EFFECT OF SOIL ACIDITY ON BARLEY PRODUCTION IN THE SOUTH-WEST OF WESTERN-AUSTRALIA .2. CEREAL GENOTYPES AND THEIR RESPONSE TO LIME

The effect of aluminium (Al) toxicity of either surface or subsurface soil on the growth of barley, and the potential for variation in response to soil acidity among agronomically adapted Australian barley genotypes, were examined at 13 sites. The effect of Al toxicity was investigated by plant analysis, using 3-5 lime application rates and Al-tolerant species (wheat, triticale), as well as barley. All cereals were supplied with complete nutrients. To measure the potential for response variation, grain yields of 14 genotypes of barley, relative to cv. Stirling, were related to soil pH at 7 sites. Grain yield of barley was increased 9-30% at 6 sites, by lime application alleviating Al toxicity. The yield of triticale and wheat cv. Aroona was not increased by lime application at any site. There was some indication that subsurface acidity may be reducing the grain yield of barley at sites with CaCl2-extractable Al concentrations of greater-than-or-equal-to 3-4 mg/g in the A2 horizon. Some barley genotypes appeared to be more tolerant than Stirling to soil acidity. Aluminium toxicity appears to be reducing barley grain yields by more than 10% at surface soil pH < 4.5 (0.01 mol CaCl2/L), or when CaCl2-extractable Al is greater-than-or-equal-to 3-4 mg/g. CaCl2-extractable Al in the surface soil was not a better indicator of Al toxicity than soil pH.