Producers with buffel grass pastures who sow legumes such as Caatinga stylo can reap the rewards for many years.
That’s according to the results of a Central Queensland MLA-funded field trial, which indicate producers can increase carrying capacity by up to 40%.
The findings, including increased pasture production and resistance to invasion by Indian couch, were presented by Department of Agriculture and Fisheries researchers, Gavin Peck and Stuart Buck, to producers who attended a field day at the Moura trial site, 180km south-west of Rockhampton, earlier this month.
In 1997 a 20ha paddock was divided in two and half planted with the buffel grass varieties, Biloela and Gayndah, as part of an MLA Producer Demonstration Site.
The remainder was planted with buffel varieties Primar and Unica, as well as the legume Caatinga stylo.
The aim was to test the legume’s influence on pasture quality and yield and, more recently, the response to applications of various rates of phosphorus (P) fertiliser.
The good news
Gavin Peck explained that producers were impressed by the performance of the legume/pasture paddock which produced 40% more pasture with a corresponding increase in carrying capacity.
“Even 18 years after the initial planting, the legume/pasture paddock is in good shape, with strong persistence of all pasture varieties including the more nitrogen-demanding Biloela buffel,” he said.
“However, in the buffel-only paddock there were symptoms of declining nitrogen availability (pasture rundown) and invasion of Sabi grass, Indian couch and native grasses. There was also a lot less Biloela buffel present.
“Producers were very relieved to hear there is a pasture alternative that will resist those less productive species.”
Impact of P fertiliser
The phosphorus trial, which started in 2012, precipitated discussion at the field day on the merits of using P and how best to apply it.
“Our trial (on P deficient soils) measured the response of pasture and legumes to five different rates of P fertiliser – zero, 10, 20, 50 and 100kg of P/ hectare,” Gavin said.
During the first summer post fertiliser application, legume yield and total pasture yield increased with increasing P rates up to the application rate of 50kg/ha, but plateaued at higher rates.
After the third summer, total pasture yield followed a similar trend as the first year of increasing pasture yields to P fertiliser application, but the proportion of grass and legume had started to change with a greater proportion of grass at the higher fertiliser rates.
Gavin said producers were keen to see further trials on the use of P fertiliser in northern grazing systems, including its economic benefit and the most cost-effective methods of application.
Gavin Peck E: email@example.com
Figure 1: Pasture dry matter production over a 6 month period (Nov 2011 – Apr 2012) for grass only compared to grass with legume pastures. The Wandoan site was established with buffel grass (cultivar Biloela) and desmanthus (cultivars Marc, Bayamo and Uman), the Moura site was established with buffel grass (cultivars Biloela and American) and Caatinga stylo (cultivars Primar and Unica).
Figure 2: Pasture dry matter production over a 9 month period (Aug 2012 – Apr 2013) for grass only compared to grass with legume pastures.
Source: Meat & Livestock Australia