E. A. Mikhailova

Comparison of Soil Organic Carbon Recovery by Walkley-Black and Dry Combustion Methods in the Russian Chernozem

This study compared soil organic carbon (SOC) recovery in the Russian Chernozem (a fine-silty, mixed, frigid Pachic Hapludoll) under four management regimes (native grassland, yearly-cut/grazed hay, continuous cropping, and continuously plowed fallow) and different depths by Walkley-Black and two dry combustion methods. The Walkley-Black method was different from both dry combustion methods and required a correction factor of 1.63 in all management regimes.

Botanical composition, soil and forage quality under different management regimes in Russian grasslands

Little is known on how management of Russian native grasslands affects botanical composition, soil and forage properties. Three fields were sampled in the V.V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia: a native grassland (not cultivated for at least 300 years), a grazed/hay field with 4 years of annual harvest followed by 1 year of rest (periodically-cut grazed/hay field), and a yearly-cut grazed/hay field. Soil samples were collected from the top 10 cm and analyzed. Plant species were identified at the sampling sites and this plant material was used to determine total elemental analysis of forage, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), in vitro true digestibility (IVTD) and lignin concentrations. Above-ground live and dead plant material and roots were analyzed for C, N and lignin. Soil sample analysis showed that fields were comparable in terms of soil chemical and physical properties. SOC and N contents were not statistically different in the native and yearly grazed/hay fields. Soil bulk density significantly increased as a result of utilization, from 0.800.09 Mg m 3 for the native grassland to 0.970.06 Mg m 3 for the yearly grazed/hay field. A total of 107 different plant species were recorded at the three fields. There were changes in plant composition among the fields. The native grassland field had the least number of plant species (41) followed by the yearly-cut grazed/hay field (68), and the periodically-cut grazed/hay field (87). There was a greater proportion of grass species (20%) in the native grassland field. Dead plant biomass and roots from the grazed/hay fields were higher in N and lignin concentrations. Forage mineral concentration was highest in the periodically-cut hay field. No significant differences were observed in terms of forage properties.

ESTIMATING VARIABILITY IN SOIL ORGANIC CARBON STORAGE USING THE METHOD OF STATISTICAL DIFFERENTIALS

The diverse nature of soils introduces uncertainty into the estimation of soil organic carbon (SOC) storage. Laboratory analyses indicate C concentration in soils, but the soil layer thickness, bulk density, and percent of fragments > 2 mm must be known in order to estimate SOC storage. Ideally, measurements of SOC concentration are performed on the same soil samples used to determine bulk density and percent of fragments > 2 mm, but this is frequently not possible. Often measurements of SOC concentration, bulk density, and percent of fragments > 2 mm are obtained separately from the same soil layer, which causes propagation of error when estimating SOC storage. Furthermore, measurements of bulk density and percent of fragments > 2 mm are more difficult to obtain than measurements of SOC concentration. Because of this, samples of bulk density and percent of fragments > 2 mm are often taken independently and less frequently than samples for SOC concentration. The objective of this study was to derive an estimation method for the variability in SOC storage estimates as a function of SOC concentration, bulk density, percent of fragments > 2 mm, and soil thickness. The method of statistical differentials, also known as the delta method, was used to obtain an estimate of the variability in SOC storage estimates. The variance estimation procedure is illustrated using previously published data for the Russian Chernozem under different management regimes. The method of statistical differentials is a valuable tool for obtaining variance estimates in a large class of problems with similar characteristics.

An Integrated WebGIS Framework for Volunteered Geographic Information and Social Media in Soil and Water Conservation

Volunteered geographic information and social networking in a WebGIS has the potential to increase public participation in soil and water conservation, promote environmental awareness and change, and provide timely data that may be otherwise unavailable to policymakers in soil and water conservation management. The objectives of this study were: (1) to develop a framework for combining current technologies, computing advances, data sources, and social media; and (2) develop and test an online web mapping interface. The mapping interface integrates Microsoft Silverlight, Bing Maps, ArcGIS Server, Google Picasa Web Albums Data API, RSS, Google Analytics, and Facebook to create a rich user experience. The website allows the public to upload photos and attributes of their own subdivisions or sites they have identified and explore other submissions. The website was made available to the public in early February 2011 at http://www.AbandonedDevelopments.com and evaluated for its potential long-term success in a pilot study.

