bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lateral Flow Above a Sloping Water Table
Authors: Luthin James N. , Day Paul R. 
Published: July 2010

AbstractThe lateral movement of water above a water table has been studied under steady‐state conditions. The dependence of the capillary conductivity on soil moisture tension has been considered in making a theoretical analysis of the problem.Lateral flow was induced in a sand‐filled tank by maintaining a small difference in head between constant reservoirs located on either side of the sand‐filled tank. The experimentally determined values of hydraulic head and quantity of flow were then compared to the theory which considered the variations of capillary conductivity with soil moisture tension. The hydraulic head determined at various points of the flow section in the steady state experiment agreed approximately with values calculated from theory. The flow calculated from knowledge of the capillary and hydraulic conductivities agreed with the measured flow.The methods of numerical analysis which were used to develop the theory can be applied to other steady‐state flow problems involving variable conductivities.
Laboratory Determination of Infiltration Rates of Disturbed Soil Samples
Authors: Peele T. C. , Beale O. W. 
Published: July 2010

AbstractA procedure for determining infiltration rates of disturbed soil samples in the laboratory, using simulated rainfall, is described. Data showing the relation of laboratory infiltration rates to those measured on cultivated areas in the field are presented. Comparisons of runoff from natural storms with infiltration rates determined in the laboratory and the field are given for several soil types. The laboratory infiltrometer, the type F field infiltrometer, and infiltration during natural storms placed the different soils in the same order. The usefulness of the laboratory infiltrometer for evaluating the effects of rotations, chemical soil conditioners, and inherent soil properties on infiltration in the surface soil of clean‐cultivated areas is briefly discussed.
The Chemistry of Zinc Added to Soils and Clays
Authors: Nelson J. L. , Melsted S. W. 
Published: July 2010

AbstractThe chemical forms which zinc assumes when added to soils and clays have been investigated, using the isotope dilution technique (with Zn65 as a tracer). After equilibrium, the added zinc was extracted by successive leaching with neutral normal NH4Ac, 2.5% HAc, and 0.1 N HCl. Variables were: (1) time of equilibrium, (2) calcium saturation, (3) amount of zinc added, (4) rate of extraction, and (5) type of clay mineral.With symmetry additions of zinc and a hydrogen soil system, practically all of the zinc taken up by the soil was replaceable with NH4Ac, whereas in a calcium soil system a part of the zinc could not be replaced with NH4Ac. The portion of the zinc not removed with NH4Ac could be extracted by repeated leaching with dilute HCl. This acid‐soluble form of zinc increased with increasing length of time of contact between the soil and the zinc solution. It apparently did not occupy exchange sites in the soils, since there was no reduction in the base‐exchange capacity of the soil with the formation of the acid‐soluble form. As smaller quantities of zinc were added to these soils and as the amount of time following the addition increased, a higher proportion of the zinc was found in the acid‐soluble form.
Uptake of Molybdenum from Everglades Peat by Several Grasses and by White Clover
Authors: Gammon Nathan , Fiskel J. G. A. , Mourkides G. A. 
Published: July 2010

AbstractThe problem of molybdenum toxicity to livestock in forage grown on Everglades peat, in practice, is met by application of copper to the soil, by copper in the mineral supplement fed to cattle and by copper drenching of severely affected cattle. The present study reports the molybdenum content of several grasses and clover that are grown in the area. Samples of clover from several fields are found to have about the same molybdenum content as the grass herbages. There is considerable variability in the molybdenum content of the different grasses tested on the Everglades peat. Kentucky 31 fescue, Pensacola Bahia, St. Augustine, Pangola and Coastal Bermuda grass, and white clover contained about 0.1 to 0.3 ppm. Mo in pot studies on unlimed peat, and 0.4 to 0.8 ppm. Mo on limed peats under greenhouse conditions. Under field conditions, the molybdenum content of these same herbages was considerably greater. Species taken from corresponding locations showed small variation in molybdenum content during the growing season when the pasture was well established, but initial samples taken at the time of the establishment of the pasture were much higher. On sandy soils, both Pangola grass and clovers showed a much higher molybdenum content for considerable periods after molybdenum fertilization, but no increase in yields. The molybdenum content of clover appears adequate where the soil has been limed. High fertilization of the pastures on peats and mucks high in molybdenum, followed by removal of the hay, and feeding the cattle on low molybdenum areas is suggested both to provide drier forage and to prevent return of the molybdenum to the pasture by manure and urine.
Houston Black Clay, the Type Grumusol: II. Mineralogical and Chemical Characterization
Authors: Kunze G. W. , Templin E. H. 
Published: July 2010

