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Wambiana grazing trial Phase 2 stocking and spelling strategies for improving carrying capacity and land condition in North Australian grazing lands

Project start date: 17 January 2011
Project end date: 12 June 2016
Publication date: 12 June 2016
Project status: Completed
Livestock species: Grassfed cattle, Grainfed cattle


The Wambiana grazing trial was initiated in 1997 to test the ability of a range of stocking strategies to cope with rainfall variability.  Phase 1 of the trial (1998 to 2010) included moderate stocking (MSR), heavy stocking (HSR), rotational wet season spelling (R/Spell) and two variable stocking strategies.  Following a project review in 2009 three of these treatments were modified to reflect learnings from Phase 1 of the trial. 

In Phase 2 (2011 to 2014) the HSR and MSR were maintained unchanged with new treatments as follows (1) R/Spelling (R/Spell) with six sub-paddocks (formerly three) (ii) Flexible stocking without spelling (Flex) and (iii) Flexible stocking with spelling (Flex+S) with six sub-paddocks.  The new ‘Flexible’ strategies allowed stocking rate adjustments to be made in a risk adverse fashion at three points through the year based on both pasture availability and climate forecast indices.

Key findings

Phase 2 results have generally confirmed trends previously recorded for the MSR, HSR and R/Spell.  Despite a run of five above average rainfall years, pasture yield and condition remain by far the lowest in the HSR and are best in the MSR and the R/Spell.  Although pasture condition in the HSR appeared to improve with the better seasons, this improvement was largely cosmetic with little, if any increase in the abundance of 3P grasses.  Wet season spelling also appears to be having a very beneficial effect in the R/Spell with condition in this treatment exceeding that the MSR.  This is despite the heavy grazing pressure experienced in the non-spelled areas of the R/Spell paddock in the wet season. Although wet season spelling has occurred in sub-sections of the Flex+S treatment since 2011/12, aside from an improvement in pasture vigour and yield, at this early stage there appears to have been no increase in the abundance of 3P grasses in this treatment.