Near-saturated hydraulic conductivity of a sandy-loam soil a few months after incorporating compost or zeolite

Little is known about compost (C) and zeolite (Z) effects on hydrodynamic properties of near-saturated coarse-textured soils. These effects were tested for a sandy-loam soil by a mini-disk infiltrometer at three pressure heads (h₀ = -6, -3 and -1 cm) and a wide range of amendment percentages, pa (0-40%). Soil hydraulic conductivity, K_-6, K_-3 and K_-1, depending on h₀, was determined 3.5 and 8.0 months after the treatment with C and 5.0 and 10.5 months after that with Z. With the C, more amendment determined smaller K_-6 (by 1.7-3.0 times), stable K_-3 and larger K_-1 (3.4-4.4 times) values on both sampling dates. With the Z, the most frequent result was that the soil hydrodynamic parameters did not change with pa. Time effects were more appreciable with the C (means for the two sampling dates differing by 2.1-3.8 times, depending on h₀) than the Z (means differing by 1.1-1.7 times). The soil treated with Z was more permeable than that treated with C in the first sampling date (percentage differences, Δ, between corresponding means = 38% - 103%, depending on h₀) but not in the second date (Δ values varying from -61% to 4%). In the first year after the treatment, near-saturated soil hydrodynamic behaviour can change appreciably following C addition but the same effect is not expected for the Z. Future investigations should include independent determination of soil pore and particle size distributions.