Mesic Typic Hapludult Research Articles

Hexavalent Chromium Reduction by Tartaric Acid and Isopropyl Alcohol in Mid-Atlantic Soils and the Role of Mn(III,IV)(hydr)oxides

Chromium is a naturally occurring transition metal and a soil contaminant in the Cr(VI) oxidation state, but reduction of Cr(VI) to Cr(III) mitigates its toxicity. Tartaric acid reduces Cr(VI) via a termolecular complex with isopropyl alcohol and Cr(VI), but its efficacy in soils has not been demonstrated. Five Mid-Atlantic soils from Maryland, U.S. were examined for their potential to enhance the reduction of Cr(VI). A control treatment (no soil +12 mM tartaric acid + 0.29 M isopropyl alcohol) reduced 0.37 mM Cr(VI) (19%) in 99 h. Reduction was enhanced to 1.97 mM (99%) with addition of a Russett Ap soil horizon (fine-loamy, mixed, semiactive, mesic Typic Hapludult). With a half-life of 18.7 h, the rate of reduction of Cr(VI) with the Russett soil sample was 20 times faster than with no soil (371 h). Soil Mn was solubilized in this reaction and plays a role in the enhanced reduction of Cr(VI). Mn(III/IV)(hydr)oxide-coated quartz sand reduced 1.24 mM (62%) Cr(VI), with all of the Mn(III,IV)(hydr)oxides solubilized. The addition of isopropyl alcohol and tartaric acid to soils enhances the reduction of Cr(VI), and this reduction is further enhanced by the catalytic behavior of Mn(II) from easily reducible Mn(III,IV)(hydr)oxides in soil.

Chicken Manure Biochar as Liming and Nutrient Source for Acid Appalachian Soil

Acid weathered soils often require lime and fertilizer application to overcome nutrient deficiencies and metal toxicity to increase soil productivity. Slow-pyrolysis chicken manure biochars, produced at 350 and 700°C with and without subsequent steam activation, were evaluated in an incubation study as soil amendments for a representative acid and highly weathered soil from Appalachia. Biochars were mixed at 5, 10, 20, and 40 g kg into a Gilpin soil (fine-loamy, mixed, active, mesic Typic Hapludult) and incubated in a climate-controlled chamber for 8 wk, along with a nonamended control and soil amended with agronomic dolomitic lime (AgLime). At the end of the incubation, soil pH, nutrient availability (by Mehlich-3 and ammonium bicarbonate diethylene triamine pentaacetic acid [AB-DTPA] extractions), and soil leachate composition were evaluated. Biochar effect on soil pH was process- and rate-dependent. Biochar increased soil pH from 4.8 to 6.6 at the high application rate (40 g kg), but was less effective than AgLime. Biochar produced at 350°C without activation had the least effect on soil pH. Biochar increased soil Mehlich-3 extractable micro- and macronutrients. On the basis of unit element applied, increase in pyrolysis temperature and biochar activation decreased availability of K, P, and S compared to nonactivated biochar produced at 350°C. Activated biochars reduced AB-DTPA extractable Al and Cd more than AgLime. Biochar did not increase NO in leachate, but increased dissolved organic carbon, total N and P, PO, SO, and K at high application rate (40 g kg). Risks of elevated levels of dissolved P may limit chicken manure biochar application rate. Applied at low rates, these biochars provide added nutritional value with low adverse impact on leachate composition.

Available Soil Phosphorus Affects Herbage Yield and Stand Persistence in Forage Chicory

