Summer Forage Crop Options for Dairy Farmers in Temperate High Rainfall Climates

Dr Richard Eckard, The Institute of Land and Food Resources,
University of Melbourne & Agriculture Victoria, Ellinbank

Summary
Pasture renovation/ summer forages trial
The niche for a summer forage crop
Criterion for selecting a forage
Pests and weeds
Comparative yields
Turnips at the top!
Spring oats - under rated!
Rape & kale - reliable
Maize & millett - for a later forage
Ryegrass - two "schools of thought"
Irrigation Efficiency

SUMMARY
 
Summer forage crops can be divided into two categories:
1. Target date forages:

Turnips remain the best value for money, where a forage crop is required from late January. Pasja, Rape then Kale remain good alternatives and, although they are lower yielding and more prone to insects and weeds, they may provide some regrowth for a second grazing. An early maturing Maize may be an option for a warmer, frost-free or sheltered farm, although this does NOT suit a pasture renovation program. In terms of irrigation efficiency turnips were, on average, twice as efficient as pasture.

 
2. Scheduled forages:

To return the land to the grazing rotation as soon as possible, a spring planted Oats will most certainly deliver at least 2, reliable, good quality and generally weed-free grazings, starting 4 to 5 weeks after planting. Selection of the Oats variety is vital, as some will run to seed before December, while others require a winter cold to seed. If grazings are required from mid-January, then Millett may be an option for a warmer, frost-free or sheltered farm. However, Oats and Millett will still require renovation back to permanent pasture in autumn, thus sacrificing additional grazing before winter.

NB! A spring renovation back to ryegrass does not yield much less than Oats or Millett over the summer period, particularly a Short Rotation ryegrass mixture like Concord and Yatsyn, and does not require renovation back to permanent pasture.

 

PASTURE RENOVATION/ SUMMER FORAGES TRIAL

The experiment was conducted on the Elliott Research Station in North West Tasmania, to compare the relative value of a range of summer forage crops suitable for a dairy pasture renovation program. The trial evaluated a range of forage crops including Maize (SR73), Millett (Shirohee), Turnips (Barkant), Hybred Brassica (Pasja), Rape (Bonar), Kale (Kestral), Oats (Esk). The yield and quality of these forages were compared with each other and with two spring pasture renovation treatments. The spring renovation treatments, both including white clover, compared a perennial ryegrass pasture to a mixture of a perennial ryegrass with a short rotation ryegrass.

The 0.5 ha of land surrounding the trial was set up as a demonstration by establishing long rows, a planter width each, of the alternative cultivars commercially available. This area included Maize (SR73 & SR78), Millett (Shirohee), Oats (Esk, Nile, Enterprise), Turnips (Appin, Barkant, Green Globe, Polybra, Purple Top), Swede (Highlander, Major Plus), Pasja, Rape (Aran, Bonar), Kale (Kestral). Ryegrass varieties include Aries, Banks, Jackeroo, Vedette, Yatsyn and the Short Rotation ryegrass Concord.

 

THE NICHE FOR A SUMMER FORAGE CROP

The establishment of a summer forage on dairy farms has become more prevalent in recent years, as dairy farmer increasing their stocking rates in keeping with the application of new technology. This increase in stocking rate highlights the feed shortages experienced during the dry summer period, forcing farmers to either conserve more fodder in the spring, irrigate their pastures through the summer or plant a summer forage crop.

As more pressure is brought to bear on the existing pasture, through increasing stocking rates, the pastures tend to degrade faster, thus requiring more frequent renovation. Establishing a summer forage crop is an ideal opportunity to both produce a much needed forage crop, incorporate lime and fertiliser nutrients into the soil and upgrade the pasture once the crop is utilised.

 

CRITERION FOR SELECTING A FORAGE

Important criterion in selecting a forage would obviously be:
a) To ensure that the pasture is not out of the grazing rotation for too long, the forage chosen must be established by the end of October, with the land drilled back to pasture by early to mid-March. This will still allow for a spring silage cut, as well as ensuring sufficient moisture and heat for the re-drilled pasture to grow before the next winter.
b) The forage of choice must also be able to deliver the forage when it is most needed, usually in late January through to the end of February.
c) a forage crop that produces the best yield and quality for the money invested,
d) a forage crop requiring a minimal herbicide and insecticide input, and
e) a crop requiring no further soil cultivation before drilling back to pasture.

