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Manure injection alters the spatial distribution of manure by concentrating it in a subsurface band which can lead to differential soil nutrient distribution and growth in small grains. This study assessed the effects of fall manure applications on soil NO3‐N, active carbon, and small grain growth compared to broadcasting and a no manure control. Soil samples were taken to represent whole plot soil means for all treatments, while in‐band (IB) and between‐band (BB) soil samples were taken in injected plots to assess nutrient spatial distribution after injection. Small grain forage samples were also taken IB and BB to assess the effects of manure injection on small grain growth. Soil samples were analyzed for NO3‐N, permanganate oxidizable carbon (POXC), and carbon mineralization (C‐min), while small grain dry matter (DM) yield and forage quality parameters were measured from plant samples. Manure injection did not result in any differences between whole plot injection and broadcast soil NO3‐N concentrations. However, injection resulted in initially elevated soil NO3‐N concentrations IB compared to BB. There were no differences in soil POXC or C‐min under manured versus unmanured soils, nor between IB and BB samples. Manure injection did not increase small grain DM yield or forage quality compared to broadcasting, nor were these measurements altered IB and BB. Even though manure injection altered the spatial distribution of soil NO3‐N, it did not affect soil C‐min, POXC, or small grain growth under the conditions seen in this study. Therefore, differential small grain growth and quality is likely not a concern under injection. Core Ideas: Manure injection increased soil NO3‐N in the injection band.There were no differences in soil permanganate oxidizable carbon and carbon mineralization between manured and unmanured treatments.Manure application, independent of method, increased small grain dry matter yield compared to no manure control.Small grain dry matter yield was not increased on the injection band compared to between injection bands. [ABSTRACT FROM AUTHOR]

Vineyard soils often contain mineralogy that can confound predictions of plant‐available potassium (K). Too little or too much K uptake into wine‐grape (Vitis varieties) tissues can negatively affect fruit chemistry, making it important to have soil tests that accurately quantify plant‐available K. Our goal was to determine the best soil sampling, processing, and extraction methods for predicting K availability in vineyard soils. We sampled soil and grapevine tissue in 39 vineyard blocks from 22 vineyards in Virginia, Maryland, and New Jersey. Plant tissue sampling included petioles at bloom and both petioles and leaf blades at veraison. Soil samples were collected from 0 to 10‐ and 0 to 38‐cm depths. We tested three soil extraction methods—Mehlich 1, Mehlich 3, and sodium tetraphenylboron (NaTPB)—on both oven‐dried and field‐moist samples. The different sampling, processing, and extracting procedures produced distinct K concentrations, with shallow 0–10 cm samples and NaTPB extraction resulting in higher K concentrations than their counterparts. Upon drying, three soils fixed K and 24 samples released K. Whole leaf (petiole plus leaf blade) samples collected at veraison had the best relationships with most soil K concentrations. The best soil testing method for predicting tissue K concentration in whole leaves at veraison was Mehlich 1 extractions of field‐moist soils from 0 to 38‐cm depth. This sampling combination appears to be best suited for growers to use when assessing K concentrations in vineyard soils. Core Ideas: Extractions from field‐moist soils had best correlation with grapevine tissue potassium (K) concentration.Soil samples collected from 0 to 38‐cm depths best predicted grapevine tissue K concentration.Soil K extracted via Mehlich 1 had better correlation with vine tissue K concentration than Mehlich 3 or sodium tetraphenylboron. [ABSTRACT FROM AUTHOR]

Preferential flow reduces water residence times and allows rapid transport of pollutants such as organic contaminants. Thus, preferential flow is considered to reduce the influence of soil matrix-solute interactions during solute transport. While this claim may be true when rainfall directly follows solute application, forcing rapid chemical and physical disequilibrium, it has been perpetuated as a general feature of solute transport—regardless of the magnitude preferential flow. A small number of studies have alternatively shown that preferential transport of strongly sorbing solutes is reduced when solutes have time to diffuse and equilibrate within the soil matrix. Here we expand this inference by allowing solute sorption equilibrium to occur and exploring how physiochemical properties affect solute transport across a vast range of preferential flow. We applied deuterium-labeled rainfall to field plots containing manure spiked with eight common antibiotics with a range of affinity for the soil after 7 days of equilibration with the soil matrix and quantified preferential flow and solute transport using 48 soil pore water samplers spread along a hillslope. Based on > 700 measurements, our data showed that solute transport to lysimeters was similar—regardless of antibiotic affinity for soil—when preferential flow represented less than 15% of the total water flow. When preferential flow exceeded 15%, however, concentrations were higher for compounds with relatively low affinity for soil. We provide evidence that (1) bypassing water flow can select for compounds that are more easily released from the soil matrix, and (2) this phenomenon becomes more evident as the magnitude of preferential flow increases. We argue that considering the natural spectrum preferential flow as an explanatory variable to gauge the influence of soil matrix-solute interactions may improve parsimonious transport models. [ABSTRACT FROM AUTHOR]