Low available soil P (ASP) may contribute to poor productivity of forage chicory (Cichorium intybus L.). The effect of ASP on forage yield and stand loss was evaluated over two harvest years for three chicory cultivars (‘Puna’, ‘Forage Feast’, ‘Lacerta’) at sites with low [West Virginia (WV), Gilpin silt loam (fine‐loamy, mixed, mesic Typic Hapludults)] or high [Pennsylvania (PA), Hagerstown silt loam (fine, mixed, semiactive, mesic, Typic Hapludalfs)] ASP. Low (LP), medium (MP), and high (HP) ASP treatments averaged 6, 27, and 41 mg kg−1 of Bray‐P for LP, MP, and HP in WV, and 30 and 41 mg kg−1 for MP and HP in PA. Across all data, critical soil P for 95% of maximum dry matter yield (DMY) was approximately 30 mg kg−1 of Bray‐P. Cumulative DMY of all cultivars increased with soil Bray‐P in the first year after planting, but in the second year, only Forage Feast DMY increased with soil Bray‐P. Cumulative DMY declined 45, 69, and 89% from the first to second year after planting for Puna, Forage Feast, and Lacerta, respectively. Across cultivars and time, stand density increased 12% as ASP increased from LP to MP, but medium to high ASP was associated with stand decline via increased bolting of Lacerta and frost heaving of Forage Feast. Across cultivars and sites, stand densities of less than 50 plants m−2 in September predicted poor cumulative DMY in the following year. Phosphorus fertilization improved overall forage chicory DMY and persistence when ASP was low, but may contribute to bolting, heaving, and stand loss at high ASP.

Pedotransfer functions in soil electrical resistivity estimation

Surface electrical resistivity tomography (ERT) is recognized as a powerful non-invasive soil survey and monitoring method. Relationships between electrical resistivity (ER) and soil water contents that are needed to infer the spatial distribution of soil moisture from the ERT results, are known to reflect soil properties. However, pedotransfer relationships that relate ER, water content, and basic soil properties other than clay content have not been developed. The objective of this work was to evaluate the improvement in the estimates of ER from soil water contents if soil basic properties are included in the pedotransfer equations. Soil — coarse-loamy, siliceous, mesic Typic (or Aquic) Hapludult — was sampled in 12 locations at ten depths across a 30 × 30-m experimental site. The resistivity was measured in disturbed samples in four-electrode cells. Water content, bulk density, texture, organic carbon, and pH were measured in these samples. The coefficient and the exponent in the power law-dependence of ER on volumetric water content were approximated with linear regressions that included any number of measured soil basic properties as inputs. A total of 1024 regressions were compared using the Akaike information criterion, and the best model was found that provided the best approximation with minimum number of regression terms. Six soil textural classes were encountered in the samples. When no pedotransfer relationships were included, the R 2 of the log-log relationships between ER and water content increased from 0.45 at 10 cm to 0.91 at 190 cm. Splitting the dataset into topsoil and subsoil subsets resulted in favorable pedotransfer relationships with R 2 about 0.85 both in topsoil and subsoil. Bulk density, clay content, sand content and pH appeared to be influential soil properties. Overall, accuracy of relationships between soil electrical resistivity and volumetric water content at ten depths in highly heterogeneous sandy soil could be substantially improved if pedotransfer relationships were established. Future work is needed on the applicability of data obtained on repacked samples to undisturbed soils and on the selection of input variables and evaluation methods for pedotransfer electrical resistivity pedotransfer functions.

Calcium Silicate Suppresses Powdery Mildew and Increases Yield of Field Grown Wheat

During three consecutive years of field trials conducted in northwestern New Jersey on a Quakertown silt loam soil (fine–loamy, mixed, active, mesic Typic Hapludult), a calcium silicate, steel slag by‐product (CSS), was added as an effective liming agent to long winter wheat (Triticum aestivum L.) and evaluated for its suppressive effects on powdery mildew disease (Erysiphe graminis DC. f. sp. tritici Em. Marchal Blumeria graminis (DC.) E.O. Speer = E. graminis DC. Oidium monilioides (Nees) Link [anamorph]). Limestone was used as the control in a completely random design, consistent for treatment during all trial years. Plots were split for one fungicide, propiconazole (1‐[[2(2,4‐Dichlorophenyl)‐4‐propyl‐1,3‐dioxolan‐2‐yl]methyl]1‐H‐1,2,4‐triazole), application per year. The field was allowed to become naturally inoculated. In 2006 disease symptoms did not appear until late in the season. Although no significant grain yield response was exhibited in 2006, powdery mildew lesions were reduced by 29% on the flag leaves of wheat plants in the CSS treated plots. In 2007, powdery mildew was not diagnosed, but non‐pathogenic Alternaria spp. leaf blotch was observed late season. Leaf blotch lesions were reduced 25% on flag leaves in the CSS‐treated plots. During 2008, powdery mildew lesions on flag leaves were 44% less and yields were 10% greater in plots treated with CSS. Our results suggest that the use of CSS as an effective neutralizer of soil acidity may have the added benefit of suppressing powdery mildew in field grown winter wheat.

