Stream bank soil and phosphorus losses within grazed pasture stream reaches in the Rathbun Watershed in southern Iowa

Stream bank erosion within agricultural landscapes is a major pathway for non-point source sediment and phosphorus loading to receiving waters. The objectives of this study were to: 1) compare the effect of livestock stocking rate on sediment and phosphorus loss from stream bank erosion in the Rathbun Watershed in southern Iowa; 2) assess the relationship between stream stage and stream bank soil erosion rates, and 3) evaluate the impacts of current riparian land-uses and stream morphologic characteristics at the field and catchment scale on stream bank erosion. Stream bank erosion rates over three years were estimated using the erosion pin method, with erosion rates correlated to pasture stocking rates and the number of high stream stage events, which were monitored using pressure transducers. The effects of stream morphology and land-use on stream bank erosion were assessed using parameters such as percent of land-use, bank soil texture, stream bed slope, and sinuosity at both the field and catchment scale. While there was no significant correlation between stream bank erosion rates and stocking rates, erosion rates within sites under Conservation Reserve Program management were significantly lower than those within grazed pastures, particularly during the winter/spring season. The length of severely eroded stream banks and compaction of the riparian area were positively related to livestock stocking rates within pasture stream reaches. Approximately 75% of the variability in stream bank erosion was found to be correlated to the frequency of high stream stage events. Overall, these data and previous studies allow the speculation that, in the long term and at the catchment scale, a high percentage of agricultural land-use in riparian areas can be either directly and/or indirectly related to alteration of stream hydrologic regimes. In order to reach equilibrium state condition, where energy input to the stream channel is balanced with the minimal channel boundary resistance, such land-use changes will result in changes in stream bank erosion and channel morphology

Riparian land-use impacts on stream bank soil and phosphorus losses from grazed pastures

An emerging challenge in watershed-scale research is to quantify the extent of sediment contributed to receiving waters from stream banks versus overland flow from critical source areas, and to develop management strategies to reduce stream bank erosion. The objective of this research was to compare the amounts of sediment and phosphorus loss from critical stream bank source areas to receiving waters via overland flow and stream bank erosion from riparian grazed pasture under different stocking densities (cow-calf pair ha -1). Rainfall simulations were used to calculate sediment and P loads from overland flow from stream-side livestock loafing and access points and lengths of stream banks not directly impacted by livestock (defined as control areas) in central, northeast, and southeast Iowa. Water samples from runoff were analyzed for suspended sediment and total phosphorus. Soil bulk density and moisture samples were also collected around rainfall simulation plots to evaluate differences in compaction between grazing practices. Stream bank erosion rates on these pasture sites were also observed over two years using the erosion pin method. Eroded stream bank length, height and soil bulk density and total soil phosphorus concentration were used to calculate total phosphorus and soil loss via stream bank erosion.;Within 15 m wide strips located on both side of the stream, livestock access paths and loafing areas together accounted for only 2.7% of the total source areas, their suspended sediment and total P contributions to streams accounted for up to 72% (86 kg ha-1), and 55% (78 g ha -1) of total sediment and phosphorus, respectively. Control areas of the riparian source areas contributed high levels of total P in surface runoff accounting for 45% (64 g ha-1) of total P loads. In some cases, significant correlations were found between stocking vi densities and soil bulk density and sediment and total phosphorus loss indicating that use of low stocking density can reduce total phosphorus and sediment loss from surface runoff.;Sediment and phosphorus loss via stream bank erosion did not reveal significant differences among the examined grazing practices. However, a highly correlated parallel relationship was found between the precipitation rates and erosion rates in given pasture sites suggesting that precipitation is one of the major controlling factors of stream bank erosion. Besides precipitation impact, lower stream bank soil bulk density significantly increased soil loss.;Results of this study would suggest that regardless of stocking densities the highly attractive nature of riparian areas within pastures results in significant contributions of sediment and total P to channel waters and the only was to effectively reduce that impact is to exclude direct access of livestock to the channel unless it is carefully armoured

Writing Crime (Fiction) around the Globe: Analyses of Identity in International Crime Novels

The twenty essays in this important volume, Investigating Identities: Questions of Identity in Contemporary International Crime Fiction, deal with the notion of identity from different angles, including cultural and stereotypical representations of ethnicity and race in crime novels from countries such as Spain, France, Chile and Germany. The authors underline their readings of crime novels with the application of major theories of both crime genre and identity, including those of Homi Bhabha and Benedict Anderson. Not only because it is one of the first studies that explore the crime genre to such an extent, but also because of its success in combining current issues of identity with multicultural and global contexts, the volume is highly recommendable to those scholars with an interest in current trends in popular literature and to serious readers of crime fiction.&nbsp