Soil water repellency can substantially alter hydrologic processes, particularly the ability of soils to infiltrate water. Water repellency often changes through time, making it difficult to simulate infiltration behaviors of water‐repellent soils using standard models. Here, we propose a simple rate‐based correction term that starts with a value of zero at the beginning of the infiltration process (t = 0) and asymptotically approaches 1 as time increases, thus simulating decreasing soil water repellency through time. The correction term can be used with any infiltration model. For this study, we selected a simple two‐term infiltration equation and then, using two data sets of infiltration measurements conducted in soils with varying water repellency, compared model error with versus without the added term. The correction substantially reduced model error, particularly in more repellent soils. At the same time, the rate constant parameter introduced in the new model may be useful to better understand dynamics of soil water repellency and to provide more consistent interpretations of hydraulic properties in water‐repellent soils. Key Points: We propose a simple correction term for infiltration models to characterize water repellency in infiltration modelsOne hundred and sixty five infiltration experiments from three different ecosystems and levels of water repellencies were used to demonstrate model effectivenessThe one parameter correction substantially reduced model error and reflected the changing rate of water repellency during infiltration [ABSTRACT FROM AUTHOR]

Soil water repellency induced by wildfires can alter hydraulic properties and hydrologic processes; however, the persistence and vertical position (i.e., depth) of water‐repellent layers can vary between systems and fires, with limited understanding of how those variations affect infiltration processes. This study occurred in two forested locations in the south‐central Appalachian Mountains that experienced wildfires in late 2016: Mount Pleasant Wildfire Refuge, Virginia, and Chimney Rock State Park, North Carolina. In each location, sites were selected to represent unburned conditions and low to moderate burn intensities. At each site, we measured the soil water repellency at the surface (ash layer or O horizon) and ~2 cm below the surface (A horizon) using the water drop penetration time method (n = 10–14). Soil water content was also measured over the upper 10 cm of the soil (n = 10), and infiltration tests were conducted using a tension infiltrometer (n = 6–8). The results showed that soil repellency was highest in the surface layer at the Mount Pleasant location and was highest in the subsurface layer at the Chimney Rock location. Soil water content was lower in unburned soil than in burned soil, especially for measurements taken immediately postfire, with soil water content negatively correlated with water repellency. Water repellency in the surface layer significantly reduced relative infiltration rates (estimated as differences between initial and steady‐state rates), whereas subsurface water repellency did not affect relative infiltration. As a result, water repellency persisted longer in sites with surface as opposed to subsurface water repellency. Finally, differences between burned and unburned sites showed that although the wildfires increased the occurrence of water repellency, they did not alter the underlying relationship between relative infiltration and water repellency of the surface soil. [ABSTRACT FROM AUTHOR]

Shrink‐swell soils possess dynamic hydraulic properties, which may limit the applicability of traditional models for simulating infiltration and overland flow. This study incorporates Green‐Ampt infiltration concepts into a multidomain porosity framework to account for variations in pore size distributions and saturated hydraulic conductivities caused by soil shrinkage and swelling. The model requires three input variables (initial water content, rainfall rate, and time) and up to 15 parameters to simulate infiltration and overland flow, though most of the parameters are universal constants or can be estimated from auxiliary measurements. In comparison, the classic Green‐Ampt model, which assumes constant hydraulic properties and a single domain, requires the same three inputs and up to seven parameters to use. Performance of the proposed multidomain model was verified with two data sets. The first came from a study in Mexico where time to ponding and soil matrix infiltration were quantified under simulated rainfall, and the second came from a study in Chile where overland flow was measured during irrigation experiments on runoff plots. By tuning two (Chile) or three (Mexico) parameters, the multidomain model provided accurate estimations of infiltration/runoff partitioning at multiple scales. Compared to the classic single‐domain model, the multidomain model had lower root‐mean‐square deviations (reducing simulated infiltration errors by 2–3 times) and Akaike Information Criterion (AIC) scores (ΔAIC ~100), thus providing better simulations of infiltration, ponding, and runoff. These results demonstrate that modeling hydrological processes in shrink‐swell soils necessitates separating soil properties mediated by the matrix from those associated with interblock shrinkage cracks. Plain Language Summary: Many soils develop cracks as they dry. During rainstorms and irrigation events, these cracks permit water to move rapidly, but we do not currently possess appropriate tools to simulate water movement in such conditions. This study proposes a mathematical model that calculates water infiltration into such soils by explicitly accounting for properties of cracks versus those of the surrounding soil. The model was verified using field observations from two locations, which demonstrated that the model can accurately simulate water infiltration, ponding on the soil surface, and surface runoff in soils containing cracks. Key Points: This model incorporates Green‐Ampt infiltration concepts into a dynamic multidomain porosity frameworkModel was verified on two soils, improving estimates of infiltration and ponding compared to the classic Green‐Ampt modelMost model parameters can be constrained using universal constants or auxiliary measurements [ABSTRACT FROM AUTHOR]

