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Wind erosion and variable weather challenge crop production in the northern Great Plains. Management that increases residue cover might mitigate wind erosion during the cash crop growing season. We evaluated horizontal sediment flux (modified Wilson and Cooke samplers) and cash crop yield across a single rotation of corn (Zea mays L.)–soybean (Glycine max (L.) Merr.)–spring wheat (Triticum aestivum L.) in paired fields with contrasting management. One field included cover crops and retained spring wheat straw (aspirational), while the other excluded both conservation practices over the 3‐year rotation (business‐as‐usual). Horizontal sediment flux rapidly decreased with days after cash crop planting (increasing crop canopy), regardless of management treatment. In 2 years (2020 corn and 2022 spring wheat), there was greater horizontal sediment flux, lower cash crop grain yield, and lower cash crop aboveground biomass in the aspirational versus business‐as‐usual field. In 2021 soybean, there was lower horizontal sediment flux, greater cash crop yield, and greater cash crop aboveground biomass in the aspirational versus business‐as‐usual field. Higher yield and lower horizontal sediment flux responses corresponded with the management treatment that produced the higher cash crop aboveground biomass. Additionally, our short‐term study indicated that in drought years, cover crops worsened the adverse effects of abnormally low precipitation on yield and biomass of 2020 corn but not 2021 soybean. Core Ideas: Sediment mass flux and grain yield were measured in response to cover cropping and wheat straw management.Horizontal sediment flux rapidly decreased with canopy development, regardless of management treatment.During drought, cover crops decreased yield and biomass of corn but not soybean.Conservation practices treatment had lower horizontal sediment flux in 2021 soybean, but not in 2020 or 2022. [ABSTRACT FROM AUTHOR]

Over the past 30 years, agricultural land use in the northern Great Plains has negatively affected soil health and associated ecosystem services through grassland conversion to cropland and a transition away from small‐grain cropping systems to warm‐season crops. Mitigating these effects requires adoption of conservation practices, but information about how conservation practices influence on soil condition and function are needed. This study sought to quantify near‐surface soil responses to crop diversity and intensity, cover crops, and livestock integration under controlled experimental conditions, and land use (dryland cropping vs. perennial agroecosystems) on working farms and ranches, all on a common Haplustoll soil in southcentral North Dakota, USA. Among dryland cropping practices, diverse, continuous cropping led to improvements in soil structure, nutrient supply potential, and biological habitat, but increased soil acidification and soil NO3–N accumulation. Cover crops had a negligible effect on soil condition and function, while livestock integration on cropland improved nutrient supply potential and biological habitat but impaired water intake into soil. Relative to dryland cropping, soil conditions and functions were consistently improved under perennial agroecosystems. Retention of perennial agroecosystems and adoption of diverse, nutrient‐efficient dryland cropping practices should be prioritized to enhance soil health in the northern Great Plains. Core Ideas: Conservation practices on croplands are needed in the northern Great Plains.Soil assessments were conducted on long‐term experiments and on‐farm research sites.Soil functions under cropland were impaired compared with perennial agroecosystems.Increased crop diversity and intensity improved soil quality indices and grain yield.Cropland conservation practices can create tradeoffs in soil function. [ABSTRACT FROM AUTHOR]

Coal surface mining in northern Great Plains USA led to reclamation experiments with soil respreading. Respread soil depth (RSD) and runoff of water redistribution (WR) effects interacted in original North Dakota studies, complicating interpretations. We determined WR and soil depth/soil quality (SQ) effects on hillslope production patterns for sites with soil wedges (2%–5% slope, 50-m length) over sodic mine spoils. At Zap, cool-season forages crested wheatgrass (CWG: Agropyron cristatum) and Russian wildrye (Psathyrostachys juncea) generally decreased as RSD increased upslope. At Stanton, alfalfa (Medicago sativa), native grasses (Bouteloua spp.), and CWG responded to RSD, increasing 70% to midslope and decreasing further. A SQ index (SQI) based on six indicator properties was highly correlated (r > 0.7) with RSD. Yield regressions with RSD or SQI were generally significant for Stanton forages and for spring wheat (Triticum aestivum) at both sites. Yield regressions with WR index (catchment area-based) indicated dominance of WR effects at Zap. Cool-season forages at Zap evidently responded to springtime runoff, while Stanton forages and spring wheat at both sites used water later in the season and responded to soil depth/SQ effects. Results suggest models for interaction of SQ and landform WR affecting productivity should include plant community composition and water-use information. [ABSTRACT FROM AUTHOR]

Long-term use of nitrogen (N) fertilizers can lead to fertility-lowering soil chemical changes. To examine this in geologically young soils in the northern Great Plains of North America, we present near-surface (0–7.6 cm) soil chemistry data from 16 years of two crop rotations: continuous crop (CC; spring wheat [Triticum aestivumL.]—winter wheat [T. aestivum]—sunflower [Helianthus annuusL.]) and crop-fallow (C-F; spring wheat—fallow) that underwent factorial tillage (none, minimum, conventional) and N rate (low, medium, high) treatments. For CC, the N rate (but not tillage) had a significant effect on pH, with the high N rate leading to the largest pH decline (−0.76). The nitrogen rate also had a significant effect on cation exchange capacity (CEC) for CC, whereby CEC increased with the N rate. Managers utilizing high N rates should be aware of the potential for soil acidification, even in the northern Great Plains of North America. [ABSTRACT FROM AUTHOR]

In the northern Great Plains (NGP) of North America, surface sampling depths of 0 to 15 or 0 to 20 cm are suggested for testing soil characteristics such as pH. However, acidification is often most pronounced near the soil surface. Thus, sampling deeper can potentially dilute (increase) pH measurements and therefore change management recommendations. Here, we show evidence from two long-term (16-19 yr) dryland cropping experiments that soil acidification at 0 to 7.6 cm was notably diluted at both 0 to 15.2 and 0 to 30.5 cm. There were significant differences among depths for both final pH and pH change over time, with final pH being progressively higher and pH change smaller at deeper depths. Even in the relatively young, highly buffered NGP soils, acidification can occur and sampling depth for testing pH could be an important confounding factor. We suggest sampling soils at depths <8 cm for testing pH in the NGP. [ABSTRACT FROM AUTHOR]