Biomass, carbon, nitrogen and soil respiration dynamics within riparian buffers and adjacent crop fields

Natural and re-established riparian buffers reduce nonpoint-source pollutants derived from upland agricultural lands and enhance terrestrial and aquatic habitat. This study was conducted in multi-species riparian buffers, cool-season grass buffers and adjacent crop fields to determine biomass, carbon, nitrogen and soil respiration dynamics. The multispecies buffers were composed of poplar (Populus x euroamericana\u27 Eugenei ) and switchgrass (Panicum virgatum L.). Crop fields were under annual corn-soybean rotation. Aboveground biomass was determined by clipping grasses in 25 x 25 cm quadrats. The dynamics of fine (0--2 mm) and small roots (2--5 mm) were assessed by sequentially collecting 5.4 cm diameter, 35 cm deep cores for the first year and 125 cm deep cores for the second year from April through November. Coarse roots were described by excavating 1 x 1 x 2 in pits and collecting all roots in 20 cm depth increments. Root distributions within the soil profile were determined by counting roots that intersected the walls of the excavated pits. Soil respiration was measured monthly from July 1996 to July 1998 using the soda-lime technique. Over the sampling period, live fine-root biomass and root C and N in the riparian buffers were significantly higher than in the crop fields. Poplar had the greatest aboveground live biomass and N and C, while switchgrass had highest aboveground dead biomass, C and N. Roots of trees, cool-season grasses, and switchgrass extended to more than 1.5 m in depth, with switchgrass roots being more widely distributed in deeper horizons. Root density was significantly greater under switchgrass and cool-season grasses than under corn or soybean. Soil respiration was significantly greater in both buffer systems than in the cropped fields. Annual soil respiration rates correlated strongly with soil organic carbon (R = 0.75, P \u3c 0.001) and fine root (\u3c2 min) biomass (R = 0.85, P \u3c 0.001). Abundant fine roots, deep rooting depths, and high soil respiration rates in the multispecies riparian buffer zones suggest that these buffer systems added more organic matter to the soil profile, and therefore provided better conditions for nutrient sequestration within the riparian buffers

Climate change in Seyhan watershed of Turkey: current signals and adaptation measures

The Seyhan watershed located in the east of the Mediterranean region of Turkey has been particularly studied because it’s one of the most important regions of Turkey in ecological terms, but also economic, since agricultural activities are highly developed. The first signs of climate change have already appeared. This article describes the expected impacts and the predictable ecological and socio-economic consequences. A better understanding of the vulnerability of the different sectors and their adaptive capacity will lead to appropriate measures

Gully and Stream Bank Erosion in Three Pastures with Different Management in Southeast Iowa

Gully and stream banks can be major sources of sediment and nutrients to surface waters, both major water quality problems in the United States. Sediment may also carry phosphorus to surface waters, the primary limiting nutrient causing eutrophication. Overgrazing can induce gully and stream bank erosion by reducing vegetation cover that weakens bank soil resistance to stream water flow. This study examines stream and gully bank erosion adjacent to continuous (CP), rotational (RP) and intensive rotational (IP) pastures, grazed by beef cattle in southeast Iowa. Stream and gully bank erosion were measured by: a) surveying the extent of the severely eroding bank areas of the stream reaches running through the pasture management site and the gullies intersecting the specific stream reach and b) randomly establishing pin plots on subsets of the surveyed eroding stream and gully banks. Soil loss for the gullies and stream banks for each site were estimated as the product of the mean bank erosion rate, bulk density and the total severely eroding bank area. Total phosphorus (TP) losses from the gully and stream banks were estimated by multiplying the total soil loss by the TP concentration of the gully and stream bank soils. Soil samples were collected from the gully banks and bed, stream banks, loafing areas and surface riparian areas to estimate TP soil concentrations. The high TP concentrations of the loafing area soils compared to the other sampled locations and their proximity to the stream indicated that these areas could be significant sources of both sediment and TP to surface waters. The gully bank soil and TP losses ranked as follows: CP (207 Mg km-1 of soil; 70 kg km-1 of TP) \u3e RP (89 Mg km-1 of soil; 40 kg km-1 of TP) \u3e IP (28 Mg km-1 of soil; 12 kg km-1 of TP). The stream banks had a different ranking for soil losses: RP (323 Mg km-1 of soil) \u3e CP (282 Mg km-1 of soil)\u3e IP (170 Mg km-1 of soil) and TP losses: RP (129 kg km-1 of TP) \u3eIP (86 kg km-1 of TP) \u3e CP (83 kg km-1 of TP). It was expected that moving from CP, the traditional pasture management practice in Iowa, to RP and IP would reduce stream and gully bank erosion but this was not always the case. Assuming that the only sources of soil and TP losses in each site were stream and gully banks, then stream banks would contribute 76%, 85% and 86% of the total soil loss and 73%, 84% and 87% of the TP from the CP, RP and IP, respectively. These results indicate that stream banks were a more substantial source of sediment and TP in these streams than gully banks

