Search

Using dairy manure and legumes in crop rotations can reduce inorganic N inputs for corn (Zea mays L.), yet these practices can also contribute to nitrous oxide (N2O) emissions. In two crop rotations we investigated how different (i) organic and inorganic N amendments and (ii) prior legume crops with broadcast manure influenced direct N2O emissions from silt-loam soils planted to no-till corn. We measured N2O fluxes from April to December for two years using closed vented chambers from soils planted to corn with no spring residue to compare inorganic N fertilizer (S-UAN) and two liquid dairy manure application methods: surface broadcasted (S-BM) and injected (S-IM). Emissions were also measured to compare the effect of crop residue of perennial forages, a green manure legume, or soybean (Glycine max L. Merr.) from soils all amended with liquid dairy manure. Nitrous oxide emissions were greatest during the 15–45 days after manure was injected compared to broadcasting, and cumulative N2O emissions were larger from S-IM (2.8–2.5 kg ha−1) than S-BM (1.4–0.7 kg ha−1) and S-UAN (0.3 kg ha−1). Cumulative and yield-scaled N2O emissions did not differ among the prior legume treatments. A ranking approach based on random forests, identified the most important variable contributing to N2O emissions in both comparisons as corn growing degree days, indicative of the asynchrony of spring legume termination and manure application with corn planting and N use; and changing environmental conditions for N mineralization and denitrification.

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity. Foundation for Food and Agricultural Research [523926]; Samuel Roberts Noble Foundation; General Mills Published version Foundation for Food and Agricultural Research (grant ID 523926), General Mills, and The Samuel Roberts Noble Foundation.

Soil health is a key element in enhancing agricultural production, environmental sustainability, and food system resilience (Farnsworth 2015; Stevens 2018). The USDA Natural Resources Conservation Service (NRCS) defines soil health as “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans” (Pankhurst et al. 1997; Farnsworth 2015; Bowman et al. 2016). A common theme points to soil health as an indicator of the soil’s ability to support life, withstand environmental stresses, and endure as an important part of a resilient ecosystem. Because one of the key individual components of soil health is carbon (C) in organic matter (Idowu et al. 2009; Morrow et al. 2016), enhancing soil health also has a prominent role to play in addressing climate change (Stockmann et al. 2013; Schipanski et al. 2014; Paustian et al. 2016). Improving soil health is a natural climate solution (NCS) that increases C storage in soils (Poeplau and Don 2015; Griscom et al. 2017; Jian et al. 2020). Given soil health’s key role in sustaining agricultural productivity and enhancing C storage, there is significant interest in promoting …

Understanding the fate of nutrients in land-applied manure is key to improving the efficiency of their use in crop production. We developed nitrogen (N) budgets for 2 years of continuously cropped corn fertilized by dairy manure via broadcast application or shallow disk injection. Major pathways and pools of N loss were monitored on 12, 0.04 ha field lysimeters in central Pennsylvania, USA to estimate the impact of manure application method on N fate: gas emissions, off-site runoff (overland and subsurface flow), crop uptake, and, soil storage. The budgets illuminated trade-offs in N cycling with each management strategy. Crop removal accounted for the largest portions of manure N applied in both budgets (16–43%). Injection manure N balances were more difficult to close because balances included a large proportion of ‘unaccounted’ N (49% and 68% of applied N for two accounting periods). Even so, results point to cumulative differences in nutrient use efficiencies that can be attributed to the greater conservation of ammonia-N with manure injection. There was an apparent build-up of soil N with manure injection that was not observed with broadcast application (in pre sidedress nitrogen test measurements). However, these trends were preliminary; over the two growing seasons covered by this study, these findings did not result in significant differences in corn yield or crop N removal.

