bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrous Oxide Emission Controls and Inorganic Nitrogen Dynamics in Fertilized Tropical Agricultural Soils
Authors: Davidson E. A. , Matson P. A. , Brooks P. D. 
Published: July 2010

AbstractUse of N fertilizers in tropical regions has recently surpassed use intemperate regions, but understanding of N2O emissions from fertilized soils is based largely on experience from temperate regions. We studied N2O emissions from a sugar cane (Saccharum officinarum L.) plantation on the Hawaiian island of Maui. Young cane fields that were routinely fertilized had >15 mg NH4+‐N and NO3−‐N kg−1 soil, whereas mature cane fields not being fertilized had <2 mg NH4+‐N and NO3−‐N kg−1 soil. Emissions of N2O were also ≈10 times higher in the young cane fields than in the mature cane. The highest nitrification potentials and N2O emissions occurred near buried irrigation lines and lowest values between plant rows. Added 15NH4+ was nitrified within 48 h in both young and mature cane fields. Hence, microbial populations exist in both young and mature cane fields that can rapidly produce NO3−, and production of N2O is controlled primarily by when and where fertilizer N is applied. In contrast to many temperate agricultural soils where mineralization‐immobilization‐turnover processes contribute significantly to the supply of crop N, rates of gross N mineralization were low, indicating that the cane crop N came primarily from applied fertilizer. In the mature cane, soil inorganic‐N remains low because of high plant and microbial demand, but in the young cane, fertilizer applications exceed the plant and microbial sinks, and N2O emissions are large. Better fertilizer management in this early stage of the cane crop cycle might significantly reduce N2O emissions.
Tillage Depth Influence on Soil Nitrogen Distribution and Availability in a Rice Lowland
Authors: Kundu D. K. , Ladha J. K. , Lapitan‐de Guzman E. 
Published: July 2010

AbstractPrevious studies using artificial barriers at selected depths have shown the importance of N supply from soil below 15 cm to rice (Oryza sativa L.). Subsoil N availability and its use by wetland rice, however, have not been evaluated under normal field conditions. We examined distribution and availability of 2 M KCl‐extractable N in 0‐ to 15‐, 15‐ to 30‐, and 30‐ to 45‐cm layers of a submerged Alfisol during three successive crop seasons, as influenced by the depth of tillage imposed at the outset of the experiment. Mineral N availability in the 0‐ to 45‐cm profile and rice N uptake in the first season were significantly higher (20–25 kg ha−1 higher mineral N and 16–18 kg ha−1 higher crop N uptake) with tillage to a depth of 40 cm than to 15 or 25 cm, the increased N supply originating largely from the 15‐ to 30‐cm layer. In two following seasons, tillage to 40 cm gave the highest mineral N in the subsoil layers, and increased rice N uptake by 12 to 14 kg ha−1, compared with tillage to 15 cm. The beneficial effects of deep tillage were attributed to the elimination of mechanical impedence to root proliferation, and lower susceptibility of subsoil N to various loss mechanisms. Initial and final analyses of Kjeldahl N in the soil profile indicated no adverse effect of practicing 40‐cm‐deep tillage once in three seasons on soil N fertility. Further study is needed to determine optimum depth and frequency of primary tillage for different soil types to enhance N use efficiency.
Magnesium and Potassium Release by Weathering in Spodosols: Grain Surface Coating Effects
Authors: Courchesne François , Turmel Marie‐Claude , Beauchemin Paul 
Published: July 2010