Emphasis is placed on developing robust, productive, economically competitive, and environmentally benign agroecosystems. In 2012, after 18 yr of a study to evaluate the effects of crop sequence and tillage, we measured soil properties at various depths to 91.4 cm and estimated soil C. The experiment, near Mandan, ND, was a split-plot design, with crop sequence as whole plots and tillage (minimum tillage or no-till) as subplots. Crop sequences included continuous spring wheat (Triticum aestivum L.) with crop residue retained or removed, spring wheat--millet [Setaria italica (L.) Beauv.], spring wheat--safflower (Carthamus tinctorius L.)--fallow, spring wheat--safflower--rye (Secale cereale L.) and spring wheat--fallow. Soil organic C, calculated by the equivalent mass method (SOCem), was consistently higher (P < 0.001) than when calculated by the fixed-depth method. Disparities between the two methods, greatest near the soil surface, were attributable to tillage. Estimates of SOCem were not affected by cropping sequence at any depth, averaging about 26, 47, 73, 114 and 156 Mg ha-1 in the 0- to 7.6-, 0- to 15.2-, 0- to 30.5-, 0- to 61.0-, and 0- to 91.4-cm partitions. Tillage had no influence at depths <30.5 cm, but no-till plots contained more SOCem than minimum tillage plots in the 0- to 61-cm (115 vs. 112 Mg ha-1 ) and 0-to 91.4-cm (158 vs. 153 2.3 Mg ha-1 ) partitions (P < 0.05). Soil organic C in the 0-to 7.6-cm depth increased by an average of 3.2 Mg ha-1 or 16% since 2001. This study suggests that C sequestration in soil is less impacted by the choice of crop sequence than by tillage. [ABSTRACT FROM AUTHOR]

The article describes how the long-term research site on native mixed-grass prairie is being leveraged for the future. Topics discussed include the start of the grazing experiment in 1915 on a native prairie that was hayed but never tilled, fertilized or planted and the need for long-term research to learn how to cope with and adapt to land use change and greenhouse gas emissions.

The article discusses the Area IV Soil Conservation Districts Cooperative Research Farm located near Mandan, North Dakota, U.S. Topics mentioned include the history and influence of one long-term cropping systems research in northern Great Plains to improve cropping system sustainability, the goals set by the Research Advisory Committee served as guide the past 30 years, and the major accomplishments such as management practices to reduce soil erosion.

Highlights: [•] Soil quality and productivity of alluvial-derived and glacial till-derived soils were compared. [•] Glacial till-derived soil had higher organic C, but soil quality index was similar for the soils. [•] Soil productivity was observed by crop sequence trials using maize, wheat, and pea. [•] Maize yield on glacial till-derived soil was lower because of much less drainable subsoil. [•] But spring wheat yield over 3 years was higher on glacial till compared to alluvial soil. [Copyright &y& Elsevier]

Assessing effects of cropping systems on soil organic mater (SOM) and soil carbon (C) changes are necessary to make accurate projections regarding sequestration and emission of CO[sub 2] by agricultural soils. This process requires substantial annual management inputs and large outlays for soil sampling and analyses. Our objectives were (1) to evaluate and test an alternative method for soil organic matter determination, (2) to determine if crop rotation and N fertilizer management significantly affected soil organic matter at the beginning (1986) or after 12 yrs (1998), and (3) to determine if total soil organic matter levels have changed after 12 years in a long-term cropping system study. Soil samples were taken in 1986 and 1998 to a depth of 150 cm in 30cm increments. Total soil organic C and organic matter by weight loss-on-ignition concentrations were determined for the soil samples taken in 1998. Results from both methods of analyses for the 1998 samples were highly correlated. No significant differences in soil organic matter by weight loss-onignition or total soil organic C concentrations between crop rotations or nitrogen (N) fertilizer rates were obtained for either sampling date, in the change in soil organic matter concentrations between dates, or total soil C amounts in the profile (0 to 150 cm) after 12 yrs (1998). Although no differences in soil organic matter (soil C) were obtained in the study, the excellent correlation between results of the two methods of organic matter analyses demonstrates that the less expensive and easier to use weight losson-ignition method can be used to make these types of assessments. [ABSTRACT FROM AUTHOR]

Presents a study which evaluated the four approaches to point-scale assessment of soil quality. Materials and methods; Description of assessment approaches; Development of data classes; Comparison of the assessment approaches; Results and discussion.

Presents information on a study which evaluated the farmers' perceptions of soil quality indicators. Materials and methods; Results; Discussion. INSET: Consumers Union Finds `Unacceptable' Pesticide Levels for....

During periods of no or low crop growth in dryland cropping systems, tillage can reduce residue coverage and thereby elevate wind erosion risk. We measured wind erosion on a silt loam, Haplustoll soil in North Dakota (456 mm precipitation yr–1) in response to levels of tillage applied once in spring during fallow following a small grain–sunflower (Helianthus annuus L.) rotation. Treatments were no‐tillage (NT), one‐pass tandem disk tillage (TDT), and two‐pass offset disk tillage (ODT). Erosion flux was measured with sediment samplers near peripheries of >1‐ha replicated plots from May through September 2003 and 2004. Soil losses in ODT, TDT, and NT were 12.0, 4.8, and 2.1 Mg ha–1, respectively, in 2003 and 2.6, 1.6, and 1.4 Mg ha–1 in 2004. The greatest loss, 12.0 Mg ha–1, was equivalent to 1‐mm soil depth. The two‐ to fivefold greater erosion in 2003, a year with 2 mo of <30% of average precipitation, appears linked to a decline in residue coverage. Coverage remained about the same in NT and increased in tilled treatments during 2004 with more average precipitation. Our measurements of wind erosion have shown how the residue‐destroying effects of a single tillage event can be considerably exacerbated by a moderate, seasonal drought. This indicates the critical importance of NT for limiting soil and residue disturbance and reducing wind erosion risk from drought‐affected plant growth failure in semiarid cropping systems. Core Ideas: Wind erosion loss was two‐ to sixfold greater under disk tillage than no‐tillage.Seasonal drought led to less weed growth and residue coverage.Seasonal drought resulted in two‐ to fivefold greater wind erosion loss.The Revised Wind Erosion Equation (RWEQ) model indicated that residue coverage conferred the greatest resistance to erosion. [ABSTRACT FROM AUTHOR]

