Typic Hapludalf Research Articles

Water infiltration influenced by agroforestry and grass buffers for a grazed pasture system

Agroforestry (AgB) and grass buffers (GB) are often adopted as alternative resource management tools in agroecosystems for environmental and economic benefits. The objective of this study was to compare the influence of AgB and GB systems under rotationally stocked (RP) and continuously stocked (CP) pasture systems on water infiltration measured using ponded infiltration and tension infiltration methods. Buffers were surrounded by a fence that prevented cattle from grazing within these areas. Soils at the site are Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf). Infiltration rates were measured using ponded ring infiltration units during 2 years for the four (AgB, GB, RP and CP) treatments with three replicates from two subareas within each treatment. Infiltration rate as a function of tension (at 50, 100, and 150 mm) was also measured using a tension infiltrometer. Water infiltration parameters were estimated using Green-Ampt and Parlange infiltration equations. Quasi-steady state infiltration rates (qs) and field-saturated hydraulic conductivity (Kfs) for buffers were about 31 and 46 times higher as compared to pasture treatments, respectively. Green-Ampt and Parlange models appeared to fit measured data with r2 values ranging from 0.91 to 0.98. The qs (measured with ponded method) in the first year for the GB treatment was the highest (221 mm h−1) and for the CP treatment was the lowest (3.7 mm h−1). For both years, estimated sorptivity (S) and saturated hydraulic conductivity (Ks) parameters were higher for buffer areas compared to the stocked pasture areas. Grazing reduced the infiltration rate for the pasture (RP and CP) treatments. Results show that the buffer areas have higher infiltration rates which imply lower runoff compared to pasture areas.

Chemical, Mineralogical, and Morphological Characteristics of a Late Quaternary Sedimentary Rock–Derived Soils in Leyte, Philippines

To understand the genesis of soils derived from a late Quaternary sedimentary rock in Leyte, Philippines, the properties of four soil profiles were investigated. Two of the profiles (PS-1, PS-4) derived from coralline limestone were shallow with less developed horizons and alkaline pH conditions and higher potential cation exchange capacity and are classified as Calcaric Phaeozems in the World Reference Base or fine, calcareous, isohyperthermic, Rendollic Eutrudepts in Soil Taxonomy. The other two profiles (PS-2, PS-3) derived from calcareous shale were deeper with well-developed horizons and characterized by high loss of bases and were classified as Haplic Alisols (Hyperdystric, Rhodic) or fine, kaolinitic, isohyperthermic, Typic Hapludalfs. The calcareous shale parent materials have much faster weathering as shown by the higher clay content and the dominance of kaolinitic and halloysitic clay minerals. In those soils developed from limestone, clay minerals were mostly calcite, smectite, vermiculite, and interstratified kaolinite/smectite. The results of this study suggest a strong influence of external material contributions, particularly volcanic-ash deposition on the progression of the soils, as reflected by higher clay and silt contents in these comparatively young soils. The most important pedogenic processes that formed the soils in the area seem to be weathering and clay formation, loss of bases and acidification, inorganic C accumulation, structure formation, desilication, and ferrugination. The nature and characteristics of the parent material, topography, and the time of pedogenesis also have assertive effects on the development of the soils.

Morphological, chemical and mineralogical characterization of developing soils and their management in the western Siwalik Himalayas

The western Siwalik Himalayas of India experienced the last climate shift 3500 years ago and the soils have been marked by rigorous human activities for a few centuries. An attempt was made to investigate the interactions between soil-forming factors and processes in soil development in relation to land forms and climate change. The hallmark of the soils is the considerable heterogeneity in solum and regolith thickness, horizon boundaries, structural development in surface soils, pH, electrical conductivity and soil mineralogy, irrespective of landscape form and position. A remarkable feature of the soils is the development of deep argillic horizons, or B horizons, in certain landscape positions. The minerals identified were quartz, micas and feldspars in the sand and silt fractions. Illite, kaolinite, vermiculite, smectite and chlorite were present in the clay fractions. Soils under forest vegetation and those recently brought under cultivation belong to Typic Hapludalfs. Soils cultivated over centuries, however, failed to qualify as Alfisols and were classified as Typic/Dystric Eutrudepts. The eroded barren soils were similarly classified as Typic Udorthents. All the soils were low to medium in available nitrogen and phosphorus. The use of nitrogen and phosphorus fertilizer is therefore needed to ameliorate nutrient deficiency and boost crop production. Because of the presence of appreciable amounts of potassium-bearing minerals, soils are likely to be non-responsive to potassium application. The soils of the Dala series (Typic Hapludalfs) are located on moderate hill slopes and thus soil erosion is less severe than for the Mansu series (Typic Udorthent). In the Chamror and Dhar series (Typic/Dystric Eutrudepts) soil erosion is not a serious problem because of terracing and the finer texture of the soils. Crops can thus be grown on profile-stored moisture during dry periods and limited grazing may be permitted.