AbstractThe effect of coatings on the rate of Mg and K release by weathering were determined on four soil horizons (Croche, Sutton, and LaTuque B and Croche C), collected from three Spodosols in southern Quebec, Canada. Rates of Mg, K, Fe, and Al release from the <2‐mm fraction of intact and treated (coatings removed with dithionite‐citrate‐bicarbonate [DCB] and H2O2) samples were measured in the laboratory using a continuous flow technique. The materials were leached with a 0.0005 M H2SO4 solution adjusted to pH 3.0 at a flow rate of 0.05 mL min−1 for 1080 h. Surface coatings were composed of Al, Fe, Si, and organic C with traces of Ca. Coating removal had no effect on cation release rates (α < 0.01) from the Croche C horizon, indicating that mineral surfaces were not altered by treatments with DCB and H2O2. Intact B horizons released Fe (3.04–4.87 µmol g−1 h−1/2) and Al (10.07–36.33 µmol g−1 h−1/2) at a faster rate than treated (Fe: 0.28–1.68 µmol g−1 h−1/2; Al: 1.21–27.34 µmol g−1 h−1/2) samples although effluent pH (pHf) was more acidic in the latter. Magnesium and K release rates were higher in treated (Mg: 0.35–2.03 µmol g−1 h−1/2; K: 0.052–0.073 µmol g−1 h−1/2) than in intact (Mg: 0.19–0.61 µmol g−1 h−1/2; K: 0.032–0.039 µmol g−1 h−1/2) samples for two of the three Spodic B horizons. In the Croche B horizon, the absence of rate differences (α < 0.01) was attributed to the incomplete removal of Al coatings from treated materials. Because differences in pHf levels could not be invoked to explain all of the observed rate variability, we suggest that the accumulation of coatings was an effective process isolating primary mineral surfaces, therefore reducing the extent of reactive surfaces available for Mg and K release.
Determining Soil Loss Using the Inventory Ratio of Excess Lead‐210 to Cesium‐137
Authors: Wallbrink P. J. , Murray A. S. 
Published: July 2010

AbstractThe anthropogenic nuclide 137Cs is widely used to measure soil movement. However, changes in 137Cs areal concentrations may not result from soil redistribution alone. There can be considerable variability in 137Cs fallout due to rain shadowing and small‐scale runon‐runoff processes at the time of deposition. Fallout 210Pb is also affected by these processes and thus areal concentrations of the two should be correlated. The ratio of fallout 210Pb to 137Cs reduces variability by up to a factor of two in undisturbed control forest sites at St. Helens, Tasmania. In addition, these two nuclides penetrate to different depths, thereby producing a varying activity ratio with depth, and this gives rise to a new method for determining soil loss. The average inventory ratios of fallout 210Pb to 137Cs from plots adjacent to the controls were measured; these had undergone “normal” and “minimal impact” logging procedures. The average core inventory ratio at the control locations was 2.24 ± 0.14 (n = 18), compared with means of 0.74 ± 0.09 (n = 10) and 1.73 ± 0.29 (n = 10) from the normal and minimal impact sites. The average depth of soil removed from the logged sites was then calculated by comparing these ratios with the inventory activity ratio curve from their respective control sites (40 ± 6 mm, normal site; 17 ± 5 mm, minimal site). We concluded that, compared with areal concentrations alone, ratios of fallout nuclides are likely to provide a less randomly variable (and thus more sensitive) method for investigating surface erosion in landscapes where vertical soil mixing is not sufficiently recent to be of concern.
Comparison of Kriging and Inverse‐Distance Methods for Mapping Soil Parameters
Authors: Gotway Carol A. , Ferguson Richard B. , Hergert Gary W. , Peterson Todd A. 
Published: July 2010

AbstractVariable‐rate technology may provide a means of increasing fertilizer use efficiency by matching applications to specific conditions at a given field location. Effective implementation of this technology depends on accurately characterizing the spatial variability of soil parameters used to define the application rate. Kriging and inverse‐distance‐squared are two commonly used techniques for characterizing this spatial variability and interpolating between sampled points. To assess the accuracy of these techniques, data sets obtained from grid sampling two field research sites were used in a prediction‐validation comparison of ordinary kriging and inverse‐distance methods using powers p = 1, 2, and 4. The accuracy of the inverse‐distance methods tended to increase with the power of distance for data sets with a coefficient of variation less than about 25% (typical of soil organic matter). However, for data sets with greater variation (such as soil NO3−), inverse‐distance prediction methods using high distance powers (2 or 4) can give very inaccurate predictions. The accuracy of predictions from kriging was generally unaffected by the coefficient of variation, and was relatively high for all of the sampling configurations considered in this study. These tendencies were also observed using 48‐ and 72‐m subsamples, although the use of wider sampling spacings greatly reduced the information in the maps constructed by each method. Careful thought should be given to the choice of sample spacing and interpolation method to be used before data are collected. Summary statistics, and the coefficient of variation in particular, are simple measures that can give an indication of the relative accuracy of the inverse‐distance and kriging mapping approaches.
Iron and Manganese Distribution in Nodules from a Young Texas Vertisol
Authors: White G. Norman , Dixon J. B. 
Published: July 2010

