Data quantifying interseeded cover crops effects on soil water and corn productivity in corn-soybean-wheat no-till cropping systems.

The data described support the research article entitled "Interseeded cover crop mixtures influence soil water storage during the corn phase of corn-soybean-wheat no-till cropping systems". Data were collected during the corn (Zea mays L.) phase from rotations with four different cover crop (CC) treatments. The study was conducted at the USDA research facility in Beltsville, MD from 2017 through 2020. The data are available from a repository at Ag Data Commons. Descriptions of crop rotations, soil water and temperature sensors, placement, and frequency of measurements are provided in the manuscript and repository. Hourly volumetric soil water content (m3 m-3) (VWC) and soil temperature (°C) data for each soil depth (0-12, 25-35, 50-60, 75-85 cm) are available from the repository. In the manuscript, daily values of soil water storage were used to estimate daily evapotranspiration (ET) and infiltration. A text file of meta information is provided in the repository describing data collection procedures, estimation of ET and infiltration, and methods used to replace sensor data having errors. Daily precipitation, maximum and minimum temperatures, net solar radiation, and windspeed collected at a nearby weather station are provided for estimating growing degree days and potential ET. Cover crop biomass (kg ha-1) prior to corn planting and corn yields are provided by replication and cover crop system treatment for the four years.

Chemical differences in cover crop residue quality are maintained through litter decay.

As plant litter decomposes, its mass exponentially decreases until it reaches a non-zero asymptote. However, decomposition rates vary considerably among litter types as a function of their overall quality (i.e., carbon:nitrogen (C:N) ratio and litter chemistry). We investigated the effects of hairy vetch (HV: Vicia villosa Roth):cereal rye (RYE: Secale cereale L.) biomass proportions with or without broadcasted poultry manure on overall litter quality before and during decomposition. As HV biomass proportions increased from 0 to 100%, the relative susceptibility of HV:RYE mixtures to microbial decomposition increased due to: (i) decrease in the initial C:N ratio (87:1 to 10:1 in 2012 and 67:1 to 9:1 in 2013), (ii) increase in the non-structural labile carbohydrates (33 to 61% across years), and (iii) decrease in the structural holo-cellulose (59 to 33% across years) and lignin (8 to 6% across years) fractions. Broadcasted poultry manure decreased the overall initial quality of HV-dominated litters and increased the overall initial quality of RYE-dominated litters. Across all HV:RYE biomass proportions with or without poultry manure, chemical changes during litter decay were related to proportional mass loss. Therefore, the relative decrease in carbohydrates and the concomitant increase in holo-cellulose and lignin fractions were more pronounced for fast decomposing litter types, i.e., litters dominated by HV rather than RYE. While our results suggest possible convergence of litter C:N ratios, initial differences in litter chemistry neither converged nor diverged. Therefore, we conclude that the initial chemistry of litter before decomposition exerts a strong control on its chemical composition throughout the decay continuum.

Metals in Soil and Runoff from a Piedmont Hay Field Amended with Broiler Litter and Flue Gas Desulfurization Gypsum.

Flue gas desulfurization gypsum (FGDG) from coal-fired power plants is readily available for agricultural use in many US regions. Broiler litter (BL) provides plant available N, P, and K but can be a source of unwanted As, Cu, and Zn. As a source of Ca and S, FGDG can reduce losses of P and other elements in runoff from BL-amended areas. Rainfall simulation plots (2.0 m) were established on a Piedmont Cecil soil growing 'Coastal' bermudagrass ( L.) for hay. Accumulation and transport of As, Cu, Cd, Cr, Hg, Pb, and Zn were evaluated after annual BL applications (13.5 Mg ha) with four FGDG rates (0, 2.2, 4.5, 9.0 Mg ha) and two FGDG treatments (0 and 9 Mg ha) without BL. Runoff As concentrations were sixfold greater with BL than without ( ≤ 0.01) and were similar to BL with FGDG at 2.2, 4.5 or 9.0 Mg ha ( ≤ 0.10). Runoff concentrations of target elements did not increase where FGDG was applied alone. After three annual applications of FGDG and BL, soil concentrations of As, Cr, Pb, Hg, and Cu were well below levels of environmental concern. Our findings indicate that runoff losses of As from BL application are not reduced with FGDG but support other research indicating no identifiable environmental risks from FGDG beneficial use in agricultural systems.

Flue gas desulfurization gypsum: implication for runoff and nutrient losses associated with broiler litter use on pastures on ultisols.

