When the one‐dimensional moisture flow equation is simplified by applying the unit gradient approximation, a first‐order partial differential equation results. The first‐order equation is hyperbolic and easily solved by the method of P. D. Lax. Three published K(θ) relationships were used to generate three analytical solutions for the drainage phase following infiltration. All three solutions produced straight lines or nearly straight lines when log of total water above a depth was plotted versus log of time. Several suggestions for obtaining the required parameters are presented and two example problems are included to demonstrate the accuracy and applicability of the method.

A new approach to soil testing, designed to improve accuracy and usefulness, is being developed. A spherical, mixed‐bed ion‐exchange resin capsule is embedded in saturated‐paste soil samples and allowed to accumulate all nutrients the soil can deliver, as a function of diffusive ion movement. This simulates the action of nutrient movement to plant roots. The approach is called the Phytoavailability Soil Test (PST). Objectives were to determine if nutrient accumulation by the resin capsule was described by diffusion models, and to investigate rate‐limiting diffusion processes. Nutrient‐uptake curves were obtained on Ap horizon samples from 20 Montana agricultural soils by measuring time dependence of K, P, and S accumulation in resin capsules during 15 d. Also, a planar system was used in which both sides of a cylinder of resins accumulated P, K, and S from saturated pastes during 96 h. Fluxes to the resin were compared with nutrient gradients, measured by two other extraction methods, on soil slices from successive distances beyond the resin‐soil interface. The mass of nutrients adsorbed by the resin as a function of time was consistent with a diffusion process, as was the concentration of nutrients in the soil vs. distance from the resin‐soil interface. The process appeared to be that termed film diffusion. Results demonstrated independence of specific nutrient diffusion and resin adsorption. The PST may provide an improved approach to soil testing because it is sensitive to nutrient diffusion, a governing factor in plant availability of most nutrients.

Captive breeding of the short-beaked echidna (Tachyglossus aculeatus) has proven a difficult challenge; as recently as 2009, there were fewer than 10 echidnas born in captivity. We present observations of captive reproductive behaviour following video surveillance and measurements of body temperature collected from six captive female echidnas over a six-year period. In the first series of observations (2009-10) we examined the efficacy of artificial burrow boxes as possible aids for reproductive success. Females with access to burrow boxes had significantly higher levels of reproductive activity (P = 0.001), there was coincidental improvement in the production of eggs or pouch young (two eggs, one unhatched and one offspring). During 2009-10, a range of reproductive behaviours (courtship, copulation and postcopulation) were documented and analysed, as were new observations of oestrous cycle activity. Female body temperature was characteristically stable during egg incubation during this study and has the potential to be used as a tool for the assessment of reproductive status. Following initial observations, burrow boxes and infrared lamps were implemented as standard husbandry in our echidna breeding facility and the effects on reproductive success were monitored, albeit less intensively, for a further four years . Although no direct causal effect could be ascribed, the use of burrow boxes and heat lamps coincided with a total of 13 young being born to four females in the last four years . These female echidnas were found to be receptive at intervals throughout the breeding season, both before and after presumed incubation phases, suggesting that captive animals exhibit polyoestry. In 2012 and 2014, the same female showed evidence of producing two young from one breeding event.

Despite a long history of captive short-beaked echidnas in zoos worldwide, there have been very few successful attempts to breed them. Perth Zoo has been successful in breeding echidnas on five occasions, with young produced over 3 consecutive years. In this paper we document the results of intensive monitoring undertaken before and during these successful breeding seasons. Video camera surveillance was used to monitor activity and reproductive behaviour of adults during the courtship and mating period and to identify the timing and duration of incubation. Temperature data loggers were used to record and compare proximal body temperature with observed behaviours. Echidnas were found to breed in June and July, with courtship lasting a mean 5.75 ± 1.7 days (range 4–9 days, n = 8). Mean duration of gestation was 21.8 ± 2.4 days (range 19–27 days, n = 7). Females incubated their single egg for a mean 11 ± 0.75 days (range 11–13 days, n = 5) in an artificial burrow with increased temperature stability.

Chlorsulfuron [2‐chloro‐N‐[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]‐benzenesulfonamide] is an anionic sulfonylurea herbicide with high soil persistence; consequently, there is interest in predicting its mobility hi agricultural soils. The objectives of this study were to determine the transport characteristics of chlorsulfuron in disturbed and undisturbed soil columns and evaluate the capabilities of LEACHM (Leaching Estimation and Chemistry Model) for predicting chlorsulfuron transport. Soil column experiments were conducted with two Montana soils (Amsterdam silt loam, file‐silty, mixed Typic Haploboroll, and Haverson silty clay loam, fine‐loamy, mixed (calcareous), mesic Ustic Torrifluvent) under unsaturated flow conditions. Unit gradient was established in all columns by balancing surface water input to outflow at the bottom of each column through a stainless steel porous plate connected to a vacuum chamber containing a fraction collector. A nonlinear least squares approach (CXTFIT) was used to fit breakthrough curves (BTCs) for Br− and 14C‐labeled chlorsulfuron using the linear equilibrium adsorption model (i.e., local equilibrium assumption or LEA model) and the bicontinuum model (i.e., nonequilibrium assumption). Observed Br− BTCs were best described by the bicontinuum model indicating physical nonequilibrium due to immobile water regions. Observed chlorsulfuron BTCs demonstrated both chemical and physical nonequilibrium during transport. The best fit to observed chlorsulfuron BTCs was obtained with the bicontinuum model using the dispersion coefficient optimized (i.e., fixed) from the Br− BTCs. LEACHM was used to generate predicted BTCs for chlorsulfuron utilizing independently measured or estimated soil physical parameters as input data. Predicted BTCs utilizing the Br−‐derived dispersion coefficient (D) and the bicontinuum model‐derived partition coefficient (Koc) did not adequately reflect observed BTCs primarily because the current version of LEACHM has no capability for accepting input parameters relating to nonequilibrium conditions. The D and Koc values for chlorsulfuron BTCs derived from the LEA model improved predictions; however, it is important to note that LEA‐derived D and Koc values for chlorsulfuron BTCs essentially compensate for nonequilibrium behavior. Finally, the experimentally determined chlorsulfuron BTCs confirmed the high mobility of this chemical at neutral soil pH values.