Ion mass balances for three small forested catchments in Sweden

Ion mass budget calculations were performed for three small, forested catchments. The study sites are situated along a deposition gradient fom high loads of sulphur and nitrogen in southwest Sweden to low deposition in the northern part of the country. The sites showed three different H⁺production/H⁺consumption patterns mainly featuring the catchment characteristics and to a lesser extent the atmospheric deposition. External proton production, with atmospheric deposition as the main source, accounted for 34–40% of the total H⁺production in southern Sweden and only for 12% in northern Sweden. This is low concidering that the two southern sites are within the most exposed area for acid deposition in Sweden. It is obvious that natural H⁺production processes can be very important also in such areas.     

Ibuprofen Sorption to Coastal Plain Soils

Ibuprofen is commonly detected in onsite wastewater systems. Such onsite systems are abundant in coastal plain areas, globally. Coastal plain soils have unique mineralogy. Rapid subsurface transport may occur in coastal plain soils due to their characteristic permeable soils and seasonally high water tables. Laboratory batch sorption studies were conducted on Norfolk, Goldsboro, and Lynchburg, three archetypical coastal plain soils, with varying physicochemical properties, to evaluate ibuprofen sorption. Sorption distribution coefficients (K_D values) across all three soils ranged from 0.63 to 1.26 L kg^?1. Sorption of ibuprofen to Norfolk and Goldsboro soils was able to be modeled using a Freundlich isotherm; however, the Lynchburg soil, was not, likely due to soil heterogeneity. In general, sorption of ibuprofen was influenced by soil organic carbon content.     

Potassium Dynamics in US Coastal Plain Soils

ABSTRACT

Potassium (K) deficiency in crops in southern US Coastal Plain soils has been documented since the l880s. Long-term soil fertility studies such as Alabama’s “Cullars Rotation” experiment (circa 1911) have been conducted with K since 1911. Other Alabama long-term experiments on several Coastal Plain and related Hapludults, Paleudults, and Kandiudults also contain K variable treatments which have been monitored since 1929. Soil test data from these long-term experiments have allowed us to answer some practical questions regarding K dynamics in Coastal Plain soils. Potassium movement through the soil profile is dependent on the soil’s cation exchange capacity (CEC) but relative accumulation is greater in the plow layer regardless of soil CEC. While subsoil K testing may be useful for identifying situations where subsoil K has been depleted, this extra effort and expense is not necessary for most cropping situations. A crop will remove most of its K from the plow layer if it is present in sufficient quantity based on soil test. Crop depletion of plow-layer K to the point where yield may be reduced is gradual and may take 10–15 years or more depending upon soil CEC and initial soil K concentration. Depletion is most rapid in low CEC soils as would be expected. However, soil test K can vary considerably during the course of a crop season with the lowest soil test K concentrations occurring immediately after harvest.     

Deep tillage management for high strength southeastern USA Coastal Plain soils

Southeastern USA production is limited in Acrisols (Paleudults and Kandiudults) because they have high strengths and low water holding capacities. Production systems with crop rotations or deep tillage before planting were compared with less intensive management. Production systems included double-crop wheat (Triticum aestivum L.) and soybean (Glycine max L. Merr.) that were drilled in 0.19 m-row widths and grown in 15 m wide, 150 m long plots with soils of varying hardpan depths. Treatments included surface tillage (disked or none), deep tillage (paratilled or none), deep tillage with winter fallow and maize (Zea mays L.) in rotation, and disked/deep tillage with an in-row subsoiler where soybean was planted in conventional 0.76 m-wide rows. Cone indices were measured near the ends of each plot (120 m apart) to assess soil strength differences among soil types and among treatments. Cone indices were 1.50 MPa higher for non-deep tilled treatments than for deep tilled treatments and 0.44 MPa higher in wheel-track mid rows than in non-wheel-track mid rows. Cone indices were also 0.28 MPa higher for soils with shallower Bt horizons. Cone indices were not significantly different for subsoiled treatments and paratilled treatments. Rainfall was erratic throughout the 5-year experiment with dry periods lasting more than 2 weeks at a time and with annual totals ranging from 520 to 1110 mm. Wheat yields were 0.67 Mg ha⁻¹ greater for deep-tilled soils (subsoiled and paratilled) than for non-deep-tilled soils. Soybean yields were 0.36 Mg ha⁻¹ greater for paratilled than for subsoiled or non-deep-tilled treatments partly as a result of the more complete disruption of the paratill and partly because paratilled treatments were managed with narrow rows. Yields did not vary significantly among the soil types despite the fact that they had different cone indices. Tillage was a more dominant factor than soil type. For wheat, lower cone indices from tillage led to higher yields. For soybean, management of uniform loosening from deep tillage and narrow rows led to higher yields.     

