bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solute Transport in Seasonal Perched Water Tables in Loess‐Derived Soilscapes
Authors: Reuter R. J. , McDaniel P. A. , Hammel J. E. , Falen A. L. 
Published: July 2010

AbstractHydraulically restrictive fragipans and argillic horizons are a common feature of loessial soils in the Palouse region of northern Idaho, resulting in perched water development during the winter and early spring. The high relief of the region may result in lateral flow of perched water and solutes. This study was initiated to quantify the rates of solute movement through perched water at three sites receiving 610, 700, and 830 mm of annual precipitation. Three transects, perpendicular to slope contours, consisting of seven, nine, and seven sampling wells, were installed at each site. Five kilograms of KBr tracer were applied in a trench upslope from the transects. Water samples were drawn biweekly to test for Br‐. Rate of Br‐ movement and saturated hydraulic conductivity (Ksat) of soil horizons were used to quantify flow of perched water. Results indicate that maximum observed Br‐ transport decreased with annual precipitation and was 86, 50, and 35 cm d‐1 at the 830, 700, and 610‐mm sites, respectively. Depth profiles for Ksat are similar among sites; values range from 63 to 129 cm d‐1 in the Ap horizons and decrease with depth to 0.10 to 0.21 cm d‐1 in the restrictive horizons. The E horizons immediately above the argillic‐fragipan horizons have Ksat values from 1.2 to 5.2 cm d‐1 suggesting that much of the rapid solute transport via perched water tables occurs in the more permeable horizons overlying the E horizons. Our results demonstrate that perched water flow through these landscapes may enhance agrichemical transport, thereby impacting both nutrient‐use efficiency and local water quality.
Soil Water Storage in Dryland Cropping Systems: The Significance of Cropping Intensification
Authors: Farahani H. J. , Peterson G. A. , Westfall D. G. , Sherrod L. A. , Ahuja L. R. 
Published: July 2010

AbstractSoil and water conservation is essential to the sustainability of Great Plains dryland agriculture. We hypothesized that cropping intensification improves the efficient use of precipitation. We evaluated long‐term observations of soil water at three locations in eastern Colorado for a range of pan evaporations (1050–1900 mm), soils, and cropping systems. Soils at various locations were mostly of the Argiustoll subgroup except for one Ustochrept and one Haplargid, both at the higher evaporation location. Normal precipitation at the three locations ranges from 400 to 425 mm yr‐1. Systems included a 2‐yr winter wheat (Triticum aestivum L.)‐fallow (WF) and more intense 3‐yr winter wheat‐corn (Zea mays L.)‐fallow and winter wheat‐sorghum [Sorghum bicolor (L.) Moench]‐fallow and 4‐yr rotations. To quantify the effectiveness of the intensified systems at utilizing precipitation, we introduce the System‐Precipitation‐Storage Index (SPSI) and System‐Precipitation‐Use Index (SPUI). Mean SPSI values were 0.19 and 0.28 for 2‐ and 3‐yr systems, respectively, meaning that the fallow periods in the 3‐yr rotation were collectively 47% more efficient at storing precipitation than fallow in WF. Inclusion of a summer crop, such as corn or sorghum, increased the fraction of precipitation allocated to growing‐season crop production (i.e., SPUI) from 0.43 in WF to 0.56 (i.e., an increase of 30%) in 3‐yr systems. The gains in efficient use of precipitation with intensification resulted from (i) reducing the frequency of the inefficient fallow preceding wheat, and (ii) using water for transpiration that would otherwise be lost during fallow through soil evaporation, runoff, and deep percolation.
Bromide Transport under Contour Hedgerow Systems in Sloping Oxisols
Authors: Agus F. , Cassel D. K. , Garrity D. P. 
Published: July 2010

