The objectives of this project were to quantify the benefits of deferred grazing, and establish criteria to help farmers identify when deferred grazing is appropriate in their farm system.
This was achieved by comparing standard rotational grazing and deferred grazing in replicated plot studies at two sites:
- Mataiwhetu Station – a summer wet property
- Otorohaea – a summer dry property.
The deferred treatment was not grazed between mid-October and the end of summer / early autumn (depending on the farm) but was rotationally grazed after the deferred period for the remainder of the study.
Comparing the effect of standard rotational grazing and deferred grazing in a replicated split-paddock study on three sites:
- Mataiwhetu Station – a summer wet property
- Otorohaea – a summer dry property
- Pukekauri Farms – a summer wet property.
Background
‘Deferred grazing’ is a management tool used to maintain pasture quality and rejuvenate paddocks on pastoral farms. In the deferred paddocks, perennial ryegrass produces seeds, new tiller buds that form at the base of existing plants remain dormant over summer and develop into new tillers in autumn. The deferred pastures are grazed to low residuals at the end of the deferred period over one or two grazing’s (e.g. to 1500 kg DM/ha) so that the ryegrass seedlings and new ryegrass tillers have access to light. The previously deferred pastures are treated as renewed pastures and are grazed carefully with light stock for short periods.
Deferred grazing has been used by some hill country farmers in the mid Northern North Island New Zealand for more than a decade. These farmers could see benefits for both the deferred pastures and for the rest of the farm and wanted to quantify those benefits through a science-led project.
Key results
Compared to standard rotational grazing, deferred grazing improved pasture performance by increased:
- ryegrass ground cover and tiller densities
- topsoil moisture
- anaerobically minerablisable nitrogen (the amount of nitrogen potentially available for plant uptake) and reduced:
- facial eczema spore counts
- weed content.
There was reduced nutritive value in the deferred paddocks during the deferred period, but pastures rapidly recovered after the deferred period. Decline in quality of the deferred pastures was not enough to offset overall farm-scale profitability.
When compared to standard rotationally grazed pastures, the deferred pastures grew less during the deferred period but more after the deferred period, so dry matter production was similar in both over the experimental period.
FARMAX modelling carried out on one of the farm sites showed there was an 8% increase in total farm and per-hectare gross margins when 15% of the farm was deferred.
Benefit for farmers
This project provided science-based evidence for the benefits of deferred grazing compared to standard rotational grazing, on three farms in the Bay of Plenty and Northern Waikato. Information from this project has been disseminated in a handbook and a fact sheet including a checklist for farmers on how to defer paddocks.
Timeline and investment
This was a three-year study with investment by B+LNZ of $180,000 over the duration.
Outputs
Farmer events
- Farmer field days throughout the project.
Popular press articles
- Country-Wide: “Giving pastures a break”
- Ballance Grow magazine: “Deferred grazing plusses”
- New Zealand Herald: “Weighing up deferred grazing benefits”
- B+LNZ Knowledge Hub article: “Deferred grazing – a tool to build farm system resilience”
Scientific publications
- New Zealand Grasslands Association Journal : "Effects of deferred grazing during late spring and summer on pasture productivity in Waikato and Bay of Plenty hill country”
B+LNZ resources
- Handbook for farmers including decision ‘rules’ to help farmers identify when deferred grazing is appropriate in their farm system.
- B+LNZ factsheet.
Partners
This was a Ministry for Primary Industries Sustainable Farming Fund project led by AgResearch and co-funded by B+LNZ, Ballance Agri-nutrients, Bay of Plenty Regional Council with in-kind support from the Waikato Regional Council, Plant & Food Research and AgFirst.
Lead Scientist: Katherine Tozer (AgResearch).
Farmers involved: Allen Coster, Rick Burke, Jon Sherlock, Brian Thomas.
B+LNZ point of contact: Cara Brosnahan.