Benefits of site-specific subsoiling for cotton production in Coastal Plain soils

The negative impacts of soil compaction on crop yields can often be alleviated by subsoiling. However, this subsoiling operation is often conducted at unnecessarily deep depths wasting energy and excessively disturbing surface residue necessary for erosion control and improved soil quality. A corn (Zea mays L.)–cotton (Gossypium hirsutum L.) rotation experiment was conducted over 4 years on a Coastal Plain soil with a hardpan in east-central Alabama to evaluate the potential for site-specific subsoiling (tilling just deep enough to eliminate the hardpan layer) to improve crop yields while conserving energy. Seed cotton yield showed benefits of subsoiling (2342 kg/ha) compared to the no-subsoiling treatment (2059 kg/ha). Averaging over all years of the study, site-specific subsoiling produced cotton yields (2274 kg/ha) statistically equivalent to uniform deep subsoiling at a 45 cm depth (2410 kg/ha) while not excessively disturbing surface soil and residues. Significant reductions in draft force were found for site-specific subsoiling (59% and 35%) as compared to uniform deep subsoiling at a 45 cm depth in shallow depth hardpan plots (25 cm) and medium depth hardpan plots (35 cm), respectively. Calculated fuel use for site-specific subsoiling was found to be reduced by 43% and 27% in the shallow and medium depth hardpan plots, respectively, as compared to uniform deep subsoiling in these same plots. Producers in the Coastal Plains who can determine (or who know) the depth of their root-impeding layer and perform site-specific subsoiling can have comparable cotton yields to traditional uniform depth subsoiling with reduced energy requirements.     

Restoration of the Rivers in Israel's Coastal Plain

Israel's chronic water shortage has aggravated problems of river pollution, as almost no dilution of inadequately treated wastewater takes place. Since the early 1990s, large investments were made to build new wastewater treatment plants, designed to produce effluents of secondary quality or better. Consequently, it became of interest to examine the possibility of using tertiary treated effluents as a water source for rehabilitation of aquatic habitats. A survey of water quality in clean and polluted segments of Israel's coastal rivers was initiated, including analyses of riverbed sediments. Although many segments are still heavily polluted, there are examples of measurable improvement in water quality, which should lead to better sediment quality. It is argued that sediments serve both as a memory bank of past pollution events and as an ongoing source of anaerobic and toxic compounds, such as sulfides and ammonium compounds. Their chemical compositions are, therefore, of much importance for river restoration processes and monitoring.     

Phosphorus Runoff from Coastal Plain Forest Soil in Louisiana

Although not a common practice, poultry litter (PL) may be used for forest fertilization. Despite usually low soil phosphorus (P) and runoff under forest, repeated or high rates of PL application may cause appreciable P loss. Phosphorus in natural runoff under loblolly pine (Pinus taeda L.) fertilized with PL, downslope P enrichment of surface soil, and P runoff during simulated rainfall (a) 5 years post-application and (b) where straw was harvested were measured. Relationships of runoff P (dissolved reactive, dissolved, and total) concentration and load to soil P (Bray 2 and water-extractable in two depths) and hydraulic conductivity were examined. Post-application loss of P was lower than reported for pasture. There was little downslope P movement. Runoff P was related to the corresponding form of soil P (R² = 0.28–0.48) but likely affected by P leached from the O horizon. Loads could be estimated from regressions.     

Conservation tillage for soybean in the U.S. Southeastern Coastal Plain

Double cropping of soybean has progressed less rapidly in the U.S. Southeastern Coastal Plains than expected by the ample rainfall and long frost-free season. Post-emergence herbicides, the management of plant residues to reduce water use by cover crops, and a no-till planter with a combination subsoiler are the innovations that have facilitated this new production. Full-season soybean (Glycine max L.) was planted following a grazed cover crop of winter rye (Secale cereale L.) or late-season soybean was planted following winter wheat harvest. In both cases, a special planter was used with an integral subsoil shank ahead of the opener. Full-season soybean under conservation tillage produced yields equal to or better than yields in conventional clean tillage. In a dry summer, soybean yields under conservation tillage exceeded conventional tillage because of suppressed early biomass production which conserved stored soil water and favored growth during the reproduction phase of the crop-cycle. Late-season soybean yields behind wheat favored the conservation tillage practice of in-row subsoil-planting into stubble. However, planting in burned-off wheat stubble produced the highest yields in this study. In a dry spring, the cover crop accelerated soil water use which resulted in lower soybean yields under conservation tillage. Comparisons of 76 vs. 97 cm row spacing were inconclusive, but the trend suggests that wider rows conserve water under periods of drought and that the narrower-row configuration favors adequate water regimes.     