Modeling soil organic matter dynamics after conversion of native grassland to long-term continuous fallow using the CENTURY model

Abstract A long-term continuous fallow experiment provides a unique opportunity to test current approximations of soil organic matter dynamics, which are the basis of many models including the CENTURY model. This study was conducted to validate the CENTURY model by comparing the simulated results for a continuous fallow scenario to long-term measurements of soil organic carbon (SOC) in a 50-year continuous fallow field, located in the V.V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia. Experimental data were obtained for soil physical properties, SOC and nitrogen (N) contents for the top 20 cm of soil at the 50-year continuous fallow field and an adjacent native grassland field. All sampled soils were classified as fine-silty, mixed, frigid Pachic Hapludolls. Live and dead plant biomass, and plant roots collected at the native site were analyzed for C, N and lignin contents. These new experimental data were incorporated into the CENTURY model parameters. Following conversion of measured SOC values to dry-combustion equivalent and correction of simulation output for changes in bulk density, the CENTURY model successfully simulated SOC dynamics in the 50-year continuous fallow field. Comparison of observed and modeled SOC concentrations yielded an R 2 value of 0.96.

TETANY POTENTIAL OF ORCHARDGRASS AND TALL FESCUE AS INFLUENCED BY FERTILIZATION WITH DAIRY MANURE OR COMMERCIAL FERTILIZER

ABSTRACT The main objective of this study was to compare potassium (K), calcium (Ca), and magnesium (Mg) utilization and grass tetany potential of orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) fertilized with dairy manure or commercial fertilizer. The study was conducted from 1994 through 2000 in Willsboro, NY on a Kingsbury clay soil (very-fine, illitic, mesic Aeric Ochraqualf) of somewhat poor drainage. The design was a split-plot in a randomized complete block with two manure rates (16.8 Mg ha−1 and 33.6 Mg ha−1) and one fertilizer treatment (84 kg N ha−1 at spring greenup and 56 kg N ha−1 prior each regrowth harvest) as the main plots and grass species as subplots replicated six times. Potassium concentration and uptake increased after two years of manure application compared to commercial fertilizer treatment and residual effects of manure were large at least three years following manure application. Calcium concentration and uptake decreased after two years of manure application compared to the commercial fertilizer treatment, but there were no differences in treatments three years after manure application had ceased. Magnesium concentration and uptake at the high manure rate did not differ from fertilizer treatment in all years. Orchardgrass was more grass tetany prone than tall fescue as a result of dairy manure application. The K/(Ca+Mg) ratio in plant tissue was as high as 3.26 for orchardgrass and as high as 2.11 for tall fescue for spring harvests at the highest manure rate. The K/(Ca+Mg) ratio in plant tissue was in the range of 0.34–1.74 (below the 2.20 critical level) for all three years with no manure application. Soil K increased in manure treatments from an initial 76.8 kg ha−1 (1993) to 171.7 kg ha−1 (1997) in the highest manure treatment. After three years of no manure applications, soil K had been reduced to the initial level.

Spectral Measurements of Alfalfa/Grass Fields Related to Forage Properties and Species Composition

ABSTRACT The relationship between plant canopy reflectance and plant nutritive value has not been extensively investigated. The goal of this study was to relate spectral canopy reflectance to plant nutritive value and species composition. Multiple grass/alfalfa fields were analyzed using a field spectrometer, and then species composition, forage nutritive quality, and plant biomass were determined. Derivative analyses of spectra as well as narrow-band vegetation indices were used to examine the relationship between canopy reflectance and plant biophysical properties. Derivative analysis found a high correlation between high-order derivatives at multiple wavelengths and some plant properties, which include species composition and neutral detergent fiber (NDF). Wavelengths in the red region and between the red and near-infrared region of the spectrum showed the highest correlation in the derivative analysis. Analysis of whole canopy reflectance using spectroscopy may provide a quick, nondestructive method to determine plant characteristics.