Conservation agriculture is often assumed to reduce soil N2O emissions. Yet, studies analyzing the specific effect of conservation agriculture practices on N2O emissions give contradictory results. Herein, we synthesized a comprehensive database on the three main conservation agriculture practices (cover crops, diversified crop rotations, and no-till and/or reduced tillage (NT/RT)) to elucidate the role of conservation practices on N2O emissions. Further, we used a random meta-forest approach to identify the most important predictors of the effects of these practices on soil N2O emissions. Averaged across all comparisons, NT/RT significantly decreased soil N2O emissions by 11% (95% CI: –19 to –1%) compared to conventional tillage. The reductions due to NT/RT were more commonly observed in humid climates and in soils with an initial carbon content < 20 g kg–1. The implementation of cover crops and diversified crop rotations led to variable effects on soil N2O emissions. Cover crops were more likely to reduce soil N2O emissions at neutral soil pH, and in soils with intermediate carbon (~20 g kg–1) and nitrogen (~3 g kg–1) contents. Diversified crop rotations tended to increase soil N2O emissions in temperate regions and neutral to alkaline soils. Our results provide a comprehensive predictive framework to understand the conditions in which the adoption of various conservation agriculture practices can contribute to climate change mitigation. Combining these results with a similar mechanistic understanding of conservation agriculture impacts on ecosystem services and crop production will pave the way for a wider adoption globally of these management practices. [ABSTRACT FROM AUTHOR]

In semiarid dryland farming regions, No-till and intensified crop rotations may improve water use. Our objective was to determine water use efficiency (WUE) and precipitation use efficiency (PUE) for spring wheat (Triticum aestivum L.; SW) grown in crop sequences representing different levels of intensification, under minimum (Min-till) or No-till. Root zone (0-122 cm) water at planting (SWP) was 2.76 cm higher for two- and three-phase sequences under Min-till than continuous spring wheat (CSW), and sequences with fallow averaged 2.65 cm higher than those without. Conversely, SWP was unaffected by sequence under No-till, with less effect of fallow. Root zone water at harvest was unaffected by the number of crop phases or fallow under Min-till. However, values for CSW exceeded the two- or three-phase sequences by 1.57 and 2.53 cm under No-till, and sequences without fallow averaged 1.52 cm more than those with fallow. The highest WUE (8.4 kg grain ha-1 mm-1 water) was observed when SW was grown in three-phase sequences compared with 7.7 kg grain ha-1 mm-1 water, for CSW and SW-fallow. Spring wheat under Min-till had higher WUE in sequences with fallow, but no effects of fallow occurred with No-till. The lowest PUE (near 3 kg grain ha-1 mm-1 precipitation) and no effects of tillage were found in sequences with fallow. However, SW in continuously cropped sequences had PUE between 5.5 and 6.4 kg grain ha-1 mm-1 precipitation and was higher under No-till. Both WUE and PUE are affected by intensification but may also be influenced by patterns of weather.

Understanding controls on soil organic carbon (SOC) will be crucial to managing soils for climate change mitigation and food security. Climate exerts an overarching influence on SOC, affecting both carbon (C) inputs to soil and soil physicochemical properties participating in C retention. To test our hypothesis that climate, C inputs, and soil properties would differently affect particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), we sampled 16 agricultural sites (n = 124 plots) in the United States, ranging in climate (mean annual precipitation (MAP)—potential evapotranspiration (PET; MAP-PET)), soil pH (5.8–7.9), and soil texture (silt + clay = 13–96%). As MAP-PET increased, soils increased in oxalate-extractable iron (FeO) and aluminum (AlO), decreased in exchangeable calcium (Caex) and magnesium (Mgex), and received greater C inputs. Soil physicochemical properties did not strongly predict POC, confirming the relative independence of this SOC fraction from the soil matrix. In contrast, MAOC was well predicted by combining AlO + [1/2]FeO with Caex + Mgex in a 'matrix capacity index', which performed better than individual soil physicochemical properties across all pH levels (r > 0.79). Structural equation modeling indicated a similar total effect of MAP-PET on MAOC and POC, which was mediated by total C inputs and the matrix capacity index for MAOC but not POC. Our results emphasize the need to separately conceptualize controls on MAOC and POC and justify the use of a unified soil matrix capacity index for predicting soil MAOC storage. [ABSTRACT FROM AUTHOR]

Integrated crop–livestock (ICL) systems have shown potential to provide a variety of environmental benefits including soil carbon (C) increases relative to conventional row cropping systems. However, studies documenting C dynamics of ICL systems in the northern Great Plains are lacking relative to other agroecosystems. Soil carbon dioxide (CO2) efflux, crop biomass, and soil organic matter (SOM) pools were monitored over 3 years in an ICL rotation (corn [Zea mays L.]/soybean [Glycine max L.]–spring wheat [Triticum aestivum L.] + cover crop–cover crop) with fall grazing, a conventional cropping system rotation (corn–spring wheat–soybean) and fall grazed and ungrazed mixed‐grass pasture near Mandan, ND. Cropped treatments were under no‐till management. Annual aboveground crop residue biomass C was similar in the ICL and conventional systems, while less in the grazed pasture (4.18, 3.83, and 1.21 Mg C ha−1 year−1 respectively; p = 0.039). Annual soil CO2 efflux was greater in the ICL, grazed, and ungrazed pasture systems than the conventional system (8.05, 8.73, 8.25, and 5.81 Mg C ha−1 year−1, respectively; p < 0.001). Among crop phases in the ICL and conventional cropping systems, cover crops contributed to greater CO2 efflux in the spring and fall. SOM and C mineralization were greater at 0–5 cm in the ICL system compared to the conventional cropping system (6.6% vs. 6.3%, p = 0.028 and 248 vs. 184 mg CO2–C kg−1, p < 0.001, respectively). Interseeded cover crops in ICL systems can contribute increased root respiration and enhanced SOM pools relative to conventional cropping systems under semiarid conditions. Core Ideas: Soil carbon (C) dynamics in integrated crop–livestock (ICL) systems are not well understood.Soil carbon dioxide (CO2) efflux and labile pools of soil organic matter (SOM) were evaluated over 3 years.Soil CO2 efflux was greater in the ICL system compared to conventional cropping.SOM and C mineralization were also greater in the ICL system compared to conventional cropping.Interseeded cover crops in ICL systems can enhance soil C pools and biological activity. [ABSTRACT FROM AUTHOR]