AbstractThe following analyses are reported on each of the several horizons of five profiles of typical Houston Black clay from widely separated sites in Texas described in Part I: particle size distribution, organic matter, calcium carbonate equivalent, exchange capacity, ethylene glycol retention and pH. In addition X‐ray diffraction analyses are reported for the following fractions: silt (0.05 to 0.002 mm.), bulk clay (<2µ), coarse clay (2µ to 0.2µ) and fine clay (<0.2µ). Differential thermal analyses are presented for the <0.2µ fraction.The average clay (<2µ) content for the 5 profiles varied between the narrow range of 57.7% and 60.8%. Fine clay (<0.2µ) was found to make up as much as 84% of the total clay fraction. The calcium carbonate equivalent varied from a minimum of 5.4% to a maximum of 70.2%. Zones of calcium carbonate enrichment resulting from leaching were not found. Organic matter in the surface horizons (0 to 18 inches) from virgin sites varied from 3.06% to 8.34%. The silt fractions are very largely quartz and calcite. Quartz predominated in the silt fraction from surface horizons, while calcite increased with depth and in three profiles assumed the dominating role in the C horizon. Montmorillonite strongly predominated the clay fraction (<2µ) and based upon X‐ray diffraction and exchange capacity studies it occurs in essentially a pure state in the <0.2µ fraction of three profiles. The exchange capacities for the A1‐1 horizons averaged 64 me. while the average for the C2 horizons was found to be 40 me.The Houston Black clay has developed from soft calcareous sediments. The mineralogical and chemical measurements indicate that no pronounced weathering of these sediments has occurred.
Moisture Utilization by Several Forage Crops
Authors: Willits N. A. , Erickson A. E. 
Published: July 2010

AbstractDuring the growing seasons 1951–53, the moisture used by 2 grasses and 2 legumes was determined by use of Bouyoucos blocks. Stage of crop development had more effect than weather on water use. Water use appeared to reach a maximum around July 1. The peak water use per day was 0.13 inches. The average was considerably less.Most of the water used from the profile by all crops was removed from the surface 9 inches (the depth of the Ap layer). Very few grass roots extended below 30 inches. The consumptive use of water under fescue sod was less than under bluegrass. Frequent clipping of the grasses resulted in less total water use but a greater percentage use from the surface layer.There was a very good correlation between the amount of water used from a horizon during a drying‐out period and the amount present in the horizon at the beginning of that period. The correlation decreased with depth. It appears that the water was removed from the horizon where it was most abundant.
Soil and Plant Responses to VAMA and HPAN Soil Conditioners in the Presence of High Exchangeable Sodium
Authors: Allison L. E. 
Published: July 2010

AbstractThis paper summarizes two experiments with polyelectrolyte soil conditioners to determine their effect on an irrigated soil—Pachappa loam—having a high content of exchangeable sodium. The conditioners were applied, at the 0.1% rate to a depth of 6 inches, with sufficient mixing to insure thorough incorporation of conditioner with soil. Sweet corn was used as the test crop.The initial study was started in 1951 and continued for 4 cropping seasons. Treatment of high‐sodium plots with VAMA in solution gave a large increase of aggregates larger than 0.10 mm. diameter, gave up to 10‐fold increases in infiltration rate, and greatly reduced modulus of rupture values, resulting in increased emergence and stand of crops. Large increases in yield of sweet corn were obtained as a result of soil physical improvement. For the 4 annual crops, the average yield increases due to treatment were 75, 200, and 260% on 3 plots having initial exchangeable‐sodium‐percentages of 29, 40, and 47, respectively.In a second and larger experiment begun in 1952, the VAMA and HPAN type of polyelectrolytes (100% active) and their respective clay formulations (25% active) were thoroughly incorporated as a dry treatment into moist soil. For high‐sodium Pachappa loam soil and at the rates of application used, there appeared to be little or no difference in performance between the two types of conditioners or between formulations for a given type. Soil and crop responses due to treatment were similar to those obtained in the first experiment.Sodium removal from the top 6 inches of soil, as a result of irrigation, was approximately twice as rapid on plots treated with conditioner as for plots not so treated. In the second experiment, the effect of the conditioner treatment in facilitating sodium removal was equivalent to a 2‐ton application of gypsum.
Fertilizer Evaluation: III. Availability Coefficient of Water‐Soluble and Citrate‐Soluble Phosphorus in Acidulated Phosphate Fertilizers
Authors: Black C. A. , Webb J. R. , Kempthorne O. 
Published: July 2010

