characteristics which make legumes important ?
- ability to fix nitrogen
- high in protein minerals and salt
- enrich soil and improve other plants
- increase the bulk and quality of pastures
- mature legumes have higher digestability and intake than grasses (70%)
- cruide protein (20%)
- Higher water use efficiency than grasses.
Theire rate of decline in quality over the season is less than that of grasses.
Describe palatability increaser and decreaser species ?
Due to over stocking
Many native Australian species are (were) vulnerable to grazing compared to say African species. Australian native herbivores are lenient grazers.
Some plant species are vulnerable to grazing while others are affected less so.
Palatable species are desirable but with continuous grazing they become decreaser species.
Unpalatable species are undesirable and become increaser species under grazing pressure (Indian couch).
decreaser species = kangaroo grass, Mitchell grass
increaser species = indian couch
intermediate = Black spear grass.
Poor pasture quality is indicated by less than 5% decreaser species. You can assess pasture quality by assessing composition of increaser decreaser species.
When considering pastures what is a state, and what is a transition ?
A state = Defined in terms of the dominant species of ground cover, vegetation structure, % ground cover or basal area of plants. It may also take into account the condition of the soil surface.
A transition = May be triggered by natural events or management actions. A change in the above being observed over the pasture.
Identify this plant
Asbestos grass
This plant is a weed,
native grass poor quality feed, fllod wiped out other native plants leading to a population explosion in Asbestos grass.
Gets stuck in the eyes and pizzle of animals as they walk around.
Identify this plant ?
Lantana
Lantana is a weed which may cause photo sensitivity
Define these four categories of weeds Agrestels, Ruderals, Environmental and noxious weeds.
Agrestels = plants which enter agricultural land, crops, cultivated areas
Ruderals = plants that enter other non agricultural disturbed sites.(town dumbs, road side etc)
Environment = Plants which are detrimental to the conservation of our natural resources
Noxious weeds = aggressive invaders which can tolerate more stress than native vegetation.
Describe seven issues which weeds may cause?
Reduce productivity in crops or animal production systems
Displace native species, or desired species
Contribute to land degradation
Could be toxic contain burs
Could be parasitic
Could cause allergies
unpalatable
Allelopathic properties - chemical released from plant to reduce competition
shade out
Cost up to 14% of an farmers income
Define the three classes of weeds under the Australian government and provide an example?
Class one = Prohibited invasive species
not usually found
exotic acacia, mimosa pigra
Class two established but causing issues
Land owners must take resonable steps to keep land free of these pest species
Hymenachne wet lands, prickly acacia
Class three common weeds which are widely established prohibited from sale.
Lantana
What is WONS
WONS = weeds of national significance
What is IPM?
Integrated pest management
Identify this plant?
Rubber vine
class two weed is able to strungle other plants
climber which may be capable of strunguling other plants.
Identify this plant
Nut grass
Most common weed in the world
able to reduce crop production by upto 80%
reproduces rapidly via three methods, rhizomes, nuts and seeds
Tolerant to herbicides and agreat range of environmental conditions.
Note buds may remain dormant.
Identify this plant, and describe it?
Leucaena
- This is a shrub legume
- multipurpose forage species
- originates from Mexico and Centra America around 22 species, we use mostly Leucocephala glabrata
- Typical mimosaceae legume flower and pods
- perenial
- palatable and digestable the alfalfa of the tropics
- huge contribution to the beef industry
- requires mycorrhiza
- harvest in 6-8 week intervals, grow 4-15 metere rows apart.
Cattle gain more weight of Leucaena then any other type of legume.
Describe the wet tropical environment for pastures?
- High rain fall > 2000 mm
- Usually on hill country as the flat land is mostly used for cropping
- Usually hot to warm, with mild winters. Note the cooler temperatures of winter are still often enough to reduce pasture growth
- Often where old rainforest used to live
- soils are often poor leached, acid due to high rainfall.
What are the two main species of pasture used in ponded pastures?
Hymenachne
and para grass
What is a ponded pastorial system ?
A specialised system - an environment created by pastorialist through construction of banks or modification of the wetaland environment.
Depens on availability of water, soil type (impervious clay), slope
Used primarily to produce fodder in the dry season
ponds can also act as nutrient sinks
Identify and describe this plant
Para grass
Used in ponded pastorial systems
good quality pasture
Grown in areas which are water logged or pondeed pastures.
Can survive in water up to 60cm deep
drought and grazing tolerant.
Identify and describe this plant?
Hymenachne
Stoloniferous grass can grow in water upto 1.5 metres deep.
reduced digestability compared to paragrass.
What is agroforestry ?
Is using trees on farms for a multitude of purposes including timber, shade and forage.
Diversifying and sustaining production
Types
cut and carry
alley system
protein banks.
What is S.A.L.T?
S.A.L.T
sloping agricultural land technology
prevents erosion on sloping country.
What is the difference between a herbacious plant, a shrub and a tree.
Herbacious = not woody
Shrub = woody, short in comparison to trees and is multi stemmed.
Tree usually a single main stem or trunk, woody with the greatest height.
