Soybeans, can they play a bigger role in coastal beef systems?

Peter Tame, AusWest Seeds, Southern Queensland & Northern Rivers NSW

Newer varieties of soybean like Hayman and Richmond have provided more options for beef producers on the coastal areas of Northern NSW and South-East Queensland and are also being used on the northern Tablelands.

We often hear the saying sugar cane, soybean and beef. In these areas soybeans fit into the livestock system as a good rotation crop for sugar cane and give beef producers’ flexibility to use soybeans as a grazing fodder crop, make silage or hay or as a stand-alone cash crop.

As a rotation crop soybean are a good option to enhance soil nitrogen, a means to break disease cycles and provide options to control weeds and grasses.

Adaptability of Soybeans

Soybean suits the range of soil types which are typical of the high rainfall zone coastal flats of South-East Queensland and Northern NSW. These regions are summer dominant high rainfall zones with soils varying from loams and clay loams to heavy self-mulching clays. Resistance to Powdery Mildew and tolerance to Manganese toxicity are key attributes in soybean varieties for these regions. Soybeans also have superior tolerance to waterlogged paddocks compared to the other summer forage legumes Cowpea and Lab Lab.

Variety Selection and Sowing Time

Higher forage yields come from planting long season varieties early in the season. Early plantings encourage the plant to maximise its forage production by extending their vegetative phase. When the shorter day length trigger is reached the plants will then go reproductive.

Maturity grouping of varieties is an indicator of photoperiod response. Varieties can be grouped in a maturity rating (1 – 8) with the lower numbers indicating shorter periods to flowering. Based on a mid-December planting, varieties of these groups will have the flowering dates indicated.

Group 5 – 120 to 125 days to flowering - Quick
Group 6 – 125 – 130 days to flowering - Medium
Group 7 – 130 - 135 days to flowering – Slow

All three groups are suitable for plantings in South-East Queensland and Northern NSW.

Maturity will also change with environment. For example Hayman maturity is around 130 days in the Darling Downs and Lockyer Valley and 136 days in the NSW north coast and Tablelands. Richmond maturity is around 112 days in northern NSW and 121 days in southern Queensland.

While all grain types can produce forage and hay, the early plantings of long season varieties are those best suited to maximise yield for either purpose.

Soil temperatures should also be considered when planting soybeans. Soil temperatures should consistently be at least 18OC at sowing depth taken at 9.00 am.

Row Spacing and its Effect on Quality

Soybean grain crops are generally planted in 70 to 100 cm rows. Row spacing for crops intended for fodder production should be narrower. Secter et al (2004) found row spacing can have a bearing on the quality of fodder but not on overall yield. Over two years looking at 76 cm spacings compared to 18 cm he found the fibre content of the 76 cm forage was higher than that in the narrower rows. This is attributed to finer stems of plants in narrow row spacing’s. However forage utilisation rates can be higher with wider row spacing’s due to less trampling.

Row spacing (cm) Acid Detergent Fibre (ADF) Nuetral Detergent Fibre (NDF)
76 417 g/kg 487 g/kg
18 324 g/kg 421 g/kg

Planting Rates

Sowing rates for forage production should be the same as those for grain production. Irrespective of the row spacing the optimum establishment of plants per hectare should be the same for either purpose.

Dryland Fair / Good conditions 20 - 25 plants /m2 established
Coastal Narrow rows < 75 cm 30 -40 plants /m2 established
Coastal Wide Rows > 75 cm 28 – 32 plants /m2 established

Source: NSW DPI

Inoculation

All seed should be inoculated with group “H” inoculant to maximise nodulation and nitrogen fixation. A well nodulated crop will not require nitrogen fertilizer applications. Nitrogen fixation can be enhanced with good levels of Phosphorus, good soil moisture, soil ph >6, and cooler soil temperatures.

Animal Health and Soybean

Hungry stock should not be put into lush soybean crops. Stock need to be introduced over time. Vaccination with 5 in 1 for pulp kidney is also important. All stock coming off dry and poor quality pastures should be vaccinated. Cattle don’t appear to suffer any photosensitivity issues from grazing soybeans.

Weather damaged mature crops or hay should not be fed to stock without further testing. Weather damage can cause infections of the fungus PHOMOPSIS which has lupinosis symptoms.

Hayman Soybean Grazing and Grain Recovery Demonstration 2016 - Nathan Jennings, North Coast Local Land Services

A demonstration looking at Hayman Soybeans for their feed quality, ability to recover from grazing and grain recovery was conducted in 2016 at Tabulam NSW with the support of the Dowley family on their farm.

Nathan’s objectives included - assess Hayman’s suitability for cattle grazing measuring

  • Forage quality
  • Animal performance
  • Potential grain recovery
  • Combined animal and grain gross margin
  • Also to see if Hayman soybean can be incorporated in a program to control Bahia grass.

Some other features were the row spacings were 80 cm. This row spacing and class of animals resulted in a very low level of trampling and crop damage. Plant establishment was 21 plants/m2.