 

PESTS AND WEEDS

The following pests can results in significant crop losses and should be checked and sprayed if necessary.
a) Lucerne flea: Most critical in the month after planting. Remember to check three weeks after spraying again, to catch those fleas that hatch after the first spraying.
b) Grubs: Around Christmas time one should check for grub attack, particularly in a Rape or Kale forage.
c) Caterpillars: In mid-January caterpillars may be a problem, mainly in the Rape and Kale forages. In this case the option does exist to graze off the forage rather than spray.

 

Of all the forages tested in the trial Turnips, Millett, Oats and ryegrass appeared most resistant to both insect and weed problems, requiring little or no control. Crops like Maize obviously require weed control by virtue of the wide row spacings required, which leaves ample room for weeds to establish. Of the Brassica crops Rape and Kale were substantially more prone to weed invasion than were Turnips.

 

COMPARATIVE YIELDS

Table 1 presents the DM yields of the scheduled forages at each harvest through the summer, under both irrigated and dryland conditions. Oats was available for grazing within 5 weeks of planting, but declined in yield thereafter. Millett yields were good in the January and February period and declined rapidly into autumn. Overall the spring-renovated ryegrass pastures did not yield poorly, compared to Oast and Millett and did not require renovation in the autumn.

Table 1. Comparative Dry Matter yields (t DM/ha) of scheduled forages at each harvest

Forage 8-Dec-95 5-Jan-96 1-Feb-96 11-Dec-96 7-Jan-97 29-Jan-97
Oats Dryland 1209 3201 858 1532 2469 1086
Irrigated 1378 3106 1012 1414 3504 2072
Millett Dryland 2224 1833 1355 2224
Irrigated 2973 2232 2742 2549
Concord + Ryegrass Dryland 3980 1938 2328 1771
Irrigated 2929 1770 3115 1716
Ryegrass Dryland 2650 2136 1552 1976
Irrigated 1814 2265 2694 1863

In Figures 1a and 1b the total DM yields of all the forages over 13 weeks are shown, for irrigated and dryland conditions, for the 1995/1996 and 1996/1997 summer seasons, respectively. Turnips were clearly the highest yielding forage and showed the greatest response to irrigation in both years.

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Figure 1a:
Total dry matter yields of summer forage crops at the end of 13 weeks in the 1995/1996 summer (year 1).

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Figure 1b: Total dry matter yields of summer forage crops at the end of 13 weeks in the 1996/1997 summer (year 2).

The relative nutritional merits of each forage is given in Table 2, showing turnips and Pasja to be highest in ME and digestibility but low in protein, particularly in turnip bulbs.  Millett had the highest protein content, followed by the other grasses.

Table 2. The metabolisable energy (ME in MJ/kg DM), crude protein (CP %) and dry matter digestibility (DMD %) of 9 forage crops at 13 weeks (Sown 1 Nov and harvested by 1 Feb)

Forage

ME

CP

DOMD

Moisture

MJ/kg

%

%

%

Perennial Ryegrass

10.3

16.6

72.4

81.6

Concord Ryegrass

10.6

16.5

74.0

81.9

Oats

10.9

13.2

75.7

83.4

Millett

11.0

21.4

76.9

85.6

Maize

10.5

15.0

73.6

86.4

Rape

12.6

11.4

85.6

85.6

Kale

12.2

14.3

83.5

85.6

Pasja

12.6

12.4

85.9

85.6

Turnip Tops

12.5

12.4

85.1

87.3

Turnip Bulbs

13.4

7.0

90.7

89.6

 

TURNIPS AT THE TOP!

What is clear from the yields presented, is that there are few forages that can compete with a Turnip crop, in terms of value for money within 12 to 14 weeks. Not only did Turnips yield over 40% higher than the next nearest forage over the 13 weeks, they were less prone to weed invasion and insect pests. Turnips also has an advantage in that they tend to compensate for minor variations in seeding rates. With a higher seeding rate individual bulbs will be smaller, but the total yield of Turnips per unit area will remain approximately the same.

As long as the Turnips are strip grazed, with a long access front, wastage is minimal compared with the other Brassica crops. After the cows have finished grazing the Turnip crop, the land is easily drilled back to pasture, as there will be little residue and stubble remaining to clog up the seed drill.

 

SPRING OATS - UNDER RATED!

Spring planted Oats is a potentially high quality summer forage particularly suited to the farmer who needs grazing as soon as possible. As long as the crop is correctly established, it can be grazed as early as 4 to 5 weeks later, with the regrowth being available every 3 to 4 weeks through to mid-February.
 