Soil archives preserve a snapshot of soils from a specific time and location, allowing researchers to re‐evaluate soils of the past in the context of the present for an improved understanding of long‐term soil change. To date, the extent of soil archive use in the peer‐reviewed literature is poorly inventoried. Here, we document the characteristics and distribution of global soil archive use, as found in 245 publications, following an exhaustive search of English language journals. Soil archive use has increased substantially since 1980, reaching 59 publications between 2016 and 2020. The age of soil archives across the compilation ranged from 5 to 160 yr, with mean and median archive ages of 48 and 37 yr, respectively. Publications using soil archives originated mostly from countries in the northern hemisphere, with the top five reporting countries including the United States (61), United Kingdom (52), New Zealand (21), Canada (18), and China (14). Land uses associated with soil archive publications were dominated by agroecosystems, specifically land planted to annual crops. Forty‐seven percent of investigations focused on changes in soil C, N, or organic matter, whereas investigations of other subjects did not exceed 20% each. The compilation is publicly available online. As demands on soils increase, archives will serve as an invaluable tool for understanding long‐term soil change in the Anthropocene era. Multiregional coordination and increased investment in curation and retention of soil archives are recommended to preserve these irreplaceable resources. Core Ideas: Archived soil samples facilitate an improved understanding of long‐term soil change.A literature review was conducted to compile metadata documenting soil archive use.Since 1980, there has been an accelerating use of soil archives in research.Research is primarily focused on soil organic matter change in agroecosystems.Resources are needed to support soil archives, especially in developing countries. [ABSTRACT FROM AUTHOR]

Rigorous economic analyses are crucial for the successful launch of lignocellulosic bioenergy facilities in 2014 and beyond. Our objectives are to (1) introduce readers to a query tool developed to use data downloaded from the Agricultural Research Service (ARS) REAPnet for constructing enterprise budgets and (2) demonstrate the use of the query tool with REAPnet data from two field research sites (Ames, IA, and Mandan, ND) for evaluating short-term economic performance of various biofuel feedstock production strategies. Our results for both sites showed that short-term (<3 years) impacts on grain profitability were lower at lower average annual crop residue removal rates. However, it will be important to monitor longer term changes to see if grain profitability declines over time and if biomass harvest degrades soil resources. Analyses for Iowa showed short-term breakeven field-edge biomass prices of $26-$42 Mg among the most efficient strategies, while results for North Dakota showed breakeven prices of $54-$73 Mg. We suggest that development of the data query tool is important because it helps illustrate several different soil and crop management strategies that could be used to provide sustainable feedstock supplies. [ABSTRACT FROM AUTHOR]

Abstract: Biologically derived emissions of carbon dioxide (CO2) and nitrous oxide (N2O) at 0 °C vary with soil depth during soil thawing. Micro-site soil properties, especially those which influence porosity and substrate availability, also vary with depth and may help explain gas emissions. Intact soil cores collected to a depth of 80 cm from an undisturbed prairie Mollisol in central North Dakota were uniformly subjected to distinct temperature steps during a simulated soil thaw (−15 to 5 °C) and sampled for CO2 and N2O emissions throughout the soil profile. Emission data were fit to a first order exponential equation (E = αe βT ). Cores were then analyzed in 10 cm depth increments for micro-site properties including root length and mass, aggregation, and organic substrate availability (available, aggregate-protected and mineral-bound pools). Both CO2 and N2O emissions at 0 °C declined exponentially with depth. Emissions of CO2 and N2O at 0 °C were strongly related to root length (R 2 = 0.80 and 0.76, respectively), root mass (R 2 = 0.56 and 0.74), large macroaggregate mass (R 2 = 0.63 and 0.54), and aggregate-protected organic matter (R 2 > 0.57), while available organic matter was related to CO2 (R 2 > 0.60) and not N2O. When CO2 and N2O emissions were normalized by available and aggregate-protected carbon pools, respectively, nutrient use efficiency increased significantly with depth. Results suggest CO2 and N2O emissions are (1) positively influenced by the rhizosphere and (2) differentially affected by substrate pool or location. CO2 emissions were more positively affected by available substrate, while N2O emissions were more positively affected by less labile, aggregate-protected substrate. [Copyright &y& Elsevier]