Current laboratory methods for determining volume and bulk density of soil clods include dipping saran-coated clods in water (a destructive process due to the permanent coating), performing physical measurements on samples with well-defined geometries, or using expensive equipment and proprietary software (such as laser scanners). We propose an alternative method for determining the volume and bulk density of a soil clod, which is nondestructive, low cost, and utilizes free and open-source software. This method (the clodometer method) uses a standard digital camera to image a rotating clod, which allows reconstruction of its three-dimensional surface and subsequent calculation of its volume. We validated the method through comparison with the standard displacement method and then used the method to create a soil shrinkage curve for a silty clay loam soil. The method had acceptable precision (relative standard errors of the mean of 0.4-1.6%), which may be further improved through future software development. [ABSTRACT FROM AUTHOR]

• BEST-WR allows to determine the soil hydraulic characteristic curves. • BEST-WR works on both hydrophilic and water-repellent soils. • We validated BEST-WR using both analytical and field data. • We assessed soil water repellency in a Mediterranean wooded grassland. Water-repellent soils usually experience water flow impedance during the early stage of a wetting process followed by progressive increase of infiltration rate. Current infiltration models are not formulated to describe this peculiar process. Similarly, simplified methods of soil hydraulic characterization (e.g., BEST) are not equipped to handle water-repellent soils. Here, we present an adaptation of the BEST method, named BEST-WR, for the hydraulic characterization of soils at any stage of water-repellency. We modified the Haverkamp explicit transient infiltration model, included in BEST for modeling infiltration data, by embedding a scaling factor describing the rate of attenuation of infiltration rate due to water repellency. The new model was validated using analytically generated data, involving soils with different texture and a dataset that included data from 60 single-ring infiltration tests. The scaling factor was used as a new index to assess soil water repellency in a Mediterranean wooded grassland, where the scattered evergreen oak trees induced more noticeable water repellency under the canopies as compared to the open spaces. The new index produced results in line with those obtained using the water drop penetration time test, which is one of the most widely test applied for quantifying soil water repellency persistence. Finally, we used BEST-WR to determine the hydraulic characteristic curves under both hydrophilic and hydrophobic conditions. [ABSTRACT FROM AUTHOR]

• We present an open-source instrumentation package for infiltration experiments. • We tested the devices under challenging field conditions. • We developed an algorithm for filtering the raw data recorded by transducers. We present a new open-source and modular instrumentation package composed of up to ten automatic infiltrometers connected to data acquisition systems for automatic recording of multiple infiltration experiments. The infiltrometers are equipped with differential transducers to monitor water level changes in a Mariotte reservoir, and, in turn, to quantify water infiltration rates. The data acquisition systems consist of low-cost components and operate on the open-source microcontroller platform Arduino. The devices were tested both in the laboratory and on different urban and agricultural soils in France and India. More specifically, we tested three procedures to treat the transducers readings, including a filtering algorithm that substantially improved the ability to determine cumulative infiltration from raw data. We combined these three procedures with four methods for estimating the soil parameters from infiltrometer data, showing pros and cons of each scenario. We also demonstrated advantages in using the automatic infiltrometers when infiltration measurements were hindered by: i) linearity in cumulative infiltration curves owing to gravity-driven flow, ii) an imprecise description of the transient state of infiltration, and iii) the occurrence of soil water repellency. The use of the automatic infiltrometers allows the user to obtain more accurate estimates of soil hydraulic parameters, while also reducing the amount of effort needed to run multiple experiments. [ABSTRACT FROM AUTHOR]