AbstractA method is described by means of which the availability coefficient of citrate‐soluble relative to that of water‐soluble phosphorus may be evaluated when mixtures of the two phosphorus fractions are present in different proportions in two or more fertilizers. Knowledge of the relative availability coefficients of these two fractions, together with knowledge of the percentage content of the fractions, permits prediction of the relative availability coefficients of phosphorus in the different fertilizers. Application of the method to data obtained from experiments in which superphosphate and various nitric phosphates were compared as sources of phosphorus for corn showed that the ratio of the availability coefficient of citrate‐soluble phosphorus to that of water‐soluble phosphorus decreased from 0.85 to 0.16 as the fraction of the fertilizer phosphorus in citrate‐soluble form increased from 0.56 to 0.95.
The Relationship of Chloride and Sulfate Ions to Form of Nitrogen in the Nutrition of Irish Potatoes
Authors: Harward M. E. , Jackson W. A. , Piland J. R. , Mason D. D. 
Published: July 2010

AbstractA greenhouse experiment using sand cultures was conducted to study the role of chloride and sulfate anions in the nutrition of Irish potatoes when different forms of nitrogen were used. The experiment consisted of two series, the first in which all N was supplied as NO3‐ and the second in which both NH4+ and NO3‐ were present. Treatments within each series consisted of plants receiving different amounts of sulfate and chloride. The initial solution concentrations of all ionic species except NH4+, NO3‐, Cl‐, and SO4= were the same for each treatment.Two distinct foliar symptoms associated with treatments were observed. The first, a tip burn associated with high SO4= treatments, was more severe when NH4+ was present than when NO3‐ was the only source of N. The second, characterized by rolling of the leaves, was obtained only with Cl‐ treatments in the presence of NH4+. This was not observed when NH4+ was used in the absence of Cl‐ or when NO3‐ was added in the presence of either Cl‐ or SO4=.Increasing Cl‐ and decreasing SO4= concentrations in the presence of NH4+ resulted in marked reduction in the yield of fibrous roots. Additions of Cl‐ generally resulted in decreases in the percentage of dry matter in the tops and this effect was more pronounced in the presence of NH4+. In the NH4NO3 series, reductions in chlorophyll content resulted from increased supply of Cl‐ and simultaneous decrease of equivalent amounts of SO4=. No change in these pigments was obtained in the NO3‐ series. The mineral content of the potato leaves was affected both by form of N and by Cl‐ and SO4= concentrations. The Cl‐ content of the leaves was markedly increased in the presence of NH4+.
A Two Nutrient‐Response Function with Determination of Economic Optima for the Rate and Grade of Fertilizer for Alfalfa
Authors: Pesek John , Heady Earl O. 
Published: July 2010

AbstractA replicated fractional factorial experiment with phosphorus and potassium fertilizer variables was conducted with alfalfa growing on Webster silty clay loam in 1952. Fertilizer was topdressed before growth was initiated in the spring, and the yields of hay determined from two cuttings. The range of fertilizer applications was wide enough to reach maximum yields.The data were analyzed and three different two‐variable equations were fitted to the observations. The equation which resulted in the best correlation with the observed data from this experiment was of the general form,
urn:x-wiley:03615995:saj2sssaj195603615995002000020025x:equation:saj2sssaj195603615995002000020025x-math-0001 where Y is the yield, and K and P the pounds of K2O and P2O5 per acre respectively. The correlation coefficient was 0.8793 and significant at the 1% level. The last four coefficients of K and P were also significant at this level, while the first coefficient of K was significant at the 5% level.It was shown how this equation representing the response surface can be used to (1) determine the rates of P2O5 and K2O combinations which resulted in the same yield levels; (2) calculate the least cost combination of the two nutrients for any given yield; (3) calculate the marginal yields of both nutrients; (4) determine the optimum level of application of each nutrient at constant levels of the other; and (5) calculate the optimum levels of both nutrients varying simultaneously.Finally, it was illustrated how the least cost combination, and rates of application of the two nutrients varied as different prices for fertilizer elements and hay were assumed under the conditions of this experiment.
The Effect of Crop Residues on Soil and Water Losses from Corn and Winter Wheat
Authors: Gard L. E. , Klingebiel A. A. , Van Doren C. A. 
Published: July 2010

AbstractSoil and water losses from plots planted to a corn, winter wheat, and lespedeza rotation were measured for 14 years. The plots, located on Grantsburg silt loam were 70 feet long and on slopes of 5% and 9%. During the period 1939–46, crop residues were removed or grazed from the plots. From 1947 through 1953, crop residues were returned to the plots. The average annual precipitation was 3 inches greater during the 1947–53 period than in the 1939–46 period. The maximum rainfall intensity (15‐minute period) for the storms producing over 80% of the total soil loss was highly significantly greater during the 1947–53 period, when crop residues were returned, than in the 1939–46 period, when crop residues were removed.Comparable individual storms that produced over 80% of the total soil loss were analyzed for each of the two periods. Soil loss “per inch of rain” from corn plots was over three times greater when residues were removed than when they were returned on both the 5% and 9% slopes. Soil loss “per inch of rain” from winter wheat plots on the 5% slope was 3.9 times greater, and on the 9% slope 2.4 times greater when the residues were removed than when they were returned.During the 1947–53 period, soil losses from winter wheat plots were more than 2 times greater from 9% slopes and over 3 times greater from 5% slopes than from similar plots planted to corn. Crop residues on the surface reduced soil losses but did not materially change the amount of runoff from soils having a very slowly permeable subsoil.Data from individual storms producing over 80% of the total soil loss from winter wheat plots for the 1939–53 period were analyzed by the multiple regression method. The partial regression coefficient was determined between soil loss per inch of precipitation and rainfall intensity in inches per hour for the most intense 15‐minute period. Keeping the variables of antecedent rainfall and total precipitation constant, the analysis indicated significant differences (1) between the rate of soil loss on 9% slopes where residues were returned as compared to where they were removed, and (2) between the rate of soil loss on 5% slopes as compared to 9% slopes where all residues were removed.
A Numerical Solution of the Differential Equation of Flow for a Vertical Drainage Problem
Authors: Day Paul R. , Luthin James N. 
Published: July 2010