Abstract: The dynamic cropping systems concept proposes a long-term strategy of crop sequencing to achieve production, economic and soil care goals through sound ecological management. This requires that agriculturalists have comprehensive information about how crop species affect following years’ crops. Little research exists about how differences in soil type and properties change crop sequence effects. Sandy loam, alluvial-derived soil in south central North Dakota, USA (400mm/yr precipitation) was the site of a crop sequence experiment in which four species – maize (Zea mays L.), dry pea (Pisum sativum L.), spring wheat (Triticum aestivum L.), and soybean (Glycine max (L.) Merr.) – were grown in strips one year and in perpendicular strips the following, with spring wheat planted a third year. No-till management was used with three replications in land and two in time. Results were compared with those from two 10×10 sequence experiments on silt loam, glacial till-derived soil. Soil water depletion (SWD) and root growth were deeper in sandy loam soil than in silt loam. During a year of above average precipitation, prior year soybean enhanced spring wheat yield on sandy loam soil by 14% above average, but prior year spring wheat reduced it by 14%. During a year of deficient precipitation, prior crop effects on spring wheat yield ranked in order of expected springtime soil water storage: dry pea, 11%; spring wheat, 4%; soybean, −5%; maize, −10%. Prior crops’ SWD largely determined spring soil water, with maize having greatest depletion. Excluding results from a year of low precipitation, prior crops’ effects on spring wheat yield on sandy loam soil were similar to results found at two sequence experiments on silt loam soil: dry pea – generally positive effect (N-production, water conservation); spring wheat – negative (disease); soybean – positive (N-production); maize – generally negative (heavier water use). Same year comparison of three crops (nine sequences) on sandy loam soil vs. silt loam showed average dry pea and spring wheat yields being equivalent (P <0.10). However, average maize yield was 37% lower on silt loam, with maize-after-maize yielding 54% less. The site with sandy loam land had topsoil with lower soil quality indicators (organic C, water holding capacity) than silt loam. However, no-till management and previous grass rendered productivity of the soils equivalent, and superior capacity of the sandy loam site subsoil to conduct water and be conducive to root growth lessened negative, water-generated crop sequence effects. [Copyright &y& Elsevier]

Abstract: The fate of carbon (C) and nitrogen (N) belowground is important to current and future climate models as soils warm in northern latitudes. Currently, little is known about the sensitivity of microbial respiration to temperature changes at depths below 15 cm. We used whole-core (7.6 cm dia. × 90 cm) laboratory incubations to determine if temperature response quotients (Q 10) for CO2 and N2O varied with depth for undisturbed prairie while plants were senescent and clipped at the surface. We collected intact soil cores from an undisturbed prairie in central North Dakota and uniformly subjected them to freezing (5 to −15 °C) and thawing (−15 to 5 °C). We measured rates of CO2 and N2O emissions at 5 °C temperature increments at 0, 15, 30, 45, 60, and 75 cm depths. During freezing, active and sterilized core emissions occurred only between 0 and −10 °C. During thawing, a simple first-order exponential model, E = αeβT, fit observed CO2 and N2O emissions (R 2 = 0.91 and 0.99, respectively). Parameter estimates for β were not significantly different across depths for CO2 and for N2O (Q 10 = 4.8 and 13.7, respectively). Parameter estimates for α (emissions when temperature is 0 °C) exponentially declined with depth for both gases for similar depth-response curves. Stepwise regressions of soil properties on α parameter estimates indicated emissions of CO2 and N2O at 0 °C during thawing were positively correlated (R 2 > 0.6) with soil porosity. Results indicate pedogenic properties associated with depth may not necessarily influence temperature response curves during thawing but will affect emissions at 0 °C for both CO2 and N2O. [Copyright &y& Elsevier]

Woody plant expansion has been documented on grasslands worldwide as a result of overgrazing and fire suppression, but changes in ecosystem structure and function accompanying this phenomenon have yet to be extensively studied in the temperate semi-arid grasslands of North America. The primary objectives of this study were to determine the influence of woody plant expansion on soil carbon (C), soil nitrogen (N), and roots to a depth of 15 cm along a 42-year (1963–2005) chronosequence encompassing grassland, woodland, and transition zones in a northern Great Plains grassland. From these data, we also estimated ecosystem-level soil C and N changes associated with woody plant expansion in the top 0–15 cm of soil. We found total soil C increased across the chronosequence from grassland (5,070 ± 250 g C m−2) to woodland (6,370 ± 390 g C m−2) ( P < 0.05) at 0–15 cm soil depth. Total soil N also increased from grassland to woodland (425 ± 16 to 556 ± 30 g N m−2) ( P < 0.05) at 0–15 cm soil depth. Coarse particulate organic matter C and N increased from grassland to woodland (940 ± 100 to 598 ± 35 g C m−2, 70 ± 10 to 35 ± 1 g N m−2) at 0–5 cm soil depth. At the ecosystem-level, we estimate C and N accumulations at 0–15 cm soil depth are occurring at a rate of 18 and 1.7 g m−2 year-1, respectively. Results of this study suggest soil resources, namely soil C and N, in the northern Great Plains are changing following woody plant expansion. [ABSTRACT FROM AUTHOR]

Agricultural land management may influence crop nutritional quality. However, few studies have explored potential connections between crop quality with different land management strategies. We analyzed mineral and crude protein concentrations in spring wheat grain (Triticum aestivum L.) samples from a study in Mandan, ND conducted from 2006 to 2014. The study introduced a perennial forage phase into an annual spring wheat cropping system, in three to four replicates, and previously found yield benefits and enhanced soil parameters in the perennial forage treatments. We determined whether integrating a perennial forage phase into continuous wheat would also affect crop nutritional quality by measuring wheat grain mineral and protein concentrations. Crude protein concentration was greater (p <.05) when wheat followed alfalfa (Medicago sativa L.) and increased linearly after 2–5 yr of established alfalfa. We observed comparable wheat grain crude protein and mineral concentrations between continuous annually fertilized wheat and unfertilized wheat following perennial forages. Negative correlations (p <.001) were observed between wheat grain yield and crude protein, potassium (K), magnesium (Mg), nickel (Ni), phosphorus (P), sulfur (S), and zinc (Zn) concentrations. Discriminate multivariate analyses showed, with 96% predictive accuracy, that differences in crude protein and mineral concentration were largely driven by year of wheat harvest. Differences between harvest years were likely due to timely precipitation at critical Growth Stage 3, during spikelet development. Study outcomes highlighted the important role of perennial forages and environmental factors to influence protein and mineral concentration in spring wheat grain. Core Ideas: Perennial forages benefit annual cropping systems. Wheat grain samples were analyzed for mineral and protein concentration. Protein was greater when wheat followed alfalfa versus intermediate wheatgrass. Grain quality was similar between annual cropping and wheat following perennials. Grain mineral and protein concentrations were influenced by environmental factors. [ABSTRACT FROM AUTHOR]