平原粉沙淤泥质海岸防护林土壤渗透特性的研究

探讨了淤泥质海岸防护林土壤的渗透特性 ,指出同一林分土壤渗透速率差异较大 ,不同样地间土壤渗透速率的差异也十分显著。林地初渗速率大 ,在降雨初期能吸收大量降雨 ,稳渗时渗透速率未必比光板地大。林地土壤渗透过程符合对数曲线 ,相关系数达极显著水平 ;渗透速率大小主要取决于土壤有机质含量和非毛管孔隙率     

A conservation tillage research update from the Coastal plain soil and water conservation research center of South Carolina: A review of previous research

In the U.S. Southeastern Coastal Plains conservation tillage (CT) became useful as a management system with the development of in-row subsoiling systems capable of planting into heavy residues. Research priorities associated with the development of CT included: reducing cover crop water loss, improving stand establishment, assessing nutrient and water management requirements, determining optimal subsoiling strategies, understanding long-term conservation tillage effects on soil properties, evaluating the interaction of crop residue removal with tillage systems, and documenting tillage impact on pests and beneficial organisms. Since the late 1970s the Coastal Plains Soil and Water Conservation Research Center in Florence, SC has made a concerted effort to study these interactions and alleviate them as obstructions to the use of CT management. These studies showed that for Coastal Plain soils such as Norfolk sandy loam (fine-loamy, siliceous thermic, Typic Paleudults) winter cover crops such as rye (Secale cereale L.) desiccated the soil profile by evapotranspiration in the spring. This delayed emergence and early season growth of corn (Zea mays L.) but not full-season soybean (Glycine max (L.) Merr.). Conservation tillage helped manage soil strength by gradually increasing soil organic matter content, restricting traffic patterns and maintaining higher soil water contents. Laboratory studies demonstrated a negative correlation (R²=0.85) between proctor soil strength and organic matter content. Conservation tillage affected nematode, Bradyrhizobium japonicum and Heliothis species populations. Alternate cropping systems using rapeseed (Brassica napus L.) as a winter crop or sunflower (Helianthus annuus L.) either before soybean or after corn provided crop cover against potential soil loss from late autumn through early spring, when bare soil is exposed to intense rainfall. Water quality questions associated with CT have been raised but remain unanswered. Although CT can reduce runoff and erosion, the crop residues can support higher insect populations and pathogen inoculum levels, and thus prompt greater pesticide use. Quantifying relationships between soil strength, macropore formation and persistence, and water infiltration with surface and subsurface water quality is the focus of new long-term evaluations. The findings of these studies, published to date, are summarized in this paper.     

Hydropedology of a coarse-loamy catena in the lower Coastal Plain,NC

The identification of the depth of seasonal saturation in soils is critical for a multitude of land uses including the siting and design of septic systems and delineation of wetlands. Often 2 chroma redox depletions are used to make this determination; however, other redoximorphic features are also related to saturation. With increasing land use intensities and environmental concerns it is important to understand exactly how redoximorphic features (RMFs) relate to saturation. The objective of this research is to relate RMFs to saturation in a coarse-loamy catena in the lower coastal plain in North Carolina. A relatively undisturbed site in eastern NC was identified and three transects were instrumented with recording wells, redox probes and thermocouples. A rain gauge was also located at the site. In all the soils investigated, ≤ 2 chroma redox depletions related to an average cumulative annual saturation percentage (CSP) of 15%. However, the ≤ 2 chroma redox depletions indicated a larger CSP in the MWD soils (19%) as compared to the SWPD soils (11%). This suggests that ≤ 2 chroma redox depletions do not mean the same thing in all soils. Regulations that rely on this single feature may be identifying different degrees of saturation and thus may have a varying implication to wastewater treatment and water quality.     

