Grazing crops in a dry year

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Where stocks are creating uneven patches in your paddocks consider:

  • stocking rate
  • water placement
  • installing electric fencing

Most Western Australian farmers have now been exposed to the concept of grazing crops, but many are reluctant to ‘put the stock in’ for fear of receiving a grain yield penalty.

Photo of grazed and ungrazed barley crops

Grazing crops too late and too intensely can result in serious grain yield losses. The Woogenellup, WA, barley crop (left) was grazed in late July/August with a high stocking rate and suffered a 21 per cent yield penalty compared with the ungrazed control (right).

As part of Grain & Graze 2, crop grazing research trials were established across the WA wheatbelt in 2011 and 2012 to determine the impact of grazing winter crops on subsequent grain yield and quality, on weeds, disease and nutrition, and on livestock carrying capacity.

Eighteen on-farm trial sites were established from Binnu in the northern wheatbelt to Esperance on the south-east coast. The host farmers sowed and managed crops as per their usual farm practice, using a range of cereal and canola varieties. Temporary electric fencing was used to divide each paddock into grazed and ungrazed areas.

The trials demonstrated that it is possible to graze crops in winter and still maintain grain yield. However, grazing resulted in more frequent yield penalties during the drier 2012 season than in the equivalent set of trials in 2011.

Grazing reduced crop yields by more than five per cent in seven out of 11 of the trials (Table 1) in 2012 compared to two out of seven trials in 2011.

 

Table 1: Impact of crop grazing on grain yield in the 2012 trials and factors thought to influence crop recovery after grazing.
 Location Crop
Change in yield (%)
Time of grazing #
Type of grazing +
 Warradarge  Wheat  –12  Late  Crash
 Miling  Wheat  –4  Average  Clip
 Badgingarra  Canola  –3  Early  Crash
 Doodlakine  Canola  –10  Average  Crash
 Kellerberrin  Wheat  –15  Average  Crash
 Williams  Barley  +5  Average  Crash
 Woogenellup  Barley  –21  Late  Crash
 Woogenellup  Canola  –8  Late  Clip
 Cascades  Wheat  –9  Early  Crash
 Gibson  Wheat  –3  Average  Clip
 Gibson  Barley  –10  Late  Clip

 # Time of grazing: Early = late June; Average = early-mid July; Late= July to early August

+ Type of grazing: Crash = heavily grazed; Clip = lightly grazed

Source: Cam Nicholson

Three possible reasons might explain the 2012 yield penalties. First, growing season rainfall was significantly less in 2012, with most sites receiving only decile 1 or 2 rainfall. Moisture stress could therefore have reduced the ability of crops to recover from grazing.

Second, several of the 2012 trial sites were located in the low-rainfall zone, where the short seasons are less suited to crop grazing.

Finally, the timing and intensity of grazing may have increased the frequency of yield penalties, with four out of the 11 crops grazed later than recommended and seven out of 11 crops grazed heavily in 2012.

It is likely these three factors interacted to exacerbate the negative effects of late and heavy grazing.

The average grazing value provided by crops was significantly less in 2012 than in 2011 (214 versus 307 DSE (dry sheep equivalent) grazing days per hectare). This was mainly due to the late start and the cold and very dry July experienced in the 2012 season.

The amount of grazing value provided by the crop is important when considering the economic implications of crop grazing. In a year such as 2012, when grain prices were high, a small yield penalty caused by crop grazing can have a large impact on grain income per hectare.

In addition, when livestock prices are low, considerable grazing value is needed to make up for any penalty in grain yield incurred through grazing.

Crop grazing top tips

  • All cereal and canola varieties can be grazed.
  • Sow as early as possible to maximise feed supply.
  • Choose weed-free paddocks when grazing cereals.
  • Select the right variety for the sowing date.
  • Adhere to withholding periods for chemicals.
  • Graze early and evenly (use 'pinch and twist' test to ensure plants are ready to be grazed).
  • Supplement stock with calcium (Ca), sodium (Na), mangnesium (Mg) (cereals) and fibre (canola).
  • Don't graze too late (before GS30, bud 10cm and mid-late July).
  • Clip rather than crash graze when approaching GS30 or Bud 10cm.
  • Apply top-up nitrogen after grazing, not before.

More information:

Philip Barrett-Lennard, Consultant AgVivo,
0429 977 042,

phil@agvivo.com.au

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Stubble grazing no problem with no-till

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Drought stimulates crop expansion

GRDC Project Code FGI00007

Region West