Corn stover removal impacts on micro-scale soil physical properties

Crop residues are a potential source for biofuel production. Yet, impacts of removal of corn ( Zea mays L.) stover and other residues as biofuel feedstocks on micro-scale soil properties affecting the behavior of the whole soil are not well understood. Data on both macro- and micro-scale soil properties under different scenarios of stover management are needed to define the threshold levels of stover removal. Previous studies on stover removal impacts on soil properties have primarily focused on macroscale properties and little or not on microscale properties. Thus, this study was designed to assess impacts of annual stover removal for 3 consecutive years at rates of 0, 25, 50, 75, and 100% on soil physical properties at the aggregate level under no-tillage (NT) continuous corn systems in a Rayne silt loam (RSL) (fine-loamy, mixed, active, mesic Typic Hapludult) with 10% slope, Celina silt loam (CSL) (fine, mixed, active, mesic Aquic Hapludalfs) with 2% slope, and Hoytville clay loam (HCL) (fine, illitic, mesic Mollic Epiaqualfs) with < 1% slope in Ohio. Aggregates were sensitive to stover removal particularly in the 0- to 10-cm soil depth. Stover removal reduced aggregate stability, tensile strength (TS), water retention (WR), and subcritical water repellency, while it increased water sorptivity but had no effect on pore-size distribution within an aggregate. The interaction of aggregate stability, strength, and subcritical water repellency with aggregate water potential was highly significantly, indicating that the magnitude of changes in aggregate structural properties due to stover removal depended on the variable antecedent soil water conditions. The aggregate stability and strength decreased while water repellency increased with increasing water potential. Impacts of stover removal on the clayey soils were equal to or higher than those on silt loam soils. Removal at rates ≥ 25% reduced the raindrop kinetic energy (KE) required to break aggregates by 13 times at HCL, while removal at rates ≥ 50% reduced the KE by 2 to 3 times at RSL and CSL for air-dry aggregates. The KE and TS decreased with increasing soil water potentials. The TS was reduced by 10% to 30% at all water potentials at RSL, by 20% to 35% between − 0.1 and − 1.5 MPa, and by 2.2 times at − 166 MPa at CSL, and by 2 to 3 times between − 1.5 and − 166 MPa at HCL under complete stover removal. Removal of stover at rates ≥ 50% reduced subcritical water repellency by 2 to 10 times in all soils. Overall, stover removal altered micro-scale soil properties, and complete stover removal had the most detrimental effects. Based on the data from previous studies on macroscale soil properties and this study, stover removal adversely affects both macro- and micro-scale soil properties.

Traffic Stress Effects on Bentgrass Putting Green and Fairway Turf

Creeping bentgrass (Agrostis stolonifera L.) has received more study and use as golf course turf than velvet bentgrass (A. canina L.). The objective of two field trials, managed as putting green and fairway turf, was to evaluate the performance of creeping and velvet bentgrass in mixed swards with annual bluegrass (Poa annua var. reptans Hausskn.) when subjected to traffic stresses. The trials were initiated on a sandy loam (fine‐loamy, mixed, mesic Typic Hapludult). Wear (no‐wear and wear) and compaction (no‐compaction and compaction) were applied in a factorial combination to 15 creeping or velvet bentgrasses. Turf quality, turf density, and bentgrass populations of cultivars were more susceptible to wear stress than compaction. Velvet bentgrass performed and resisted the spread of annual bluegrass better than most creeping bentgrasses. Cultivars that formed denser turf performed well in both trials; ‘Vesper’, ‘7001’, and ‘Penn A‐4’ had the best overall performance. Interactions indicated ‘SR 7200’, ‘Penn G‐2’, and ‘Providence’ were susceptible to compaction. ‘Pennlinks’ and ‘Penncross’ were ineffective at maintaining desirable bentgrass populations particularly in the putting green trial. Management strategies that minimize wear damage may have a greater impact on turf quality and bentgrass populations in mixed stands than practices intended to manage compaction, particularly on well‐drained soil.

