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Barley benefits from grazing

Martin B. Lovegrove and Robert D. Wheeler

South Australian Research & Development Institute, GPO Box 397 Adelaide 5001 lovegrove.martin@saugov.sa.gov.au

Abstract

In South Australia, barley growers are becoming increasingly interested in grazing crops as a form of canopy management and to provide early sheep feed. Information is limited on the effect of grazing on barley grain production and the most appropriate variety. In 2007 a field experiment was conducted in South Australia’s high rainfall Mid-North region at Tarlee. The experiment aimed to assess the effect of simulated grazing regimes on dry matter production, rate of crop development, grain yield and grain quality within a range of barley cultivars. The experiment incorporated nine barley cultivars together with Wallaroo oats, which is more traditionally used for grazing in South Australia. The cultivars were assessed under four defoliation (simulated grazing) regimes, continuously grazed (beginning at 2-leaf stage, grazing 6 times in 4 weeks), early grazing only (GS20) and late grazing only (GS30), against an ungrazed control. A replicated split plot design was used. Grazing was found to delay anthesis by up to 5-10 days depending on variety and grazing treatment. A single late graze removed more dry matter than continuous grazing over a four-week period. There was found to be no interaction between barley cultivar and grazing treatment for harvested grain yield. However, late grazing reduced barley grain yield while early and continuous grazing treatments had no impact on grain yield. The late grazed treatment produced significantly lower grain protein content than all other treatments and met South Australian malting grain receival specifications. All barley varieties produced greater dry matter compared to Wallaroo oats across all grazing treatments. This research has shown barley to be a viable grazing alternative to oats with good grain recovery and little impact on grain quality.

Key Words

Barley, agronomy, grazing, canopy management

Introduction

South Australian farmers are embracing grazing cereals as a viable option for an early fodder source for livestock. Cordon (2007) indicated that growers are returning to grazing of Wallaroo oats as they are a versatile crop that produces high levels of dry matter. Research carried out by McInerney (2007) suggested that barley can produce greater dry matter when compared to wheat and oat crops. McInerney (2007) confirmed the potential for wheat, barley and oats to recover from grazing and still produce good grain yields and an improved gross margin. There can also be a potential benefit to crop grain production. Sisler & Olson (1951) estimated that lodging could cause yield loss in barley and wheat of up to 40%. Grazing can reduce the plant height and pre anthesis biomass of crops, thereby reducing the likelihood of lodging since lodging susceptibility has a clear relationship with plant height (Crook and Ennos, 1994). This experiment aimed to assess the effectiveness of simulated grazing regimes on dry matter production, rate of crop development, grain yield and grain quality within a range of barley cultivars.

Methods

A simulated grazing trial was established in 2007 at Tarlee, South Australia. The experiment was designed with nine barley cultivars plus Wallaroo oats. The barley cultivars examined (Baudin, Flagship, Fleet, Hindmarsh, Keel, Maritime, Schooner and WI3416) are known to differ in growth rates, habit and lodging potential in addition to inherent grain protein and receival quality. Cultivars were sown to achieve a plant density of approximately 150 barley plants/m2 using seed treated with VincintC for control of smuts and bunts. The site was direct drilled with a small plot seeder on May 30th using narrow points with press wheels following. The barley seed was sown with 75 kg/ha of 10:22 fertilizer, sown at 35mm depth and 170mm row spacings. 150kg/ha of urea was broadcast on the trial on the 5th of July. Simulated grazing and stock trampling effects were undertaken using a medium roller and ‘ride-on’ lawn mower. Four defoliation regimes were carried out including; ‘continuously grazed’ (beginning at 2-leaf stage, grazing 6 times in 4 weeks), ‘early grazing’ (GS20) and ‘late graze’ at GS30, with an ‘ungrazed’ control. The plots (17 m2) were harvested (when?) with a small plot grain harvester and grains weighed. A sub sample was tested for hectolitre weight, 1000 kernel weight, grain protein (dry basis), retention (%>2.5 mm screen) and screenings (%<2.2 mm screen). A split plot trial design with 3 replicates was used with grazing treatment the main plot and cultivar as the sub plot. Data were analysed with Genstat 10th Edition using 2 way ANOVA.

