bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Harvesting for Afforestation: II. Survival and Growth of Trees
Authors: Kowsar A. , Mehdizadeh P. , Vaziri E. , Boersma L. 
Published: July 2010

AbstractAlternative methods of afforestation which do not require irrigation must be developed for arid regions. One such method is to concentrate water received by a watershed without vegetation on a smaller area where trees are planted. This can be done by making portions of the surface of a watershed area impervious to water through application of asphalt. This principle was tested near Tehran, Iran, by constructing 2‐m wide terraces on contour lines at 5‐m intervals resulting in a watershed to spreading area ratio of 1.5. Asphalt was sprayed at the rate of 1 liter/m2 in December 1969. Seedlings of Robinia pseudacacia L., Cupressus arizonica G., and Fraxinus rotundifolia Mill., tree species commonly used in irrigated afforestation projects in Iran, were planted in March 1970 on the terraces. Runoff from asphalt‐treated areas did not significantly increase the survival of the tree seedlings. The 23.4 mm of rain in July 1970, completely overwhelmed treatment effects. This rain was a rare event for the Tehran area. The increases in growth of height, crown cover, and stem cross section due to the asphalt treatment at the end of a 5‐year period were 61.5, 60.9, and 53.0%, respectively, for Robinia pseudacacia L.; 14.6, 15.4, and 31.6%, respectively, for Cupressus arizonica G.; and 29.4, 79.6, and 23.9%, respectively, for Fraxinus rotundifolia Mill.Regression equations were developed correlating growth with amount of water and age of trees. Amount of water received in April and May in any given year was found to determine growth of height and crown during the following year. Amount of water received in April through October was found to determine the growth of stem cross section during the following year.
Comparison of a Laboratory and Commercial Block Digester for Plant Analysis
Authors: Prasad M. , Spiers T. M. 
Published: July 2010

AbstractThe design of a block digester fabricated in the laboratory is presented. The digester was capable of attaining 380°C in about 1 hour. Variation of temperature in different parts of the block was about 2°C greater compared to the Technicon block digester (BD‐40) at 328°C. Nitrogen, P, and K, and Ca, Mg, Fe, Zn, Mn, and Cu values from either block were in good agreement for all crops studied using H2SO4 + Se digestion, and HNO3 + HCIO4 digestion. Precision was good from both blocks using either digestion method although the Technicon block generally gave a slightly higher precision for HNO3 + HCIO4 digestion. In addition, when one sample was placed in six or eight different positions on the block for the H2SO4 digestion in order to maximize differences between replicates, a slightly higher C. V. was recorded with our digester. The construction cost of the latter which has a somewhat smaller capacity and no automation was only about 20% of the purchase price of the Technicon digester.
Recovery of 15N‐Labeled Fertilizer from Manured and Sludge‐Amended Soil
Authors: Pomares‐Garcia F. , Pratt P. F. 
Published: July 2010

AbstractA greenhouse pot experiment was conducted with various rates of manure (0, 20, 40, and 60 metric tons/ha) and sludge (0, 10, 20, and 30 metric tons/ha) combined factorially with 0, 50, 100, 150, and 200 mg N/kg soil as (NH4)2SO4 labeled with 15N, using barley and sudangrass as test crops. Most of the N from (NH4)2SO4 was recovered by the first cutting of barley forage (from 37.2 to 70.2%); the N from (NH4)2SO4 recovered by sudangrass, the last crop of the cropping sequence, ranged from 0.7 to 8.9%. No significant effect of both wastes and (NH4)2SO4 rates on the overall inorganic N fertilizer recovered by the crops was found. The difference method underestimated the (NH4)2SO4‐N recoveries by the crops under sludge treatments. The depression in the mineralization rate of sludge by the (NH4)2SO4 applied was proposed to account for these discrepancies.A fertilizer N balance, in which the sum of (NH4)2SO4‐N removed by the crops plus the N accumulated in the soil was subtracted from the (NH4)2SO4‐N input, was used to estimate the fertilizer N losses. These losses were 7.8, 9.1, and 13.1%, respectively, for control (unamended), manure and sludge treatments.With increasing rates of (NH4)2SO4, the nitrogen “A” values defined as the N available in the soil in terms of N from (NH4)2SO4, increased in the control, remained almost constant with manure, and decreased with sludge treatments.
Salt and Water Stress Influences Nitrogen Metabolism in Red Kidney Beans
Authors: Frota J. N. E. , Tucker T. C. 
Published: July 2010

