
TY  - JOUR
A1  - Naidu, R 
A1  - Mcclure, S 
A1  - Mckenzie, NJ 
A1  - Fitzpatrick, RW 
T1  - Soil solution composition and aggregate stability changes caused by long-term farming at four contrasting sites in South Australia
JF  - Soil Research
JO  - Soil Res.
Y1  - 1996
VL  - 34
IS  - 4
SP  - 511
EP  - 527
KW  - organic matter, Gapon coefficient, chemical composition, sodicity, microscopy.
UR  - https://doi.org/10.1071/SR9960511 
N2  - The effect of long-term farming on the cation exchange capacity (CEC), organic carbon content, soil solution composition, and aggregate stability was investigated using contrasting soils from 4 sites in the Mid North of South Australia. Undisturbed and farmed profiles were characterised at each site. Farming led to a 10&ndash;50% decrease, approximately, in organic matter and CEC in the surface horizon. Scanning electron microscopic study of the surface and selected subsurface soils revealed poor aggregation, compaction, reduced porosity, and a decrease in aggregate particle size in the farmed surface soils. Intra-aggregate binding in the undisturbed soils appeared to be largely due to fungal hypha, with the roots largely contributing to inter-aggregate binding of soil particles. Electrical conductivity (EC) of soil solutions was generally 2&ndash;3 times higher in the undisturbed soils than farmed soils, suggesting increased leaching of ions associated with loss of tree cover. This was also supported by a decrease in the concentrations of mobile ions such as Cl&#45;and Na&#43; in the farmed soils. The concentrations of Na&#43; and K&#43; decreased with farming leading to a decrease in the Gapon selectivity constant for Na&ndash;Ca and K&ndash;Ca exchange. The changes in soil solution composition together with the decline in organic matter concentrations resulted in increased sensitivity of soils to dispersion. 
ER  -