Results

Seasonal Conditions

At sowing time for Tarlee, South Australia, in 2007, there was abundant soil moisture but though winter to early spring conditions became dry. Rainfall events during late spring were timely despite being below average and allowed for average grain yields.

Anthesis

Ungrazed, the early cultivars Hindmarsh, Keel, Maritime and Fleet commenced anthesis around the 13th of September as shown in Table 1. Continuous grazing treatments were found to delay time of anthesis in these cultivars by 8-10 days compared to the ungrazed control. The midseason cultivars Flagship and Schooner commenced anthesis around the 17th of September with grazing similarly delaying anthesis up to 6 days. The later season cultivar Baudin, began anthesis on the 30th of September and was generally least affected by grazing with continuous grazing the only treatment to considerably delay anthesis. Wallaroo oats was found to be similar to most barley varieties in response to early and continuous grazing but anthesis was delayed 7-10 d by late grazing.

Table 1. Effect of grazing on barley and oat cultivar anthesis date – Tarlee, 2007

Un grazed (U)

Early graze (E)

Late graze (L)

Continuous graze (C)

Baudin

30 Sept - 4 Oct

1 Oct - 5 Oct

1 Oct - 6 Oct

5 Oct -7 Oct

Hindmarsh

16 Sept - 20 Sept

19 Sept - 23 Sept

20 Sept - 23 Sept

25 Sept - 30 Sept

Keel

14 Sept - 19 Sept

19 Sept - 22 Sept

19 Sept - 22 Sept

21 Sept - 27 Sept

Flagship

18 Sept - 22 Sept

20 Sept - 26 Sept

23 Sept - 28 Sept

24 Sept - 29 Sept

Schooner

17 Sept - 22 Sept

20 Sept - 27 Sept

23 Sept - 28 Sept

24 Sept - 29 Sept

Maritime

13 Sept - 18 Sept

16 Sept - 21 Sept

20 Sept - 23 Sept

21 Sept - 28 Sept

Wallaroo oats

20 Sept - 27 Sept

21 Sept - 29 Sept

1 Oct - 4 Oct

27 Sept - 2 Oct

Fleet

14 Sept - 20 Sept

17 Sept - 22 Sept

20 Sept - 25 Sept

24 Sept - 29 Sept

WI3416

20 Sept - 25 Sept

22 Sept - 26 Sept

27 Sept - 30 Sept

26 Sept - 2 Oct

Dry Matter (DM) production

Dry matter production measurements were not replicated however, the late grazing treatments produced on average more DM for removal than early or continuous grazing (see Figure 1) while across all grazing regimes; barley cultivars produced more DM for removal than Wallaroo oats. Within the early grazing treatments, Flagship producing the most DM, followed by Hindmarsh and Maritime. Under continuous grazing, Hindmarsh produced the most DM, Baudin was the lowest producing barley variety with this grazing treatment. When grazing late, Maritime produced the most DM.

Figure 1. Effect of cultivar and grazing on Dry matter production (kg/ha)–Tarlee, South Australia, 2007.

Grain Yield & Harvest Index

All barley cultivars responded similarly to grazing treatments for grain yield – the continuous and early grazing treatments had no significant effect on grain yield while late grazing significantly decreased grain yield (see Table 2). Early grazing had no impact on harvest index with continuous and late grazing increasing the harvest index.

Table 2 Effect of grazing treatment on barley and oat grain yield (t/ha) and Harvest Index % , Tarlee 2007

Treatment

Grain Yield t/ha

Harvest Index

Continuous grazing

3.957

ab

43.43

a

Early grazing

4.169

ab

42.89

b

Late graze

3.659

b

44.08

a

Nil graze

4.218

a

42.03

b

LSD (P=0.05)