AbstractBoth salinity and water deficit reduce yields of crop plants. This study was an attempt to provide a better understanding of these stress effects on N metabolism and the utilization of NH4‐N and NO3‐N.Red kidney bean plants (Phaseolus vulgaris L.) were grown under salt stress (NaCl), water stress (carbowax), and in a normal nutrient solution (control). The 15N in NO3‐, NH4+, α‐amino acids, total soluble‐N, and protein‐N in plant shoots were analyzed after the plants received (15NH4)2SO4 and K15NO3 in nutrient solution for 6, 12, 24, and 48 hours. Sodium chloride and carbowax resulted in equal accumulations of NO3‐, NH4+, and free α‐amino acids in bean shoots. Protein synthesis was significantly reduced in bean shoots when the plants were subjected to NaCl salinity and carbowax, with either source of N, and the inhibition was more severe under salt stress than water stress.
Cation‐exchange Capacity of Clay‐rich Soils in Relation to Organic Matter, Mineral Composition, and Surface Area
Authors: Martel Y. A. , De Kimpe C. R. , Laverdière M. R. 
Published: July 2010

AbstractRegression analyses were used to correlate organic matter, texture and surface area values to the cation‐exchange capacity (CEC) of clay‐rich soils in the lowlands of Quebec. The Ap, Bg and Cg horizons of 11 Gleysolic soils (Aqu‐Suborders) were analyzed for CEC, exchangeable bases and acidity, total and fine clay contents, organic matter, surface area and mineralogical composition. The soils contained illite, chlorite, smectite, and vermiculite in addition to quartz and feldspars. In the Ap horizon, total clay (r = 0.815**) and fine clay (r = 0.841**) contents were better related to CEC than organic matter (r = 0.566**) and surface area (r = 0.570**). In the Bg and Cg horizons, surface area (r = 0.918** and 0.814**) gave the best correlation with CEC. As calculated by multiple regression equations, CEC values of organic matter increased with depth from 56.5 to 223 meq/100 g, while CEC values of total clay decreased from 37.7 to 22.5 meq/100 g and that of fine clay decreased from 57.5 to 50.7 meq/100 g. Variations in the mineralogical composition, although small, were sufficient to explain nearly 50% of the variations in the CEC. Clay mineralogy is important to predict the CEC of such soils where the contribution of clay is 3.5 to 5 times greater than that of organic matter.
Hard Red Spring Wheat Straw Yields in Relation to Grain Yields
Authors: Bauer Armand , Zubriski Joseph C. 
Published: July 2010

AbstractResidue management planning programmers utilize a constant straw/grain ratio to predict wheat (Triticum aestivum L.) straw yields. The efficacy of this approach was evaluated for conventional height and semidwarf hard red spring wheat cultivars. Functional relationships between grain yields and straw/grain ratios were determined from data obtained in the northern Great Plains. Straw/grain ratios ranged from 0.72 to 4.71. Single correlation coefficients, r, were −0.643** and −0.589** for semidwarf and conventional (n = 117 and 72) over a grain yield range of 240 to 5,850 kg/ha. “Best fit” regression (n = 189) was Y = 3.152 − 0.000753X + 0.0000000655X2 (Y = straw/grain ratio). About 78% of 49 observations fell within the 0.05 confidence limits at >3,000 kg/ha grain yield, but <30% at lower yields. Straw yields predicted by regression were within ±1,000 kg/ha in 74, 51, and 84% of the observations at grain yields of <1,600, 1,600 to 3,000, and >3,000 kg/ha, respectively. A single, constant straw/grain ratio will predict straw yields with less accuracy than ratios obtained from regression.
The Nitrogen‐15 Abundance in a Wide Variety of Soils
Authors: Shearer Georgia , Kohl Daniel H. , Chien Sen‐Hsiung 
Published: July 2010

