Beschreibung:
<jats:title>Summary</jats:title><jats:p>The organo‐mineral fractions of seven New Zealand topsoils, which are members of a climosequence, were isolated by ultrasonic dispersion in water and separated into sand‐, silt‐ and clay‐size fractions. Several soils contained stable aggregates of mainly silt‐size, comprising cemented clay‐size particles. The tendency of one soil (McKerrow) to form larger aggregates of sand‐size was explained by its distinctive mineralogy.</jats:p><jats:p>Total organic carbon and total nitrogen were used to indicate the amounts of organic matter in the organo‐mineral fractions. The degree of humification of the organic matter was assessed by a pyrolysis‐gas chromatography technique, which proved superior to the more conventional C/N method.</jats:p><jats:p>In the sand‐size fractions the climate, and especially annual precipitation, strongly influenced the amounts of organic matter, whereas in the clay‐ and silt‐size fractions it was the composition of the organic matter that was influenced.</jats:p>