Mine-soil treatment using stabilized manure rapidly sequesters large quantities of organic carbon and nutrients. However, the nutrient-rich soil conditions may become highly conducive for production and emission of N2O. We examined this possibility in a Pennsylvania coal mine restored using poultry manure stabilized in two forms: composted (Comp) or mixed with paper mill sludge (Man + PMS) at C/N ratios of 14, 21, and 28 and compared those with the emissions from conventionally treated soil. The mine soil was extremely well drained with 59% coarse fragments. Soil–atmosphere exchange of N2O and CO2 was determined using a sampling campaign of ten measurements between 16 June and 14 September 2009 (90 days) and 13 measurements between 28 June and 9 November 2010 (134 days) using static vented chambers at ambient and increased moisture (water added) content. Potential denitrification was determined in a laboratory incubation experiment. While non-amended mine soil did not have a measurable potential for denitrifying activity, the manure-based amendments introduced the potential. Soil water filled pore space was less than 60% on most sampling days in both ambient and water-added plots. Daily N2O-N emissions ranged between 40 and 70 g N ha−1 with cumulative emissions of 2–4 kg N ha−1 from non-amended, lime and fertilizer (L + F) and Comp, and 3–10 kg N ha−1 from Man + PMS treatments. The maximum emission obtained from Man + PMS represented

Mine-land reclamation for biomass production is often achieved by means of large applications of N and organic C with amendments that could create soil conditions favorable for N2O production and emissions. To investigate this possibility, we conducted a laboratory experiment using mine soil collected from an active surface coal mine site near Philipsburg, Pennsylvania. During a 37-d incubation period, we measured N2O and CO2 fluxes from non-amended soil and from soil amended with ammonium nitrate (L + F), composted poultry manure (Comp), poultry manure alone (Man) and mixed with 3 rates of paper mill sludge (PMS) to obtain carbon to nitrogen ratios of 14, 20 and 27 (Man + PMS14, 20 and 27), each at 60% and 80% water filled pore space (WFPS). Results showed that manure alone leads to a greater emission of N2O under laboratory conditions than with L + F. However, composting manure effectively reduced the emissions compared to that of L + F despite a large addition of organic C and N. Composted manure-treated soil emitted less than all other manure-based treatments at both 60% and 80% WFPS. The emissions were greater from soil amended with the Man + PMS treatments compared to non-amended and L + F-amended soil, and it increased during periods of intense microbial activity created by the application of manure and PMS. Higher water content increased emissions particularly during periods of intense microbial activity coupled with inorganic N availability. Cumulative N2O emissions from manure-treated soils represented less than 0·1% loss of total applied N. Copyright © 2014 John Wiley & Sons, Ltd.

Amending soils with biochar can sequester C and improve soil properties, such as nutrient holding capacity and water retention. While biochars generally have a long residence time in soil, the turnover of biochar C can be influenced by both biochar characteristics and soil properties. Biochar can also potentially alter the rate of decomposition of native soil organic matter (SOM). The turnover of switchgrass (Panicum virgatum L.)-derived biochar C was evaluated in the laboratory using soil from four marginally productive sites in central Pennsylvania. Carbon dioxide emissions from unamended soil, biochar-amended soil, and pure biochar were monitored during 189-d incubations, and data were fit to a two-pool exponential model to estimate the amount and mean residence time (MRT) of C in labile and stable pools. Carbon-13 signatures of emitted CO₂ were also determined to estimate the proportion of emitted CO₂ derived from the biochar. Mixing biochar with each of the soils reduced the apparent MRT of C in both labile and stable pools, but the magnitude of change depended on the soil. Overall, the biochar was largely stable in each soil, with only 1.1 to 2.1% of the added biochar C emitted during incubation. There was no measurable effect of biochar amendment on the turnover of native SOM in any of the soils. Therefore, we conclude that amendment of our soils with switchgrass-derived biochar can effectively increase net C sequestration.