AbstractOne hundred thirty‐nine soil samples from 20 states were analyzed for 15N abundance. Soil characteristics and environmental conditions at the sampling sites varied widely. The total N of surface soil samples had a mean δ15N value (per mill 15N excess) slightly but significantly higher than the mean value for soils collected from deeper layers, although the relationship between δ15N and soil depth was not consistent from location to location. Differences among mean δ15N values for the total N of soil samples collected from cropland, pasture, uncultivated land (with native herbs), and forest were not striking. There was no systematic effect of variation in the rate of application of N fertilizer on the δ15N of the total N of soils. The mean δ15N value of surface soils, with respect to atmospheric N, was +9.22 and the standard deviation was 2.10 δ15N units. The range within which 90% of the samples fell was +5.1 to +12.3 δ15N units. Less than half of the variation among the soils in δ15N of the total N could be accounted for by differences in environmental variables or soil characteristics.
Elemental Distribution in the Light Mineral Isolate of Soil Separates
Authors: Drees L. R. , Wilding L. P. 
Published: July 2010

AbstractThe light mineral isolate (specific gravity < 2.89) was quantitatively separated from the 50–250µm, 20–50µm, and 5–20µm fractions of selected A and B soil horizons derived from loess and outwash deposits. Elemental Ti, Zr, Fe, K, and Ca were determined by X‐ray spectroscopy both on total and light mineral isolates. More than 75% of Ti, Zr, Fe, and Ca occurs in the light mineral isolates of the 5–20µm fraction while the 50–250µm light mineral isolate contains 25 to 70% of these elements. With the exception of K, there is a progressive concentration of above elements as particle‐size decreases. Essentially 100% of the K occurs in the light mineral isolate independent of particle‐size. The concentration of Ti and Zr is greater than can be accounted for by mineral grain counts in the light isolate. Little or no co‐association of Fe with Ti, Zr, Ca, or K could be established in secondary Fe‐oxide grain coatings. It is concluded that much of the Ti, Zr, and Fe concentrated in the light mineral isolates occurs as micro‐inclusions of accessory minerals within primary host minerals such as quartz and feldspars. Caution must be exercised in allocating elemental percentages of a given size fraction to specific detrital minerals.
Reactions of Ammonium Ortho‐ and Polyphosphate Fertilizers in Soil: III. Effects of Associated Cations
Authors: Sample E. C. , Khasawneh F. E. , Hashimoto I. 
Published: July 2010

AbstractDiammonium phosphate (DAP), triammonium pyrophosphate monohydrate (TPP), and ammonium polyphosphate (APP) were surface applied on columns of Hartsells fine sandy loam, a Typic Hapludult, and the influence of these three salts on movement, distribution, and precipitation of soil and fertilizer cations was investigated.In general, the NH4+ ions derived from the fertilizer salts moved in association with the phosphate anions in the form of salt diffusion, and also moved by counter diffusion in exchange for some of the exchangeable soil cations. This latter mode of transport resulted in movement of NH4+ a few millimeters beyond the limits reached by phosphates.Exchangeabe Ca in the first 6 mm of soil contacted by the fertilizer solution from DAP was replaced by NH4+, and the displaced Ca2+ was precipitated in place by phosphates. Displaced Ca was transported in the fertilizer solution of TPP and APP for 6 to 8 mm before it was precipitated. Reactions of phosphates with displaced Ca2+ caused its activity in these soil zones to drop sharply and created a Ca gradient opposite to that of the phosphates. Consequently, Ca moved from soil on the farther side of the phosphate front into a Ca phosphate sink. This movement of Ca was partly in exchange for NH4+ (counter cation diffusion) and partly following hydrolysis from exchange sites.Depletion of exchangeable cations, especially at or just beyond the fertilizer solution front, caused soil pH to drop as much as 1 pH unit below the initial soil value. Within the soil zone affected by phosphates, pH was about 7.5 with DAP and 6.7 to 7.2 with APP and TPP. Differences in pH between soil in the outer zones reached by phosphates and the inner layers ranged from 1.7 to 2.7 pH units.Soil Al was influenced greatly by all three fertilizer solution. With DAP, the reaction products simply reprecipitated in place without undergoing any movement. Increased acid extractability was the only evidence of the presence of fresh precipitates involving Al. In addition to such a reaction, however, movement of Al occurred with TPP and APP, and there was evidence of rather‐well‐defined zones of precipitation involving Al pyro‐ or polyphosphates. There was no evidence to implicate Fe in reactions similar to those described for Al.
Studies in Soil Manganese: I. Factors Affecting Manganese Extractability
Authors: Salcedo I. H. , Warncke D. D. 
Published: July 2010

