Prairie Soils Research Articles

Book Review: Quantitative Phytolith Analysis: A Working Example from Modern Prairie Soils and Buried Holocene A Horizons

Book Review: Quantitative Phytolith Analysis: A Working Example from Modern Prairie Soils and Buried Holocene A Horizons

Determination of Thiencarbazone in Soil by Oriental Mustard Root Length Bioassay

Using an oriental mustard root length bioassay, thiencarbazone bioavailability and dissipation in five Saskatchewan soils was investigated under laboratory conditions. Thiencarbazone bioavailability was assessed at 0 to 3.9 µg ai kg−1. Thiencarbazone concentrations corresponding to 50% inhibition (I50values) obtained from dose-response curves varied from 0.56 to 1.71 µg kg−1. Multiple regression analysis indicated that organic carbon content (P = 0.018) and soil pH (P = 0.017) predicted thiencarbazone bioavailability. Thiencarbazone dissipation was examined in soils incubated at 23 C and moisture content of 85% field capacity. Thiencarbazone half-lives estimated from dissipation curves were 9 to 50 d, and organic carbon content (P = 0.002) and soil pH (P = 0.008) were significant factors affecting thiencarbazone dissipation. Thiencarbazone bioavailability decreases and dissipation rate is slower in Canadian prairie soils of high organic matter content and low soil pH. Because root length of oriental mustard plants also was reduced by ammonium, therefore ammonium-containing or -producing fertilizers can cause false positive results for thiencarbazone soil residues. Canaryseed roots had the same sensitivity to ammonium as oriental mustard roots but were not inhibited by thiencarbazone. Therefore canaryseed root length bioassay was effective in identifying inhibition caused by ammonium toxicity. Use of oriental mustard root and canaryseed root bioassays together can aid in interpreting bioassay results for detection of thiencarbazone residues.

Retention and nitrification of injected anhydrous NH3as affected by soil pH

Benke, M. B., Goh, T. B., Karamanos, R., Lupwayi, N. Z. and Hao, X. 2012. Retention and nitrification of injected anhydrous NH3as affected by soil pH. Can. J. Soil Sci. 92: 589–598. Anhydrous ammonia is an economical and extensively used fertilizer, yet loss after injection can reduce its agronomic efficiency. A laboratory experiment was conducted to examine how soil properties affect ammonia retention and nitrification following anhydrous NH3injection using 10 different Canadian prairie soils. Soils were also injected with atmospheric air for comparison. Following injection, soils were incubated for up to 216 h at field capacity. Among the soil properties studied [pH (1:2 water), clay, total N, and organic C contents], only pH was negatively related (R2=0.55, n=10, 24 h incubation) to percentage injected N retained by soil. The amount of N retained by soil 24 h following injection was 92±2% (mean±SEM) when pH <6, compared with 64±2% when pH>7.5. Rate of nitrification increased (P<0.001) about 48–96 h following injection and was greater in pH>7.5 than pH<6 soils. There was no difference (P>0.05) in bacterial diversity between ammonia- and air-injected soils. The slower nitrification rates suggest that potential leaching and denitrification losses in acid soils could be smaller than in alkaline soils.

Retention and nitrification of injected anhydrous NH3 as affected by soil pH

Benke, M. B., Goh, T. B., Karamanos, R., Lupwayi, N. Z. and Hao, X. 2012. Retention and nitrification of injected anhydrous NH 3 as affected by soil pH. Can. J. Soil Sci. 92: 589-598. Anhydrous ammonia is an economical and extensively used fertilizer, yet loss after injection can reduce its agronomic efficiency. A laboratory experiment was conducted to examine how soil properties affect ammonia retention and nitrification following anhydrous NH3 injection using 10 different Canadian prairie soils. Soils were also injected with atmospheric air for comparison. Following injection, soils were incubated for up to 216 h at field capacity. Among the soil properties studied [pH (1:2 water), clay, total N, and organic C contents], only pH was negatively related (R 2=0.55, n=10, 24 h incubation) to percentage injected N retained by soil. The amount of N retained by soil 24 h following injection was 92±2% (mean±SEM) when pH 7.5. Rate of nitrification increased (P<0.001) about 48-96 h...