This study evaluates the dynamics of soil organic carbon (SOC) under perennial crops across the globe. It quantifies the effect of change from annual to perennial crops and the subsequent temporal changes in SOC stocks during the perennial crop cycle. It also presents an empirical model to estimate changes in the SOC content under crops as a function of time, land use, and site characteristics. We used a harmonized global dataset containing paired‐comparison empirical values of SOC and different types of perennial crops (perennial grasses, palms, and woody plants) with different end uses: bioenergy, food, other bio‐products, and short rotation coppice. Salient outcomes include: a 20‐year period encompassing a change from annual to perennial crops led to an average 20% increase in SOC at 0–30 cm (6.0 ± 4.6 Mg/ha gain) and a total 10% increase over the 0–100 cm soil profile (5.7 ± 10.9 Mg/ha). A change from natural pasture to perennial crop decreased SOC stocks by 1% over 0–30 cm (−2.5 ± 4.2 Mg/ha) and 10% over 0–100 cm (−13.6 ± 8.9 Mg/ha). The effect of a land use change from forest to perennial crops did not show significant impacts, probably due to the limited number of plots; but the data indicated that while a 2% increase in SOC was observed at 0–30 cm (16.81 ± 55.1 Mg/ha), a decrease in 24% was observed at 30–100 cm (−40.1 ± 16.8 Mg/ha). Perennial crops generally accumulate SOC through time, especially woody crops; and temperature was the main driver explaining differences in SOC dynamics, followed by crop age, soil bulk density, clay content, and depth. We present empirical evidence showing that the FAO perennialization strategy is reasonable, underscoring the role of perennial crops as a useful component of climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

Simulation models quantify the impacts on carbon (C) and nitrogen (N) cycling in grassland systems caused by changes in management practices. To support agricultural policies, it is however important to contrast the responses of alternative models, which can differ greatly in their treatment of key processes and in their response to management. We applied eight biogeochemical models at five grassland sites (in France, New Zealand, Switzerland, United Kingdom and United States) to compare the sensitivity of modelled C and N fluxes to changes in the density of grazing animals (from 100% to 50% of the original livestock densities), also in combination with decreasing N fertilization levels (reduced to zero from the initial levels). Simulated multi-model median values indicated that input reduction would lead to an increase in the C sink strength (negative net ecosystem C exchange) in intensive grazing systems: −64 ± 74 g C m −2  yr −1 (animal density reduction) and −81 ± 74 g C m −2  yr −1 (N and animal density reduction), against the baseline of −30.5 ± 69.5 g C m −2  yr −1 (LSU [livestock units] ≥ 0.76 ha −1  yr −1 ). Simulations also indicated a strong effect of N fertilizer reduction on N fluxes, e.g. N 2 O-N emissions decreased from 0.34 ± 0.22 (baseline) to 0.1 ± 0.05 g N m −2  yr −1 (no N fertilization). Simulated decline in grazing intensity had only limited impact on the N balance. The simulated pattern of enteric methane emissions was dominated by high model-to-model variability. The reduction in simulated offtake (animal intake + cut biomass) led to a doubling in net primary production per animal (increased by 11.6 ± 8.1 t C LSU −1  yr −1 across sites). The highest N 2 O-N intensities (N 2 O-N/offtake) were simulated at mown and extensively grazed arid sites. We show the possibility of using grassland models to determine sound mitigation practices while quantifying the uncertainties associated with the simulated outputs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Replacing alfalfa hay with lespedeza pellets reduces urine N and increase fecal N. • Replacing alfalfa hay with lespedeza pellets reduces N, DM and fiber digestibility. • Only minute quantities of condensed tannins from lespedeza survive sheep digestion. • Feeding lespedeza pellets with alfalfa hay may reduce long-term growth of sheep. Abstract Sustainable ruminant livestock production could benefit from feedstuffs containing condensed tannin (CT) if they maintained or improved livestock health and productivity while reducing the excretion of urinary nitrogen (N), which can be readily lost to the environment. Such feedstuffs would be most useful if they were easy and inexpensive to grow and could be field dried and pelletized for ease of transport and storage. One feedstuff that may meet these criteria is pelleted sericea lespedeza (SL; Lespedeza cuneata). Therefore, a 4 × 4 Latin square trial was conducted with four mature male sheep fed four proportions of pelleted SL with alfalfa (Medicago sativa) hay cubes, to determine effects on digestion and N excretion, and the fate of the CT during digestion. Pelleted SL contained (g/kg dry matter; DM) 182 CT, 23.3N, 341 aNDF, 227 ADF, 87 ADL and 55 ash, while the cubed alfalfa hay contained (g/kg DM) 28.5N, 381 aNDF, 284 ADF, 78 ADL and 137 ash. The SL pellets were consumed readily, but increasing their proportion in the ration DM from 0 to 0.4 linearly decreased apparent digestibility of DM from 59.7 to 49.9% and N from 74.7 to 53.4%, with associated reductions in urinary N excretion. Evaluation with 1H-13C heteronuclear single quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopy detected trace amounts of intact CT in sheep feces and analysis of the feces from the 0.4 lespedeza pellet ration using the HCl-butanol-acetone-iron assay indicated that 96% of the CT had been modified into non-proanthocyanidin components. Fiber analysis conducted with and without sulfite indicated an accumulation of sulfite-resistant CT-protein complexes in feces which likely contributed to the reduction in digestibility of fiber and N. This study has shown that SL pellets reduced urinary N excretion and diverted feed N to feces, but their inclusion in the diet reduced the apparent digestibility of DM and N. Complexes of CT, protein and fiber were the main contributor to the poor digestibility of aNDF and ADF in diets containing SL pellets. Findings presented here suggest a potential negative effect of these SL pellets on long-term sheep productivity in contrast to short-term productivity improvements due to the ability of the SL pellets to reduce gastrointestinal parasite populations. [ABSTRACT FROM AUTHOR]