AbstractEffects of 12 solution/soil ratio‐shaking time combinations upon Mn extracted by 0.1N HCl, 0.1N H3PO4, 0.005M DTPA, and 1N NH4OAc from 12 Michigan and Indiana soils were studied. A solution/soil ratio of 25 with 120 min of shaking maximized extractable Mn by the four extractants. However, with 0.005M DTPA and 1N NH4OAc shaking time and solution/soil ratio had little effect on extractable Mn. When results were correlated with Mn uptake by soybeans [Glycine max (L.) merr.], the best correlation was obtained with a solution/soil ratio of 5 and 120 min of shaking for 0.1N HCl and 0.1N H3PO4. Correlation of plant Mn uptake with DTPA‐ and NH4OAc‐extractable Mn was relatively independent of solution/soil ratio‐shaking time combinations used.
Effect of Chisel Versus Moldboard Plowing on Soil Erosion by Water
Authors: Johnson C. B. , Moldenhauer W. C. 
Published: July 2010

AbstractWe conducted an experiment using simulated rainfall on a field that was chisel plowed annually for 13 years before the experiment to compare erosion from this condition with moldboard plowing in the same field. One treatment was fall moldboard plowed, a second fall chiselled with some residue left on the surface, and a third was untilled in the fall with all residue removed in the spring. All three treatments were disked lightly in the spring. After the initial experiment was completed, residue was added so that all treatments had about 20% surface cover.During the initial rain application with no residue added, soil losses from the third treatment without surface residue were the same as those from the chisel plowed and disked surface with some surface residue. Both these treatments had only 23% of the soil loss of the moldboard plowed and disked treatment. During succeeding simulated rainfall under wet and very wet soil conditions, soil loss from the disked only treatment was up to 80% of that for the moldboard‐plowed treatment. When residue was added to all treatments, soil loss from the chisel‐plowed treatment was less than one‐half that from the moldboard‐plowed treatment.
Effects of Reduction and pH Changes on Phosphate Sorption and Mobility in an Acid Soil
Authors: Holford I. C. R. , Patrick W. H. 
Published: July 2010

AbstractSuspensions of a silt loam in 0.01M CaCl2 (1:6) were incubated at redox potentials of 500, 280, 65, and −150 mV for 26 ± 2 days in factorial combination with pH treatments of 5.0, 6.5, and 8.0. Samples were then removed and equilibrated with graded concentrations of KH2PO4 under O2‐free conditions. Isotopically‐exchangeable P was measured on the zero treatment and P sorption on the other treatments after 24 hours equilibration. Sorption properties of the soil were determined by application of the Langmuir equation.The largest changes occurred in the most reduced treatment (−150 mV) and at pH 8.0. At pH 5.0, an unnaturally low pH for an anaerobic soil, reduction to −150 mV decreased P sorption at solution P concentrations below 20 ppm because of the reduction and dissolution of ferric hydrous oxides. At higher concentrations sorption was increased by ferrous phosphate precipitation due to the very high concentrations of soluble Fe. At pH 6.5, reduction caused a very large increase in P sorption apparently because of increased adsorption on freshly precipitated amorphous ferrous hydroxides. At pH 8.0, P sorption was deceased at P concentrations below 2 ppm, probably because of increased surface negative charge, but increased at higher P concentrations due to precipitation of Ca phosphates. At all pH values, reduction increased the concentration of native P in solution. At pH 6.5 this was caused by an increase in labile P due to the release of P occluded and precipitated in ferric compounds. At pH 5.0 and 8.0 it was caused by a decrease in P bonding energy. Reduction to −150 mV caused the largest increase in soluble P and the smallest increase in P sorption capacity at pH 5.
Effect of Limestone Variables on Amendment of Acid Soils and Production of Corn and Coastal Bermudagrass
Authors: Haby V. A. , Anderson W. B. , Welch C. D. 
Published: July 2010