Sorption and dissipation of aged metolachlor residues in eroded and rehabilitated soils

Sorption and dissipation of aged metolachlor were characterized in rehabilitated and eroded prairie soils using sequential batch slurry (conventional) and accelerated solvent extraction (ASE). In spite of an almost twofold difference in soil organic carbon (OC) content, S-metolachlor sorption coefficients (K(d)) and dissipation rates (DT(50)) were the same in soils from different landscape positions within an eroded landform. Soil was moved within the landform to increase productivity. In areas receiving topsoil addition, S-metolachlor K(d) was higher and DT(50) was longer than in eroded areas. The efficiency of extraction was higher for ASE than for conventional extractions. No consistent aging effect on K(d) was observed. Mineralization in 8 weeks accounted for < 10% of the applied metolachlor. The results of this laboratory study support a field dissipation study. Both showed that S-metolachlor has the same retention and dissipation rate throughout an eroded landform, which was not expected owing to the large variability in soil properties, including OC concentrations. Altering soil properties by adding topsoil increased metolachlor sorption and persistence. The method of extraction (conventional versus ASE) affected calculated sorption coefficients and dissipation rates. In all cases, groundwater ubiquity scores (GUSs) categorized metolachlor as having intermediate mobility.

Effects of Soil Factors on Phytotoxicity and Dissipation of Sulfentrazone in Canadian Prairie Soils

Studies were conducted to examine the effects of soil properties on sulfentrazone phytotoxicity and dissipation under laboratory conditions. The pH values of five soils from Saskatchewan were altered through acidification with hydrochloric acid (HCl) and alkalization with calcium carbonate (CaCO3). The phytotoxicity of sulfentrazone to sugar beet (Beta vulgaris L. Beta 1385), determined using a shoot length bioassay, was reduced when soil pH was lowered and was greater when soil pH increased. Concentrations corresponding to 50% inhibition (I50 values) obtained from the dose–response curves were correlated with soil pH, demonstrating the relationship between soil pH and sulfentrazone phytotoxicity. Dissipation of sulfentrazone was examined in soils incubated at 25 °C and moisture content of 85% field capacity. Sulfentrazone dissipation followed a two-compartment model, and sulfentrazone half-lives estimated from the dissipation curves ranged from 21 to 111 days. Half-lives were correlated with soil pH (R = –0.857, p = 0.014) and soil organic carbon content (R = 0.790, p = 0.034) but not with clay content (R = 0.287, p = 0.533). Soil characteristics, particularly soil pH and organic carbon content, affect the bioactivity of sulfentrazone and influence both sulfentrazone efficacy in weed control and its potential for carry-over injury to subsequent crops.

Overview of Mollisols in the world: Distribution, land use and management

Liu, X., Burras, C. L., Kravchenko, Y. S., Duran, A., Huffman, T., Morras, H., Studdert, G., Zhang, X., Cruse, R. M. and Yuan, X. 2012. Overview of Mollisols in the world: Distribution, land use and management. Can. J. Soil Sci. 92: 383–402. Mollisols – a.k.a., Black Soils or Prairie Soils – make up about 916 million ha, which is 7% of the world's ice-free land surface. Their distribution strongly correlates with native prairie ecosystems, but is not limited to them. They are most prevalent in the mid-latitudes of North America, Eurasia, and South America. In North America, they cover 200 million ha of the United States, more than 40 million ha of Canada and 50 million ha of Mexico. Across Eurasia they cover around 450 million ha, extending from the western 148 million ha in southern Russia and 34 million ha in Ukraine to the eastern 35 million ha in northeast China. They are common to South America's Argentina and Uruguay, covering about 89 million and 13 million ha, respectively. Mollisols are often recognized as inherently productive and fertile soils. They are extensively and intensively farmed, and increasingly dedicated to cereals production, which needs significant inputs of fertilizers and tillage. Mollisols are also important soils in pasture, range and forage systems. Thus, it is not surprising that these soils are prone to soil erosion, dehumification (loss of stable aggregates and organic matter) and are suffering from anthropogenic soil acidity. Therefore, soil scientists from all of the world's Mollisols regions are concerned about the sustainability of some of current trends in land use and agricultural practices. These same scientists recommend increasing the acreage under minimum or restricted tillage, returning plant residues and adding organic amendments such as animal manure to maintain or increase soil organic matter content, and more systematic use of chemical amendments such as agricultural limestone to replenish soil calcium reserves.