AbstractContour hedgerows promote infiltration, thereby reducing runoff and soil erosion on sloping lands. The increase in infiltration could increase the leaching of mobile chemicals. The objective of this study was to determine the effect of hedgerows on Br‐ transport in two Hapludox soils with 21 to 30% slope in the Philippines. In Exp. 1, KBr at the rate of 200 kg Br‐ ha‐1 was broadcast in June 1991 at corn (Zea mays L.) planting on (i) the alleyways of plots with pruned hedgerows of Gliricidia sepium (Jacq.) Klunth ex Walp. and paspalum (Paspalum conjugatum Bergius) (hedgerow treatment) and (ii) open field plots (control). In Exp. 2, KBr was applied at the same rate as in 1991 in strips in the hedgerow and control plots that had not received the KBr application the previous year. After Br‐ application, Br‐ was analyzed in hand‐augered soil samples at increments to 105 cm and in soil solution samples taken with suction lysimeters at the 30‐, 60‐, and 90‐cm depths. Estimated pools of Br‐ (kg ha‐1) at a given depth were usually less for the suction lysimeter than for soil samples, possibly due to percolating water bypassing Br‐ in soil aggregates above the depth of lysimeter sampling. After about 500 mm of rainfall, 50% of the Br‐ had leached below the 30‐cm depth in the hedgerow plots. Slightly greater lateral, but less vertical, Br‐ movement occurred for the control. If NO3 leaches to or below the observed Br‐ leaching depths, it would become unavailable to acidsensitive food crops displaying shallow rooting depths.
Forest Peatland Drainage and Subsidence Affect Soil Water Retention and Transport Properties in an Alberta Peatland
Authors: Silins Uldis , Rothwell Richard L. 
Published: July 2010

AbstractWater table level control by drainage improves forested peatland sites for tree growth, but can also result in subsidence of the peatland surface. The purpose of this study was to investigate the effects of changes to peat bulk density associated with postdrainage subsidence on peat hydrologic properties at a peatland drained for forestry in north‐central Alberta, Canada. Peat hydrologic functions were determined by inverse techniques developed for multistep outflow experiments (MULSTP). Seven years after drainage, mean peat bulk density (0–40‐cm depth) was 63% greater and mean soil water retention (−5 to −15000 cm pressure head) was 66% greater than peat from the nearby undrained control area. Subsidence after drainage was associated with loss of pores >600‐µm diam. with concurrent increases in 3‐ to 30‐mm‐diam. pore‐size classes. Mean saturated hydraulic conductivity was 1.69 and 14.46 cm h‐1, while mean unsaturated hydraulic conductivity (−5 to −15000 cm pressure head) was 0.014 and 0.004 cm h‐1 in peat from drained and undrained areas, respectively. Changes in water transport characteristics and in the pool of “plant‐available” soil water will probably be beneficial to tree growth in the drained area.
Soil Aggregation and Organic Matter Mineralization in Forests and Grasslands: Plant Species Effects
Authors: Scott Neal A. 
Published: July 2010

AbstractPlant‐soil feedbacks can alter N cycling rates in terrestrial ecosystems, but the mechanistic relationship between species characteristics, soil properties, and N dynamics is unclear. Plant species may affect patterns of soil aggregation, which can affect soil C and net N mineralization. This mechanism was examined in two common garden experiments: one containing five tree species (European larch [Larix decidua Miller], red oak [Quercus rubra L.], red pine [Pinus resinosa Ait.], white pine [Pinus strobus L.], and Norway spruce [Picea abies (L.) Karst]) and one containing six grass species (big bluestem [Andropogon gerardi Vitm.], indiangrass [Sorghastrum nutans (L.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scrib.], switchgrass [Panicum virgatum L.], little bluestem [Schizachyrium scoparium (Michx.) Nash.], and sideoats grama [Bouteloua curtipendula (Michx.) Torr.]). The grass monocultures are burned annually. Soils were wet sieved into four size classes (>2000, 250‐2000, 53‐250, and <53 µm). Unsieved soil was incubated aerobically for 30 and 387 d to examine C and net N mineralization. For tree species, aggregate weighted mean diameter (WMD) differed between species (P = 0.01), and correlated positively with fungal biomass (r = 0.56). Large macroaggregate (>2000 µm) C concentration ranged from 15 to 26 g kg‐1, and was lowest for Norway spruce and red oak (P = 0.07). Aggregate WMD correlated weakly (and negatively) with potentially mineralizable N (r = −0.57) and in situ net N mineralization (r = −0.67), but positively (again weakly) with potentially mineralizable C (r = 0.49). Grass species had no effect on aggregate‐size distribution or organic matter concentration in spite of twofold differences in root biomass and threefold differences in N cycling rates. Species‐induced changes in soil aggregation explained little of the variation in whole‐soil C and N cycling rates, and are therefore unlikely to be an important mechanism explaining species effects on ecosystem processes.
Nitrogen Movement with Furrow Irrigation Method and Fertilizer Band Placement
Authors: Benjamin J. G. , Porter L. K. , Duke H. R. , Ahuja L. R. , Butters G. 
Published: July 2010