Subsurface leachate migration from a reject coal pile in South Carolina

Transport of contaminants from coal storage areas through the rooting zone has the potential to negatively affect shallow ground water and terrestrial vegetation. Reject coal piles represent a worst-case scenario for contamination from coal storage areas because of the long residence time of the coal. Preliminary hydrologic data were collected from an area of stressed vegetation adjacent to an inactive ash basin and reject coal pile in South Carolina. The water table is near the surface (< 60 cm) in this wetland area and water movement is primarily to the west, toward the Savannah River. Acid leachate migration from the reject coal pile has contaminated the water-table aquifer with sulfate (up to 22 200 mg L^?1) and metals (Fe to 9560 mg L^?1) Al to 1110 mg L^?1) A shallow plume of contaminated ground water parallels the reject coal pile and is elongated in the direction of ground-water movement. The plume is migrating westward at a calculated velocity range of 6.3 to 10.4 m yr^?1. Leachate migration from the reject coal has produced a highly acidic (pH down to 2.2) and highly saline (EC to 11.8 dS m^?1) rooting zone and is most likely responsible for the stressed vegetation in the study area.     

Hydrologic and wetland characteristics of a piedmont bottom in South Carolina

A four hectare mixed bottomland hardwood site on Ninety Six Creek in the Piedmont of South Carolina near Ninety Six, SC was studied for two years to characterize wetland traits. The soils were thermic Fluventic or Fluvaquentic Dystrochrepts predominantly Shellbluff series and well drained. Overbank flooding occurred on the average of 4 times per year and 1.5 times during the growing season for a 13 year period. High water table levels during the early growing season were related to rainfall events. A hydrologic model (WATRCOM-2D), soils, water table levels, and GIS techniques were used to estimate the portion of the bottom that met wetland criteria similar to those defined in the 1987 and 1989 federal wetland delineation manuals. Less than one hectare met these criteria. The wetland “status” of the vegetation within the bottom and adjacent slope was not correlated with water table levels, predicted wetland areas, or landforms. Wetland traits of the site were closely related to hydric soil traits within the upper 25 cm of the Chewacla and Chenneby soils and landform characteristics. Wetlands in this bottom were primarily driven by local precipitation and not by overbank flooding as originally suspected. Songbirds and small mammals were relatively abundant in the small bottom during the spring and summer of 1992. Protection of only the jurisdictional wetlands in this bottom would not be adequate to sustain riverine functions (conveyor) and to provide wildlife travel corridors between adjacent forested areas.     

Effect of Coal Combustion By-products on Phosphorus Runoff from a Coastal Plain Soil

Coal combustion by-products can lower soil phosphorus (P) solubility, but few studies have assessed their effect on runoff P. A soil with elevated P content was amended with fluidized bed combustion ash, flue gas desulfurization gypsum, and anthracite refuse ash at rates of 0–40 g kg^?1 soil, and runoff from small plots was monitored over 3 years. In the first year, by-products lowered dissolved P in runoff by up to 47% below the untreated control; however, effects did not persist into the remaining years of the study. Total P losses were not significantly affected by coal combustion by-products, likely because of elevated particulate P losses. Water-extractable P was up to 40% less in treated soils than in untreated soils across the 3 years. Results demonstrate that although coal combustion by-products readily lower P solubility in soils, their impact on P losses in runoff can be undermined by erosional processes.     

Impacts of coal pile leachate on a forested wetland in South Carolina

This study was conducted to: (1) determine the probable cause of several areas of stressed and dead vegetation adjacent to a 15-yr-old reject coal pile in western South Carolina and (2) identify the factors limiting successful revegetation of the site. Data from an earlier study suggested that solution pH, total dissolved solids (TDS) and electrical conductivity (EC), and/or elevated trace element concentrations may have contributed to the stress and dieback. Soil water in the two vegetation kill zones is saline (TDS>10 000 mg L^?1 and EC>4 dS m^?1), highly acidic (soil pH<3.5), and high in Al and Mn (Al conc.>200 mg L^?1 and Mn conc.>10 mg L^?1). Soil water in areas of sparse vegetation is brackish (TDS>1000 mg L^?1 and EC>2 dS m^?1) and acidic (soil pH<4.0), with elevated Al values (> 40.5 mg Al L^?1). Tissue samples were collected from volunteer loblolly pine (Pinns taeda L.) seedlings growing in the study area and analyzed for essential and non-essential elements. Seedling tissues did not contain abnormal concentrations of nutrients or trace elements. The strong relationship between the zones of vegetation stress and dieback and solution pH and soluble salt concentrations, and the lack of excessive metal accumulations by tree seedlings which have become established in the less toxic portions of the study area, suggest that low solution pH and high soluble salts are more important factors limiting plant establishment on this site than solution metal concentrations. The results of this study demonstrate the importance of site hydrology in determining the impacts of coal waste disposal on adjacent ecosystems.     