Soil and crop response to harvesting corn residues for biofuel production

Corn ( Zea mays L.) stover is considered one of the prime lignocellulosic feedstocks for biofuel production. While producing renewable energy from biomass is necessary, impacts of harvesting corn stover on soil organic carbon (SOC) sequestration, agricultural productivity, and environmental quality must be also carefully and objectively assessed. We conducted a 2 1/2 year study of stover management in long-term (> 8 yr) no-tillage (NT) continuous corn systems under three contrasting soils in Ohio to determine changes in SOC sequestration, CO 2 emissions, soil physical properties, and agronomic productivity. These measurements were made on a Rayne silt loam (RSL) (fine-loamy, mixed, active, mesic Typic Hapludult) with 6% slope, Celina silt loam (CSL) (fine, mixed, active, mesic Aquic Hapludalfs) with 2% slope, and Hoytville clay loam (HCL) (fine, illitic, mesic Mollic Epiaqualfs) with < 1% slope. Stover treatments consisted of removing 0, 25, 50, 75, and 100% of corn stover following each harvest. At the start of the experiment in May 2004, these percentages of removal corresponded to 5, 3.75, 2.5, 1.25, and 0 Mg ha − 1 yr − 1 of stover left on the soil surface, respectively. Annual stover removal rate of > 25% reduced SOC and soil productivity, but the magnitude of impacts depended on soil type and topographic conditions. Stover removal rate of 50% reduced grain yield by about 1.94 Mg ha − 1 , stover yield by 0.97 Mg ha − 1 , and SOC by 1.63 Mg ha − 1 in an unglaciated, sloping, and erosion-prone soil ( P < 0.05). The initial water infiltration rates were significantly reduced by > 25% of stover removal on a RSL and CSL. Plant available water reserves and earthworm population were significantly reduced by 50% of stover removal at all soils. Increases in soil compaction due to stover removal were moderate. Stover removal impacts on SOC, crop yield, and water infiltration for HCL were not significant. Results from this study following 2 1/2 yr of stover management suggest that only a small fraction (≤ 25%) of the total corn stover produced can be removed for biofuel feedstocks from sloping and erosion-prone soils.

Aggregate Disintegration and Wettability for Long-Term Management Systems in the Northern Appalachians

Assessment of the structural properties of discrete soil aggregates is fundamental to understanding soil erosional processes. Management-induced changes in soil organic carbon (SOC) concentration may signifi cantly alter aggregate properties. The disintegration and wetting characteristics of individual aggregates and their relationships with SOC concentrations were determined for a Rayne silt loam (fi ne-loamy, mixed, mesic Typic Hapludult) under long-term (>22 yr) moldboard plow (MP), no-till with (NTm) and without manure (NT), pasture, and forest systems in the northern Appalachian region. Aggregate disintegration was assessed based on the kinetic energy (KE) of simulated raindrops required to detach 1- to 8-mm aggregates at −0.01, −0.1, −1, and −154 MPa soil water potentials. Management affected aggregate resistance to the erosive energy of raindrops (P 5.0 μJ) for disintegration and those from MP soils the lowest (<1.9 μJ). At the −0.01 MPa potential, the KE needed to disintegrate aggregates in NTm was about three times higher than for NT, indicating that manure addition improved aggregate stability. Aggregates from cropland had very low water repellency, but those from forest management have some water repellency. Aggregate disintegration was correlated with measured soil erosion in which MP required the lowest raindrop KE to produce the highest runoff and soil loss. The SOC concentration explained 48% of the variability in aggregate disintegration and 86% in aggregate wetting. Long-term management altered aggregate disintegration, but its effects on aggregate wetting within agricultural practices were small.