The incorporation of swine manure with tillage effectively reduces ammonia (NH3) emissions and conserves crop available nitrogen (N) but is not compatible with no-till and many other conservation tillage programs. Rolling-tine aerators potentially provide a means to enhance manure infiltration with limited disruption of the soil surface; however, the impact of the range of aerator configurations and manure placements has not been widely studied. We measured NH3 emissions, conducted presidedress nitrate (NO3) tests (PSNT), monitored corn (Zea mays L.) grain yield when swine manure was incorporated with combinations of two aerator toolbar offset angles (0° and 10°) and two manure placements (broadcast before aeration and banded behind aerator), and compared those measurements to unincorporated surface application and an unmanured control. Additional plots were established with five rates of mineral N fertilization to determine N response curve and estimate fertilizer N equivalent of the applied manure. Measurement of cumulative NH3 emissions using a dynamic chamber method showed that offsetting the aerator toolbar by 10° reduced emissions by 65% to 75%, with both manure placements, compared to surface application. However, no consistent reductions in NH3 emissions were observed when the toolbar was not offset. While reduction in NH3 with the offset toolbar could conserve substantial amounts of plant available N, the soil disturbance caused by the offset tines would not be compatible with most conservation tillage programs. Presidedress NO3 test values increased when NH3 emissions were reduced. In 2009, both the angled and straight aerator treatments with manure banded behind the aerator resulted in significantly higher corn grain yield than all other treatments despite reductions in NH3 emissions only when the toolbar was angled. Correlation of yield from manure application treatments with the N response curve for multiple mineral N application rates showed a greater than expected response to manure application. Yield responses are an indication that aeration has benefits in addition to N conservation. We do not recommend the rolling-tine aerator if reducing NH3 emissions in conservation tillage is the primary goal, but future study into other yield-increasing benefits of aeration is needed.

The efficient use of water and nitrogen represents a primary concern to agricultural production in Northwest China. A 2-year field experiment was conducted to assess the separation of nitrogen (N) fertilizer and irrigation water with alternating furrow irrigation (SNWAFI) in a maize (Zea mays L.) production system. Irrigation water use efficiency and nitrogen use efficiency with SNWAFI were generally greater than with conventional irrigation and fertilization (CIF). Response surfaces indicated that maximum maize yields were obtained with 238 kg urea-N ha−1 and 106 mm irrigation water in 2008 and 244 kg urea-N ha−1 and 95 mm of irrigation water in 2009. When the predicted yields were highest (6,384 and 6,549 kg ha−1), water use efficiency, N uptake, and N use efficiency were greater with SNWAFI than CIF. Conversely, soil NO3–N change during maize growing season decreased with SNWAFI compared CIF. With SNWAFI, optimizing irrigation water and N fertilizer rates can maximize yield, save irrigation water, and reduce N leaching.

Management decisions both at the field and off-site have the potential to contrib- ute to climate change mitigation and adaptation. Climate change threatens to increase the potential for soil erosion, reduce soil quality, lower agricultural productivity and negatively impact food security and global sustainability, making it one of the most severe challenges we will face in the 21st century. This paper looks at the potential of management to help us, not only mitigate climate change, but also to help us adapt to a changing climate. Different aspects of carbon management, nitrogen management, manure management, management in low-input systems (sustainable agriculture), and grazing land management are discussed as examples. Management decisions regarding conservation practices, such as no-till, con- servation agriculture, and returning crop residue to the field to increase nutrient cycling, can contribute to carbon sequestration and help us mitigate and adapt to climate change. Additionally, management of grasslands, restoration of degraded/desertified lands, nitrogen management to reduce greenhouse gas emissions, precision conservation management at a field and/or watershed level, and other management alternatives can also help us mitigate and/or adapt to climate change. Management for climate change mitigation and adaptation is key for environmental conservation, sustainability of cropping systems, soil and water quality, and food security. This paper suggests, based on a review of the literature, that management decisions that reduce soil erosion, increase carbon sequestration to improve soil functions, soil quality, and soil health, and contribute to the resilience of soils and cropping systems will be needed to respond to climate change and related challenges such as food security. Our review suggests that without management decisions that increase soil and water conservation, food security for the world's growing population will be harder to achieve.

