Grazing Winter Crops – FAQ – 3/3

All this week on Table Talk, we are focusing on the theme of Grazing Crops.

In our first post, we looked at the following questions:

  1. How can cereal grain crops be utilised by livestock?
  2. Does variety matter?
  3. When can I start grazing?
  4. How do I graze? What stocking rate should I use?
  5. When should stock be removed?

In our second post, we looked at:

  1. What is the nutritive value of grazing crops? What growth rates should I expect?
  2. What livestock health issues should I be concerned about?

And in our final post, we focus on:

  1. Does grazing winter crops reduce grain yield?
  2. Have any cost benefit analyses been done on grazing crops?
  3. What else should be considered?

Does grazing winter crops reduce grain yield?

Careful grazing can minimise yield risk. Results from a range of trials has substantiated this.

  • Research from Kondinin Group (2016) found that grazing crops can add to productivity of mixed farming systems without compromising crop yield. Yields of grazed and un-grazed areas did not differ markedly being within 5 per cent at all locations except for Binnu and Neridup, where yield was 12–15 per cent less in the grazed area.
  • FarmLink Research through Murrumbidgee Grain & Graze Project (2004-2008) found grazing can be successfully carried out at significantly higher stocking rates than traditionally recommended to utilise the high quantity of dry matter produced during winter. They found that high stocking rates combined with long grazing periods (~ six weeks) reduced grain yields, but losses may be offset by income from additional liveweight gains, depending on prices.
  • DAFWA and GRDC research in the WA wheatbelt found that Grazing of cereal and canola crops in winter reduced grain yield by between 8 and 21% at seven of eleven sites. Grain yield was unaffected by grazing at four of eleven sites.
  • Grain and Graze3 (GRDC) found that provided grazing does not extend beyond the point where animals eat too many of the elongating floral meristems, the crop can regrow and produce grain. Cereal crops can compensate for the removal of some meristems by means of increased tillering. Grazing will reduce the leaf area index of the crop, which in turn will slow its growth during the post-grazing period. All else being equal, this will reduce grain yield. However, the reduced leaf area after grazing also means that the soil accumulates more water until the crop canopy recovers. This water will then be used later in the growing season (e.g. during grain filling), when the water-use efficiency for grain production is higher. As a result, an early-season grazing can increase yield in years with a dry spring.
  • Stock should be removed before GS31 (stem elongation) to prevent yield losses. (FarmLink Research through Murrumbidgee Grain & Graze Project (2004-2008))
  • Phillip Barrett-Lennard of agVivo stated in most cases, crop grazing does reduce grain yield.

When crop grazing is managed appropriately, yield reductions in the 0 to 10% range should be expected.

MLA research found that management of grazing can reduce any impact on yield. However, the following issues can have a negative impact:

  • time – if the remaining season length post grazing is too short to allow the plant to recover,
  • rainfall / other factors limiting plant growth – if the plant is unable to gain the resources that it needs to compensate from grazing before harvest
  • competition – if weed burden is high enough to out-compete the cereal
  • severity of grazing – if the plants are left with insufficient energy to re-grow efficiently

Have any cost benefit analyses been done on grazing crops?

CSIRO and NSW Department of Primary Industries research indicates that gross margins for dual-purpose wheat at the paddock level are about $100/ha to $400/ha more than a grain-only enterprise.

Research in south-eastern Australia that explored the whole-farm implications of introducing dual-purpose wheat and/or canola found that complimentary grazing of dual-purpose wheat and canola could provide large increases in farm profit margin (up to $1500 crop ha–1 ) when sown on up to 15% of the farm. Dual-purpose wheat or canola alone provided smaller but still significant potential increases in whole-farm productivity and estimated profit margin.

The Nullawil Best Wool Best Lamb Group looked at the financial implications of rotational grazing cereal crops and specialist fodder crops in a Mallee farming system and determine the cost of production of a kilogram of meat per hectare in these systems and compare these costs with previous practices.

In Year 1 of the trial (2012), the benefit cost (BC) analysis of the trial to date has revealed that for the varieties under investigation the following;

  • Moby Barley BC ratio of 6.1:1or $579.50 : $95.00 Gross/ha/sowing cost
  • Jivet annual ryegrass BC ratio of 10.3:1 or $987.50 : $95.00 Gross/ha/sowing cost
  • Subzero and Perun Festulolium BC ratio of 10.3:1 or $987.50 : $85.00 Gross/ha/sowing cost

In Year 2 (2013) the benefit cost (BC) analysis of the trial in 2013 has revealed that for the varieties under investigation the following;

  • Moby Barley BC ratio of 10.57:1 or $1004.15/ha Gross
  • Subzero held for late grazing BC ratio of 2.6:1 or $221.00/ha

A Grain & Graze, National Landcare Program trial in Victoria presented the experiences of seven farmers grazing winter cereals across four enterprises (prime lamb, merino and beef).

  • The economic benefits were positive in all cases and ranged from $10.80/ha to $84.06/ha. When comparative grain yields were also included, this range became $21.56/ha to $430.80/ha.

What else should be considered?

  • Dr Hugh Dove’s GRDC funded research paddocks must be prepared well in advance of sowing to ensure maximum establishment of young plants and crops need to be sown early to capture the benefits of grazing.
  • Phillip Barrett-Lennard of agVivo outlined that research by Curtin and Whisson (2014) suggested a fairly simple “rule of thumb” applied, where every 2 days of grazing delayed flowering by 1 day.
  • Grazing delayed flowering in winter wheats by up to 16 days, which can have implications for sowing times to manage frost/heat stress. (FarmLink Research through Murrumbidgee Grain & Graze Project (2004-2008))
  • Have to remember that when grain prices were high, a small yield penalty caused by crop grazing can have a large impact on grain income per hectare (DAFWA and GRDC).
  • Grain and Graze3 (GRDC) state that on the positive side:
    • in paddocks with high weed burdens, sacrificial grazing may provide an ideal opportunity to control weeds late in growth without having to switch to a pasture phase.
    • In dual purpose systems, reduction in vegetative material through an early season grazing may reduce stubble burdens following harvest. High stubble burdens can hamper following crop establishment, and can be difficult to reduce after harvest if livestock numbers are limited or there are restrictions to traditional methods of disposal (tillage, burning).
  • Grain and Graze3 (GRDC) state that on the negative side:
    • Lower yielding areas a reduction in stubble biomass may have consequences for stubble carryover, ground cover and hence erosion risk.
    • Soil compaction is often cited as a negative, particularly for cattle and on clay soils in wet conditions. In tramline farming systems, livestock could be seen as incompatible with cropping practices.

We hope you’ve enjoyed this series on Grazing Winter Crops.