Evaluation of left ventricular systolic function with pulsed wave tissue Doppler in rheumatic mitral stenosis

Background: Mitral stenosis (MS) is still the most common complication of acute rheumatic fever in Turkey. Rheumatic carditis affects not only cardiac valves but also myocardium. In this study, we aimed to evaluate the subclinical left ventricular (LV) systolic dysfunction and contraction of short and long axial circumferential and longitudinal fibers by pulsed wave tissue Doppler in rheumatic MS patients who have preserved LV systolic function in 2D echocardiography.Methods: Fifteen severe, 20 moderate rheumatic MS patients hospitalized for mitral balloon valvuloplasty, and 15 patients who had normal echocardiographic findings were included in the study. After routine conventional transthoracic echocardiographic examination, LV myocardial systolic velocities were evaluated with pulsed wave tissue Doppler in the short and long axis with simultaneous electrocardiographic monitoring.Results: Long axis first systolic velocity (SW1) of mild-moderate and severe MS was much lower than normal group (10.7 ± 2.3 in normal group vs. 7.9 ± 1.3 in mild-moderate MS group vs. 6.2 ± 1.4 in severe MS group, p < 0.001). Long axis Q-SW1 duration was longer in mild-moderate MS group (145 ± 32 in normal group vs. 199 ± 43 in mild-moderate MS group, p = 0.001). Short axis Q-SW2 duration was longer in normal group compared to mild-moderate and severe MS groups (298 ± 41 in normal group vs. 245 ± 37 in mild-moderate MS group vs. 234 ± 26 in severe MS group, p < 0.001). Significant correlation between mitral valve area and SW1, Q-SW1 was determined (p = 0.01).Conclusions: Even if LV functions are normal with conventional 2D echocardiography, subclinical systolic dysfunction exists in MS. Also, there is a dyssynchrony between contraction of longitudinal and circumferential myofibrils

Stocking Rate and Riparian Vegetation Effects on Physical Characteristics of Riparian Zones of Midwestern Pastures

Grazing at high stocking rates May Increase sediment and nutrient loading of streams pasture Through Transport in precipitation runoff and bank erosion. A 3-yr (2007-2009) grazing study was Conducted on 13 cool-season grass pastures to quantify effects of stocking rate and botanical composition on forage sward height, proportions of bare and manure-covered ground, and bank erosion adjacent to streams. Pastures ranged from 2 ha to 107 ha with stream Reaches of 306 m to 1778 m That has drained watersheds of 253 to 5660 ha. Bare and manure-covered ground Were Measured at 15.2-m distance perpendicular to the stream at 30.5-m intervals at up to 30 locations on each side of the stream by the line transect method in May, July, September, and November of each year.At the midpoint of the 15.2-m line, forage sward height was Measured with a falling plate meter (4.8 kg · m -2 ) and plant species identified. In November 2006, fiberglass pins (1.6 × 76.2 cm) 73.7 cm Were driven into the stream bank at 1-m intervals from the streambed to the top of the bank along 10 transect equidistant locations on each side of the stream bank erosion to measure During spring, summer, and fall of each year. Increasing pasture stocking rates Increased manure-covered ground and Decreased sward height, but did not Affect proportions of bare ground. The greatest, intermediate, and Least net soil erosion rates occurred During the winter / early spring, late spring / early summer, and late summer / fall seasons. Stocking rates Between measurements, Expressed as cow-days · m -1 stream, Were not related to bank erosion. Increasing stocking rates per unit of stream length will cover manure Increase and decrease forage sward height, but not Affect proportions of bare ground or bank erosion rates pasture adjacent to streams.THEREFORE, managing stocking rates May reduce nutrient loading of streams pasture

Effects of Stocking Rate, Botanical Composition, and Stream Bank Erosion on the Physical Characteristics of the Streamside Zones of Pastures (Three-year Progress Report)

Grazing management practices that allow cattle to congregate near pasture streams may result in the loss of vegetative cover and promote accumulation of manure near the streams, increasing the risk of nonpoint source pollution of the strea

Effects of Stocking Rate and Botanical Composition on the Physical Characteristics of the Riparian Zones of Pastures (A Two-Year Progress Report)

Grazing management practices that allow cattle to congregate near pasture streams may result in the loss of vegetative cover and promote accumulation of manure near the streams, increasing the risk of nonpoint source pollution of the stream. The objective of this project was to evaluate the effects of stocking rate of pastures and the botanical composition of the pastures’ riparian zone on the forage sward height and the proportions of bare and manure-covered ground along the banks of pasture streams