Climate change is expected to increase the intensity of precipitation, but our ability to model the consequences for soil respiration are limited by a lack of data from soils that are saturated and draining. In this study, we used large intact soil columns (28 × 30 cm) to 1) quantify changes in CO 2 flux as soils drain from saturated conditions, and 2) to determine which soil water metrics best predict instantaneous maximum CO 2 flux. The columns were from three agricultural landscape positions that vary in soil properties. We simulated water table fluctuations that were observed at the field site (and predicted to increase in future climate scenarios) by flooding the columns from bottom to surface and then allowing the columns to drain for 96 h while monitoring volumetric soil water content (VWC), water filled pore space (WFPS), water content normalized to field capacity, matric potential, and CO 2 flux. Mean cumulative CO 2 flux was 4649 mg CO 2 ―C m − 2 96 h − 1 . Regardless of landscape position, CO 2 flux rates exhibited a single maximum slightly below saturation, near field capacity. This result suggests that many field studies have not captured soil respiration rates when water availability is optimum for heterotrophic respiration. Across landscape positions, matric potential was the most consistent indicator of instantaneous maximum CO 2 flux, with maximum fluxes occurring within the narrow range of − 0.15 to − 4.89 kPa. In contrast, instantaneous maximum CO 2 flux rates occurred between 95 and 131% of water content normalized to field capacity, 72–97% WFPS, and 29–45% VWC. Thus, our data suggest that instantaneous maximum CO 2 flux rates, a key parameter in ecosystem models, can be predicted across an agricultural landscape with diverse soils if matric potential is used as a water scalar.

Anticipated increases in precipitation intensity due to climate change may affect hydrological controls on soil N 2 O fluxes, resulting in a feedback between climate change and soil greenhouse gas emissions. We evaluated soil hydrologic controls on N 2 O emissions during experimental water table fluctuations in large, intact soil columns amended with 100 kg ha -1 -KNO 3 -N. Soil columns were collected from three landscape positions that vary in hydrological and biogeochemical properties (N = 12 columns). We flooded columns from bottom to surface to simulate water table fluctuations that are typical for this site, and expected to increase given future climate change scenarios. After the soil was saturated to the surface, we allowed the columns to drain freely while monitoring volumetric soil water content, matric potential and N 2 O emissions over 96 h. Across all landscape positions and replicate soil columns, there was a positive linear relationship between total soil N and the log of cumulative N 2 O emissions (r 2 = 0.47; P = 0.013). Within individual soil columns, N 2 O flux was a Gaussian function of water-filled pore space (WFPS) during drainage (mean r 2 = 0.90). However, instantaneous maximum N 2 O flux rates did not occur at a consistent WFPS, ranging from 63% to 98% WFPS across landscape positions and replicate soil columns. In contrast, instantaneous maximum N 2 O flux rates occurred within a narrow range (-1.88 to -4.48 kPa) of soil matric potential that approximated field capacity. The relatively consistent relationship between maximum N 2 O flux rates and matric potential indicates that water filled pore size is an important factor affecting soil N 2 O fluxes. These data demonstrate that matric potential is the strongest predictor of the timing of N 2 O fluxes across soils that differ in texture, structure and bulk density.

Oxidation of soils with 333 mM potassium permanganate (KMnO4) has been identified as a means to quantify labile soil carbon (C) and may have potential for rapid measurement of biologically active soil C. In the current study, active C pools in several soils were estimated by oxidation with a range of KMnO4 concentrations and compared to estimates determined from carbon dioxide evolution during 28‐d incubations. Digestion with 333 mM KMnO4 identified larger active C pools than did incubation data. However, shaking soils for 15 min with 2.5 mM KMnO4 provided estimates of active C that accounted for 1.5 to 1.9% of the total C pools and were not significantly different than those estimated using incubation data. Oxidation with dilute KMnO4 appears to be feasible to rapidly quantify active soil C pools. However, measurements are dependent on KMnO4 concentration and shaking time, so great care is needed to assure consistent results. This article is not subject to U.S. copyright law.