Twenty-five years of changes in soil cover on Canadian Chernozemic (Mollisol) soils, and the impact on the risk of soil degradation

Huffman, T., Coote, D. R. and Green, M. 2012. Twenty-five years of changes in soil cover on Canadian Chernozemic (Mollisol) soils, and the impact on the risk of soil degradation. Can. J. Soil Sci. 92: 471–479. Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.

Soil microbial communities under model biofuel cropping systems in southern Wisconsin, USA: Impact of crop species and soil properties

Biofuel-induced landscape change will have an enormous impact on terrestrial ecosystems in the near future due to globally escalating energy demands, but investigations into the biological properties of soil under potential biofuel crops have not been well documented. The soil microbiota plays a significant role in ecosystem services and especially their regulation of carbon and nutrient cycles. To improve our knowledge about the structure of soil microbial community and the factors that influence it, we analyzed microbial lipids and various soil physicochemical factors under model biofuel cropping systems of corn, switchgrass and mixed prairie in southern Wisconsin, USA. Principal component analysis of lipid biomarkers from soil microbial communities indicated that there were consistent differences among the crop species. Microbial biomass was significantly lower in corn than prairie soils, with switchgrass intermediate to these systems. An increase in fungi to bacteria ratio was coinciding with a net growth in fungal biomass when converting conventionally managed corn system to perennial systems, which indicates the microbial community change could be affected by the creation or expansion of niches for certain functional groups, rather than rebalancing of competitive interactions among these groups. The soil microbial community structure under corn was distinct from the perennial systems with markers indicative of greater in situ stress in annual corn sites and a reduced proportional abundance of arbuscular mycorrhizal fungi and an increased of gram-positive bacteria. Redundancy analysis (RDA) using 21 lipid biomarkers concurrently with 17 physicochemical indices showed that these properties correlated with different subsets of the microbial communities. We conclude that the cropping system shifted the microbial community composition at this regional scale, which may also affect the microbial processes associated with these differing communities. This may be significant when scaled up from regional to national, continental or global scales.

Resource quality in a soil food web

Numerous factors affect the resource quality of detritus, including N content, lignin content, C lability, and concentrations of tannins or phenols. Although many studies have examined the responses of detrital food webs to resources of differing quality, few have independently varied different components of resource quality. I measured the response of soil nematodes to artificial substrates in which two components of resource quality were manipulated. Two different N concentrations (2% and 1%, corresponding to C/N ratios of 21 and 41) were crossed with two different C labilities (sugar/cellulose/lignin ratios of 1.6:5.2:1 and 0.6:2.4:1). The responses of nematodes from a coastal prairie soil to the artificial substrates were measured over 2 months in two separate experiments. Effects of resource quality were more pronounced in the first experiment, in which a larger quantity of substrate was added to microcosms. Bacterivorous nematodes were 3.4 and 1.2 times more abundant in high N treatments than low N treatments in the first and second experiments, respectively. Carbon lability had a smaller effect on bacterivores in the first experiment and no effect in the second. Fungivorous nematodes were more abundant in high labile C treatments in the first experiment, but not the second. Fungivores did not respond to different N levels. Despite previous findings that soil bacteria are primarily C limited, N appears more limiting than labile C for the bacterial channel of this soil food web, but other aspects of resource quality that correlate with N content may have driven treatment differences.