Umidade do solo no semiárido pernambucano usando-se reflectometria no domínio do tempo (TDR)

Objetivou-se com o presente trabalho investigar a variabilidade temporal do conteúdo superficial da água no solo, através da reflectometria no domínio do tempo (TDR), em consequência das características de precipitação ocorridas no semiárido pernambucano, estudando esta dinâmica sob diferentes tipos de cobertura superficial do solo. O estudo foi realizado em uma encosta de uma bacia representativa, em um Argissolo Amarelo Eutrófico típico, onde foram instaladas quatro parcelas experimentais dotadas de duas sondas TDR, para investigação da umidade do solo e do sistema para monitoramento do escoamento superficial. Os tratamentos adotados foram: cobertura natural (CN), solo descoberto (SD), palma forrageira (P) e barramentos, associados à cobertura morta (B+CM). A partir dos resultados obtidos durante o período de ocorrência de chuvas erosivas, a umidade do solo apresentou elevada variabilidade no tempo, estando relacionada aos diferentes tipos de cobertura e propriedades do solo. A cobertura morta mostrou ser a prática conservacionista mais adequada para manutenção da umidade do solo.

Effect of dairy manure slurry application in a no-till system on phosphorus runoff

Incorporation of manure slurry under reduced tillage conditions remains a challenge in the northeastern US. New technologies to directly incorporate slurry are available but their agronomic and environmental benefits have generally not been quantified. This study evaluated the effects of five manure slurry application methods on phosphorus (P) loss in runoff (broadcasting with and without incorporation by tillage, shallow disk injection, banded application and aeration, and pressurized injection) and a control (no manure). Research was conducted over a 2 year period in central Pennsylvania on a well-drained Hagerstown silt loam (fine, mixed, semiactive, mesic Typic Hapludalf) under corn (Zea mays L.) production. Approximately 72 h after dairy (Bos Taurus) slurry application (56,000 l ha−1) to 10 × 13 m plots, a single rainfall simulation (68 mm h−1) was conducted in triplicate on 10 × 2 m areas within the plots. Trends in total P losses in runoff (kg ha−1) from plots varied between years and treatments. Aeration yielded lower losses than all other treatments in 2006 and was amongst the lowest in 2007 with losses statistically similar to shallow disk and pressure injection. Remarkably, few differences were apparent in losses of dissolved reactive P between treatments, reflecting high variability in runoff depths. Indeed, variability in runoff depths resulted in some unexpected trends, including high loads from the unamended control and modest loads from the tillage treatment. Results highlight tradeoffs in alternative manure slurry application practices but point to the potential to significantly lower runoff P losses from reduced tillage systems receiving manure slurry.

Soil structure and flow rate-controlled molybdate, arsenate and chromium(III) transport through field columns

Preferential flow in soil causes rapid movement of chemicals and contamination at the tile-line level. Soil structure and flow rate effect on transport velocity of MoO 4 2−, H 2AsO 4 −1, and Cr + 3 was assessed for three soils differing in vadose structure. Triplicate, 50 cm long, 35 cm diameter field soil columns of Lamellic Hapludalf, Typic Udorthent, Typic Hapludalf from southwestern Germany were obtained. The metals solute prepared in 3.5 mM LiCl was applied as pulse, and flushed with synthetic rainwater of pH 5.5 at constant flow rates generated by + 10, −10, and −40 mm water heads at the column surface. The tracers' breakthrough data were fitted to a convective–dispersive flow equation with mobile and immobile soil water partition. Additionally, blue dye was rained on site, and X-ray tomography of one representative column from each soil was carried out to identify preferential flow paths in the field soils. Lamellic Hapludalf (sandy loam) had a dominantly massive structure, and blue dye flowed as vertical fingers. Typic Udorthent (silt loam) had well-connected macropores, and dye moved as macropore flow with radial diffusion. Typic Hapludalf (silty clay) had well-connected pores throughout the profile, and dye moved the deepest with smallest dyed area. Chloride moved sampling 0.30 to 0.33 fraction of porosity in the massive soil irrespective of flow rate; and depending on flow rate, it moved through only 0.05 to 0.15 fraction of porosity in the structured silt loam/silty clay soil columns. MoO 4 2−, H 2AsO 4 −1 and Cr + 3 leached as fast as Cl −1 under ponded flow and with large retardation under unsaturated flow suggesting macropore flow of the adsorbing solute in the well-structured soils. The massive soil effectively retained H 2AsO 4 −1 and Cr + 3 but allowed MoO 4 −2 to leach at all the flow rates. Retardations of the absorbing tracers were in the order of Cr + 3 > H 2AsO 4 −1 > MoO 4 −2 > Li + 1 . Depending on soil structure, the effective porosity and retardation increased, and dispersion decreased with reduced flow rate. The study concludes that strongly graded, coarse to medium angular/prismatic soil peds allow adsorbing solute to leach at reduced flow rate, and the field description of soil structure helps discern areas where preferential flow can potentially cause subsoil contamination.

