Soil porosity in a peach orchard as influenced by water table depth

The objective of the study was to investigate modifications induced in soil porosity, pore shape, and pore size distribution in a peach orchard field experiment caused by different levels of shallow water table. Pores larger than 30 ?m were measured on soil thin sections using the electro-optical image-analysis (Quantimet 720) technique; the porosity inside the small aggregates was measured by the mercury intrusion method. Total porosity was significantly higher when the level of the water table was lower and showed a cycling pattern being higher at the end of the dry summer season and lower at the end of the wet winter. Elongated pores constituted the highest proportion of porosity and showed the largest differences between water table levels. Changes in pore shape and size distribution were also observed. The proportion of large elongated pores (50-500 ?m) was higher where the level of the water table was deeper. Consequently, the shallow water table seemed to deteriorate the soil structure reducing the porosity to a level inadequate for plant development. © 1989.