Above-ground vs. below-ground interactive effects of mammalian herbivory on tallgrass prairie plant and soil characteristics

To better understand how mammalian herbivory affects tallgrass prairie, I set up field exclosures to test effects of above-ground herbivory (AGH) (Bison bison L. is a potential above-ground herbivore), below-ground herbivory (BGH) (Geomys bursarius and Spermophilus tridecemlineatus are potential below-ground herbivores), and the interaction of the exclusion of both, on tallgrass prairie plant species, plant community parameters, and soil parameters in the Flint Hills of Northeastern Kansas. I found that (1) AGH reduced the cover of some forbs but increased the cover of others while both AGH and BGH decreased the cover of dominant C4 grasses, (2) no treatments significantly affected species richness but ABH reduced total cover and maximum height of the vegetation while BGH reduced species evenness and maximum height, and (3) no treatments affected soil pH or soil nitrogen but BGH reduced soil organic matter, soil phosphorus, and soil potassium. Whereas above-ground mammalian herbivory has significant effects on individual plant populations and plant community structure, it is BGH that mainly affects soil parameters. Results suggest that for prairie patches where both kinds of herbivory are present, these effects may be additive leading to cumulative effects on tallgrass prairie plants both directly, through herbivory, and indirectly, through soil changes.

Human Interference of the Soil Nematodes Community and Flora Influence

For human interference residential areas under around the prairie soil nematodes community meadow spatial and temporal features were studied, and the results showed that soil nematodes to capture residential sample article 4658No./100 g dry soil, fence of soil nematodes in capture of article 6622/100 g dry soil ，Human interference effect of advantage of the temporal and spatial distribution of residential areas, around sample of Bursapbrelenchus umbrella slippery blade, smooth the blade of Aphelenchoides, slippery blade of Aphelenchus, spiral of Helicotylenchus for advantage of; The fence of small stem of Rhabditis, head of Cephalobus leaves, Liz axon Acrobeles, class of short body of Pratylenchoicles for advantage of nematode, the floristic analysis showed around residential food nets by certain degree disturbance, fence of interference in smaller, food nets stable mature.

Diffuse-Reflectance Mid-infrared Spectral Properties of Soils under Alternative Crop Rotations in a Semi-arid Climate

We carried out mid-infrared (mid-IR) spectral interpretation of soils 0–5 and 5–15 cm deep in selected alternative crop rotations (ACR) treatments and an adjacent native prairie soil. Ashing and spectral subtraction shows that absorbance at 3700–2850 and 1700–1550 cm−1 indicates organic absorbance. Prairie soils, with their greater carbon (C) content, have different spectral properties from the cropped soils. Prairie soils have greater absorbance at the 2950–2870 cm−1 and the 1230 cm−1 CH bands. The soils from the different depths had different spectral properties, with the soils 0–5 cm deep having stronger absorbance at the 1055 cm−1 carbohydrate band, at 1270–1460 cm−1, and at the 1730 cm−1 ester band. The soils 5–15 cm deep are characterized by greater absorbance at the clay band. Soil C and nitrogen (N) correlated negatively with the 3700 cm−1 clay band and the 1830 cm−1 quartz band and correlated positively with the 2920 cm−1 because of aliphatic CH absorbance.

Association of specific organic matter compounds in size fractions of soils under different environmental controls

