Water yield values are given for 35‐cm columns of two soil types, Ramona and Yolo loam. Three to four surface cm of water were withdrawn from the columns in periods of about a week, using 900 cm of water tension. Simultaneous tension values are given for four locations along the column during wetting and drying periods. Some effects of preparing the disturbed soil samples and of length of soil column are indicated. A method is suggested for calculating capillary conductivity by the use of data obtained during transient changes of moisture content and tension in a soil column. Values for Ramona loam are calculated for a tension range of 76 to 627 cm of water. Although the method is not precise, conductivity values are obtained with less complicated equipment and in a shorter time than is possible by the use of previously described methods. Capillary conductivity values seem to vary with tension independent of tension gradients.

The objective of this study was to determine whether moisture transmission properties of stony soils could be evaluated using samples of the same soil in which the stony fraction (> 2 mm) had been excluded. Experiments were conducted in the laboratory on soil columns with and without stones. Unsaturated hydraulic conductivity (K) was measured with a transient outflow method over the matric potential range of −0.05 to −50 bars using tensiometers and soil psychrometers. The soils studied were Rock Valley gravelly loamy sand (Mojave Desert, Nevada) and Tubac and Rillito gravelly sandy loams (Sonoran Desert, Arizona). On a weight basis, these soils contain up to 40% stones > 2 mm in diameter.If expressed as a function of matric potential, hydraulic conductivity values were similar, with or without stones. Soil water potential as measured by tensiometers or by thermocouple psychrometers is not affected by stones because these instruments respond to moisture changes in the soil portion only. When K was expressed as a function of volumetric water content, the apparent conductivities were higher for a given water content when stones were present. A simple correction of water contents of stone‐free samples, based on the stone volume of each soil, adequately accounted for differenecs observed when water contents were computed on a total volume basis.

Equations were developed to describe the mass transfer of organic chemicals through soil and evaluated for various soil conditions. Movement due to diffusion was assumed to be negligible. The model assumed the relationship ∂S/∂t = α(Kc − S) where S is the adsorbed concentration [mass per total volume], c is solution concentration [mass per total volume], t is time, and K and α are constants. The model also considered the effect of applying various amounts of chemical to the soil surface and allowed for a prior adsorbed concentration in the soil ahead of the wetting front. The following are conclusions drawn for the case when the soil is initially free of organic chemical.K influences the depth of maximum concentration of organic in solution but does not affect the value of that concentration. The organic chemical will move in solution as a wave through the soil. The lower K the more spread out the wave will be. The depth of movement of maximum concentration is equal to the depth of water penetration divided by K.The concentration of material adsorbed on the soil also moves down as a wave. The position of maximum adsorbed concentration is about the same as for the maximum concentration in solution. Increasing K causes an increase in concentration of adsorbed material.Application of greater amounts of organic chemicals to the soil surface has the effect of increasing the concentration of organic both in solution and adsorbed but does not influence the depth of movement greatly except at initial time periods.Increasing the value of α has the effect of making the wave of chemical moving through the soil narrower and increasing the concentration of the organic in solution as it moves through the profile as compared to a lower value of α.

The time required to leach a slug of saline, sodic geothermal brine from the point of injection to the tile outlet of an artificially drained field is calculated. Sprinkler, complete, and partial ponding leaching methods are compared as a function of drain spacing and initial location of the spill. Calculated results are presented as dimensionless parameters which scale the drainage system dimensions and the soil water transport properties. Ponded leaching required more water, but less time to leach brine out of the system for all situations except where the brine spill occurs near the midpoint between tile lines.A simple calculation is proposed to estimate the leaching fluid volume required to remove excess Na+ from the exchange complex. Good agreement was attained between simulated and experimental results involving a laboratory soil column. For fine‐textured soils in the Imperial Valley of California it may require up to 30 pore volumes of leaching fluid to replace Na+ with Ca2+ if saturated gypsum solution is used in reclamation. Application time per pore volume was calculated to be in excess of 1 year for all cases except ponded leaching directly over a tile line.

The utility of several laboratory procedures for approximating field values of unsaturated hydraulic conductivity over the suction range 30 to 100 cm of water was studied. Conductivity was measured at the 68‐cm depth using neutron probe and tensiometer data taken during drainage of a bare plot of Ramona sandy loam. Conductivity was measured in the laboratory on 10‐ by 30‐cm intact cores by the transient flow (TF) method of Richards and Weeks and was calculated by both the Marshall (M) equation and Millington and Quirk (M&Q) equation using moisture characteristic curves from laboratory measurements on intact cores and from the field data.The TF values were all higher than field values but, when used with a matching factor, they satisfactorily approximated field conductivities. This study, the first test of this TF method against field data indicated that the method of calculating the flow velocity influenced the results and that the best results were obtained from a computer program which used a numerical differentiation subroutine.When used with matching factors, conductivities calculated (for 33 pore classes) by the M equation and M&Q equation were good approximations of field conductivity, though less satisfactory than results from the TF computer calculations. The best M&Q values were calculated from a field moisture characteristic while the M values were satisfactory when calculated either from the field moisture characteristic or from one measured in the laboratory on intact 6 by 10‐cm cores.It is recommended that the conductivity value to be used in calculating the matching factor for any of these methods be measured in the field within the suction range being studied.