0.367

0.91

Grain Quality

The defoliation treatments affected grain quality parameters. Mean grain retention levels were significantly reduced under the continuous grazing regime compared to early and nil grazing, but when compared to the late grazing regime. There was no significant effect of grazing on retention in Fleet, Keel, Maritime, Schooner, WI3416 and Wallaroo oats. However, Baudin produced lower retention when continuously grazed relative to all other grazing treatments and Flagship produced higher retention with early grazing relative to all other grazing treatments. All malting barley cultivars produced retention levels above South Australian malt receival specifications at all grazing treatments. Grain screenings levels were within the malt and feed receival standards across all cultivar and grazing treatments. Early and nil grazing treatments produced lower screenings across all cultivars when compared to continuous and late grazing regimes. Test weights were above minimum acceptable levels for South Australian malt and feed receival standards. Early and nil grazing treatments produced significantly higher test weights across all cultivars when compared to continuous and late grazing treatments. There was found to be no interactions for 1000-grain weight or grain protein between cultivar and grazing treatments. Early and nil grazing treatments produced significantly greater 1000-grain weight when compared to continuous and late grazing. Late grazing resulted in significantly lower levels of grain protein that enabled malt cultivars to meet acceptable receival specifications than nil, early and continuous grazing which were not significantly different.

Conclusion

Within the experiment, cultivar anthesis date was delayed by 6 to 10 days depending on variety and grazing treatment and anthesis being delayed more as cultivar anthesis date was advanced. Varieties with known similar maturity dates responded similarly to grazing treatments. The delay of anthesis with grazing is a result of delaying the progression of growth whilst being grazed.

Relative to nil, early and continuous grazing, late grazing reduced harvested grain yield. Despite this, late grazing can provide the greatest accumulated dry matter for removal by grazing livestock, presenting as an option to periodically spell pasture paddocks through winter. Depending on the grower situation this may be a useful management tool to reduce or avoid crop lodging, as shown with Harvest Index increase from late and continuous grazing. Early grazing presents as an option for early feed, whilst pastures are establishing, with no impact on final grain yield. The amount of dry matter available for grazing livestock varied between cultivar and grazing regime, with all barley cultivars producing more than Wallaroo oats. Hindmarsh produced more dry matter compared to other varieties when continuously grazed while Flagship and Maritime produced more when grazed early or late. Depending on which grazing method is undertaken by livestock and grain producers, the cultivar grown can impact on the DM available for feeding stock.

Grazing impacted on harvested grain quality. Retention was lowest under the continuous grazing treatment with no difference between all other treatments. Early and nil grazing regimes had the lowest screening levels, the highest test weights and the highest grain weight. This could have resulted from stress placed on the crop following the delay in anthesis and the low availability of moisture later in the season. Despite these effects on grain quality all treatments produced grain well within the South Australian malt and feed receival standards.

There was no effect of nil, early and continuous grazing treatments on grain protein but late grazing produced significantly lower grain protein levels. These results indicate that late grazing can be a practical option for reducing grain protein and may be a useful tool to increase the value of a malt barley crop, particularly when there is a large premium.

Grazing has been simulated in this research, therefore other considerations like preferential grazing, row spacing, stocking rate and trampling effect must be taken into account.

Grazing attributes of newer barley varieties Hindmarsh, Maritime and Flagship will be investigated to attain further information of the opportunity of these varieties to be used for dual purpose with a focusing on early grazing, having no impact on grain yield, and late grazing timing reducing grain protein.

References

Cordon, N. (2007), Oats offer grazing and flexibility. http://www.ruralsolutions.sa.gov.au/news/newspaper_articles/archive_newspaper_articles/articles_2007/december_2007/oats_offer_flexibility__and__profitability Accessed 25/06/08

Crook, M.J. and Ennos, A.R. (1994) Stem and root characteristics associated with lodging resistance in four winter wheat cultivars. Journal of Agriculture Science (Cambridge), 123: 167-179

McInerney, E. (2007), Cereal grazing on Eyre Peninsula. Eyre Peninsula Farming System 2007 Summary, pp 75-78

Sisler, W.W. and Olson, P.J. (1951) A study of methods of influencing lodging in barley and the effect of lodging upon yield and certain quality characteristics. Scientific Agriculture 31 : 117-186.

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