AbstractIron and Mn distributions in the black nodules from the BCk3 horizon of the microlow position of a Burleson soil, a fine, montmorillonitic, thermic, Udic Haplustert, from a terrace of the Brazos River were mapped with scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) x‐ray analysis. Spherical nodules were concentrically banded, and the irregularly shaped nodules lacked well‐developed banding of Fe and Mn. More and better expressed banding was found by decreasing pixel size used for mapping and by increasing the count time per pixel for banded nodules. Bands of higher or lower Fe and Mn concentration were not coincident. The Mn/Fe weight ratios of individual nodules analyzed by EDS were between 0.71 to 2.85. Banded nodules had a narrower range of Mn and Fe concentrations and a narrower range in Mn to Fe ratios than unbanded nodules. Barium concentration in the nodules was unusually high, averaging 30 g kg−1, and correlated strongly with Mn concentration. Some interelement correlations (e.g., Fe vs. Mn, r = −0.56; Fe vs. Al, r = −0.58) reflected partitioning into the oxide or silicate minerals of the soil. Fractured nodules revealed the interior to have only a few very small pores. The 30 nodules examined are well developed solid bodies that are expected to persist in the soil environment. They appear to contain unique and important information about the weathering history of the Burleson soil and the landscape in which it occurs. The order and expression of the banding is a relict of the redox history of the nodules, which can be used to induce the redox history of the soil.
The Microbial Activity Season in Southeastern Hydric Soils
Authors: Megonigal J. P. , Faulkner S. P. , Patrick W. H. 
Published: July 2010

AbstractThe growing season requirement is an often overlooked part of the definition for hydric soils. The current technical definition for a hydric soil states that flooding or soil saturation must occur during the portion of the year when soil temperature at 50 cm is >5°C. In this study, we defined the portion of year when soils were >5°C at 50 cm as the microbial activity season and reserved the term growing season for plant activity. In the technical criteria for hydric soils, specific microbial activity season months have been assigned to each of the soil temperature regimes. Our objectives were to determine the portion of the year when southeastern U.S. hydric soils are <5°C at 50 cm and to estimate rates of microbial activity during winter flooding. We found that 34 bottomland hardwood forest soils in South Carolina, Louisiana, and Mississippi were never <5°C at 50 cm during a period of 2 to 3 yr. Also, winter rates of soil respiration and O2 consumption (1.6 mL O2 L−1 air d−1) are apparently sufficient to cause anoxia in saturated soils. Based on the available data, we recommend a 12‐mo microbial activity season for southeastern bottomland hardwood forests. Additional data will be necessary to determine the relationships between temperature, soil saturation, and development of redoximorphic features in southeastern soils.
Hydroperiod Influences on Nutrient Dynamics in Decomposing Litter of a Floodplain Forest
Authors: Lockaby B. G. , Murphy A. L. , Somers G. L. 
Published: July 2010

AbstractLack of clarity regarding the relationship between hydroperiod and decomposition dynamics has long been a barrier to the development of a clear understanding of floodplain biogeochemistry. Relationships between hydroperiod and decomposition processes were investigated using a controlled, field approach on the Ogeechee River floodplain in south Georgia. The study intent was to develop cause‐effect relationships between specific flooding regimes and decomposition parameters. Microcosms designed to manipulate flooding regimes were installed and used in combination with litterbags containing abscised foliage. Treatments were designed to mimic realistic hydroperiod‐nutrient inflow scenarios and included: a nonflooded control, flooded for 6 mo, flooded for 3 mo, flooded intermittently for 4 mo, flooded for 3 mo with elevated P inflow, and flooded for 3 mo with elevated N inflow. Mass, C, N, and P dynamics were studied for a 106‐wk period. Flooding stimulated mass, C, N, and P loss. The data suggest that single, brief flooding regimes may stimulate mass and C loss to the greatest extent. The proportion of N and P remaining after 106 wk was only marginally different among flooding regimes. However, temporal patterns of immobilization‐mineralization were strongly influenced by the nature of the flooding regime.
Soil Organic Matter Mineralization after Compost Amendment
Authors: Sikora L. J. , Yakovchenko V. 
Published: July 2010

