An evaluation of the physical properties of some Gisborne Plains soils for irrigation purposes

Undisturbed samples were taken, at depths from 7 to 80 cm from six soils representative of major series on the alluvium of the Gisborne Plains. Determinations were made of hydraulic conductivity at the water contents prevailing soon after drainage, of the tension/water content relationship, and of air content at a tension of 50 cm of water (‘large pores’). Hydraulic conductivities were high to medium for soils classed as recent, and low for the gleyed recent and older gley soils; large pore contents were reasonably high for all soils, and capacities for storing plant-available water were average for five of the soils but above average for the soil on the most recent flood deposits. Replicated samples were taken at certain depths. Statistical analysis on the test results from these showed that the standard errors of the properties measured were rather low and that hydraulic conductivity was isotropic. Soil horizons containing Taupo Pumice had anomalous properties, including low density, high hydra...