Calibration of a water content reflectometer and soil water dynamics for an agroforestry practice

Water content reflectometers allow temporal and continuous assessment of spatial differences in soil water dynamics. We hypothesized that volumetric soil water content estimated by the water content reflectometers (CS616 Campbell Sci. Inc., Logan, UT) is influenced by clay content and temperature and therefore site- and or soil-specific equations are required for accurate estimations of soil water. Objectives of the study were to develop calibration equations and to evaluate soil water dynamics for an agroforestry system using the improved calibration equation. Putnam silt loam (fine, smectitic, mesic Vertic Albaqualfs) and Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalfs) soils were selected with 23–54% clay. Soils were packed in cylinders and sensors were monitored at 5, 10, 15, 20, 25, 30, 35, and 40°C. Calibration equations for volumetric water content (θv) as a function of sensor measured period, temperature, and clay content were developed. Coefficient of determination (r2) and root mean square error (RMSE) were used to compare goodness of fit. RMSE varied between 0.028 and 0.040 m3 m−3 for soil specific and soil-combined linear and quadratic equations with period. Coefficients of determination ranged between 0.89 and 0.96 for these calibrations. RMSE decreased and r2 increased as temperature was included. The effect of temperature varied with water content, with the strongest effect at high water contents. Clay content did not contribute significantly to improve predictability. Water content estimated by the linear calibration equation with period and temperature showed differences in θv influenced by vegetation and soil depth, and closely followed precipitation events and water use by vegetation. The field study showed significant differences between the two treatments. Also the importance of temperature correction is emphasized during periods with large diurnal fluctuations and site specific calibration equations. Results of the study showed that water content reflectometers can be used to estimate θv with less than ±4% error and may need site specific calibration and a temperature correction to research more precise estimates.

Nutrient transfer by runoff under no tillage in a soil treated with successive applications of pig slurry

High rates and successive applications of pig slurry can cause nutrient transfer by surface runoff. The aim of this study was to evaluate the importance of surface runoff in transferring nitrogen (N), phosphorus (P) and potassium (K) under a no tillage system and for successive applications of pig slurry. The research was carried out in the Agricultural Engineering Department of the Federal University of Santa Maria, Brazil, from 2002 to 2007 in a Typic Hapludalf soil. Pig slurry rates of 0, 20, 40 and 80m3ha−1 were applied, scattered on the surface, before the sowing of each species in a cultivation sequence. On average 119, 238 and 475kgha−1yr−1 of N; 102, 203 and 406kgha−1yr−1 of P and 43, 87 and 173kgha−1yr−1 of K were added, for rates of 20, 40 and 80m3ha−1 of pig slurry, respectively. Samples of water runoff from the soil surface were collected during the entire period and the minerals, N, P and K were determined. Successive applications of pig slurry decreased surface runoff. In relative terms, the K losses were higher than N and P. As regards total nutrients applied through pig slurry, losses through surface runoff were of 2.74, 1.61 and 1.37% of mineral N; 6.29, 5.01 and 3.51% of available P and 17.16, 9.01 and 11.14% of available K, for the three rates of applied pig slurry, respectively. Repeated applications of pig slurry on a no tillage managed soil caused losses of N, P and K from the soil through surface runoff, in the sequence: K>P>N. The losses of N and K are positively related to the volume of surface runoff, whereas the losses of P are positively related to the quantities of P added through pig slurry. Applications of pig slurry along the years decrease the surface runoff.