AbstractAlternate‐furrow irrigation has been proposed as a method to increase irrigation water use efficiency, increase capture and storage of rainfall during the irrigation season, and decrease deep percolation of water. We hypothesized that less fertilizer leaching would occur if the applied fertilizer were spatially separated from the irrigation water in a furrow irrigation system. A study was conducted on a Fort Collins loam (fine‐loamy, mixed, superactive, mesic Aridic Haplustalf) in 1994 and 1995 near Fort Collins, CO. Nitrogen uptake by corn (Zea mays L.) and N leaching were determined with alternate‐furrow and every‐furrow irrigation water applications, each with fertilizer bands of 15N‐enriched (NH4)2SO4 placed either in the row or in the furrow. In 1994 fertilizer N leached to ≈1 m for the every‐furrow irrigation with fertilizer placed in the irrigated furrow, but to 0.5 m or less for the other treatments. In 1995 the fertilizer leaching was similar among the treatments because of less irrigation and more rainfall during the growing season. There were no statistically significant differences for irrigation water placement effects on plant biomass or total N uptake, indicating that alternate‐furrow irrigation is not detrimental to crop production compared with every‐furrow irrigation for similar applications of water. This study showed that placing fertilizer in the nonirrigated furrow of an alternate‐furrow irrigation system or placing fertilizer in the row with either alternate‐ or every‐furrow irrigation has the potential to decrease fertilizer leaching without reducing crop productivity.
Modeling the Crack Network of Swelling Clay Soils
Authors: Chertkov V. Y. , Ravina I. 
Published: July 2010

AbstractThe dynamic crack network in swelling clay soils is a major factor determining their hydraulic properties and particularly preferential flow, with important consequences for ecologically adverse processes. We developed a physically based probabilistic model for the prediction of crack network geometry that takes into account the dependence of the crack concentration on soil depth. Starting with the similarity of crack networks in rocks and soils, we used the multiple cracking and fragmentation model available for rocks. In the case of cracked soils, two fundamental parameters of the model, the average spacing between cracks and the crack connectedness, become specific functions of depth. We constructed these functions for “steady‐state” cracking after long drying times using a number of reasonable physical assumptions and introducing two additional parameters: the maximum crack depth, zm, and the thickness of the intensively cracked layer, zo. With continued drying, the ratio zm/zo ≅ 10 and the limiting values of these parameters are determined. Applications of the model include estimates of crack width, cross‐sectional area, and volume in clay soils, given a knowledge of the water content profile and the shrinkage curve of the clay soil matrix. Published data of four field and lysimeter experiments from different geographical areas were analyzed for validation of the model. A satisfactory correspondence was obtained between predicted and measured crack parameters.
Spatial Dependence of Soil Enzyme Activities along a Slope
Authors: Bergstrom D. W. , Monreal C. M. , Millette J. A. , King D. J. 
Published: July 2010

AbstractThis study measured the spatial dependence of soil enzyme activities and other properties of the Ap horizon in a Gray Brown Luvisol (Hapludalf). Soil samples were collected at 74 positions along a slope following harvest of soybean [Glycine max (L.) Merr.] and fall tillage. Parameters measured were activity of dehydrogenase, urease, glutaminase, phosphatase, arylsulfatase, and β‐glucosidase; water, organic carbon (OC), mineral N, and inorganic P contents; the light fraction of soil organic matter; and depth of the Ap horizon. Rank correlation indicated significant relationships between water and dehydrogenase, urease, glutaminase, phosphatase, and arylsulfatase activities, and between water and OC content. Depth of the Ap horizon, water content, and arylsulfatase activity were strongly spatially dependent; OC and inorganic P contents and phosphatase activity were moderately spatially dependent. Other properties showed little or no spatial dependence. The ranges of spatial dependence were similar for depth of the Ap horizon, inorganic P content, and phosphatase activity (≈20 m). The range for arylsulfatase activity was 16 m, while that of OC content was 32 m. The relatively long range estimate for water content (98 m) was influenced by a trend along the slope. Maps of water and OC contents and phosphatase and arylsulfatase activities indicated similar spatial patterns along the slope. The magnitude of these soil properties was minimal in the middle or upper portion of the slope, and maximal at the footslope. Similarity in spatial patterns along the slope was interpreted as evidence for influence of water or OC content on amounts of phosphatase and arylsulfatase at that scale.
Manuring and Soil Type Influence on Spatial Variation of Soil Organic Matter Properties
Authors: Bragato G. , Primavera F. 
Published: July 2010