AbstractThree particle size ranges of calcitic and dolomitic limestones were applied at 4.5, 9, and 13.5 metric tons/ha. Evaluations were designed to determine the most efficient treatment for neutralizing soil acidity, and increasing crop production in Katy fine sandy loam (pH 5.2) and Boy loamy fine sand (pH 5.4). Liming effects were evaluated by soil and plant analyses. Efficiency rating (ER) was used to describe the limestone particle size ranges. Finer limestone particles were assigned higher relative efficiency values. The sum of the products of particle size percentage ranges multiplied by the relative efficiency assigned those ranges, times the neutralizing value of that limestone is the ER.Increases in soil pH were proportional to limestone ER and application rate. Calcitic limestone neutralized soil acidity more rapidly than did dolomitic. We found a statistically significant increase in calcium (Ca) in the 30‐ to 46‐cm depth of Boy loamy fine sand at the 13.5 metric ton/ha rate of ER 110 calcitic limestone. This was probably due to 689 kg of N/ha applied as NH4NO3 the first year following limestone treatment. Magnesium (Mg) increased in the 30‐ to 46‐cm depth due to all dolomitic treatments.Limestone did not increase the yield of corn (Zea mays L.) or Coastal bermudagrass (Cynodon Dactylon L. Pers.) in the harvest year.All treatments of calcitic limestone significantly increased the Ca percentage in corn. All dolomitic limestone treatments except the ER 26 material applied at 4.5 metric tons/ha increased Mg concentration in corn leaves and Coastal bermuda‐grass. Manganese toxicity occurred in corn plants growing in nonlimed plots the third season following treatment. Soil acidity and reducing conditions contributed to the toxicity.
Nitrate‐Nitrogen Leaching Following Urea Fertilization and Irrigation
Authors: Bauder J. W. , Schneider R. P. 
Published: July 2010

AbstractWheat (Triticum aestivum) was grown in undisturbed columns of Gardena silt loam, a coarse‐silty, mixed Pachic Udic Haploboroll, to evaluate NO3‐‐N leaching from urea under irrigation. Optimum and excessive irrigation rates and 135 kg N/ha (as urea in single application vs. three increments applied during the growing period) were compared in factorial combination. Chloride was added to all columns for comparison with NO3‐‐N. Leachate samples were collected throughout the study and analyzed for NO3‐‐N, NH4+‐N and Cl‐. Columns were dismantled at crop maturity and sampled for residual NO3‐‐N. Total N was determined in wheat at maturity.Leaching fractions (LF) differed significantly between optimum and excessive irrigation but were not affected by applied urea. Cl‐ moved with the wetting front. Leaching patterns for NO3‐‐N and Cl‐ were similar, but a slight lag in NO3‐‐N was observed. Concentration of NO3‐‐N in drainage water from all columns was initially similar (30 ppm NO3‐‐N), but then decreased as leaching volume changed. Maximum NO3‐‐N leaching occurred with split urea and excess irrigation. Minimum leaching occurred with optimum irrigation and split urea. Total NO3‐‐N leachate load was directly correlated with leachate volume. Soil solution concentrations at crop maturity were as much as 170 µg NO3‐‐N/ml. Residual NO3‐‐N varied among treatments and revealed as many as three peaks in NO3‐‐N concentration in the profile, indicating that N leaching occurred following each urea application. The results indicate marked NO3‐‐N movement from urea under excessive irrigation.
Effect of Nitrogen Source and Management on Ammonia Volatilization Losses from Flooded Rice‐Soil Systems
Authors: Vlek P. L. G. , Craswell E. T. 
Published: July 2010

AbstractAmmonia volatilization was studied by equipping capped greenhouse pots with a forced‐draft system with external acid trap or by placement of open pots in a closed gas‐lysimeter (allowing plant growth) with internal acid traps. In both systems air turbulence was optimized to simulate undisturbed open systems. Flooded soils were fertilized with approximately 50 or 100 kg N/ha of granular urea (GU), ammonium sulfate (AS), and two modified urea products—sulfur‐coated urea (SCU) and urea supergranule (USG). The first three materials were broadcast and incorporated, whereas the last was placed at a depth of 8 cm.Ammonia volatilization from urea proceeded rapidly following hydrolysis of urea in the floodwater, leading to losses of up to 50% of the applied urea within 2 to 3 weeks. Ammonia loss from (NH4)2SO4 occurred to a lesser extent due to a lack of alkalinity and occurred at a nearly constant rate, accumulating to ∼15% loss in 3 weeks. Ammonia losses from the modified urea materials were negligible.Soil pH had little effect on the pH of the floodwater and, thus, on the ammonia volatilization process. However, ammonia volatilization losses were generally reduced by factors that reduced the level of ammoniacal N in the floodwater, such as increasing soil CEC and reduced N application.Daily ammonia volatilization losses correlated well (r = 0.92) with the NH3(aq) concentration of the floodwater sampled between 1000 and 1100 hours each day. This observation holds promise for the development of a simple technique for assessing ammonia volatization losses from flooded soils based on simple physical and chemical parameters of the floodwater.