Hydraulic properties and ‘field capacity’ of Himatangi sand

Abstract

Abstract Bulk density, particle size, soil water retentivity, and saturated and unsaturated hydraulic conductivity data from Himatangi sand are reported. The soil under a 4 m2 area was wet by ponding and the subsequent decline in soil water contentmonitored using a neutron probe. The drainage rate from the top 550 mm of the soil profile was greater than 1 mm/day for 6 daysafter ponding ceased, indicating that the commonly accepted concept of field capacity is inappropriate for this soil. Simple theory is developed which allows prediction of drainage losses under different soil water and evapotranspiration conditions. If the upper limit of readily available water is taken as the storage when the drainage rate from a 550 mm deep root zone is 1 mm/day, and the lower limit is taken as the storage at a matric potential of-50 kPa, then the readily available water holding capacity is only 8 mm. This suggests that carefully controlled high frequency irrigation is necessary if both drainage losses and plant water ...