Gypsum has been shown to reduce runoff on soils prone to crust formation in the southeastern United States. Increased infiltration from gypsum applications could therefore help reduce runoff P and other nutrient losses from application of broiler litter (BL), a nutrient-rich fertilizer. In rainfall simulation experiments in June 2009 and May 2011, runoff and nutrient (N, P, Ca, Mg) losses in runoff were compared among treatments consisting of 0, 2.2, 4.5, and 9.0 Mg ha flue gas desulfurization gypsum (FGDG) combined with 13.5 Mg ha of BL and two control treatments of (0-0) and (9.0-0.0) Mg ha (FGDG-BL). A randomized block design with three replications was set up on a Cecil (Typic Kanhapludult) soil growing Coastal bermudagrass ( L.) for hay near Watkinsville, Georgia. Amendments were applied each April from 2009 to 2011. A reduction in runoff of 30% each year from the (9.0-13.5) compared with the (0-0) treatment was not statistically significant. Gypsum was effective in reducing concentration and load in one of the two study years: P and NH-N in 2009 (up to 83%) and NO-N in 2011 (up to 73%). A combination of factors related to weather extremes, timing of FGDG and BL applications, and their implication on soil and vegetation responses at different landscape positions might have caused the different responses between years. Additional studies focused on isolating the impacts of such factors would be helpful to ascertain the effectiveness of multiyear applications of FGDG as a best management practice to reduce P and other nutrient losses in soils of the southeastern United States.

Influence of biochar on nitrogen fractions in a coastal plain soil.

Interest in the use of biochar from pyrolysis of biomass to sequester C and improve soil productivity has increased; however, variability in physical and chemical characteristics raises concerns about effects on soil processes. Of particular concern is the effect of biochar on soil N dynamics. The effect of biochar on N dynamics was evaluated in a Norfolk loamy sand with and without NHNO. High-temperature (HT) (≥500°C) and low-temperature (LT) (≤400°C) biochars from peanut hull ( L.), pecan shell ( Wangenh. K. Koch), poultry litter (), and switchgrass ( L.) and a fast pyrolysis hardwood biochar (450-600°C) were evaluated. Changes in inorganic, mineralizable, resistant, and recalcitrant N fractions were determined after a 127-d incubation that included four leaching events. After 127 d, little evidence of increased inorganic N retention was found for any biochar treatments. The mineralizable N fraction did not increase, indicating that biochar addition did not stimulate microbial biomass. Decreases in the resistant N fraction were associated with the high pH and high ash biochars. Unidentified losses of N were observed with HT pecan shell, HT peanut hull, and HT and LT poultry litter biochars that had high pH and ash contents. Volatilization of N as NH in the presence of these biochars was confirmed in a separate short-term laboratory experiment. The observed responses to different biochars illustrate the need to characterize biochar quality and match it to soil type and land use.

Runoff water quality during drought in a zero-order georgia piedmont pasture: nitrogen and total organic carbon.

Approximately 11% of the Southern Piedmont (1.8 million ha) is used for pasture and hay production, mostly under low-input management. Few studies have investigated in the region long-term nitrogen and carbon losses in surface runoff, which can be significant. We present 1999 to 2009 hydrologic and water quality data from a rotationally grazed, 7.8-ha, zero-order pasture (W1) near Watkinsville in the Georgia Piedmont. Annual rainfall was 176 to 463 mm below the long-term average (1240 mm) in 7 of the 11 yr. There were 20 runoff events during 86 mo of below-average rainfall (deficit period), compared with 54 events during 46 mo of nondeficit period. Mean event flow-weighted concentration (in mg L) was 0.96 for nitrate-nitrogen (NO-N), 0.97 for ammonium-nitrogen (NH-N), 3.70 for total nitrogen (TN), and 9.12 for total organic carbon (TOC) ( = 43-47; limited due to instrument problem). Nutrient loads (in kg ha per event) averaged 0.04 for NO-N, 0.03 for NH-N, 0.19 for TN, and 0.54 for TOC. Total loads for N and TOC were 6 to 11 times greater from nondeficit than from deficit periods. The observed N concentrations, while well below maximum drinking water standard limits, could pose risk for eutrophication, which can be stimulated at lower concentrations. However, the ability of headwater streams, such as the one downstream of W1, to reduce nutrient concentrations might partially alleviate this concern. The results of this study point to the need to use a long-term dataset that includes measurements made in drought and wet years when evaluating the efficacy of water quality standards.

17beta-Estradiol and testosterone in drainage and runoff from poultry litter applications to tilled and no-till crop land under irrigation.

