Effect of varying organic matter contents of compacted soils on soil-water properties and modulus of rupture

Due to its high organic matter content, peatmoss can be highly beneficial to agricultural soils. In this research, the impact of varying organic matter contents at different compaction levels on water retention, saturated hydraulic conductivity, and modulus of rupture of three soils; sandy clay loam, clay loam, and clay, has been investigated under laboratory conditions. Compaction changed the ability of the soils to hold moisture, increased modulus of rupture, and decreased the plant available water capacity. On the other hand, organic matter generally increased the ability of the soils to hold moisture, expanded the available water capacity, and decreased the modulus of rupture of compacted soils. Modulus of rupture for sandy clay loam varied from 2.09 to 1.29 kg cm⁻² with varying volumetric water content at 5% organic matter content, from 1.95 to 1.23 kg cm⁻² at 10% organic matter content, and from 1.50 to 1.11 kg cm⁻² at 15% organic matter content. Modulus of rupture for clay loam varied from 2.40 to 1.47 kg cm⁻² with varying volumetric water content at 5% organic matter content, from 2.31 to 1.35 kg cm⁻² at 10% organic matter content, and from 2.04 to 1.24 kg cm⁻² at 15% organic matter content. For clay, modulus of rupture varied from 2.98 to 2.16 kg cm⁻² with varying volumetric water content at 5% organic matter content, from 2.91 to 1.77 kg cm⁻² at 10% organic matter content, and from 2.76 to 1.65 kg cm⁻² at 15% organic matter content.