Monopodial
What is coppicing?
cutting or loping plants to reduce height
What is a browse species or top feed?
Herbage for livestock from a tree or shrub.
Identify and describe this species ?
Gliricidia
Forage tree legume
Tolerant of different soil types
Often used as a shade tree for cocoa
fast growing
easy coppicing
often used as a supplement
Good quality forage CP 20-30% and DMD 60-65%
Identify and describe this species?
Calliandra
Small tree 2-12m forage tree legume
native to central America
not drought tolerant so survives best in the wet tropics
slight cool tolerance
bright red flower
CP 20% and DMD 40-60%
Describe and identify this plant ?
Sesbania
Asian, African, Australian origins
fast growing 4.5m in 6 months
water logging ok eg rice paddies
Tolerant of saline and alkaline soils
CP 20-25% and DMD 66-75%
Describe five properties of soils?
- Climate
- Parent material
- Organisms
- Relief time
Describe the four main soil forming processes?
Additions
- water as precipitation and run off
- deposited sediments
- N2 from legumes
- O2 and CO2 from the atmosphere
- salts in groundwater
Translocatoion
- Clay organic matter, carbonates, oxides and leachates
- nutrients circulated by plants
- soluble salts in water
- soil moved by animals
Losses
- soil by erosion
- water, nutrients and elements by leaching
- water via transpiration
- N2 by dentrification
- Carbon from organic matter
Transformations
- Mineral decomposition
- reduce particle size by physical weathering
- structure development
- clay and organic matter changes
- humus from organic matter.
What are soil horizons and soil profiles ?
Horizones
- layer approximately parallel with the earths surface
- interrelated by processes of formation and degradation
Soil profile
- Complete vertical succession of soil horizons
- continue down to - parent material, other consolidated substrate material, a selected depth (2m) in unconsolidated materials.
Major soil horizons, soil formed in granodiorite (igneous rock) ?
Top soil
A Horrizon (A!, A2, A3). Zone of maximum biological activity
Sub soil
B horizon zone of accumulation clay, iron etc
Deep soil
C horizon the weathered soil material
Describe top soil?
- the organically enriched surface horizon(s)
- contains the bulk of plant roots
- is the major entry point into the soil of air and water
- provides the chief nutrient reservoir in the soil
The Northeastern rangelands are composed of three major soil types, what are these soil types ?
Red, yellow and grey Kandosols
Red Chromosols
Grey and brown Vertosols
Describe sub-soil?
The horizons in the soil profile below the topsoil, and above the soil parent material.
Describe soil organic matter, the most important of all soil properties?
- Composed of the living tissues and dead remains of plants and animals
- living soil microbes, bacteria, fungi 1000-3000 million individuals per gram of good soil.
- dark coloured, amorphous, very fine organic material made from the decomposition products of dead organisms.
Why is SOC important?
SOC = soil organic carbon
soil organic carbon * 1.72 = soil organic matter (SOM)
SOC forms aggregates and stabilises water movement pathways in soil
SOC may be up to 10 to 12 % by weight of highly organic peaty topsoils
SOC needs to atleast comprise 1.8% in good soil (SOM>3%)
IN QLD SOC commonly comprises less than 0.9% in poorly damages soils.
Discuss soil colour, and the Munsell colour system ?
Munsell colour system
- is a continum
- arranged by hus, value and chroma (intensity)
- assess the soil dry and wet against the Munsell colour chart
indicates water logging, organic matter content, oxidation state of iron.
- dark colours indicate a wet soil with a high organic matter content
- red soils contain Fe2O3 an oxidized iron oxide good drainage and airation.
- yellow soils FeO(OH) a hydrated iron oxyhydroxide generally poorly drained
- grey soils iron leached out of the soil matrix very poor drainage or seasonal water logging.
Soil texture what is it, and what soil properties does it affect?
Describes the relative proportions of sand, silt and clay?
- relative sizes of soil particles with clay being alike to talcum powder, silt marbles, sand tennis balls and gravel very large
- light textured soils are sandy
- heavy textured soils are clayey
Loamy soils are an equal mix of sand, silt and clay
Texture effects
- water entry and holding capacity
- ease of cultivation
- susceptability to erosion
- susceptability to compaction
What is soil structure?
Soil structure relates to the arrangement of primary soil particles into natural aggregates called ‘peds’
shape
size
and grade
PED types = grannular, lenticular, platy, angular etc
What is an apedal soil?
Soil material which lack aggregations so are either massive coherent brick like or single grained loose like beach sand.
What soil properties would you use to describe soil?
- Upper and lower depths of each horizon
- Horizon colour
- Field texture
- Coarse fragments
- Structure
- Consistence
- Field PH
- Boundaries between horizons
Describe the grey Vertosols?
- Cracking clay soils
- mudstone and clay rich sedimentary parent materials
- uniform clay texture down the soil profiles
- very strongly structured, weakly differentiated soil horizones
- very strong swell-shrink on wetting and drying
- neutral- alkaline PH
- calcareous and gypseous profiles (poorly leached soils)
- moderate to high cation exchange capacity
- moderate to high fertility
What are the characteristics of a red, yellow and grey Kandosol of the rangelands ?
