Krasnozems - a profile

摘要: Since the first soil map of Australia by Prescott in 1931, acid red soils developed from basalt have been specifically recognized spite their very limited area occurrence eastern North Queensland to Tasmania a rainfall zone about 1000 4000 mm. Until early 1950s these were known as loams, but term krasnozem became formalised 1953 with publication Stephen's Manual Australian Soils. Over past 40 years, extensively studied because favourable agronomic properties led intensive land use. The krasnozems are brown, acid, strongly structured clay (50-70% clay) ranging depth less than 1 m over 7 m. Their mineralogy is dominated kaolin and iron aluminium oxides, this ensures that variable charge low cation exchange capacity usually significant anion capacity. Free oxide contents range 18% Fe. Red basalt-derived occur number other countries, 'typical' Russian appear similar mineralogical chemical apparently lack characteristic strong polyhedral structure only one metre deep. mostly classified Oxisols Soil Taxonomy Ferralsols FAO-Unesco scheme. In new classification they classed Ferrosols more specific definition subdivision class into lower categories given, together relationship morphologically soils.