Many integrated crop-livestock system (ICL) studies have been conducted, but few report cattle performance and forage nutrients. Here, we report one year of cattle weight gains for Angus yearling heifers and steers grazing ICL plots (ICL) or tame grass pastures (PAS) in four replicates. Five yearlings (avg. BW 390 ± 26 kg) were randomly assigned to graze each plot while provided ad libitum water and trace mineral salt. Cattle assigned to ICL grazed three crop rotations: 1) corn interseeded with soybean (C/S), 2) spring wheat interseeded with cover crop and 3) cover crop planted into spring wheat from the previous year. Yearlings in ICL were stocked first on green C/S, grazing an average of 60 days. Beginning C/S biomass was 1,827 ± 638 g m-2, yearling end BW was 465 ± 34 kg and ADG 1.28 ± 0.27 kg. Yearlings then grazed residual cover crop growth, averaging additional 42 d grazing while supplemented with a ration of baled cover crop forage, wheat straw, and corn. Ration intake averaged 15.35 ±0.6 kg animal-1 d-1. Final BW of ICL yearlings on cover crops averaged 499 ± 34 kg, ADG of 0.79 ± 0.29 kg. Yearlings assigned PAS were provided 1,911 ± 162 g m-2 at the beginning of grazing for 69 days, had final BW 443 ± 35 kg, ADG of 1.01 ± 0.22. Forage nutrient analyses are reported in Table 1, showing that individual crops are similar in ADF and TDN, but vary in crude protein content. Performance of ICL cattle exceeded that of PAS while on corn and soybean but decreased ICL performance while grazing cover crop was likely due to extreme cold weather at the time of grazing. Nutrient values reported here can be used to plan and predict cattle growth while grazing crop residues instead of pastures. [ABSTRACT FROM AUTHOR]

Phenolic plant secondary metabolites actively participate in a broad range of important reactions that affect livestock, plants and soil. In soil, phenolic compounds can affect nutrient dynamics and mobility of metals but their role in northern Great Plains agroecosystems is largely unknown. We evaluated the effects of three phenolic compounds on plant nutrient extractability in agricultural soil. Soil samples (0–10 cm) from pasture and cropped sites near Mandan, North Dakota, USA were treated with water (control) or aqueous solutions of increasingly complex compounds; benzoic acid (BA), gallic acid (GA), or β -1,2,3,4,6-penta- O -galloyl- d -glucose (PGG) at four concentrations (1.25, 2.5, 5 or 10 mg compound gram −1 soil). We measured extractable nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and manganese (Mn) in treatment supernatants and after a subsequent incubation in hot water (16 h, 80 °C). While significant quantities of nitrogen were extracted with water, each compound reduced N extracted in a concentration dependent manner with greatest response to BA (about 25%). However, PGG reduced the solubility of N only during the hot water incubation, suggesting its effects are mostly on organic forms of N. Unlike N, GA and PGG increased extraction of P, relative to water, while BA had less effect. Extraction of the major cations, K, Ca, and Mg, was strongly increased by BA and GA but unaffected by PGG. Extraction of Mn was increased most by treatments of GA but less so by BA. The effects of PGG on Mn were consistent with GA when expressed on a molar basis. These findings suggest plant secondary compounds affect nutrient dynamics in soil, and thus may be part of future management strategies to improve nutrient-use efficiency. [ABSTRACT FROM AUTHOR]

Anecdotal accounts regarding reduced US cropping system diversity have raised concerns about negative impacts of increasingly homogeneous cropping systems. However, formal analyses to document such changes are lacking. Using US Agriculture Census data, which are collected every five years, we quantified crop species diversity from 1978 to 2012, for the contiguous US on a county level basis. We used Shannon diversity indices expressed as effective number of crop species (ENCS) to quantify crop diversity. We then evaluated changes in county-level crop diversity both nationally and for each of the eight Farm Resource Regions developed by the National Agriculture Statistics Service. During the 34 years we considered in our analyses, both national and regional ENCS changed. Nationally, crop diversity was lower in 2012 than in 1978. However, our analyses also revealed interesting trends between and within different Resource Regions. Overall, the Heartland Resource Region had the lowest crop diversity whereas the Fruitful Rim and Northern Crescent had the highest. In contrast to the other Resource Regions, the Mississippi Portal had significantly higher crop diversity in 2012 than in 1978. Also, within regions there were differences between counties in crop diversity. Spatial autocorrelation revealed clustering of low and high ENCS and this trend became stronger over time. These results show that, nationally counties have been clustering into areas of either low diversity or high diversity. Moreover, a significant trend of more counties shifting to lower rather than to higher crop diversity was detected. The clustering and shifting demonstrates a trend toward crop diversity loss and attendant homogenization of agricultural production systems, which could have far-reaching consequences for provision of ecosystem system services associated with agricultural systems as well as food system sustainability. [ABSTRACT FROM AUTHOR]

A correction is presented to the article "Perennial forages influence mineral and protein concentrations in annual wheat cropping systems."

The article reports on the necessity of management systems to improve soil quality and regenerate ecological processes. It is indicated that conserving and restoring soil can supply soil productivity and sustain environmental quality. The Agricultural Research Service (ARS) of the U.S. Department of Agriculture created the Greenhouse Gas Reduction through Agricultural Carbon Enhancement network (GRACEnet) to study soil C sequestration and greenhouse gas emissions.