Inherent chemical recalcitrance and association of organic matter (OM) with minerals are mechanisms responsible for the long term preservation of OM in soils. The structural characteristics of OM are also believed to control specific interactions between OM and soil minerals. However, the extent of the relationship between recalcitrance and mineral protection and the specificity of these chemically driven interactions are not clearly understood at the molecular level. To measure chemical patterns of OM sequestration in sand-, silt-, clay-size and light fractions, we analyzed three soils, which mainly differed in carbon content and overlying vegetation, but have similar clay mineralogy, using biomarker analysis and nuclear magnetic resonance (NMR). Despite differences in environmental controls, long chain aliphatic compounds generally accumulated in the fine fractions of all soils. This accumulation is likely due to the strong interaction between recalcitrant forms of OM and soil minerals. For example, polymethylene and >C 20 organic acids accumulated in fine fractions, while lignin-derived phenols were protected from oxidation in silt-size fractions. Diffusion edited solution state 1H NMR suggested that contributions from microbial-derived OM was greater in finer fractions, which is likely due to the accumulation of microbial-derived compounds or higher microbial activity in clay micro-sites. Our data suggest that, for these Prairie soils, the specific structure of OM and not environmental factors is responsible for long term preservation of OM in mineral fractions. Further research is necessary to understand the interplay between these preservation mechanisms such that the long term fate of OM can be further elucidated.

Impact of Long-Term Alfalfa Cropping on Soil Potassium Content and Clay Minerals in a Semi-Arid Loess Soil in China

Alfalfa cropping has been considered an efficient method of increasing soil fertility. Usually nitrogen increase in root nodules is considered to be the major beneficial effect. A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil, initially containing illite and chlorite, in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping, soil potassium (K) content and soil clay minerals. The results indicated that soil K significantly accumulated after cropping, with a peak value at about 15 years, and decreased afterwards. The accumulated K was associated with the K increase in the well-crystallized illite, which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability. The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa soil. Plant biomass productivity peaked at near 9 years of culture, whereas soil K and clay minerals continued to increase until cropping for 15 years. This suggested that K increased in the topsoil came from the deep root zone. Thus alfalfa continued to store K in clays even after peak production occurred. Nitrogen did not follow these trends, showing a general decline compared with the native prairie soils that had not been cropped. Therefore, the traditional alfalfa cropping can increase K content in the topsoil.

Metagenomic comparison of direct and indirect soil DNA extraction approaches

Full pyrosequencing runs of both direct-extracted (high yield, low DNA size) and indirect-extracted DNA (low yield, high DNA size) from the same prairie soil show that the sequence distribution of the majority of the metabolic functions and species detected were statistically similar. Although some microbial functions differed at the 95% confidence interval in bootstrap analyses, the overall functional diversity was the same.

RADON EMANATION IN SASKATCHEWAN SOILS

Saskatchewan prairie soils in central Canada were studied from areas where many homes are known to exceed the Health Canada indoor radon guideline of 200 Bq m. This study sampled 32 soils from 11 sites, which varied in clay content and presence of bedrock materials. Soils were analyzed for (238)U, (226)Ra, (222)Rn in soil gas, bulk density, moisture, and particle size. Radon emanation from the soil samples varied from 10% to 43% and increased significantly with clay content with radon concentrations in soil gas of 18-38 kBq m(-3). Total uranium in soils was 2.1-4 ppm and 26-51 Bq kg(-1) dry weight for (238)U, (234)Th, and (226)Ra. Homes built on soils with high clay content may be at greater risk of high radon levels, particularly when the soils are dry and cracked, enhancing their permeability to gases such as radon. One sample of coal bedrock, originating from Tertiary marine shales, was particularly high for total uranium (53 ppm), (238)U, (234)Th, and (226)Ra activities (68-1,303 Bq kg(-1)) with radon emanation up to 1,363 kBq m(-3).

Prairie ecosystems and the carbon problem

There has been great interest in carbon (C) storage in terrestrial landscapes and the potential for trading C released during fossil‐fuel combustion for C stored in agricultural landscapes. This is particularly important in the Great Plains of North America, where increased C storage under conservation tillage represents millions of dollars in C credits. However, we contend that the logic behind such trading is imperfect on multiple levels. We suggest that increased C storage in Great Plains soils with conservation tillage can, at best, only partially replenish what was previously emitted by tillage of native prairies. Furthermore, there is disagreement on whether reduced tillage actually does increase C storage in prairie soils. Use of alternative agricultural practices that emulate natural prairie diversity, processes, and function, as well as the establishment of permanent prairie reserves, will aid in recovery of previously lost C and provide for increased biodiversity and resilience in the face of changing climate conditions.

