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The performance of a range of annual pasture legumes on acid saline soils in Tasmania

E.J. Hall1 and P.M. Evans2

1 Tasmanian Institute of Agricultural Research, PO Box 46 Kings Meadows Tas.
2
Agriculture Victoria, Pastoral and Veterinary Institute, Private Bag 105 Hamilton, Vic.

ABSTRACT

The herbage production of 60 accessions and cultivars representing 32 annual legumes from the genera Trifolium, Ornithopus, Melilotus, Lathyrus and Vicia was assessed on an acid saline soil at Symmons Plains in the Northern Midlands of Tasmania. The soil type is a sandy clay loam with a pH of 5.4 (1:5 water) and an electrical conductivity (EC) (1:5 water) ranging from 0.2 to 3.25 dS/m. There were significant differences in dry matter production between species, with Ornithopus hybrid cv. Spectra, T. michelianum cv. Bolta, T. squamosum and T. resupinatum having the highest mean yields across all levels of salinity. However, there were significant differences in the rate of change in herbage production with changing salinity levels between species and also between accessions of the same species.

KEY WORDS

Annual legumes, salinity, acid soil, herbage production.

INTRODUCTION

Dry-land salinity affects over 2.5 million hectares of Australian farmland (20,000 ha in Tasmania) and is expanding at the rate of 2 to 3 per cent a year. Legumes are considered to be either sensitive or only mildly resistant to salinity, with only a few tolerant species known (1). Those recognised to be more salt tolerant include Berseem clover (T. alexandrium) (2), Sweet clover (M. alba) (3), Persian clover (T. resupinatum) (3,4) Morrocan clover (T. isthmocarpum) (R.Reid pers. comm.) and Balansa clover (T. michelianum) (3,4). Rogers and Noble (5) reported that intra-specific variation in salt tolerance is common in some Trifolium species. The aim of this work was to examine the performance of a range of annual legume species on an acid saline soil in Tasmania, specifically looking at the behaviour of different accessions and species under a gradient of salinity.

MATERIALS AND METHODS

An experiment was established at Symmons Plains in the Northern Midlands of Tasmania on the 28th April 1999. The mean annual rainfall for this area is 684mm. The soil type is a sandy clay loam with a pH of 5.4 (1:5 water), Colwell P 36 mgkg-1 and Colwell K 87 mgkg-1. EC (1:5 water) ranged from 0.2 to 3.25 dS/m across the site. Sixty accessions and cultivars from the genera Trifolium, Ornithopus, Melilotus, Lathyrus and Vicia were drilled into 5m x 1.5m plots. A split plot randomised block design with three replicates was used. Each plot was split into treatments of nil lime and 4 t/ha lime. Treatments were applied by hand two weeks prior to sowing. Fertiliser was predrilled at 300kg/ha of 0-6-17 NPK. Inoculated seed was sown at a rate of 10 kg/ha for all treatments. Seedlings were counted in four 0.0625m2 quadrats per plot six weeks after emergence. Dry matter production of the best 23 accessions/cultivars (Table 1) was determined by herbage cuts of one 0.25m2 quadrat per plot and oven drying at 100C. At the same time, five soil cores were removed from each plot to a depth of 7.5cm for EC measurements. Analysis of variance using salinity levels as a covariate were carried out on the data.

RESULTS AND DISCUSSION

All lines germinated well except Berseem clover. Plant counts at week six showed that seedlings of species with poor adaptation to higher EC levels had not survived. The application of lime had no significant effect on seedling survival or herbage production. There were significant differences in herbage production between and within species, in their response to increasing salinity, l.s.d. (P=0.05) 743.7 (Table 1). At slight to moderate salinity (0.25 to 0.9 dS/m), Spectra and Bolta, were the highest yielding lines with more than 3 t DM/ha. At very saline levels (0.91 to 1.75 dS/m) Nitro Plus and SA 2998, were the most productive with 2.3 and 1.4 t DM/ha respectively. At the highly saline level (> 1.75 dSm), SA2998 was the only line to produce over 1 t DM/ha while Tas 2254, produced 0.8 t DM/ha.

