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Pasture and cereal responses to applied lime in central NSW

C.L. Mullen

NSW Agriculture, PO Box 865, Dubbo NSW 2830

Soil acidity is a significant problem on many of the light textured soils derived from granite, sandstone and ironstone in the central-west of NSW. Several hundred thousand hectares of farming and pasture country are affected. Many of these soils have a history of poor barley and wheat production and low legume pasture growth. Many of these soils are naturally acid but acidity has been aggravated by farming and pasture development. A program of on-farm investigations commenced in 1981 to define the extent of the problem and to develop strategies to overcome them. These investigations were centred on the Dubbo, Narromine, Gilgandra and Tomingley districts.


The responsiveness of pastures and cereal crops to applied lime was evaluated in 12 trials over 10 years. Fine lime was applied and incorporated to 10 cm depth at rates of nil, 1.25 and 2.5 tonnes/ha. Trial design was a randomised split plot design with 3 replications. Plot sizes were mainly 10 x 20 m. Pasture measurements were usually taken using random quadrats (0.6 x 0.6 m) in early spring. Trial sites were managed on a rotational basis with 1 to 2 years cropping followed by a 3- to 4-year phase under legume-based pasture. Sites were either cropped to wheat, oats, barley and triticale or sown to the most suitable subterranean clover, medic, serradella or lucerne pasture.

Results and discussion

Soils: The soil pH (CaC1) range varied between 4.1 and 4.9 with exchangeable aluminium levels ranging between 1-2% and 30%. Exchangeable calcium was low on most sites (40-50%) and CEC values were generally <3 meq/100 gm.

Pasture: Subterranean clover gave a significant response to lime on all sites with percentage dry matter response varying from 33 to 430%. Responses tended to be greatest in the first and second year, and diminished with time (molybdenum was not a contributor).

Serradella responded to lime although percentage dry matter response was of less magnitude than subterranean clover which had percentage dry matter responses of 7-71%. Serradella showed the same trend as subterranean clover with responses diminishing with time.

Lucerne establishment and growth declined very rapidly when pH (CaC12) dropped below 5.0 and exchangeable aluminium was greater than 1-2%. Very large dry matter responses to lime were recorded in two trials (1194 and 1218% dry matter yield response).

Cereals: The response to lime varied markedly between the cereals with barley and wheat responding much more than the acid tolerant oats and triticale. The average grain yield response of barley, wheat, oats and triticale to 2.5 t lime/ha was 0.55, 0.51, 0.32 and 0.34 t/ha respectively. This represented a yield response of 128%, 76.7%, 32% and 23.7% for barley, wheat, oats and triticale respectively.


This project is partly funded by the Grains Research and Development Corporation and NSCP.

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