Quantitative Relationships between Soil Macropore Characteristics and Preferential Flow and Transport

Quantitative relationships between soil structure, especially macropore characteristics, and soil hydraulic properties are essential to improving our ability to predict flow and transport in structured soils. The objectives of this study were to quantitatively relate macropore characteristics to saturated hydraulic conductivity (Ksat) and dispersivity (λ) and to identify major macropore characteristics useful for estimating soil hydraulic properties under saturated condition. Large intact soil columns were taken from two land uses (cropland and pasture) of the same soil type (a Typic Hapludalf), with four replicates for each land use. The soil columns were scanned using X‐ray computed tomography (CT) to obtain macropore parameters including macroporosity, length density, mean tortuosity, network density, hydraulic radius, path number, node density, and mean angle. The Ksat of the whole soil column, as well as each soil horizon within the column, and solute breakthrough curve (BTC) of CaBr2 were determined for each column. For all eight soil columns studied, macroporosity and path number (the number of independent macropore paths between two boundaries) explained 71 to 75% of the variability in the natural logarithm of Ksat values of the whole soil columns as well as of individual soil horizons. The traditional convection–dispersion equation (equilibrium model) simulated the BTCs well for all soil columns except one with an earthworm hole passing through the entire column, for which the two‐region model (non‐equilibrium model) was required. The path number, hydraulic radius, and macropore angle were the best predictors for λ, explaining 97% of its variability. Correlation between λ of the whole soil columns and Ksat values of the Bt horizons (but not A horizons) implied that the dispersivity was mainly controlled by the horizon with the lowest Ksat in the soil columns. These results indicate that the most useful macropore parameters for predicting flow and transport under saturated condition in structured soils included macroporosity, path number, hydraulic radius, and macropore angle.

KARAKTERISTIK PEDOLOGI DAN PENGELOLAAN REVEGETASI LAHAN BEKAS TAMBANG NIKEL: STUDI KASUS LAHAN BEKAS TAMBANG NIKEL POMALAA, SULAWESI TENGGARA

<p>Post-mining land management needs to be done by taking into account a holistic approach concerning the improvement of physical, chemical and biological properties of soil as growth media, in order to support the rehabilitation plans. The objective of this study were: (i) to conduct quantitative and comprehensive an inventory of pedological properties of nickel post mining land, (ii) to analyze the potential and limitations of post mined land, (iii) act designed environmental management, based on the characteristics of the revegetation of the land and the environment. The results showed that the soil in Pomalaa could be classified in Typic Hapludox, clayey, mixed, isohypertermic (P1) dan Typic Hapludalfs, loamy, mixed, isohypertermic (P2), while the material in ex mining area are overburden or parent material. The soil has developed from peridotite and peridotite-serpentinite ultramafic material. This soil has low natural fertility and require efforts to improve the physical properties. Ex-mining area has a high rate of erosion. Poor tree growth in revegetation area has been determined caused by a deficiency of Ca, Fe, Cu, or Mn. The possibility of Ni and Cr toxicity in plants needs to be further investigated. Local resources in the form of slag can be used for revegetation, especially converter slag. The results obtained from this study can be used to give the advice of post-nickel mining land management, based on land characteristics. A better management advice covers two issues, namely improvements of the management action actually implemented and improvements in technical rehabilitation.<br />Keywords: Pedological processes, post nickel mining land, revegetation</p>

Effect of Integrated Nutrient Management on Soil Physical Properties and Crop Productivity under a Maize (Zea mays)–Mustard (Brassica campestris) Cropping Sequence in Acidic Soils of Northeast India

A five-year (2001/02–2006/07) field experiment was carried out on acidic clay loam soil classified as Typic Hapludalf with a maize–mustard crop sequence to study the effect of continuous application of nitrogen, phosphorus, and potassium (NPK) fertilizers alone and in combination with lime, farmyard manure (FYM), and biofertilizers on soil physical properties, soil organic carbon (SOC), soil microbial biomass carbon (SMBC), and crop yields on the hilly ecosystem of Meghalaya. Significant improvement in the soil physical conditions of the soil was observed under integrated application of organic manure and inorganic fertilizers. Addition of NPK fertilizers along with organic manure, lime, and biofertilizers increased soil organic carbon (SOC) content, aggregate stability, moisture-retention capacity, and infiltration rate of the soil while reducing bulk density. The SOC content under the treatment of 100% NPK + lime + biofertilizer + FYM was significantly greater (68.58%) than in control plots. Maize and mustard crop yields also significantly increased (4.73- and 21.09-folds, respectively) with continuous application of balanced inorganic (100% NPK) + lime + biofertilizer + FYM as compared to the control plots. However, crop yields drastically reduced under application of integrated nutrients without FYM as compared to the treatment with FYM application. Thus, the results suggest that integrated use of a balanced inorganic fertilizer in combination with lime and organic manure sustains a soil physical environment that is better for achieving higher crop productivity under intensive cropping systems in the hilly ecosystem of northeastern India.