Table 1. Seedling numbers at six weeks from sowing (plants/m2) and Spring herbage dry matter production (kg DM/ha) at three levels of electrical conductivity (6).

Species

Accession/Cultivar

slight – moderate
(0.25 – 0.9 dS/m)

very saline
(0.91 – 1.75 dS/m)

highly saline
(> 1.75 dS/m)

   

plant/m2

DM

plant/m2

DM

plant/m2

DM

Ornithopus compressus

Tas 1700

147

771

33

22

-

-

Ornithopus hybrid

Spectra

230

3150

129

1060

-

-

Trifolium carmeli

Tas 2266

130

1694

27

139

76

0

Trifolium clusii

SA 2998

89

873

113

1354

71

1309

Trifolium clusii

Tas 439

17

162

-

-

0

0

Trifolium diffusum

SA 17357

149

1355

109

191

-

-

Trifolium hirtum

95Tur47hir

111

1205

50

18

-

-

Trifolium isthmocarpum

Bulk

54

640

82

607

-

-

Trifolium michellianum

Bolta

89

3043

-

-

47

84

Trifolium purpureum

Tas 1042

78

1709

21

39

4

0

Trifolium resupinatum

132625

13

181

37

228

4

0

Trifolium resupinatum

Nitro Plus

31

1292

89

2279

94

344

Trifolium resupinatum

Tas 1041

92

904

28

575

-

-

Trifolium resupinatum

Tas 1646

60

76

-

-

91

0

Trifolium resupinatum

Tas 611

33

342

31

291

4

18

Trifolium resupinatum

Tas 622

16

1027

84

724

49

321

Trifolium salmoneum

Tas 2254

191

1481

110

339

36

786

Trifolium squamosum

SA 370

120

2432

71

1052

36

8

Trifolium striatum

Tas 1698

56

619

29

20

4

0

Trifolium subterraneum

Denmark

187

1944

111

644

40

0

Trifolium vesiculosum

Arrotas

67

1153

16

10

7

0

Trifolium vesiculosum

MO 92

50

1833

22

58

7

0

Vicia Sativa

Tas 697

73

954

73

282

53

0

l.s.d. (P=0.05) plants/m2 = 56.3, l.s.d. (P=0.05) DM = 743.7
' - ' There were no plots of this accession/cultivar at this salinity level

The level of tolerance within the six Persian clover lines was also significantly different (P<0.05), at the slight to moderate salinity level Nitro Plus produced 126% more than the next best Persian clover and at the very saline level it produced 315% more dry matter than the next best. Melilotus alba, highly salt tolerant in Victoria, failed at this site, probably due to the low soil pH, as it has failed in other acid soil sites in Tasmania.

CONCLUSION

These results confirm the tolerance of Balansa and Persian clovers to moderate levels of salinity. The behaviour of T. clusii, T. squamosum, T. salmoneum and Spectra serradella is encouraging and warrants further investigation. Additional species/accessions with combined tolerance to acid and saline conditions needs to be sourced and evaluated.

ACKNOLEDGMENTS

We thank Andrea Hurst, Robert Howard and Gary Martin for their technical assistance. The project was supported by the Woolmark Company, the Grains Research and Development Corporation, DNRE and TIAR.

REFERENCES

1. Kaddah, M.T. 1967. Agronomy Journal. 54, 421-425.

2. Winter, E and Lauchli, A. 1982. Australian Journal of Plant Physiology. 9, 221-226.

3. Evans, P.M. and Cameron, N.L. 1998. Proceedings 9th Australian Agronomy Conference, Wagga Wagga, 174-177.

4. Evans, P.M. and Snowball, R. 1993. Proceedings 7th Australian Agronomy Conference, Adelaide, 53-56.

5. Rogers, M.E. and Noble, C.L. 1989. In: Management of Soil Salinity in South Eastern Australia. (Ed E. Humphreys et al.) Soil Science Society, Albury. pp 191-200.

6. Anon 1999. Saltline Tasmania Vol2(2) pp 5-6, DPIWE Tasmania.

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