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Lime response of various native grasses

M.L. Mitchell, S.M. Ring and R.P. Fisher

Department of Agriculture Victoria, Rutherglen Research Institute, Rutherglen VIC 3685
NSW Agriculture, Agricultural Research Institute, Private Mail Bag, Wagga Wagga NSW 2650

Pastoral soils in the above 500 mm rainfall zones of northern Victoria and southern NSW are prone to be acid, especially if they have a low pH buffering capacity and more strongly aged soils types, for example, podsolics and deep sandy soils are likely to be acid in sub-surface horizons (1,2). Productivity of these pastures is reduced due to the low soil pH. As pH declines aluminium and manganese become more soluble and inhibit plant production. At present the species options available to farmers are very limited. Some native grass species such as weeping grass appear to be quite acid tolerant in the Goulburn district (3). A glasshouse pot trial was conducted to determine the lime response of various native grasses, to examine their potential production oil acid soils.

Methods

The native grasses to be evaluated in the trial were weeping grass, Microlaena stipoides (Labi LI.) R Br., kangaroo grass, Thetnedatriandra Forssk., wallaby grass, Danthonia racemosa R.Br., and common wheat gass,Elytnus scaber (R.Br.) A.Love. Control species of barley cv. Schooner and wheat cv. Matong were used, the lime response of these species was already known. Soil types used were: one high in aluminium and low in manganese (Binnaway), another high in manganese and low in aluminium (Dunn) and a third high in both aluminium and manganese (Robertson). On each soil type there were seven different pH levels and several different manganese anid aluminium levels. Pots were watered to weight on a regular basis. When shoot growth had reached about two grams (six to eight weeks), roots and shoots were harvested. Roots were washed and dry weights determined. Root length and shoot dry weights were al3o determined. A randomised block design was used with two replicates.

Results and discussion

Root data showed the same response trends to aluminium and manganese as the shoot data. Weeping grass and kangaroo grass are very highly acid tolerant. Weeping grass has balanced tolerance to aluminium and manganese whereas kangaroo grass is more aluminium tolerant. Wallaby grass was highly tolerant, and common wheat grass was highly sensitive compared to the control species of wheat and barley (which are tolerant and sensitive respectively).

These data suggest that if the native grass species of weeping grass and kangaroo grass were either selected or bred to also be tolerant of increased nitrogen rates and were competitive under grazing, these species may contribute to production on acid soils. Species such as common wheat grass would only be sown in areas of alkaline soils.

References

Coventry, D.R. 1985. Proc. 3rd Aust. Agron. Conf., Hobart. pp. 126-43.

Helyar, K.R., Cregan, P.D. and Godyn, D.L. 1990. Aust. J. Soil Res. 28, 523-37.

Munnich, D., Simpson, P. and Nicol, H. 1991. Native Grass Workshop Proc., AWC. p. 167.

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