Forage Nutritive Value in an Emulated Silvopasture

Incorporating trees into pastures may alter forage nutritive value. The objective of this study was to determine nutritive value in response to trees and slope position in an emulated (no animals) silvopasture. In 1995, black walnut (Juglans nigra L.) and honey locust (Gleditsia triacanthos L.) trees were planted within three block plots of predominantly tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) pasture. Soils on the site, (Unison and Braddock) are fine, mixed mesic Typic Hapludults, well drained, with moderately steep slopes (10–25%). Trees were planted down slopes in rows to create low‐, medium‐, and high‐tree densities at shoulder‐, mid‐, and toe‐slope positions. Forage from sampling sites (n = 54) under field treatment combinations was harvested May, June, and July in 2002 and 2003. Concentrations of neutral and acid detergent fiber (NDF, ADF), acid detergent lignin (ADL), crude protein (CP), total nonstructural carbohydrate (TNC) and Ca, P, Mg, and K were determined. Few differences due to treatment were observed for NDF and ADF concentrations. Concentrations of TNC decreased with greater tree density and appeared to follow tree leaf growth. Crude protein concentrations were typically greater under honey locust trees. Forage mineral concentrations frequently were greater with increased tree density. Trees appear to have both positive and negative effects on forage nutritive value, and their effects on animal performance warrants further research.

Changes in Long‐Term No‐Till Corn Growth and Yield under Different Rates of Stover Mulch

Removal of corn (Zea mays L.) stover for biofuel production may affect crop yields by altering soil properties. A partial stover removal may be feasible, but information on appropriate rates of removal is unavailable. We assessed the short‐term impacts of stover management on long‐term no‐till (NT) continuous corn grown on a Rayne silt loam (fine loamy, mixed, active, mesic Typic Hapludults) at Coshocton, Hoytville clay loam (fine, illitic, mesic Mollic Epiaqualfs) at Hoytville, and Celina silt loam (fine, mixed, active, mesic Aquic Hapludalfs) at South Charleston in Ohio, and predicted corn yield from soil properties using principal component analysis (PCA). The study was conducted in 2005 on the ongoing experiments started in May 2004 under 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% of stover corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha−1 of stover, respectively. Stover removal promoted early emergence and rapid seedling growth (P &lt; 0.01). Early‐emerging plants grew taller than late‐emerging plants up to about 50 d, and then the heights reversed at Coshocton and were comparable at other two sites. Stover management affected corn yield only at the Coshocton site where average grain and stover yields in the T200, T100, T75, and T50 (10.8 and 10.3 Mg ha−1) were higher than those in the T0 and T25 treatments (8.5 and 6.5 Mg ha−1) (P &lt; 0.01), showing that stover removal at rates as low as 50% (2.5 Mg ha−1) decreased crop yields. Soil properties explained 71% of the variability in grain yield and 33% of the variability in stover yield for the Coshocton site. Seventeen months after the start of the experiment, effects of stover management on corn yield and soil properties were site‐specific.

Soil hydraulic properties influenced by corn stover removal from no-till corn in Ohio

Corn ( Zea mays L.) stover removal for biofuel production and other uses may alter soil hydraulic properties, but site-specific information needed to determine the threshold levels of removal for the U.S. Corn Belt region is limited. This study quantified impacts of systematic removal of corn stover on soil hydraulic parameters after 1 year of stover management under no-till (NT) systems. These measurements were made on three soils in Ohio including Rayne silt loam (fine-loamy, mixed, active, mesic Typic Hapludult) at Coshocton, Hoytville clay loam (fine, illitic, mesic Mollic Epiaqualfs) at Hoytville, and Celina silt loam (fine, mixed, active, mesic Aquic Hapludalfs) at South Charleston. Interrelationships among soil properties and saturated hydraulic conductivity ( K sat) predictions were also assessed. Earthworm middens, K sat, bulk density ( ρ b), soil water retention (SWR), pore-size distribution, and air permeability ( k a) were determined for six stover treatments. Stover treatments consisted of removing 0 (T100), 25 (T75), 50 (T50), 75 (T25), 100 (T0) and adding 100 (T200)% of corn stover corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha −1 of stover, respectively. Stover removal reduced the number of middens, K sat, SWR, and k a, and increased ρ b at all sites ( P < 0.01). Compared to normal stover treatment (T100), complete stover removal (T0) reduced earthworm middens 6-fold at Coshocton and about 14-fold at Hoytville and Charleston. Geometric mean K sat decreased from 3.1 to 0.1 mm h −1 at Coshocton, 4.2 to 0.3 mm h −1 at Hoytville, and 4.2 to 0.6 mm h −1 at Charleston while soil ρ b increased about 12% in the 0–10-cm depth at Coshocton and Hoytville from T100 to T0. The SWR for T0 was about 70% of that for T100 and 58% of that for T200 at 0 to −6 kPa suctions across sites. The log k a for T200, T100, and T75 significantly exceeded that under T50, T25, and T0 at Coshocton and Charleston. Differences in the number of middens, ρ b, SWR, K sat, and k a between T100 and T200 were not generally significant although the T200 retained slightly more water for the 0 to −100 kPa at Charleston and had higher k a at Hoytville compared to T100. Measured parameters were strongly correlated, and k a was a strong K sat predictor. Stover harvesting induces rapid changes in soil hydraulic properties and earthworm activity, but further monitoring is needed to ascertain the threshold levels of stover removal for soil-specific conditions.