AbstractThe addition of composts and manures to soils has often resulted in increased plant yields that are not obviously related to the nutrients in the added organic material. A study was conducted to determine if compost additions to soil resulted in increased mineralization of soil organic matter (SOM). The organic matter of a Sassafras sandy loam soil (fine‐loamy, siliceous, mesic Typic Hapludult) was labeled with 14C by incubating uniformly labeled wheat (Triticum aestivum L.) straw with the soil through a minimum of 60 wetting‐drying cycles during 2 yr. A municipal solid waste‐biosolids compost (MSWC) or a biosolids compost (BC) was added to the labeled soil or to acid‐washed sand and incubated for 1440 h. Decomposition of MSWC was low with 95% of the compost‐C remaining in sand or soil after 1440 h. Ninety‐two percent of BC‐C remained in sand and 86% remained in soil after 1440 h. Total and 14CO2 data indicated that neither compost stimulated SOM decomposition. Municipal solid waste‐biosolids compost reduced slightly SOM decomposition at 545 and 715 h. The soil, however, stimulated BC decomposition. Nitrogen mineralization of the BC + soil mixture was greater than soil alone, and the N apparently came from the compost. The benefits from addition of BC to Sassafras soil was not attributed to increased mineralization of SOM.
Soil Organic Matter Pools during Early Adoption of Conservation Tillage in Northwestern Canada
Authors: Franzluebbers A. J. , Arshad M. A. 
Published: July 2010

AbstractChanges in soil organic matter (SOM) pools during adoption of reduced (RT) or zero tillage (ZT) can influence soil physical properties, nutrient cycling, and CO2 flux between soil and atmosphere. We determined soil organic C (SOC), soil microbial biomass C (SMBC), basal soil respiration (BSR), and mineralizable N to a depth of 200 mm at the end of 3, 5, and 6 yr after implementation of tillage management on a Falher clay (fine, montmorillonitic, frigid Typic Natriboralf) near Rycroft, Alberta, in a canola (Brassica campestris L.)‐wheat (Triticum Aestivum L.)‐barley (Hordeum vulgare L.)‐fallow cropping system. At the end of 6 yr, SOC was not different among tillage regimes and averaged 8.6 kg m−2. At the end of 3 and 5 yr, SMBC was not significantly different among tillage regimes, but at the end of 6 yr SMBC was 7% greater in RT and 9% greater in ZT than in conventional tillage (CT). Basal soil respiration and mineralizable N at the end of 6 yr were not different among tillage regimes following barley and averaged 2.7 g CO2‐C m−2 d−1 and 5.0 g inorganic N m−2 24 d−1, respectively. However, BSR following fallow was 2.2, 2.5, and 2.6 g CO2‐C m−2 d−1 in CT, RT, and ZT, respectively. Mineralizable N following fallow was 5.8 g inorganic N m−2 (24 d)−1 in RT and ZT and 7.3 g inorganic N m−2 (24 d)−1 in CT. At 0 to 50 mm, there was no significant increase in SOC at the end of 6 yr, a 17 to 36% increase in SMBC, and a 12 to 69% increase in BSR with ZT compared with CT, depending on rotation phase. Relatively small changes in SOM pools with adoption of conservation tillage may be attributable to the large amount of SOM initially present and the cold, semiarid climate that limits SOM turnover.
Leaching of Nitrogen from Slow‐Release Urea Sources in Sandy Soils
Authors: Wang F. L. , Alva A. K. 
Published: July 2010

AbstractApplication of readily soluble forms of N fertilizers to sandy soils may cause leaching of NO3‐N resulting in contamination of groundwater. The leaching loss of N may be reduced to some extent by using slow‐release forms of N. An intermittent leaching and incubation technique, to mimic natural occurrence of rainfall and dry conditions, was used to examine the leaching of N from readily soluble (NH4NO3) and slow‐release fertilizers [isobutylidene diurea (IBDU) and a polyolefin resin‐coated urea, Meister] in Wabasso (sandy, siliceous, hyperthermic Alfic Haplaquod) and Candler (hyperthermic, uncoated Typic Quartzipsamment) soils. After 29 d, the cumulative recovery of the applied fertilizer N in the leachate for the treatments decreased in the following order: NH4NO3 (88‐100%) > IBDU (27–32%) > Meister (11.5–11.7%). A significant portion (19.5–35.5%) of the total N leached from IBDU and Meister was in the urea form in the initial leaching; however, after 9 d, NO3 and NH4 forms represented the major portion of leachate total N. Although N from NH4NO3 was leached completely from the Candler sand, 12% of the applied N (as NH4NO3) was not recovered in the leachate from the Wabasso sand. Cumulative NH4‐N leached from the Wabasso sand was only 58% of that from the Candler sand. The results demonstrate that the amounts and forms of fertilizer N leached from the sandy soils depend on the solubility of the fertilizer, the soil type, and the duration of intermittent leaching.
Indigenous Knowledge and Classification of Soils in the Andes of Southern Peru
Authors: Sandor J. A. , Furbee L. 
Published: July 2010