Formas de perdas de cobre e fósforo em água de escoamento superficial e percolação em solo sob aplicações sucessivas de dejeto líquido de suínos

As aplicações sucessivas de dejeto líquido de suínos podem aumentar os teores de cobre e fósforo na camada superficial do solo, aumentando as perdas de suas formas por escoamento superficial e percolação. O trabalho teve por objetivo avaliar as perdas e as formas de cobre e de fósforo na solução escoada, na superfície e percolada em solo submetido a aplicações sucessivas de dejeto líquido de suínos, em sistema plantio direto. O experimento utilizado neste estudo foi instalado no ano de 2000, sobre um solo Argissolo Vermelho distrófico arênico. Os tratamentos foram aplicações sucessivas de 0, 40 e 80m³ ha-1 de dejeto líquido de suínos a lanço e na superfície do solo, em sistema plantio direto. Para este trabalho, foram coletadas soluções escoadas e percoladas, durante o ciclo da aveia preta (Avena strigosa), no inverno de 2006, quando o solo apresentava um histórico de 16 aplicações de dejeto. Nas soluções, foi quantificado o sedimento e determinados os teores de Cu, P, cátions e ânions, pH, carbono orgânico dissolvido (COD) e condutividade elétrica (CE). Usando o programa Visual MINTEQ, versão 2.15, se realizou a especiação iônica de Cu e P nas soluções. As maiores perdas de cobre e fósforo do solo ocorrem por escoamento superficial, em áreas submetidas a aplicações sucessivas de dejeto líquido de suínos em sistema plantio direto. O potencial contaminante desses elementos ficou evidenciado pela presença do cobre na forma predominante orgânica (CuCOD) e do fósforo nas formas livres (HPO4(2-) e H2PO4-), na solução escoada.

Identification of Nutrient Deficiencies at Calcareous Soils for Maize

Identification of nutrient deficiencies at calcareous soils for maize (D Nursyamsi): A pot experiment was conducted to identify nutrient deficiencies at calcareous soils for maize (Zea mays, L.) in green house of Indonesian Soil Research Institute using top soil (0-20 cm) samples taken from Bogor (Typic Hapludalfs) and Blora (Typic Haplustalfs). The experiment used Randomized Completely Block Design, minus one test with 12 treatments and three replications, as well as maize of P21 variety as plant indicator. The results showed that use of N, P, K, Zn, Cu, Fe, and Mn fertilizers increased soil macro nutrients, i.e.: soil total-N, Olsen-P, HCl-P, and HCl-K, as well as soil micro nutrients, i.e.: soil DTPA-Zn, Cu, Fe, and Mn at both tested soils. Use of maize straw compost increased soil organic-C, total-N, HCl-K, and exchangeable Ca at Typic Hapludalfs and increased only soil organic-C and total-N at Typic Haplustalfs. Use of animal manure compost increased soil organic-C, exchangeable Ca and Mg, and CEC. Use of N, P, K, S, Zn, Cu, Fe, and Mn fertilizers increased each plant nutrients uptake at the soils. Use of both organic matters increased plant N, P, K, and Fe uptake at Typic Hapludalfs as well as increased only plant N, P, and K uptake at Typic Haplustalfs. Identification result showed that maize growth suffered from N, P, and K deficiencies at Typic Hapludalfs as well as N and P deficiencies at Typic Haplustalfs. Beside the nutrients, soil organic matter was also found out as limiting factor for maize growth in the soils.

Acúmulo e formas de cobre e zinco no solo após aplicações sucessivas de dejeto líquido de suínos

As aplicações sucessivas de dejeto líquido de suínos no solo podem aumentar os teores e alterar as formas de Cu e Zn no solo. O presente trabalho teve como objetivo estimar o acúmulo de Cu e Zn e suas formas em solo submetido a aplicações sucessivas de dejeto líquido de suínos, em sistema plantio direto com rotação de culturas. O trabalho foi desenvolvido em um Argissolo Vermelho distrófico arênico na área experimental do Departamento de Engenharia Agrícola da Universidade Federal de Santa Maria (RS). Os tratamentos consistiram na aplicação de 0, 20, 40 e 80 m³ ha-1 de dejeto líquido de suínos. Foram realizadas 17 aplicações de dejetos de maio de 2000 até o momento da coleta do solo, em outubro de 2006. Amostras de solo foram coletadas nas camadas de 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20, 20-25, 25-30, 30-35, 35-40, 40-50 e 50-60 cm, secas ao ar, passadas em peneiras de 2 mm e moídas em grau de ágata. Em seguida, foram preparadas e analisados os teores pseudototais após extração pelo método 3050B da EPA, disponíveis por meio da extração com HCl 0,1 mol L-1, além do fracionamento químico do Cu e do Zn. Nos dejetos de suínos foram determinados os teores pseudototais de Cu e Zn. As aplicações sucessivas de dejeto líquido de suínos no solo aumentaram os teores de Cu e Zn das camadas superficiais, com migração até 12 e 10 cm de profundidade, respectivamente. O Cu e Zn adicionados são acumulados no solo em formas biodisponíveis, sendo preferencialmente ligados às frações orgânica e mineral, respectivamente.