Thirteen million [corrected] metric tons of poultry litter are produced annually by poultry producers in the U.S. Poultry litter contains the sex hormones estradiol and testosterone, endocrine disruptors that have been detected in surface waters. The objective of this study was to evaluate the potential impact of poultry litter applications on estradiol and testosterone concentrations in subsurface drainage and surface runoff in irrigated crop land under no-till and conventional-till management. We conducted an irrigation study in fall of 2001 and spring of 2002. Four treatments, no-till plus poultry litter, conventional-till plus poultry litter, no-till plus conventional fertilizer, and conventional-till plus conventional fertilizer, were evaluated. Flow-weighted concentration and load ha(-1) of the two hormones were measured in drainage and runoff. Soil concentrations of estradiol and testosterone were measured. Based on comparisons to the conventional fertilizer (and control) treatments, poultry litter did not add to the flow-weighted concentration or load ha(-1) of either estradiol or testosterone in subsurface drainage or surface runoff. Significant differences were, however, observed between tillage treatments: flow-weighted concentrations of estradiol were greater for no-till than conventional-till plots of the June irrigation; and runoff loads of both estradiol and testosterone were less from no-till than conventional-till plots for the November irrigation. Although the differences between no-till and conventional-tillage appeared to affect the hydrologic transport of both hormones, the differences appeared to have inconsequential environmental impact.

Rainfall and tillage effects on transport of fecal bacteria and sex hormones 17beta-estradiol and testosterone from broiler litter applications to a Georgia Piedmont Ultisol.

Poultry litter provides nutrients for crop and pasture production; however, it also contains fecal bacteria, sex hormones (17beta-estradiol and testosterone) and antibiotic residues that may contaminate surface waters. Our objective was to quantify transport of fecal bacteria, estradiol, testosterone and antibiotic residues from a Cecil sandy loam managed since 1991 under no-till (NT) and conventional tillage (CT) to which either poultry litter (PL) or conventional fertilizer (CF) was applied based on the nitrogen needs of corn (Zea mays L) in the Southern Piedmont of NE Georgia. Simulated rainfall was applied for 60 min to 2 by 3-m field plots at a constant rate in 2004 and variable rate in 2005. Runoff was continuously measured and subsamples taken for determining flow-weighted concentrations of fecal bacteria, hormones, and antibiotic residues. Neither Salmonella, nor Campylobacter, nor antimicrobial residues were detected in litter, soil, or runoff. Differences in soil concentrations of fecal bacteria before and after rainfall simulations were observed only for Escherichia coli in the constant rainfall intensity experiment. Differences in flow-weighted concentrations were observed only for testosterone in both constant and variable intensity rainfall experiments, and were greatest for treatments that received poultry litter. Total loads of E. coli and fecal enterococci, were largest for both tillage treatments receiving poultry litter for the variable rainfall intensity. Load of testosterone was greatest for no-till plots receiving poultry litter under variable rainfall intensity. Poultry litter application rates commensurate for corn appeared to enhance only soil concentrations of E. coli, and runoff concentrations of testosterone above background levels.

Fecal bacteria and sex hormones in soil and runoff from cropped watersheds amended with poultry litter.

The application of poultry litter to agricultural fields can provide plant nutrients for crops and forage production, but fecal bacteria and the sex hormones estradiol and testosterone are components of litter that can be detrimental to the environment. Our objective was to determine if applications of poultry litter to small watersheds would contribute to the load of fecal bacteria and sex hormones to soil and runoff. We, therefore, investigated the fate and transport of fecal bacteria, estradiol and testosterone from surface applied poultry litter to four small watersheds. Poultry litter was applied to meet the nitrogen requirements of pearl millet (Pennisetum glaucum L.) in 2000 and grain sorghum [Sorgham bicolor (L.) Moench] in 2001. Neither Salmonella nor Campylobacter were detected in the litter but the fecal indicator bacteria were. The average load of total coliforms,Escherichia coli, and fecal enterococci applied with the litter was 12.2, 11.9, and 12.7 log10 cells ha(−1), respectively. The average load of estradiol and testosterone was 3.1 and 0.09 mg ha(-1), respectively.Runoff events first occurred seven months after the first litter application in 2000, and three weeks after the second application in 2001.Only for the 25 July 2001 runoff event three weeks after the second litter application, were the concentrations of total coliforms, E. coli,and fecal enterococci in runoff greater than background concentrations which were on average 5.2, 1.1, and 2.9 log10 MPN 100 ml(−1),respectively [corrected]. Average background levels of total coliforms, fecal enterococci,and E. coli in surface soil were 8.2, 7.9, and 3.5 log (10) cells kg(−1) soil. At the rate of litter application the concentrations of estradiol and testosterone in the litter did not appear to impact the background levels in the soil and runoff. Because concentrations of sex hormones in litter from other broiler operations are known to be greater than in the litter we applied, further study on the connection between concentrations of sex hormones in poultry litter and operational practices is recommended.