AbstractIndigenous cultures throughout the world have substantial, systematic knowledge of soils gained during many generations of land use; however, little of this knowledge has been scientifically documented. Recent literature indicates that knowledge among traditional cultures could add to scientific understanding of soils and be useful in international agricultural development. This study investigated indigenous soil knowledge in the Colca Valley, Peru, where terrace agriculture has been practiced for at least 15 centuries. Previous research suggested enhanced tilth and fertility of ancient agricultural soils, measured by criteria such as thickened A horizons, lower bulk density, and greater levels of organic C, N, and P relative to nearby uncultivated Mollisols. Long‐term soil conservation is partly attributed to traditional management practices such as terracing, a form of conservation tillage, fertilization, and irrigation. To test the hypothesis that a body of knowledge underlies traditional soil management practices, interdisciplinary studies were conducted, involving linguistic evaluation of soil terms, anthropological field interviews, soil and geomorphic mapping, and basic morphological and laboratory characterization of soils identified by farmers. Anthropological research revealed a hierarchical soil classification system, with up to four categorical levels and about 50 soil and earth material names, that emphasizes soil texture and other properties important in agricultural management. Soil analyses indicated a fairly close correspondence between indigenous texture classes and those used in U.S. soil classification. Local farmers recognize several soil features and horizons such as duripans, soil variation with depth, distribution of soils on the landscape, and changes in soil behavior under different conditions.
Biodynamic vs. Conventional Farming Effects on Soil Structure Expressed by Simulated Potential Productivity
Authors: Droogers P. , Bouma J. 
Published: July 2010

AbstractEffects of alternative farming systems on soil structure need to be quantified to judge the sustainability of the systems. This study was conducted to compare two farming systems by converting “static” basic soil properties into a “dynamic” assessment using simulation modeling. Increasingly popular biodynamic farming systems use no commercial fertilizers and pesticides but apply organic manure and compost. Soil conditions on four fields on two farms where biodynamic and conventional soil management had been practiced for about 70 yr were investigated with morphological and physical methods. Soils (Loamy, mixed, mesic Typic Fluvaquents) were pedologically identical. Four procedures were used to express differences in soil structure as a function of different management: (i) morphological description; (ii) measurement of basic and static soil parameters such as bulk density, organic matter, and porosity; (iii) measurement of soil hydraulic characteristics; and (iv) determination of simulated water‐limited yields. The latter procedure provides a criterion that is quantitative, is directly related to a practical aspect of soil behavior, and reflects the highly nonlinear soil‐water processes. The WAVE simulation model was used to predict water‐limited potato (Solanum tuberosum L.) yields with climatic data of 30 yr. Basic static soil parameters were not significantly different but simulated yields were significantly different and were 10 200 and 10 300 vs. 9400 and 9700 kg dry matter tuber yield ha−1 yr−1 for the biodynamic and the conventional fields, respectively. Simulation modeling of crop yields thus provides a relevant expression for the production potential of the two different farming systems.
Reaction in Soil of Phosphorus Released from Poultry Litter
Authors: Robinson J. Stephen , Sharpley Andrew N. 
Published: July 2010

AbstractPoultry production generates large amounts of litter or manure, which can be a valuable source of P for crops. However, litter application rates are usually based on data for mineral P fertilizer recommendations. In order to determine if this is agronomically and environmentally sound, the availability, fractions, and sorptivity of P from poultry litter or KH2PO4 were determined in six Oklahoma soils following incubation for up to 28 d. An average 50% more P from KH2PO4‐treated (78 mg kg−1) than from leachate‐treated soils (52 mg kg−1) was bioavailable, as determined by extraction with Fe‐oxide‐impregnated paper strips, after 28‐d incubations. Conversely, more NaHCO3‐extractable P was found in leachate‐treated (66 mg kg−1) than KH2PO4‐treated soils (42 mg kg−1). Calculated from Langmuir isotherms, P sorption maxima averaged 548 mg kg−1 for leachate‐treated and 304 mg kg−1 for KH2PO4‐treated soils, while binding energies averaged 0.527 and 0.456 L mg−1, respectively. The higher P sorption maxima and binding energies of leachate‐treated soils may result from the formation of Ca‐P complexes, given the increased Ca content of these soils. The different reaction in soil of P added as poultry litter leachate to that added as KH2PO4, indicates manure application rates should be based on soil tests that are sensitive to P source‐dependent sorption characteristics and/or manure trials, and not just on mineral fertilizer trials.