Pasture Persistence Flashcards
Define pasture persistence
the continued yield and performance of a pasture over time
Define poor pasture persistence
when a desirable species is replaced by a weedy, undesirable species
What are the 8 Factors Affecting Pasture Persistence
Summer dry conditions, high temperature, soil fertility, pests and diseases, grazing management, pugging, genetics, endophytes
How many factors affecting pasture persistence need to combine to cause severe damage?
2-3
Explain the gradual deterioration of pasture components
Total DM production drops over time and the composition changes where weed species which are not as nutritious increase, whilst the sown species decreases. But overtime this all decreases.
Name 3 uncontrollable factors which may affect pasture persistence
Temperature, rainfall, soil type
Name 3 controllable factors that can affect pasture persistence
species choice, soil fertility, grazing management
What are the 4 areas which policies can be made in to enhance pasture persistence?
livestock type, stocking rate, calving and lambing date, supplement use, summer crops
What is the main factor to consider when choosing species to maintain pasture persistence
Match the species to the environmental conditions
How can soil fertility be managed for optimal fertility/nutrient requirements of the pasture species?
Do soil testing, ensure N, P K, S and soil pH is adequate
How can summer crops improve pasture persistence in dry climates?
Takes the pressure of the pasture platofrm whilst providing high ME feed to compensate for reduced summer pasture growth to maintain residuals and allow healthy leaf canopy to be formed without damaging growing points.
How can supplements be used to promote pasture persistence ?
Have an advantage over crops as you can store them for a long period of time. It is also good for feed budgetting as the quantity is known before feeding.
How can pasture establishment increase pasture persistence?
If conditions are created to allow for a healthy pasture to establish within the first month after sowing then persistence is increased.
What are the 4 focus points for grazing management to maximise pasture persistence?
Before, during and after a dry period, as well as during wet conditions
How high should pasture covers be before a dry period and why?
1000-2500kgDM/ha - maximise net accumulation and resilience
What is the main aim of grazing management before the dry period
Have a high population of healthy, well grown plants
What is the relationship between tiller size and tiller number?
If tiller numbers go down, leaf size increases. If leaf size goes down, tiller numbers increase.
Explain the seasonal cycle of white clover
Old stolons die in mid-spring, with stolon growth and clover recovery in late spring. In the summer, stolons produce alot of shoots, want to minimize the shading of the ryegrass to get more PAR.
How is ryegrass persistence impacted during dry periods?
Long periods of soil moisture stress, evapotranspiration and temperatures
What are the implications of overgrazing in extended dry spells?
Killing ryegrass plants, allows weed species to come in.
Explain on-off grazing and when it should be used
On-off grazing occurs when animals are removed as soon as the residual is reached, being moved to a feed pad or sacrifice paddock. Sacrificing animal intake short-term for long-term pasture persistence. Do this during dry-periods.
What other methods can be used to improve pasture persistence during a dry-period?
Supplements and decreasing feed demand through selling stock or once-a-day milking dependent on the price of milk/meat.
Why is it important not to graze too soon after the dry-period has ended?
Pasture needs time to recover and accumualte the buffer of herbage until it can be grazed again
When should ryegrass be grazed?
At the 2-3 leaf stage, when the majority of the tillers have reached this 2.5 tiller stage.
How much can pugging damage reduce dry matter by?
Up to 35%
What are two grazing strategies which can be used in wet conditions?
On-off grazing and restoring pastures
Explain the process of restoring pugged pastures
under sowing with Italian or hybrid ryegrasses, localised broadcasting or oversowing with species to minimize bare areas and weed takeover.
What is the cost of pastoral weeds to the NZ economy?
$1.2 billion per year
What did Harris say will lead to adequate weed control / increase pasture persistence?
knowledge of the weed flora, habitat preferences and competitive characteristics of desirable species can allow seed mixtures to be sown to minimize this.
How much did grazing increase when drought area pasture mixes were changed from perennial ryegrass to cocksfoot, tall fescue and phalaris?
112% more grazing
What impact does lax grazing have on ryegrass tiller density and how does this impact pasture persistence?
Decreases tiller density, increased ability for weeds such as dock to invade pasture.
List 7 of the factors causing gaps in pasture
pugging/trampling, drought, shading, lack of fertlity, undergrazing/over grazing, insect attack, waterlogging
What did Boswell and Crawford find to be the best grazing heights for maximum pasture density?
grazing to 3cm rather than 6cm , grazing below this reduced tiller density, especially in dry conditions