Potassium availability in a hapludalf soil under long term fertilization

In a system in which fertilization is recommended, diagnosis of soil K availability and the establishment of critical levels are made difficult by the possibility of a contribution of non-exchangeable forms of K for plant nutrition. Due to its magnitude, this contribution is well diagnosed in long term experiments and in those which compare fertilization systems with positive and negative balances in terms of replacement of the K extracted by plants. The objective of this study was to evaluate K availability in a Hapludalf under fertilization for sixteen years with the addition of K doses. The study was undertaken in an experiment set up in 1991 and carried out until 2007 in the experimental area of the Soil Department of the Federal University of Santa Maria (Universidade Federal de Santa Maria - UFSM), in Santa Maria (RS), Brazil. The soil was a Typic Hapludalf submitted to four doses of K (0, 60, 120 and 180 kg ha-1 K2O) and subdivided in the second year, when 60 kg ha-1 of K2O were reapplied in the subplots in 0, 1, 2 and 3 times. As of the fifth year, the procedure was repeated. Grain yield above ground dry matter and total K content contained in the plant tissue were evaluated. Soil samples were collected, oven dried, ground, passed through a sieve and submitted to exchangeable K analysis by the Mehlich-1 extractor; non-exchangeable K by boiling HNO3 1 mol L-1 and total K by HF digestion. Potassium fertilization guidelines should foresee the establishment of a critical level as of which the recommended dose should accompany crop needs, which coincides with the quantity exported by the grain, without there being the need for the creation of broad ranges of K availability to predict K fertilization. In adopting the K fertilization recommendations proposed in this manner, there will not be K translocation in the soil profile.