AbstractThe spatial variability of microbial biomass C and three humification indexes (the degree of humification, DH; the index of humification, HI; and the humification rate, HR) were investigated in order to evaluate their usefulness as indicators of the response of soil organic matter to altered soil environments. The investigation was carried out by examining the topsoil layer of an experimental field characterized by the presence of four phases of one soil series and, except for the addition of cattle manure in part of the field, by fairly uniform agricultural practices. A rectangular area of 350 by 800 m was sampled on a square grid scheme coupled with nesting. The experimental objective was to determine if the investigated properties were influenced by changes in soil type and by the addition of cattle manure. All properties measured showed spatial dependence at the sampling distances adopted. Two groups of properties were identified based on their degree of spatial variability: microbial biomass C, DH, and HI exhibited short‐range variability, whereas HR varied across longer distances. Microbial biomass C and HR showed a spatial pattern related to soil amendment and soil types, respectively. Therefore, these variables provided complementary information about the condition of soil organic matter in the study area.
A Simple Multisampler for Hydraulic Soil Probes
Authors: Zerkoune M. A. , Shapiro C. A. , Post L. 
Published: July 2010

AbstractNutrient distribution near fertilizer bands is studied by sampling soil perpendicular to band orientation. These studies require intensive hand sampling, which is time consuming and difficult. More research can be conducted if sampling techniques are improved and made cost effective. We designed and constructed a multisampler system that fits a hydraulic probe and doubled sampling efficiency. The system consists of a sampler, sampling tubes, a template, and a tray to hold soil boxes. These components can be used to construct a sampler and a template that correspond to a specific sampling scheme, and can be adapted to a wide range of configurations. The system can be constructed with tools readily available at most farm shops and the materials are easily obtainable.
Noninvasive Water Content and Electrical Conductivity Laboratory Measurements using Time Domain Reflectometry
Authors: Persson Magnus , Berndtsson Ronny 
Published: July 2010

AbstractA noninvasive approach for measurements of near‐surface water content (θ) and bulk electrical conductivity (σa) using time domain reflectometry (TDR) is presented. In this approach, an ordinary three‐rod TDR probe is used together with a polyvinyl chloride (PVC) surface block that surrounds half the measurement volume. Theoretical and experimental results show that an analytical solution of the apparent dielectric constant Ka and the σa of the soil is possible. Thus, the suggested technique does not require a separate calibration of the relationship between the measured effective Ka and Ka of the soil. The variability of the measurements was shown to be slightly higher than using the traditional approach. The spatial sensitivity of the suggested technique was also investigated. It was shown that using a three‐rod TDR probe with a rod spacing of 0.05 m allows the θ and σa to be measured in the uppermost 2 cm of the soil.
Short‐term Changes in Soil Carbon and Nitrogen Pools during Tillage Management Transition
Authors: McCarty G. W. , Lyssenko N. N. , Starr J. L. 
Published: July 2010

