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Establishment and tillering of phalaris and cocksfoot on an acid soil

A.M. Ridley, A.L. Avery, S.M. Windsor

Rutherglen Research Institute, Rutherglen, Victoria 3685

Establishment and persistence of Phalaris aquatica (phalaris) has become a problem on some acid soils in north-eastern Victoria. Such soils, while naturally acid to depth, have acidified further (1). Sown Dactylis glomerata (cocksfoot) now persists more strongly than phalaris probably due to its greater aluminium tolerance (2, 3). The aims of this study were to assess the establishment and tillering ability of phalaris and cocksfoot under different pH treatments.


The site chosen was a naturally acid granitic soil (Dy 3.41) with a mean pre treatment pHcaci of 4.12 for 0-80 cm. Soil pH treatments (lime or elemental sulphur) equivalent to lime rates of -0.4, 0, 0.5, 1.5 and 5.5 t CaCO3/ha were incorporated in February 1987. Plots were sown to either mixtures of Sirosa phalaris or Porto cocksfoot with sub clover in mid-May 1987. There were 4 replicates of each treatment. Soil was sampled at 0-10 cm depths for pH and aluminium (soil solution ratio 1:5 0.01 M CaCl2) in August 1988. Plant establishment, tillers/plant and number of flower heads/plant were assessed 20 months after sowing.

Results and discussion

Analysis of variance showed that phalaris (plants/m2) established best on the 2 highest lime treatments where tiller number and flower heads per plant were also increased. Plant number, tiller number and flower heads/plant were each regressed against initial profile pH, post-treatment pH and aluminium in the 0-10 cm depth. Establishment was strongly correlated with initial profile pH (r2=0.75), and with post-treatment pH (r2=0.58). Initial profile pH gave a better correlation of tillers/plant (r2= 0.47) and heads/plant (r2= 0.57) than either post-treatment pH or aluminium.

Cocksfoot establishment was not correlated with pH treatment but tillers/plant and heads/plant were increased with lime treatment. Regression showed that there was a weak correlation of heads/plant with initial profile pH (r2=0.32), 0-10 cm post-treatment pH (r2=0.36), and aluminium (r2= 0.35).

Phalaris plant number at establishment is adversely affected by low subsoil pH. Establishment, tillering and flower head numbers of phalaris are increased with liming of an acid soil. Despite its aluminium tolerance, tillering and heading ability of cocksfoot is adversely affected by low pH. Implications for naturally acid pasture soils are that liming may well be beneficial for cocksfoot production as well as for phalaris establishment and subsequent production.

1. Ridley, A.M., Helyar, K.R. and Slattery, W.J. (1989, in prep.).

2. Cregan, P.D. (1980). Dept. Agric., NSW Agbull., No. 7.

3. Culvenor, R.A., Oram, R.N. and Fazekas de St. Groth, C. (1980). Aust. J. Agric. Res. 31:383-95.

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