It is vital to select the correct variety of Oats. Cultivars like Enterprise and Cluan require increasing daylength in order to seed, so would immediately attempt to seed after spring planting. Other varieties like Nile and Esk require vernalisation (winter cold) in order to stimulate a seeding response. These varieties would be ideal for spring planting as they should only attempt to seed with the onset of winter.
 

It is also vital that the Oats crop is not allowed to grow too long between grazings or cuttings, as this allows the growing point to rise up the stem above normal grazing height. If this growing point is grazed off, that tiller will not regrow and the result is an overall poor regrowth. If correctly grazed, the Oats crop will produce at least 3 grazings and a reasonable hay crop in March.

RAPE & KALE - RELIABLE

Both Rape and Kale, although susceptible to insect damage, are high yielding forages suitable for grazing from early February through to March. These two forages can be grazed more than once, but the regrowth is usually not as reliable and high-yielding as the first. When drilling these varieties back to pasture the brassica regrowth may need to be sprayed with a herbicide and the stumps mown off to ensure a good pasture establishment.

MAIZE & MILLETT - FOR A LATER FORAGE

Being sub-tropical forages, Millett and Maize battle in colder climates. However, the performance of these forages should not be judged before mid-January, when their growth rate begins to peak. The 2.2 - 3.0 t/ha harvested from the Millet in mid-January, was almost fully regrown by the first week of February. It would not be unrealistic to expect three grazings/harvests of similar magnitude from the Millett before the Autumn cold retards further regrowth.
 
Some of the better early-maturing varieties of Maize will begin to tassel by the early February and would be ready for harvest by the end of March. It must be emphasised that the yields presented for Maize over 13 weeks (Figure 1) would be an unfair reflection of the performance of Maize, as even the early maturing varieties require a least 16 weeks to realise their potential. On the other hand, if the fodder crop is part of a pasture renovation cycle, then waiting 25 weeks for Maize to mature would not allow sufficient heat units for pasture to establish before the following spring.
 

RYEGRASS - TWO "SCHOOLS OF THOUGHT"

The ryegrass spring renovation treatments were aimed at investigating two "schools of thought".
a) For those farmers who apply the principles of Intensive Pasture Management, and are looking for a long-term permanent pasture, the establishment of a perennial ryegrass and clover pasture would be best suited. In this case Vedette was included to improve winter production and Jackeroo for extended summer production.
b) An increasing number of farmers are finding that a regular pasture renovation program (every 4 years) more than pays for itself in the additional forage produced. A simple calculation will show that a dairy pasture renovation can pay for itself within 4 to 6 months, through improved production and quality of pasture. Under these conditions it would be logical to include a short-rotation ryegrass in the renovation, as we know that this will out-produce a pure perennial ryegrass pasture for the period in question. It is not surprising, therefore, that an increasing number of farmers are using a short-rotation ryegrass in a mixture with perennial ryegrass.

 

Remember that the spring renovation to ryegrass (Table 1 and Figure 1) yielded similar to many of the other forages, while there was also no delay in returning the land back to pasture at the end of the crop. This time delay taken into account means that, apart from the higher yielding forages like Pasja and Turnips, there are few forages that will clearly out yield a highly productive pasture.

 

IRRIGATION EFFICIENCY

In terms of irrigation efficiency (measured as tonne of dry matter produced per Mega litre irrigation applied) turnips were clearly superior to all the other forages (Table 2), showing a 1.5 t/ML response in a wet summer and a 2.2 t/ML response in a dry summer. If irrigation or effluent supply was limited, the economics of irrigating pasture, relative to turnips, would be questionable.

Table 2. The irrigation efficiency (t DM/ML) of the forages.

95/96

96/97

Forage

Irrigation efficiency

(tonne DM/ML irrigation)

Oats

0.1

0.7

Millett

0.4

0.7

SR Ryegrass

-0.5

0.3

Perennial Ryegrass

-0.3

0.4

Kale

-0.1

0.8

Rape

-0.3

1.1

Pasja

n/a

0.9

Turnip-tops

1.1

0.8

Turnips-bulbs

0.4

1.4

Bulbs & Tops

1.5

2.2

Maize

-1.0

0.1

 

ACKNOWLEDGMENTS

The project is financed by the Dairy Research and Development Corporation in conjunction with the Tasmanian DPIF and the University of Tasmania. The fertiliser was donated by Pivot Agriculture and the seed donated by Heritage seeds, Wrightson Seeds, Roberts and Snowy River Seeds.
 

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Last modified:16 August, 2004                         Please Note: Disclaimer             Authorised and maintained by:Richard Eckard
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