Changes in Soil Test Phosphorus from Broiler Litter Additions

Nutrient surpluses on the Delmarva Peninsula have led to a continual accumulation of soil test phosphorus (STP), a potential source for transport of phosphorus (P) to surface waters. This article examines the effects of initial soil test P concentrations and broiler litter additions on STP accumulation. Broiler litter (BL) was applied at rates of 0, 2.5, 5, 7.5, and 10 g kg−1 (dry weight) to three soils: an Evesboro sandy loam (Mesic, coated Typic Quartzipsamments), a Pocomoke sandy loam (coarse‐loamy, siliceous, thermic typic Umbraquults), and a Matapeake silt loam (fine‐silty, mixed, semiactive, mesic Typic Hapludults). Soils and BL were incubated for 16 weeks with subsamples analyzed after 4 and 16 weeks. There was a linear increase in STP (Mehlich‐3), water‐soluble P (WS‐P), iron‐oxide strip‐extractable P (FeO‐P), and Mehlich‐3 phosphorus saturation ratio (M3‐PSR) with broiler litter additions. Regression analysis indicated few significant differences in STP response to added BL between soils within the same soil group having different initial STP levels. Correlation analysis and stepwise regression indicated that increases in WS‐P and FeO‐P from added BL were more closely related to the degree of P saturation of the soil rather than traditional STP measurements. Therefore, decisions regarding manure placement within a watershed should be based on the potential P sorption capacity of the soil as well as potential P transport pathways when the goal is the reduction of P transfer to waterbodies.

Response of Woodland-planted Ramps to Surface-applied Calcium, Planting Density, and Bulb Preparation

Concern about over-harvesting wild populations of ramps (Allium tricoccum Ait.) has led to interest in planting ramps as an under-story agroforestry crop. To see if ramps would respond to Ca amendments in an acidic site, we planted three types of ramps bulbs and broadcast slaked lime (3316 kg·ha–1) or gypsum (7704 kg·ha–1) on a Rayne silt loam (fine-loamy, mixed, mesic Typic Hapludults). After 3 years, surface-applied slaked lime raised Ca levels as deep as the 22.5 to 30 cm layer, which showed an increase of 0.34 cmolc·kg–1, and increased pH in the 2.5 to 5.0 cm layer from 3.96 to 4.67. Gypsum application raised Ca concentration in the 22.5 to 30 cm layer from 0.2 in the control to 0.7 cmolc·kg–1, but had little effect on pH anywhere in the profile. In plots harvested after 2 years, both amendments increased plant survival and per-plant weight, compared to controls. In plots harvested after 3 years, ramps grown in the slaked lime treatment were heavier than in the gypsum treatment indicating that slaked lime, which raised pH as well as supplied Ca, was probably the better amendment. Single or joined bulbs survived better than bulbs obtained by breaking joined bulbs in two. While more research is needed to overcome limitations to commercial planting of ramps in acidic sites, our data show that Ca application is beneficial to growth and survival of ramps.

Leachate migration from spent mushroom substrate through intact and repacked subsurface soil columns