Different positions within soil macroaggregates, and macroaggregates of different sizes, have different chemical and physical properties which could affect microbial growth and interactions among taxa. The hypothesis that these soil aggregate fractions contain different eubacterial communities was tested using terminal restriction fragment length polymorphism (T-RFLP) of the 16S ribosomal gene. Communities were characterized from two field experiments, located at the Kellogg Biological Station (KBS), MI, USA and the Ohio Agricultural Research and Development Center (OARDC), Wooster, OH, USA. Three soil management regimes at each site were sampled and management was found to significantly affect T-RFLP profiles. The soil aggregate erosion (SAE) method was used to isolate aggregate regions (external and internal regions). Differences between eubacterial T-RFLP profiles of aggregate exteriors and interiors were marginally significant at KBS (accounting for 12.5% of total profile variance), and not significant at OARDC. There were no significant differences among macroaggregate size classes at either site. These results are in general agreement with previous studies using molecular methods to examine microbial communities among different soil macroaggregate size fractions, although further study of communities within different aggregate regions is warranted. Analysis of individual macroaggregates revealed large inter-aggregate variability in community structure. Hence the tertiary components of soil structure, e.g. arrangement of aggregates in relation to shoot residue, roots, macropores, etc., may be more important than aggregate size or intra-aggregate regions in the determination of the types of microbial communities present in aggregates. Direct microscopic counts were also used to examine the bacterial population size in aggregate regions at KBS. The proportion of bacterial cells with biovolumes O0.18 mm 3 was higher in aggregate interiors than in exteriors, indicating potentially higher activity in that environment. This proportion was significantly related to percent C of the samples, while total bacterial cell counts were not. q 2005 Elsevier Ltd. All rights reserved.

The availability of N limits productivity in tallgrass prairie. Spring burning is common because it results in greater plant productivity despite reducing net N mineralization. To better explain how burning affects inorganic N availability in tallgrass prairie, the partitioning of 15N among plant and soil pools was measured in June and August 1994. Approximately 2.5 microgram N g(-1) soil was injected as either NH4 or NO3 to a depth of 15 cm within cores in burned and unburned prairie. Cores were removed from the field 6 d after injection, and 15N recovery in plant and soil N pools was determined. No more than 14% of the applied 15N remained in inorganic form 6 d after application. The largest portion of the applied 15N (35-80%) was recovered in the soil organic nitrogen pool (N(o)). Burning significantly increased the immobilization of both NH4 and NO3 within N(o), and microbial biomass accounted for greater than or equal to 50% of the 15N recovered in N(o). Accumulation of 15N in plants accounted for less than or equal to 35% of the applied 15N with a majority recovered from roots. Burning had little effect on 15N recovery in plants; however, 15N accumulations in roots were significantly greater when NO3 was used. Results indicate that immobilization within soil organic matter (SOM) controls the availability of both NH4 and NO3 to plants. Increased immobilization in soils with burning probably results largely from increased microbial N demand resulting from greater litter inputs with wider C to N ratios. Further research is needed to determine if abiotic mechanisms for N immobilization also significantly influence N availability in prairie soils.

Soils with excessive phosphorus (P) levels due to manure application are an environmental concern because water extractable P (WEP) in runoff from these soils can contribute to increased amounts P in surface water, which can contribute to eutrophication of freshwater. Phosphorus based manure management is an option to reduce WEP and thereby reduce agricultural P runoff. In P based manure management, manure is applied to meet the P needs of a crop or not to exceed a given soil test level. Because P base manure management does not supply enough nitrogen (N) to meet the needs of the crop, addition fertilizer N needs to be applied. Fertilizer N applied to soils may increase the rate of mineralization of organic matter and lowers soil pH and therefore may affect the solubility of soil inorganic and organic P pools. The extent to which this may affect WEP or plant P availability is not known. Thus, laboratory and greenhouse studies were conducted to determine the effects of P based manure management on WEP and ...