- low fertility
- sandstone and sandy sedimentary parent material
- non calcareous profiles (well leached soils)
- weakly differentiated soil
- usually gradational texture changes down the soil profile
- stable, massive structure and earthy fabric
- acid-neutral PH
- low cation exchange capacity
- very low quality
What are the characteristics of red chromosols soil types of the QLD rangelands ?
- granitic rock parent materal
- non calcareous well leached soils
- top soils well differentiated from sub soil horizons
- abrupt texture increase from top soil to sub soil
- massive topsoils over strongly structured subsoils
- neutral PH
- moderate cation exchange capacity
- low-moderate fertility
What is the law of the minimum?
The level of plant production can no greater than that allowed by the most limiting of the essential plant growth factors.
Plant yield increases with increasing nutrient concentration eg fertilisers.
Liebig 1843
What are the main nutrient deficiencys in the Northeastern rangelend soils?
Nitrogen
grossly dificient in most Australian soils
fertiliser legumes or incorporate organic matter to increase nitrogen
Phosphorus
Deficient or grossly deficient in most Australian soils
replaced via fertiliser
A phosphorus defciency could lead to botulism in animals (bone chewing disease) - causes paralysis and the animal usually dies
Sulphur
deficient in the balsaltic terrains in the Northeastern rangelands
direct supplementation into animals through feeds and licks
Disscuss what is botulism?
Usually caused by a deficiency in phosphorus or lack of feed
- when cattle consume carcass material or feed polluted with spores
- causes paralysis the animal usually dies
- treatment is only possible in the early stages and requires a antitoxin
- peg leg gait and bone chewing
- Consumption of botulism spores can cause mortalitie rates as high as 25% of the herd
Clostridium botulinum - the most poisonous of poisons
- neurotoxin secreted by bacterium Clostridium botulinum
- anearobic bacterium thrives in decaying animal and plant matter in warm and moidst conditions
Prevent through vaccination and nutrition
Name four properties which affect availability of elements in the soil to plants?
- Amount
1. fertilisers - Rate of release
1. mineral or organic material - Form of the element in soil
- surface area
- chelates provide metals eg iron in a plant available form
- Soil chemical processes
- cation exchange reactions
- PH
- surfaces of soil colloids
Disscuss exchangable cations in the soil?
Nutrient supply is available through cations + or anions - in the soil solution.
Fine particles of inorganic minerals and organic matter generally carry a net negative charge and thus attract nutrient cations.
Electrical neutrality = is preserved by cations held closely on the surface of the colloid, forming a diffuse double layer of electrical charge.
CEC Cation exchange capacity
The capacity of a soil to hold cations on colloid surfaces, and to supply those nutrient cations to the soil solution for uptake by growing plants
CEC is an important measure of soil fertility
What is the effect of having sodium or calcium dominant soils ?
Sodium dominated soils are unstable and disperse.
monovalent, large radius, large hydration shells.
This causes dispersion pushing the colloids apart.
Calcium dominated soils
form aggregates and are stable.
calcium saturated colloids have thin diffuse double layers.
Ca2+ colloids can approach each other and by electrostatic attraction, form stable aggregates
Explain what is happening in this diagram ?
Name the three groups of drought resistant plants ?
- Perenial drought resistance plants
Dormant throughout the dry season reinitiate growth at the start of the wet season eg spinifex
- Perenial drought evading
Some or all of the plant becomes rank dies once all available moisture is used up, restarts growth with rain eg Mitchell grass
- Short lived draught evading
Short lived dying during the dry season regrow during the wet from dormant seeds. eg Flinders grass.
How can management prevent land degradation ?
- early wet season spelling of 3P grasses
overgrazing may kill 3P grasses after the dry season, as most 3P grasses use energy reserves in their roots to produce new leaf.
- 50% utilization
Describe native pastures ?
Native pastures
- well adapted to Australian conditions
- short growing season (March, April)
- low nutritive and digestability value post flowering
- vulnerability to over grazing
- see saw growth pattern (quantity and quality) between the wet and dry season
Describe sown pastures ?
Sown pastures
- holds nutritive value for longer than native pastures
- may produce better during than winter
- withstand higher grazing pressure
- less variability in growth between the dry and wet seasons
- allows for a faster growth rate and greater flexability for market access
- respond better to artificial conditions such as fertilisation and irrigation
- more stable stocking rates
- vigorous and productive
What is the importance and complications of legumes ?
The importance of legumes
- tropical legumes have a crude protein content of 15 %, and they maintain these protein levels longer than grasses
- rhizobium
- increase the whole pasture production
Issues with legumes
- Slow to establish may be overtaken by weeds / competition with weeds
- some potentially toxic
- insects can kill reduce production
- some do not grow well in acid or clay soils
- some temperate legume species cause bloat
- some require good nutrition/ fertilizer to be productive
Best time of year to sow pasture legumes is Jan-Feb
What is SOM ?
SOM
- Soil organic matter
- composed of living soil microbes and living tissues decomposition of plants and animals
- humus - very fine organic matter made from the decomposition of dead organisms.