Field weathering of spent mushroom substrate (SMS) produces soluble compost leachate that percolates into underlying soils and may adversely impact groundwater. Laboratory experiments were conducted to investigate movement and retention of SMS leachate solutes in subsurface soil columns. Spent mushroom substrate leachate with high concentrations of dissolved organic matter (DOM) and inorganic salts was passively loaded to intact and repacked columns of Bt1 soil (fine-loamy, mixed, semiactive, mesic Typic Hapludults) and effluents were monitored for changes in chemical composition. Transport of SMS leachate in undisturbed soil cores was mainly via preferential flow, whereas matrix flow was predominant in repacked soil columns. Leachate DOM and phosphate were sorbed by soil minerals while Cl −, SO 4 2 - , Na + and NH 4 + were eluted. Leachate K + displaced exchangeable native cations and was retained. Biodegradation of leachate DOM resulted in reduction and elution of soil Mn and Fe, especially in repacked columns. Persistent anoxia also inhibited nitrification. Precipitation of gypsum and CaCO 3 blocked preferential flow channels, and movement of SMS leachate was subsequently reduced. The results demonstrate that SMS leachate migrates via rapid preferential flow initially, followed by matrix flow at a lower rate. Leachate solutes may transport to depth in soil profiles through preferential channels. To protect water resources, weathering of deep SMS piles should be conducted on compact surfaces or in fields with a condensed soil layer (no structural cracks) above the groundwater table, and measures controlling leachate runoff be imposed.

Repeated Biomass Removal Affects Soybean Resource Utilization and Yield

Soybean [Glycine max (L.) Merr.] producers in many regions of the USA are confronted with significant yield losses because of crop damage from white‐tailed deer (Odocoileus virginianus). Our objectives were to quantify soybean resource utilization and yield responses to variety, row spacing, and simulated repeated biomass removal. Field research was conducted in 2000 and 2001 on a Quakertown silt loam soil (fine‐loamy, mixed, mesic Typic Hapludult) near Pittstown, NJ. Biomass removal during early vegetative and vegetative/reproductive growth extended the soil wetness duration index on average by 1.5 and 2.9 d compared with the control from the 0‐ to 30‐ and 30‐ to 60‐cm soil depths in 2000 and by 5.1 and 2.1 d in 2001. Biomass removal during early vegetative growth delayed pod maturity up to 7 d compared with the control, but biomass removal during reproductive growth hastened pod maturity by as much as 3 d. Averaged across row spacing and biomass removal, variety ‘APK394NRR’ yielded 12 and 24% lower than ‘93B53’ in 2000 and 2001. In 2000, averaged across variety and biomass removal, the 20‐ and 41‐cm row widths yielded 19 and 16% less than the 76‐cm row width. Averaged across variety and row spacing, all biomass removal treatments lowered yield compared with the control except the midvegetative/early reproductive treatment in 2001 (661 vs. 663 g m−2). The greatest yield reductions occurred (up to 89%) when biomass was removed repeatedly during vegetative and reproductive growth. Management implications for soybean producers include variety selection and row spacing to diminish the effects of deer damage.

Surface Runoff along Two Agricultural Hillslopes with Contrasting Soils

The targeting of critical surface runoff‐producing zones should account for the influence of subsurface soil characteristics. In this study we assessed the runoff response of contrasting colluvial and residual soils. The study was conducted along two hillslopes within a 39.5‐ha mixed land use watershed in Pennsylvania. Six sites (four colluvial, two residual) were monitored for runoff, hydraulic head, water table depth, and soil water content. A total of 111 rainfall events were monitored during the periods of July to December 2000, April to December 2001, and April to December 2002. Two high‐intensity (5‐min peak &gt; 8 cm h−1) events had return periods of 2.5 and 4 yr. The colluvial soils are somewhat poorly and moderately well drained with fragipans and high clay content (37–44%) argillic horizons (fine, mixed, semiactive, mesic Aquic Fragiudalfs); the residual soils are well drained with moderate clay content (24%) argillic horizons (fine‐loamy, mixed, semiactive, mesic Typic Hapludults). Across all events, overall runoff yields averaged 2.4% from the four colluvial sites and 0.01% from the two residual sites. The two colluvial sites with the greatest runoff production were located at the base of a primarily colluvial hillslope. The largest events at these sites occurred during periods of surface saturation (soil surface to a depth of at least 30 cm). These results suggest that nonwinter P management for these residual soils should focus on rare, large events. Nutrient management planning could be improved if runoff estimation methods were to better integrate information on subsurface and upslope soil hydrologic properties.