AbstractIt is well established that distribution of organic C and N within a soil profile is substantially influenced by long‐term conversion of soil from plow‐tillage to no‐tillage management, but little is known about the short‐term changes in the character of soil organic matter during transition between these two soil management systems. To characterize the changes in composition of organic C and N pools in soil during tillage transition, we measured total N, organic C, active N, biomass N, and biomass C at depth intervals of 0 to 2.5, 2.5 to 5, 5 to 12.5, and 12.5 to 20 cm within the profile of soil during the first 3 yr in the transition from plow tillage to no tillage. The results obtained showed that transformation of a soil profile from that typical of plow tillage management to one characteristic of no tillage occurred rapidly within a 3‐yr period of transition. In this time period, stratification of organic matter in the profile progressed significantly toward that which occurs after 20 yr of no‐tillage treatment. For example, substantial increases in total N (30%), organic C (38%), biomass N (87%), and biomass C (33%) were detected in the top layer of notillage soil along with corresponding decreases of 6%, 7%, 35%, and 15% of those respective components in the bottom layer. With transition, the biomass C, biomass N, and active N pools increased more rapidly in the upper soil profile than did the total pools of C and N. Although the characteristic profile of no‐tillage soil developed quickly during tillage transition, evidence was equivocal for any significant increase in organic matter content within the first 3 yr after conversion to no‐tillage management.
Corn Yield and Nitrogen Uptake in Monoculture and in Rotation with Soybean
Authors: Omay A. B. , Rice C. W. , Maddux L. D. , Gordon W. B. 
Published: July 2010

AbstractIncreasing crop N use efficiency and minimizing environmental risk require an accurate assessment of N taken up by the crop from different sources. We conducted this study to: (i) compare the grain yields of corn (Zea mays L.) in monoculture and in rotation with soybean [Glycine max (L.) Merr.]; (ii) determine the contributions of N from fertilizer, soil, and legume residue to corn in the rotation; and (iii) compare N fertilizer recovery in monoculture and in rotation. Two existing (>10 yr) irrigated corn‐soybean rotation areas in Kansas were used. The soils were Crete silt loam (fine, smectitic, mesic Pachic Argiustolls) and Eudora loam (coarse‐silty, mixed, superactive, mesic Fluventic Hapludolls). To trace the N through the rotation, 15N microplots (2.4 m2) were established int he corn. Microplots also were established in soybean to separately follow 15N from roots + soil and shoots to corn. Crop rotation and fertilizer addition increased corn yield at both sites for two growing seasons. Averaged for 2 yr, the amount of N needed in the continuous corn to achieve yield equal to that in rotation with no N added was equivalent to 144 kg N ha‐1 in the Crete silt loam and 155 kg N ha‐1 in the Eudora loam. Response to N was greater on the Eudora loam, probably because of textural and organic matter differences. In the Eudora soil, significantly higher amounts of soil N were taken up at harvest by corn in rotation, whereas, in the Crete soil, corn in monoculture took up significantly higher amounts of soil N. Corn plants recovered 3 kg N ha‐1 (3%) from soybean residue in the Eudora soil and 5 kg N ha‐1 (14%) in the Crete soil. The main value of legume residue appears to be long‐term maintenance of soil N to ensure adequate delivery to future crops.
Aggregation of Soil Cropped to Dryland Wheat and Grain Sorghum
Authors: Unger P. W. , Jones O. R. , McClenagan J. D. , Stewart B. A. 
Published: July 2010

AbstractSuccessful and sustainable semiarid dryland cropping depends on effective soil water storage and erosion control, which are influenced by surface soil aggregate size and stability. We hypothesized long‐term tillage and cropping system treatments affect water‐stable aggregate size distribution, aggregate water stability, and dry soil aggregation. A study on a Torrertic Paleustoll from 1982 to 1994 at Bushland, TX, involved tillage methods (no‐tillage, NT; stubble mulch tillage, SMT) and cropping systems for dryland winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] production. In 1994, mean percentages of >4‐mm water‐stable aggregates at 0 to 2 cm were 3.5 with NT and 1.0 with SMT in wheat, sorghum, fallow, rotation phase, or crop comparison plots. Mean percentages of <0.25‐mm aggregates were 49.0 with NT and 37.8 with SMT. More small aggregates with NT help explain why infiltration was 90% greater with SMT than with NT during fallow after sorghum and 26% greater with SMT during fallow after wheat in a similar study on the same soil when surface coverage by residues was limited (25% with SMT, 57% with NT for sorghum; 73% with SMT, 86% with NT for wheat). Aggregate sizes differed due to cropping system, rotation phase, and crop, but aggregate water stability and dry aggregation differences generally were nonsignificant. Both NT and SMT are deemed suitable for dryland crops under conditions as in this study because neither resulted in unfavorable soil conditions or major yield differences.