제주도 토양인 동귀통의 분류 및 생성

제주도의 서북부 해안지역의 용암류 대지에 주로 분포하고 있으며 Ineeptisols로 분류되고 있는 동귀통을 재분류하고, 그 생성을 구명하기 위하여 동귀통 대표단면의 형태적 특성을 조사하고, Soil Taxonomy의 표준 분석방법인 Soilsurvey laboratorγ methods manual에 따라서토양을 분석하여 Laboratory data sheets를 작성하였다. Ap층(0~17 cm)은 농앙회갈색( 10YR 3/2)의 미사질양토이고, BA층(17~42 cm)은 농암회갈색(10YR 3/2)의 자갈이 있는 미사질양토, Bt1층(42~60 cm)은 농암회감색(10YR 3/2)의 자갈이 있는 미사절식양토, Bt2층(60~85 cm)은 암갈색(10YR 4/6)의 자갈이 있는 미사질식양토, BCt층(85~130cm)은 적갈색(5YR 4/3), 갈색(7.5YR 4/4), 또는 암회색(10YR 4/1)의 미사질식양토이다. 현무암 및 현무암에서 유래된 화산분출쇄설물을 모재로 하는 토양으로 주로 밭으로 이용되고 있다. udic 토양수분상과 thermie 토양온도상을 보유하며, 배수등급은 약간 양호이다. 동귀통은 andie 토양 특성을 보유하고 있지 않으며, 42~130cm 깊이에 점토집적층인 argillie층을 보유하고 있고, 전 토층에서 염기포화도(양이온 합)가 35% 이상으로 높다. 따라서 동귀통은 Ineeptisols이나 Andisols이 아니라 Alfisols로 분류되어야 한다. Udic 토양수분상을 보유하고 있으므로 동귀통은 Udalfs 아목으로 분류할 수 있으며, Hapludalfs의 분류조건을 충족시키고 있다. 또한 Typic 아군의 분류조건을 충족시키므로 Typic Hapludalfs로 분류할 수 있다. 토성속 제어부위에서의 토성속이 식양질이고, 토양온도상이 mesic 온도상이기 때문에 동귀통은 Fine silty, mixed, thermie famuily of Dystric Eutrudepts가 아니라 Fine loamy, mixed, thermic family of Typic Hapludalfs로 분류되어야 한다. 비교적 건조한 제주도 서부 및 북부 해안지방의 용압류대지에 주로 분포하는 동귀통은 화산분출에 의하여 형성된 화산분출쇄설물을 모재로 하고 있는데도 Andisols이 아니라 Alfisols로 생성 발달되고 있다. Andisols로 생성 발달되지 않은 동귀통은 안정한 지형인 용암류 대지에 분포하고 있으므로 토양이 거의 침식되지 않고 충적물이 별로 퇴적되지 않기 때문에 오랫동안 토양수의 하향이동에 따른 점토 집적작용과 염기 용탈작용을 받게 된다. 그 결과 점토집적층인 argillic층이 생성되고, 기준 깊이에서 염기포화도(양이온 합)가 35% 이상인 Alfisols로 생성발달하고 있다. This study was conducted to reclassify Donggui series based on the second edition of Soil Taxonomy and to discuss the formation of Donggui series in Jeju Island. Morphological properties of typifying pedon of Donggui series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon has very dark grayish brown (10YR 3/2) silt loam A horizon (0~17 cm), gravelly very dark grayish brown (10YR 3/2) silt loam BA horizon (17~42 cm), gravelly very dark grayish brown (10YR 3/2) silty clay loam Bt1 horizon (43~80 cm), brown (7.5YR 4/6) silty clay Bt2 horizon (80~105 cm), and brown (10YR 5/4) silty clay Bt3 horizon (105~150 cm). It is developed in lava plain and are derived from basalt and pyroclastic materials. The typifying pedon contains 1.3~2.1% oxalate extractable (Al + 1/2 Fe), less than 85% phosphate retention, and higher bulk density than 0.90 <TEX>$Mg/m^3$</TEX>. That can not be classified as Andisol. But it has an argillic horizon from a depth of 22 to 150 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. That can be classified as Ultisol, not as Andisol and Inceptisol. It has udic soil moisture regime, and can be classified as Udalf. Also that meets the requirements of Typic Hapludalf. It has 18-35% clay at the particle-size control section, and have thermic soil temperature regime. Therefore Donggui series can be classified as fine loamy, mixed, thermic family of Typic Hapludalfs, not as fine silty, mixed, thermic family of Dystric Eutrudepts.

Agroforestry and grass buffer effects on water quality in grazed pastures

Conservation practices including agroforestry and grass buffers are believed to reduce nonpoint source pollution (NPSP) from pastured watersheds. Agroforestry, a land management practice that intersperses agricultural crops with trees, has recently received increased attention in the temperate zone due to its environmental and economic benefits. However, studies are limited that have examined buffer effects on the quality of water from grazed pastures. Six treatment areas, two with agroforestry buffers, two with grass buffers, and two control treatments were used to test the hypothesis that agroforestry and grass buffers can be used to effectively reduce NPSP from pastured watersheds. Vegetation in grass buffer and pasture areas includes red clover (Trifolium pretense L.) and lespedeza (Kummerowia stipulacea Maxim.) planted into fescue (Festuca arundinacea Schreb.). Eastern cottonwood trees (Populus deltoides Bortr. ex Marsh.) were planted into fescue in agroforestry buffers. Soils at the site are mostly Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalfs). Treatments were instrumented with two-foot H flumes, water samplers, and flow measuring devices in 2001. Composite water samples were analyzed for sediment and total nitrogen after each runoff event to compare treatment differences. Treatments with agroforestry and grass buffers had significantly lower runoff volumes as compared to the control. The loss of sediment and total nitrogen were smaller for the buffered treatments. The results of this study suggest that establishment of agroforestry and grass buffers help reduce NPSP pollution from pastured watersheds. It is anticipated as trees grow and roots occupy more soil volume, the reduction in N in runoff will increase on the agroforestry watershed.