Phosphorus use efficiency and long-term trends in soil available phosphorus in wheat production systems with and without nitrogen fertilizer

Selles, F., Campbell, C. A., Zentner, R. P., Curtin, D., James, D. C. and Basnyat, P. 2011. Phosphorus use efficiency and long-term trends in soil available phosphorus in wheat production systems with and without nitrogen fertilizer. Can. J. Soil Sci. 91: 39–52. Efficient use of phosphorus (P) in crop production is important for economic and environmental reasons, and to prolong the life of a limited resource. Short-term studies often show low recovery of fertilizer P, but P use efficiency may be underestimated because the value of residual P in the soil is ignored. Our objective was to determine fertilizer P use efficiency in two wheat production systems [continuous wheat (CW) and a 3-yr rotation of summer fallow-wheat-wheat (FWW)] using data from a 39-yr study (1967–2005) at Swift Current, SK. Each rotation received either P only (P) or nitrogen plus P (NP) fertilizer. Annual grain P removal was monitored (all straw was returned to the soil) and changes in soil available P (0- to 15-cm layer) were measured by the Olsen bicarbonate method. In 1993, subplots which received no additional P were established to evaluate the residual effect of P fertilizer applied in the preceding 27 yr. Where P was applied each year, grain P removal averaged 54 to 78% of fertilizer P, with values as high as 65 to 109% in 1994 to 2005, the period of lowest water deficit. The P-only treatments removed 13% less P in grain, on average, than NP treatments. In the P-nly systems, Olsen P content increased linearly with time, but in the NP systems it reached a maximum after 20–22 yr and then stabilized. The cumulative P balance (fertilizer P minus P removed in grain) accounted for 60% of the variability in Olsen P accumulation over the course of the experiment. In CW, Olsen P content increased by 0.15 kg ha−1 for each kg ha−1 of P added in excess of crop removal. The rate of Olsen P accumulation was greater (0.20 kg ha−1 for each kg ha−1 of excess fertilizer P) in the FWW rotation possibly due to P mineralization during the summer fallow year. When P was withheld between 1994 and 2005, total grain production in the CW rotation was reduced slightly (by 10%), but there was no significant effect on FWW. Crop P removal (1967–2005) where P was withheld in the final 12 yr was equivalent to 105 and 90% of fertilizer P added to the NP and P-only systems, respectively. We concluded that residual P in prairie soils is retained in forms that are available to plants; wheat crops may therefore recover close to 100% of applied fertilizer P given sufficient time.

Primary and Residual Effects of Abrams Tank Traffic on Prairie Soil Properties

Mechanized maneuver training can impact soil quality in many ways, most notably through soil displacement and compaction. To identify indicator variables for inclusion in monitoring programs on military lands, a replicated small‐plot study of tracked vehicle disturbance effects on tallgrass prairie soil properties was initiated on Fort Riley, KS, in 2003. A range of disturbances encompassing soil surface texture, environmental conditions, and traffic intensity were evaluated. Soil physical (rutting and compaction) and chemical (soil organic matter and nutrients) properties were monitored annually on curve and straightaway track areas through 2007. Rut depth remained significant (P ≤ 0.05) for curves of inside and outside tracks in both soil surface textures throughout the study and was more severe for repeated vs. single traffic events. Bulk density increased with disturbance under wet soil conditions, repeated traffic, and on curve areas but recovered to undisturbed levels within 1 to 3 yr. Soil compaction as measured by penetrometer resistance was more severe for traffic under wet soil conditions and remained significant (P ≤ 0.05) at depths of 5 to 10 cm in both soil surface textures throughout the study. Residual effects of tank traffic on soil chemical properties were generally mild, but soil C was reduced following disturbance under wet soil conditions, repeated traffic, and on curve areas and required 3 to 4 yr to recover to undisturbed levels. The results of this study emphasize the importance of suitable impact management to maintain the sustainability of tallgrass prairie for military training activities.