Two blocks were grazed with 15 weaner cattle/ha

  • 1st block 25th Jan to 9th Feb
  • 2nd block 9th Feb to 15th Feb

These blocks had 4.8 t/ha DM and 4.98 t/ha DM at the start of grazing respectively.

Both blocks recovered well from grazing to produce acceptable grain yields and quality:

  Block 1  Block 2
 Grain Production 1.62 t/ha 1.72 t/ha
Protein 40.6% 41.9%
Oil 23% 21.7%
ME 13.3 13.4
Digestibility 87% 87%

 The weaners weight gain (21days) was 113 kg/ha with a sale price of $3.20 = $362 /ha

The grain return was $1002 /ha at a sale price of $600.00 /t

Which results in a return of $1364 (equivalent to 2.3 t/ha of Soybeans)

The crop responded well when the weaners were removed 9 days into flowering.

The Bahia grass control has been effective.

The results of this demonstration show some of the potential benefits that soybeans offer in coastal beef systems. The returns from live weight gain and grain recovery indicate the flexibility soybeans offer as a grazing option and cash crop. Further evaluation will be undertaken as a proof of concept.

Conclusion

Soybeans are a very good source of quality feed providing several management options to farmers. They are a high source of protein and energy with high levels of digestibility. High animal growth rates are more likely to be achieved with soybean forage than summer grasses and forage sorghums.

Soybeans are suited to a number of soil types and conditions but do best in high rainfall areas along the coast with high summer dominant rainfalls.

Best results for forage production for grazing, hay or silage production are from long season varieties such as Hayman sown early in the planting window.

References 

  • NSW DPI Ag Summer Crop production Guide 2014 p 59
  • Qld DAF, Field Crops and Pastures, Broadacre Field Crops, Soybeans, 4th May 2010
  • NSW DPI, Agriculture, Broadacre-crops, Forage, Summer Legume Forage. - Summer Legume Forage Crops: - Cowpea, lab lab, and soybean
  • A review of forage Soybean production Quality and Yield, Asher Wright, 7 Jan 2013
  • Forage Soybean for Grazing Hay and Silage, Uni Florida, AR Blout, DL Wright, RK Sprankel, TD Hewitt and RO Myer. SS-AGR-180. Revised Jan 2017
  • Seiter, SC. Altemose, M Davis. 2004. Forage Soybean yield and quality response to plant density and row distance. Agronomy Journal 96, 966-970
  • Principles of Field Crop Production, 3rd Edition. Jim Pratley, p 381
  • Grazing and Grain Recovery of Soybeans Demonstration – Conducted by Neil Jennings, Senior Land Officer, North Coast Local Land Services

Soybean Quality

Beef finishing operations require high protein and high energy feeds to achieve live weight gains and meat quality. Soybean forage is very high in crude protein, digestibility, metabolisable energy and low in fibre. Soybean are also considered to be a low bloat risk for cattle.

Crude protein levels of the leaves can be 20% or more and the stems 10% dependent on the crop growth stage and seasonal conditions. The combination of these two components is generally superior to most tropical grasses and forage sorghums.

The level of digestibility in most legumes is 50 – 55 % on a whole plant basis. Leaves are more digestible than stems, (60 -75% and 50 –55% respectively). Animal intake declines as the leaf availability declines. Cattle will selectively graze leaf over stem. Table 1 below shows a range of forage legume feed values.

Table 1: Forage legumes showing range of feed values - Source Feeds Evaluation Unit NSW Ag

   Crude protein  Acid Detergent Fibre % Digestible Drymatter % ME (MJ/kg DM
Soybean  Leaf only 22      
  Stem only 5      
  Whole plant 15 33 63 9.4
Lucerne 10% Flower 18 35 65 9.2

This table shows how good soybean quality can be which is close to that of lucerne, but superior to forage sorghum.

Desirable Feed values required to fatten stock are:

  • Crude protein needs to be >11%.
  • Metabolisable Energy needs to be 10 – 12 MJ/kg DM
  • Desirable Levels of DDM should be high while ADF is best at low levels

Timing of Grazing vs Hay or Silage of Soybeans

Soybean not only has the ability to produce quality forage but it also has a source of energy and protein in the seed.There is generally a trade-off by grazing a crop and maximising the volume of hay or silage produced. If the crop is intended to be grazed, one option is to do so early, while the plants leaf/stem ratio is high. As the plant grows the stem will increase in size and volume. As such the higher stem fibre will detract from the crude protein quality of the leaf.

The best quality hay and silage is made when the pods are half filled. A well grown forage crop can reach yields of 25 t/ha or 10 tonnes/ha DM at maturity.

The beans are a source of high protein (40%) along with its oil content of 20 %. This stage should be just prior to leaf drop (growth stages R5 to R7) which means the leaf also adds to the quality from the forage. Forage volume has been maximised at this stage. It is also an important stage at which a crop can be grazed. Soybean regrowth is poor after grazing so this is often considered the optimum grazing time.

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