Abstract: Satellite assessment of aboveground plant residue mass and quality is essential for agro-ecosystem management of organic nitrogen (N) because growers credit a portion of residue N towards crop requirements the following spring. Precision agriculture managers are calling for advanced satellite models to map field-scale residue mass and quality. Remote sensing has proven useful for assessing the concentration of foliar biochemicals under controlled laboratory conditions, but field-scale satellite model validation for quantitative, landscape-scale N assessment is needed. We addressed this problem by building ground-truth models for sugar beet N-credit and testing these models with alternate satellite sensor imagery. We recorded spectral reflectance and measured leaf carbon (C) and N in situ at leaf and canopy levels near the end of the growing season using 1nm bandwidth spectroradiometer. We performed univariate correlation analyses between spectral reflectance and the variables N, C:N ratio and biomass to determine spectral signature models for leaf quality and spectral signature models for plant biomass. The 1nm hyperspectral data were convolved to fit Landsat 5, SPOT 5, Quick-Bird 2, and Ikonos 2 multi-spectral satellite bands and models created using stepwise linear regression. Biomass formulae for each sensor were applied to satellite imagery acquired at peak season, while leaf quality formulae were applied to imagery acquired just prior to harvest. August sugar beet fields in the St. Thomas, ND vicinity were identified and aboveground biomass mapped with 10–20% error, depending upon the sensor. Sugar beet leaf N was similar for all sites and varieties tested (31mgg-1dw), so biomass primarily influenced N-credit estimates. Measured C:N ratio variability was identified and mapped to delineate areas where C:N ratio was outside the normal distribution. The general model for each sensor maps N-credit per unit area and delineates aberrant, low leaf quality areas as zones with high C:N ratio. In summary, we provide separate spectral models for N-credit and leaf quality applicable to available multi-spectral sensors for precision sugar beet N management. [Copyright &y& Elsevier]

There are concerns that restored grasslands currently under the Conservation Reserve Program (CRP) will experience increased soil erosion when they are returned to crop production. Our objective was to compare runoff, erosion, and erodibility on CRP land converted to annum hay production (permanent hayed, PH) and crop production under conventional-till (preplant disk tillage, CT) and no-till (NT) management. Erosion study was conducted in central North Dakota on Typic Argiustoll soil 6 yr after the CRP land had been converted to hay production and crop production with a spring wheat (Triticum aestivura L.) -winter wheat-dry pea (Pisum sativum L.) rotation. Runoff volumes and soil loss (by alum precipitation of sediment) were measured on 1.5 by 5 m bordered plots on 4% slope under a rainfall simulator delivering 1- to 3-h rains at 50 or 75 mm h-1, followed by three rains of 20 min or less at rates from 25 to 125 mm h-1. Erodibility was calculated from ratios and regressions of soil loss rates versus runoff rates measured at relative steady state. Runoff rates from 50 and 75 mm h-1 rains for CT, NT, and PH averaged 9, 12, and 21 mm h-1, respectively, and supported soil loss rates of 20, 7, and 8 g m-2 h-1. Erodibility of undisturbed CT, NT, and PH was 1.65, 0.29, and 0.28 g m-2 mm-1, respectively, showing NT did not differ from PH and that CT management increased erodibility six-fold above PH. Thorough disk tillage increased erodibility three-fold over CT, 15-fold over NT, and nine-fold over PH. Complete, nondisturbing residue removal increased erodibility less than tillage, from 1.2 times for CT to 2.5 times for NT. Chemically weeded NT exhibited the same Iow erodibility as the grassland PH treatment under the conditions of study-4% land slope, above average precipitation, and a residueproductive crop rotation. However, erodibility of tilled NT was significantiy higher than that of tilled PH, showing the higher inherent stability of grassland surface soil with its perennial plant root structures. [ABSTRACT FROM AUTHOR]

A major limitation to building credible soil carbon sequestration programs is the cost of measuring soil carbon change. Diffuse reflectance spectroscopy (DRS) is considered a viable low-cost alternative to traditional laboratory analysis of soil organic carbon (SOC). While numerous studies have shown that DRS can produce accurate and precise estimates of SOC across landscapes, whether DRS can detect subtle management induced changes in SOC at a given site has not been resolved. Here, we leverage archived soil samples from seven long-term research trials in the U.S. to test this question using mid infrared (MIR) spectroscopy coupled with the USDA-NRCS Kellogg Soil Survey Laboratory MIR spectral library. Overall, MIR-based estimates of SOC%, with samples scanned on a secondary instrument, were excellent with the root mean square error ranging from 0.10 to 0.33% across the seven sites. In all but two instances, the same statistically significant (p < 0.10) management effect was found using both the lab-based SOC% and MIR estimated SOC% data. Despite some additional uncertainty, primarily in the form of bias, these results suggest that large existing MIR spectral libraries can be operationalized in other laboratories for successful carbon monitoring. [ABSTRACT FROM AUTHOR]

• We developed water budgets for 18 Long-Term Agroecosystem Research sites. • We estimated uncertainty of all the water budget components. • The average water budget uncertainty was 25% of precipitation. • Uncertainties were greatest for percolation and evapotranspiration. • LTAR sites span a 0.4 – 1.1 evaporative fraction and a 0.8 – 4.8 aridity index. Understanding the movement and storage of water within agricultural landscapes as functions of management and climate is essential for more efficient and sustainable water use. However, knowledge of water storage and fluxes on U.S. agricultural lands is largely incomplete. The Long-Term Agroecosystem Research (LTAR) network provides a unique and geographically diverse set of agricultural study sites in the United States. The objectives of this study were to: 1) characterize the hydrologic variability across the LTAR network; 2) identify data gaps in the water budgets across the LTAR network; and 3) identify opportunities to leverage the LTAR network to improve understanding of water budgets across agricultural landscapes. For each of the 18 LTAR sites, we developed water budgets on an average annual basis. Uncertainty propagation methods combined individual component uncertainties to calculate an overall water budget uncertainty. Datasets length ranged from three to 50 years. The network covers a range of precipitation from 240 to 1400 mm yr−1, evapotranspiration from 228 to 1080 mm yr−1, and surface runoff and subsurface flow from negligible to 560 mm yr−1. However, uncertainties of where all the water is going remained high, in part because soil water storage and downward movement of water were often neglected or measured for very short periods, resulting in average water budget uncertainty of 25% of the water inputs. More accurate measurement of the major inputs and outputs, and direct measurement of water content and percolation are key to understanding how agricultural lands affect terrestrial water budgets. [ABSTRACT FROM AUTHOR]