CT-measured macropores as affected by agroforestry and grass buffers for grazed pasture systems

Agroforestry and grass buffers have been proposed for improving water quality in watersheds. Soil porosity can be significantly influenced by buffer vegetation which affects water transport and water quality. The objective of the study was to compare differences in computed tomography (CT)-measured macroporosity (>1,000-μm diam.) and coarse mesoporosity (200- to 1,000-μm diam.) parameters for agroforestry and grass buffer systems associated with rotationally grazed and continuously grazed pasture systems. Soils at the site were Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf). Six replicate intact soil cores, 76.2 mm diam. by 76.2 mm long, were collected using a core sampler from the four treatments at five soil depths (0–50 cm at 10-cm intervals). Images were acquired using a hospital CT scanner and subsequently soil bulk density and saturated hydraulic conductivity (K sat) were measured after scanning the cores. Image-J software was used to analyze five equally spaced images from each core. Bulk density was 5.9% higher and saturated hydraulic conductivity (K sat) values were five times lower for pasture treatments relative to buffer treatments. For the 0–10 cm soil depth, CT-measured soil macroporosity (>1,000 μm diam.) was 13 times higher for the buffer treatments compared to the pasture treatments. Buffer treatments had greater macroporosity (0.020 m3 m−3) compared to pasture (0.0045 m3 m−3) treatments. CT-measured pore parameters were positively correlated with K sat. The project illustrates benefits of agroforestry and grass buffers for maintaining soil porosity critical for soil water and nutrient transport.

Agroforestry and Grass Buffer Influences on Macropores Measured by Computed Tomography under Grazed Pasture Systems

Agroforestry buffers, which include trees, grass, and shrubs, have been proposed for improving water quality in watersheds. The objectives of the study were to compare differences in macropore (&gt;1000‐μm diam.) and coarse mesopore (200–1000‐μm diam.) parameters measured by computed tomography (CT) within agroforestry buffer (AgB) and grass buffer (GB) systems associated with rotationally grazed pasture (RG) and continuously grazed pasture (CG) systems, and to examine relationships between CT‐measured pore parameters and saturated hydraulic conductivity (Ksat). Pasture and GB areas included red clover (Trifolium pratense L.) and Korean lespedeza [Kummerowia stipulacea (Maxim.) Makino] planted into fescue (Festuca arundinacea Schreb.), while AgB included eastern cottonwood trees (Populus deltoides W. Bartram ex Marshall ssp. deltoides) planted into fescue. Soils at the site were Menfro silt loam (fine‐silty, mixed, superactive, mesic Typic Hapludalf). Intact soil cores were collected from the four treatments at five soil depths. Five equally spaced images were acquired from each core and were analyzed with Image‐J software. The CT‐measured soil macroporosity was 13 times higher (0.053 m3 m−3) for the buffer treatments than the pasture treatments (0.004 m3 m−3) for the surface 0‐ to 10‐cm soil depth. Buffer treatments had greater macroporosity (0.02 m3 m−3) than RG (0.005 m3 m−3) or CG (0.004 m3 m−3) treatments. The Ksat values for buffer treatments were five times higher than pasture treatments. Soil bulk density was 5.6% lower for the buffer treatments than the pasture treatments. The CT‐measured pore parameters (except macropore circularity) were positively correlated with Ksat This study illustrates the benefits of agroforestry and grass buffers for maintaining soil pore parameters critical for soil water transport.

Natural Ferrihydrite as an Agent for Reducing Turbidity Caused by Suspended Clays

Biologically impaired waters are often caused by the turbidity associated with elevated suspended sediment concentrations. Turbidity can be reduced by the addition of positively charged compounds that coagulate negatively charged particles in suspension, causing them to flocculate. This research was conducted to determine the effectiveness of ferrihydrite, a poorly crystalline Fe oxide, as a flocculating agent for suspended clays similar to those found in high-turbidity waters of the Mississippi delta. Clay concentrations of 100 mg L(-1) from a Dubbs silt loam (fine silty, mixed, active, thermic Typic Hapludalfs), a Forestdale silty clay loam (fine, smectitic, thermic Typic Hapludalfs), and a Sharkey clay (very fine, smectitic, thermic Chromic Epiaquerts) were suspended in 0.0005 mol L(-1) CaCl(2) solutions at pH 5, 6, 7, or 8. Natural ferrihydrite with a zero point of charge at pH 5.8 was acquired from a drinking water treatment facility and mixed with the suspension at concentrations of 0, 10, 25, and 50 mg L(-1). After settling periods of 24 and 48 h, percent transmittance was measured at a wavelength of 420 nm using a 3-mL sample collected at a depth of 2 cm. The greatest reductions in turbidity after 24-h equilibration were recorded for the pH 5 suspensions of the Dubbs (31%) and Forestdale (37%) clays at a ferrihydrite concentration of 10 mg L(-1) and for the Sharkey clay at a ferrihydrite concentration of 25 mg L(-1) (relative to the 0 ferrihydrite treatment). Water clarity for all samples further increased after 48 h. These results indicate that the effectiveness of ferrihydrite, as a means of reducing turbidity associated with suspended clays, is greatest at pH values below its zero point of charge.