Differences in surface soil aggregation under six different crops

Abstract

The effects of lupin, field pea, barley, canola, linseed and lentil crops on the surface (0-0.10 m) aggregation of a red earth at Wagga Wagga, New South Wales, were investigated in the field under identical cultivation and agronomic practices. Soil friability after cropping was in the order lupin > lentil > canola > field pea = linseed > barley. Both lupin and canola cropping produced significantly stronger aggregates (measured as tensile strength of the aggregates) than barley, lentil and field pea. There was no significant difference (P>0.05) in water-stable macro-aggregation after growing the different crops. However, there was a significant (P<0.05) correlation between the tensile strength of the aggregates and amount of dispersed clay released from moist soil (-10 kPa), possibly indicating different abilities of crops to modify soil bondings affecting aggregate strength.