Pasture resting to improve condition of pastures used by cattle in north Australia Lester Pahl (lester.pahl@daff.qld.gov.au) Queensland Dept. of Agriculture, Fisheries and Forestry Toowoomba, Queensland, Australia Joe Scanlan, Giselle Whish, Neil MacLeod, John McIvor and Robyn Cowley
Outline of Presentation This modelling of pasture resting was done for the northern grazing systems project 1. Reasons for resting pastures during the growing season 2. Principles of pasture resting 3. Practice of resting pastures on properties
Reasons for resting pastures Pasture degradation in north Australia is well known
Reasons for resting pastures Abundance of palatable, productive perennial (3P) grasses in pastures is a key indicator of pasture and land condition Land condition simply classified as A, B, C and D: A > 80% 3P grasses B 50 to 80% 3P grasses C 20 to 50% 3P grasses D < 20% 3P grasses A B C D
Reasons for resting pastures More perennial grasses means more growth, greater resilience to climate, and higher cattle productivity Relative to A condition land, pasture growth and carrying capacity is: 25% lower for B condition land 55% lower for C condition 75% lower for D condition Translates into very large reductions in cattle productivity and profit
Reasons for pasture resting Reasons for pasture resting are accepted, but empirical evidence of the benefits and costs are limited pasture resting trials are few in number, short duration, and small in area Modelling can extend the findings of research trials, and evaluate pasture resting over longer time periods and larger areas of land Used the GRASP model Simulates pasture growth and animal production using daily climate records
Land type modelling experiment Examined recovery of C condition land type Compared 3 lengths of resting No rest 2 month rest (start 1 st Dec) 6 month rest (start 1 st Dec) Compared four frequencies of resting every yr, 3 out of 4 yrs, every 2nd yr, every 4th yr Resting evaluated at four fixed stocking rates 5.6 Ha/AE, 4.5 Ha/AE, 3.9 Ha/AE, 3.2 Ha/AE Modelled these strategies for 100 yrs 1900 to 2000 averages for 20 different 20-yr time periods
Percent perennial grass Percent perennial grass Modelling results: 2 month v.s. 6 month rest 90 80 70 60 50 40 30 20 10 0 No rest 1 in 4-2 mo 2 in 4-2 mo 3 in 4-2 mo 4 in 4-2 mo 5.6 Ha/AE 4.5 Ha/AE 3.9 Ha/AE 3.2 Ha/AE 90 80 70 60 50 40 30 20 10 0 No rest 1 in 4-6 mo 2 in 4-6 mo 3 in 4-6 mo 4 in 4-6 mo 5.6 ha/ae 4.5 ha/ae 3.9 ha/ae 3.2 ha/ae
Some principles of pasture resting The longer and more frequent rest occurs, the more pasture condition improves more likely there will be some good growing conditions includes the early growing season when grasses are most susceptible to grazing includes late growing season when grasses are setting seed and accumulating root reserves allows for a range of flowering times that occur for different grass species allows new seedlings to establish, grow and set seed, and existing plants to expand Longer and more frequent rests are required when: stocking rates are high pastures are in very poor condition soil fertility is low
Property modelling experiment Applied a 6-month rest (begin Dec 1 st ) every 4 years to 4 paddocks on a property that had 7 paddocks All 4 paddocks were in C condition Only one paddock rested for 6 months each year Cattle from rested paddock were spread evenly across the other three paddocks (stocking rate increased by 33% during the growing season)
Percent perennials Percent perennials Percent perennials Percent perennials Outcomes at the property level On average, pasture rest improves pasture and land condition, and increases cattle productivity But, outcomes are sensitive to climate and stocking rate 100 100 90 80 90 80 No Rest Pdk1 70 60 50 40 No Rest Pdk1 Pdk2 Pdk3 Pdk4 70 60 50 40 Pdk2 Pdk3 Pdk4 30 30 20 20 10 10 0 100 90 80 70 60 50 40 30 20-year period No Rest Pdk1 Pdk2 Pdk3 Pdk4 0 100 90 80 70 60 50 40 30 20-year period No Rest Pdk1 Pdk2 Pdk3 Pdk4 20 20 10 10 0 20-year period 0 20-year period
Conclusions Regular pasture rest during the growing season can. improve pasture and land condition, and increase cattle productivity and profit Barriers to regular resting at the property level Resting pastures can reduce cattle productivity/income Variable climate and stocking rates can delay benefits We cannot tell producers exactly what is required Higher mustering/transaction costs for cattle Costs associated with cattle from rested paddocks Wet seasons and calving prevent mustering Lack of paddocks Pasture resting on properties is often opportunistic
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