Widening the grazing window
19 June 2019
Ian and Fiona Koch, from Moculta in SA have extended grazing days through winter and early‑spring feed gaps by growing polyculture pastures containing a mix of different varieties.
A 56ha polyculture pasture grown by the couple was monitored as part of an MLA‑funded Barossa Improved Grazing Group project during 2018.
It was found that, by planting a mix of early, mid and late‑maturing species, an additional 116 days of grazing were gained despite a dry season, and soil health improved.
Ian and Fiona’s sheep graze stubble during summer and ewes are moved onto hill country for lambing. Lambing is spread out to ease pressure on paddocks, beginning with stud ewes in April, commercial Merinos in May and the crossbred component in June.
A three‑year pasture phase is used to combat herbicide‑resistant ryegrass and provide feed through winter and spring, with around 100ha taken out of cropping and planted to annual pastures each year.
The annual pastures are then used for weaning stud lambs and finishing lambs from the commercial flock.
The paddock monitored for the project was treated with grape marc (a by‑product of the local Barossa Valley wine industry) to improve soil health before it was sown on 8 May.
Ian and Fiona planted a polyculture pasture which included Wimmera ryegrass, oats, barley, vetch, Lunch radish and clover (Balansa and Arrowleaf).
“We select varieties that are easily sourced and inexpensive, and aim to include around four grasses and four broadleaf species in each mix, with different maturing times so sheep can feed on different plants throughout the grazing period,” Ian said.
Factors in the pasture choice include past experience, seed availability and cost.
The sheep graze pastures from as early as June if seasonal conditions require grazing pressure to be eased on the hill country.
During the trial, a range of products were applied to the pasture from project partner Hi‑Tech Ag Solutions, including liquid fertiliser between grazing phases and a granulated fertiliser at sowing.
Measuring the output
Grazing period 1
8 June: 117 Merino rams at 14 months old and averaging 70.7kg were put into the paddock at 6 dry sheep equivalents (DSE)/ha. There was approximately 1,500kg of dry matter (DM)/ha available and sheep had access to a magnesium‑based loose lick mineral supplement.
After 30 days, the rams averaged 85.4kg – a daily weight gain of 455g/head/day.
12 September: Ian and Fiona have only recently started measuring weight gain so are still building data for comparison; however, their sale rams averaged 99.9kg, compared to 94.2kg in 2017.
Pasture quality was high, with a feed sample showing 18.9% crude protein, 11.8 megajoules of metabolisable energy and 40.8% fibre.
10 July: Rams were removed when there was approximately 1,900kg DM/ha remaining – indicating average pasture growth rates of 20kg DM/ha/day.
The paddock was rested for a month and treated with liquid fertiliser which included natural amino acids, fortified carbon and trace elements.
Grazing period 2
15 August: 472 Merino weaners off shears came into the paddock at a stocking rate of 13 DSE/ha for 31 days.
20 September: The season was tough, with only 217mm cumulative rainfall to September, so Ian culled 70 head to reduce grazing pressure.
25 September: The paddock was fenced into two sections and the mob divided – 220 ewes went into a 14ha portion (24 DSE/ha) and 182 ram weaners grazed the larger, 42ha section (7 DSE/ha).
The Barossa Improved Grazing Group (BIGG) is a network of five producer groups in the Barossa and eastern Mount Lofty Ranges regions of SA which aims to deliver greater productivity and better natural resource management outcomes for its 300 members.
BIGG technical facilitator Georgie Keynes said as part of an MLA Producer Demonstration Site (PDS), the group developed three major sites at Koonunga, Keyneton and Mt Pleasant– Eden Valley. Different pasture varieties and blends were sown and measured at each of the sites from 2016 to 2018 to determine how they could be used to fill seasonal feed gaps.
Twelve minor sites were developed on local farms in 2017 and 2018 to test the successful pasture blends sown on the major sites.
“Not all farming systems are the same, so this gave producers a chance to look at some of the pasture options available so they could consider what might suit their enterprise and environment,” Georgie said.
The Barossa Valley traditionally receives 550–600mm of annual rainfall, mainly in winter, with occasional summer rainfall as a result of thunderstorms.
The autumn break is expected in May and the main growing season generally occurs in late winter–spring, with pasture quality and growth declining in late October.
“Over the three years, the PDS presented a range of seasonal conditions which provided the opportunity to see how different pasture varieties and pasture management strategies performed under variable conditions,” Georgie said.
In 2016, there was above‑average rainfall, a cold winter (with little pasture growth) and a wet, mild spring and summer which delivered above‑average pasture‑growing conditions.
In 2017, the region received a late break in June, average winter rainfall and slightly lower‑than‑average spring rainfall, while 2018 was exceptionally dry, with less than half the annual average rainfall, a dry autumn with no break and very little rainfall through spring.
Pasture strategies across the PDS sites included:
- extending the growing season with a mix of early and late varieties
- establishing lucerne to provide year‑round feed opportunities
- increasing production by combining ryegrass with forage cereals
- using native pastures at critical times of the production calendar (such as lambing)
- using stored soil moisture to grow summer forage crops
- running high stocking rates
- producing silage in a rotational grazing system.
Lifetime Ewe Management and Pasture Principles groups were run in conjunction with the PDS to provide producers with more information on grazing management.
Georgie said the PDS identified the need for producers to identify their feed gap and target varieties to fill it.
“This could include using blends of varieties to provide opportunities to capitalise on all rainfall events,” she said.
“For example, using early and late ryegrasses within a mix to make the most of any late spring rainfall event while still providing high quality pasture through late winter and spring.
“It’s also important to select pasture varieties which provide grazing and fodder conservation to increase flexibility and opportunities. For example, using a forage cereal to fill a winter feed gap through grazing, followed by fodder conservation (hay or silage) to fill summer feed gaps.”