Soybean Response to Plant Density and Residual Soil Management

ABSTRACT Proximity determines the feasibility of using animal manures in cash crop farming systems. However, sustainable farming practices balance nutrient inputs and outputs to minimize the buildup of potentially deleterious levels of soil nutrients. The objectives of our research were to determine the residual effect of dairy (Bos taurus) manure application to corn (Zea mays L.) on subsequent continuous soybean [Glycine max (L.) Merr.] growth and seed yield at different plant densities under previous soil management regimes. The 3-year study was conducted on a Quakertown silt loam (fine-loamy, mixed, mesic Typic Hapludult) at an upland New Jersey location. Soybean was planted at 371,494, and 618,000 seeds ha−1 and previous soil management treatments applied to corn from 1995–1998 were a control (no sidedress N or manure), sidedress N, manure, and manure plus sidedress N. Light interception, dry matter, and nitrogen accumulation at R1-R2 were poor predictors of seed yield. Seed yield in manure treatments was 48% greater than non-manure treatments in a dry year, the first residual year after manure application, but was similar or minimally greater in the two years with average precipitation. These data provide additional rationale to follow sustainable practices that distribute manure more evenly across landscapes to minimize buildup of excessive levels of soil nutrients.

Pumpkin Yield and Disease Response to Amending Soil with Silicon

Field experiments were conducted with Cucurbita pepo L. `Howden' pumpkin in 2000 to 2001 to study the effects of silicon (Si) amendment of soil with and without the use of fungicides on yield and powdery mildew suppression. A Quakertown silt loam soil (fine-loamy, mixed, mesic Typic Hapludult) with an initial soil pH of 5.7 was amended with either CaCO3 or CaSiO3 at the rate of 7840 kg·ha-1 of calcium carbonate equivalent. Fungicides were applied on a 7-10 day schedule to half of the plots as a 2 × 2 factorial, beginning when the first powdery mildew lesions were detected in the field. Silicon amendment increased pumpkin yield by 60% in 2000 but Si did not influence yield in 2001. Infection with bacterial leaf spot reduced yield on all plots in 2001. Fungicide applications increased yield only in 2001. In 2000, Si amendment had the effect of delaying foliage senescence but it was not clear if this was the result of an effect of Si on disease activity or crop physiology. In Aug. 2001, Si amendment generally reduced powdery mildew severity, but only at the 10% level of significance. In Sept. 2001, the combination of Si amendment plus fungicide application was more effective in reducing powdery mildew severity than either Si or fungicide alone. Silicon amendment resulted in a 5-fold increase in plant Si concentration. Soil pH measured after harvest in 2001 indicated no significant difference in pH between plots amended with CaCO3 (pH = 6.8) and CaSiO3 (pH = 6.9). In New Jersey, the cost of these liming materials is similar. Thus, the selection of CaSiO3 as a liming material as needed for soil pH correction has the potential benefits of suppressing powdery mildew and increasing pumpkin yield without increasing the cost of production.

Optimum Nitrogen Fertilization of Cool‐Season Grasses in the Northeast USA

Many studies have looked at the economically optimum N application rate (cost of N vs. increased yield) for cool‐season forage grasses, but few of these studies have also addressed the effect of N fertilization on livestock or environmental health. The objective of this study was to determine the N application rate to cool‐season grass species that optimizes economic return without elevating herbage or soil NO3–N levels. Four N rates were applied in split applications to established stands of orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb.), and timothy (Phleum pratense L.) near State College, PA, on a Murrill silt loam (fine‐loamy, mixed, mesic Typic Hapludults) soil. Harvest treatments of three and four times per year were imposed on each Grass × N treatment. Economically optimum N rates (EONR) were 284, 368, and 299 kg N ha−1 or 26, 32, and 29 kg N Mg−1 of forage harvested for orchardgrass, tall fescue, and timothy, respectively. Smooth bromegrass did not reach an economic plateau at the highest (402 kg ha−1) N rate. At EONR, NO3–N concentration exceeded 1000 mg kg−1 in forage from early season harvests when four harvests per year were taken but not when three harvests per year were taken. Soil NO3–N concentration generally was not elevated above background levels when EONR was applied to orchardgrass or tall fescue. Our results, in conjunction with results from New York, indicate that the EONR for the cool‐season grasses and harvest systems evaluated is 5 to 10 kg N Mg−1 of dry forage greater than current recommendations in New York and Pennsylvania. However, continued research is needed in a wider range of climates and soil types using various N sources.