Seasonal mass balance of major ions in three small watersheds in a maritime environment

Three watersheds (16.4, 544, and 83 ha) at distances of 0.5, 20, and 40 km from the Atlantic coast have been monitored for major ion chemistry of precipitation input and streamflow from May 1977 to November 1978. More than 200 precipitation and stramflow samples were analyzed for Na, K, Ca, Mg, chloride and sulphate, as well as pH, conductivity, alkalinity, and compared to similar studies at Hubbard Brook, New Hampshire, U.S.A., and Kejimkujik National Park, Nova Scotia. Major ion chemistry reflects proximity to Atlantic and Bay of Fundy coastal sources of marine aerosols. Evidence is presented implying biological reduction of H ⁺ and S04 to H₂S during summer months for two consecutive growing seasons. Weighted mean annual pH values of precipitation for the three watersheds in Nova Scotia range from 4.11 to 4.63. More than 50% of the H ⁺ in precipitation is retained in the watersheds (with the exception of the ombrotrophic Fink Cove ecosystem), principally at the expense of basic cations being leached from the watersheds. Acidic deposition of Nova Scotian precipitation is predominantly as sulphuric acid, in contrast to ammonium sulphate, characteristic of continental precipitation.     

Fluoride deposition via litterfall in a coastal-plain pine plantation in South Carolina

The concentration of fluoride in needles, its effects on tree defoliation and on decomposition of needles (litter), and its subsequent accumulation in the upper soil horizons were observed in pine plantations near and far from a new aluminum smelter. Pinus taeda and Pinus palustris stands within 0.8 km of the smelter had significantly higher levels of foliar F than a P. taeda stand 1.8 km from the source. Neither temporal patterns nor amounts of needlefall were altered by airborne F from the smelter. In addition, elevated levels of foliar F did not affect the rate of decomposition of pine needles over a period of 6 mo. Soluble F in soil samples increased significantly in the upper 10 cm of the soils at the sites nearest the F source over a period of 7 yr since the start of F emissions.     

Spatial variability of Southeastern U.S. Coastal Plain soil physical properties: Implications for site-specific management

Our objectives were to describe the field-scale horizontal and vertical spatial variability of soil physical properties and their relations to soil map units in typical southeastern USA coastal plain soils, and to identify the soil properties, or clusters of properties, that defined most of the variability within the field. The study was conducted on a 12-ha field in Kinston, NC. A 1:2400 scale soil survey had delineated three soil map units in the field: Norfolk loamy sand, Goldsboro loamy sand, and Lynchburg sandy loam. These are representative of millions of hectares of farmland in the Coastal Plain of the southeastern USA. Sixty soil cores were taken to ∼ 1-m depth, sectioned into five depth increments, and analyzed for: soil texture as percentage sand, silt, and clay; soil water content (SWC) at − 33 and − 1500 kPa; plant available water (PAW); saturated hydraulic conductivity (Ksat); bulk density (BD); and total porosity. A penetrometer was used to measure cone index (CI) at each sample location. Variography, two mixed-model analyses, and principal components analysis were conducted. Results indicated that soil physical properties could be divided into two categories. The first category described the majority of the within-field variability and included particle size distribution (soil texture), SWC, PAW, and CI. These characteristics showed horizontal spatial structure that was captured by soil map units and especially by the division between sandy loams and finer loam soils. The second class of variables included BD, total porosity, and Ksat. These properties were not spatially correlated in the field and were unrelated to soil map unit. These findings support the hypothesis that coastal plain soil map units that delineate boundaries between sandy loams versus finer loam soils may be useful for developing management zones for site-specific crop management.     

河北滨海平原区土地整理工程质量评价体系研究

土地整理能有效保持土地可持续利用、提高土地质量和促进土地集约利用的方式,并且对于缓解人地矛盾、改善农业生产条件和生态环境、保证粮食安全以及促进经济社会健康发展起着重要的作用。土地整理工程质量的好坏对项目工程质量的直接监督检查和最后的验收、确认显得尤为重要,因此对土地整理工程质量评价就是必不可少的一个环节。该文在国内相关研究分析基础上,依据土地整理的理论和方法,通过评价指标基准值和权重确定,得出适合滨海平原区土地整理工程质量评价体系,构建评价模型。通过此评价体系得出一八农场整理项目综合分值为0.859工程质量为一级优秀,同时证实此评价模型对河北滨海平原地区土地整理有一定的指导作用。