Abstract

Organic manures affect soil properties, however, little is known about raw mature crop residue effects on water movement and storage in soils of low density like Andosols. It was hypothesized that water movement and storage in an andosol would be affected if the soil was mixed with raw mature crop residue. Therefore, the objective was to determine the water status in an andosol mixed with raw mature chickpea (Cicer arietinum) residue. Two treatments; amended and unamended soils were investigated. Saturated hydraulic conductivity was determined following the constant head method. Plant available water was estimated after determining water retention using the pressure plate apparatus at 3 and 1500 kPa water tension. The saturated hydraulic conductivity was approximately two-fold higher in the amended compared to the unamended soil. Water retention and plant available water were not affected by the raw mature chickpea residue. Since the bulk density was ~0.9 Mg/m³ in both treatments, porosity was similar. Therefore, increased aggregate stability was the most likely reason for the increased water movement in the amended soil. Addition of crop residues into such as a soil could be desirable in situations where it is necessary to enhance water flow in the soil profile without affecting water storage and plant available water, for example to improve the bearing capacity of wet mollic Andosols during tillage.

Key words: Aggregate stability, soil texture, soil organic matter, water retention, bulk density.