In 1994 a long-term field trial with 9 lime–gypsum combinations and 2
tillage treatments (reduced tillage and direct drill) was established on a
sodic red-brown earth soil [surface pH(water) 6.5] at a property
near Peak Hill, NSW, Australia. The lime-gypsum treatments were: L0G0 (lime 0
t/ha, gypsum 0 t/ha), L0G1, L0G2.5, L0G5, L1G0, L2.5G0, L5G0, L1G1,
and L2.5G1.
After 3 years, higher rates of lime and gypsum or their combinations
significantly (P < 0.01) increased exchangeable and
soluble calcium and decreased exchangeable and soluble sodium in the
0–100 mm layer of the soil. Gypsum was found to decrease the total
soluble cation concentration (TCC) in some instances, while lime maintained
TCC at 1995 levels. Soil pH was significantly higher on all lime plots and
electrical conductivity was slightly higher on plots treated with lime than on
control plots. Organic carbon levels were significantly higher in plots with
gypsum and high levels of the lime–gypsum combination (L2.5G1). The
effectiveness of the lime treatments was influenced by the initial soil pH (as
suggested by the findings of other studies).
The lime, and to a lesser extent the gypsum treatments, improved the physical
properties of the soil as measured by the Emerson aggregate test, penetrometer
resistance, infiltration, and water availability. A tillage effect was also
present resulting in less dispersion, decreased penetrometer resistance, and
higher infiltration rates in plots prepared with reduced tillage practices
than direct drill plots. Plant-available water content (AWC) was significantly
higher in the surface soil of plots treated with L2.5G1 than control
treatments. The L5G0 and L0G5 treatments did not significantly improve the
AWC. Crop yields were increased by some of the lime–gypsum treatments in
both 1995 and 1996. Corresponding with the increased AWC, the L2.5G1 treatment
produced the highest crop yields. Plots with reduced tillage had consistently
higher yields than those with direct drill treatment.
Long-Term Effects of Calcium-Based Liming Materials on Soil Fertility Sustainability and Rye Production as Soil Quality Indicators on a Typic Palexerult