Big Bluestem (Andropogon gerardii; Poaceae) Communities in the Carolinas: Composition and Ecological Factors

Abstract Andropogon gerardii (Big Bluestem) is a dominant grass of the North American tallgrass prairie. It is also found in remnant populations in the eastern United States, including North and South Carolina, often in association with other species with prairie affinities. We characterized eight A. gerardii population sites across various physiographic regions of North and South Carolina. A total of 362 quadrats (1 m × 1 m) were sampled during the 2006–2008 growing seasons for species occurrence and site and quadrat frequency. Associated species were assigned a commonness index (CI). A Sørensens Community Coefficient was used to determine floristic similarities among the sites. In addition, soil samples in three quadrats were sampled at each site at three depths (0–10 cm, 11–20 cm, and 21–30 cm) and analyzed for pH; organic C and N contents; extractable P, K, Ca, Mg, Zn, Mn; and CEC (cation exchange capacity). A total of 306 vascular plant species was identified comprising 64 families, including 99 (32%) graminoids. There were 61 (20%) Poaceae and 63 (20%) Asteraceae. Species per quadrat ranged from 1 to 13 with a mean of 5. Andropogon gerardii had the highest CI value (5900), followed by Rubus spp. (1260). Community Coefficient values were < 0.5 for all pairings between sites, indicating high divergence in species composition among even nearby sites. There were 14 rare or watch-listed species identified, including the federal endangered Helianthus schweinitzii at Troy Prairie. A total of 153 (50%) of the species had been previously described as occurring in prairie-like associations. Soil pH values varied from 4.8 to 6.9 among the sites and depths. Ca and Mg nutrient values were also highly variable. Andropogon gerardii was found at high frequencies across all sites, indicating its broad tolerance for a variety of edaphic conditions.

Stable carbon and oxygen isotopes of soil carbonates at depth in the Russian Chernozem under different land use

Limited information is available about stable carbon and oxygen composition of soil carbonates at depth in the Russian Chernozem under different land use. This study was conducted to determine the stable isotope geochemistry of disseminated carbonates in the Russian Chernozem, one of the typical soils in grasslands. Three sites were sampled: a native grassland field (not cultivated for at least 300 years), an adjacent 50-year continuous fallow field in the V.V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia, and a continuously cropped field in the Experimental Station of the Kursk Institute of Agronomy and Soil Erosion Control. All sampled soils were classified as fine-silty, mixed, frigid Pachic Hapludolls. The stable carbon isotope composition of carbonates varied with depth and land use: in the native grassland field &dgr;13C was in the range of −6.1−(−7.7)‰; in the continuous fallow &dgr;13C was in the range of −5.7−(−9.8)‰ Pee Dee Belemnite (PDB); and in a continuously cropped field &dgr;13C was in the range of −5.1−(−10.2)‰ PDB. The stable oxygen isotope composition of carbonates also varied with depth and land use: in the native grassland field &dgr;18O was in the range of −6.9−(−9.4)‰; in the continuous fallow &dgr;18O was in the range of −6.2−(−10.7)‰; and in a continuously cropped field &dgr;18O was in the range of −7.0−(−9.4)‰. More research is needed to investigate the effect of cultivation on stable isotope signatures of pedogenic carbonates.

Suther Prairie: Vascular Flora, Species Richness, and Edaphic Factors

Abstract Piedmont prairie communities of the southeastern United States were common prior to European settlement. Suther Prairie in Cabarrus County, North Carolina is among the best-known examples of such an ecosystem. This study provides a complete floristic list of species observed at the site from 1997–2007. Sampling over the 10 yr period included fixed transects and general floristic inventories. During the 2006–07 growing seasons, additional transects and 90 randomly placed 1 m2 quadrats were established for sampling species frequency. Soil in six of these random quadrats was sampled at three depths (0–10 cm, 11–20 cm, 21–30 cm) for pH, organic C, total N, and extractable P, K, Ca, Mg, Zn, Mn, Cu, B, and Na. There were 208 species documented during the 10 yr sampling period. In 2006–07 142 new species were identified, but 49 previously documented species were not re-located. Of the 208 species, 66 were graminoids (36 grasses and 30 sedges/rushes). Ninety of these had previously been reported from prairie habitats. Obligate or facultative wetland species comprised 32% of the list. Thirteen species were rare, watch-listed, or uncommon for North Carolina. Big Bluestem (Andropogon gerardii) and Eastern Gamagrass (Tripsacum dactyloides var. dactyloides) had the highest frequency of occurrence during the 2006–07 sampling. Species richness was 6.8 species per m2. Levels of Ca and Mg were much higher than normal for Piedmont soils, and there was significant variation in soil C, N, P and Zn levels among the sampled depths.