Microbial biomass and enzyme activities are affected by management practices and can be used as sensitive indicators of ecological stability. Microbial biomass C (MBC), microbial biomass N (MBN) and eight enzyme activities involved in the cycling of C, N, P and S were studied in the surface (0–5 cm) of an Irwin silty clay loam soil (fine, mixed, mesic, Pachic Arguistoll) in a tallgrass prairie ecosystem. Treatments of annual spring burning and N fertilization were initiated in 1986 and encompassed: (1) unburned–unfertilized, (2) burned–unfertilized, (3) burned–fertilized, and (4) unburned–fertilized. Activities of dehydrogenase, β-glucosidase, urease, deaminase, denitrifying enzyme, acid phosphatase, alkaline phosphatase, and arylsulfatase were assayed. Long-term burning and N fertilization of the tallgrass prairie soil reduced MBC and MBN relative to the unburned–unfertilized treatment. The effects of burning and N fertilization varied among the enzymes and the time of sampling. Long-term burning significantly (P

The biodegradation of organic carbon drives biogeochemical cycles. Incubations of water soluble organic carbon (WSOC) are popular tests for determining the amount of readily biodegradable organic carbon. However, tests differ in length of incubation, filtration prior to incubation, and method of incubation. We compared the fraction of biodegradable water soluble organic carbon (BWSOC) in soil by varying these factors. With all combinations, WSOC decreased to a minimum during the first 6 days then consistently increased at the later stages of the incubation. The mean BWSOC content of the soils ranged from 0.13 to 3.54, and depended on the length of the incubation and the combination of filters used before and after incubation. Similar amounts of BWSOC were measured during aerobic and anaerobic incubations.

Sustainable nutrient management requires redistribution of livestock manure from nutrient-excess areas to nutrient-deficit areas. Field experiments were conducted to assess agronomic (i.e., corn yield) and environmental (i.e., ammonia volatilization and surface nutrient loss) effects of different poultry litter application methods (surface vs. subsurface) and timings (fall vs. spring) in a potential manure-importing region in the Chesapeake Bay Watershed in the United States. All four litter treatments (205 kg nitrogen ha-1) produced grain yields (10.9–12.8 Mg ha-1) nearly equivalent to or higher than the 11.5 Mg ha-1 yield expected from the same mineral nitrogen rate. Compared with surface application, subsurface application significantly reduced ammonia emission (p < 0.0001), runoff volume (fall: p = 0.02; spring: p = 0.004), and loads of nitrate nitrogen (p < 0.0001; p = 0.003) and dissolved phosphorus (p < 0.0001; p = 0.004) soon after application. Integrating subsurface manure application technologies into the manure redistribution programs would help ensure that the surplus nutrients being relocated provide a maximum agronomic impact and minimum environmental impact to the importing region. J. Liu and D.B. Beegle, Dep. of Plant Science, Pennsylvania State Univ., University Park, PA 16802, USA; P.J.A. Kleinman, C.J. Dell, T.L. Veith, L.S. Saporito, and R.B. Bryant, Pasture Systems and Watershed Management Research Unit, USDA-ARS, University Park, PA 16802, USA; K. Han, State Key Laboratory of Crop Biology, Key Laboratory of Crop Water Physiology and Drought-tolerance Germplasm Improvement, College of Agronomic Sciences, Shandong Agricultural Univ., Tai’an, Shandong 271018, China; D.H. Pote, Dale Bumpers Small Farms Research Center, USDA-ARS, Booneville, AR 72927, USA. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. USDA is an equal opportunity provider and employer. Core Ideas • Manure redistribution adds fertility benefits to recipient fields. • Subsurface application of poultry litter has environmental benefits. • Redistribution plus subsurface application benefits both farmers and the environment. Published February 12, 2016