AbstractThe drainage rate of a uniform soil overlying a continuous gravel substratum is difficult to predict because of the fact that the soil moisture tension and the capillary conductivity of the soil vary with the water content. Richards' differential equation of flow furnishes a theoretical basis for analysis. The equation can be solved numerically by finite differences when the capillary conductivity and the water content have been determined at various values of the soil moisture tension. An illustration and experimental test of the method are given for the drainage of a column of fine sand.
Phosphate Supply Pattern of Various Soils
Authors: Fried Maurice , Shapiro R. E. 
Published: July 2010

AbstractThe pattern of phosphate supply in soils of different phosphate level was investigated by three techniques: continuous soil leaching, successive hourly equilibrations, and intermittent leaching in the presence of growing plants. All three approaches gave similar results.The pattern of phosphate supply for the four low phosphate‐fixing soils could be predicted by assuming the phosphate released was a desorption phenomenon as described by the Langmuir adsorption isotherm. The pattern of phosphàte supply for the three high phosphate‐fixing soils could be predicted by assuming that in the presence of water a saturated solution of a chemical compound was formed.The level of phosphorus in the initial water extract was not a good indication of plant‐available phosphorus. Both the intensity of soil phosphate supply and the capacity of the soil to rapidly renew this supply must be evaluated to adequately describe plant‐available phosphorus in the soil.
Nitrogen, A Key Factor in Fertilizer Phosphorus Efficiency
Authors: Olson R. A. , Dreier A. F. 
Published: July 2010

AbstractThe action of N in promoting fertilizer P utilization was studied in the field and greenhouse over a period of 4 years using P32 tagged superphosphate as the tool for uptake evaluation. Wheat and oats were used as indicator crops on several soils, employing different rates, times, and methods of application, and different forms of N and P.Fertilizer N stimulates plant use of fertilizer P throughout a wide range of soil conditions. The NH4+ ion apparently exceeds NO3‐ in this capacity, especially during early stages of plant growth, the maximum influence of either occurring with intimate association of the fertilizer N and P. In greenhouse plant production, a rate of slightly > 20 pounds of N per acre is sufficient to bring about the maximum proportionate change in fertilizer P use over soil P. With a given low rate of P application, the N effect may be as much as doubling the rate of fertilizer P use with little change in soil P use. The phenomenon apparently accounts for the reported greater early utilization of P from ammonium phosphates than from non‐ammonium bearing but otherwise similar orthophosphate compounds.There seems little doubt of a physiological function of N stimulating root activity in the absorption of fertilizer P, in consideration of several earlier works and the observations here. This, coupled with observed root concentration in the zone of joint N‐P placement could largely account for the greater fertilizer P uptake under consideration. Whatever the full explanation, this is a principle of utmost significance in plant nutrition, practical application of which probably can be obtained only with a current annual crop where fertilizing the crop at a low rate, rather than the soil at a high rate, is practiced.A related incidental finding is the high efficiency associated with side‐band placement of N + P fertilizer in small grain seedings. Such a placement has advantage over placement with the seed in that the entire quantity of N required can be supplied with the P application without endangering germination and stand under limited soil moisture conditions, while at the same time permitting the maximum N effect on fertilizer P to be manifest.
The Effect of Liming on the Utilization of Soil and Fertilizer Phosphorus by Several Crops Grown on Acid Organic Soils
Authors: Lawton K. , Davis J. F. 
Published: July 2010

AbstractThe effect of liming two strongly acid Rifle peat soils on the growth and absorption of soil and fertilizer phosphorus by field beans, sudan grass, and corn was studied under greenhouse conditions.The dry weight of field beans was markedly increased by applying up to 12 tons of CaCO3 per acre. In contrast, the growth of corn was depressed when more than 3 tons of CaCO3 per acre was applied. Liming had little or no effect on the yield of sudan grass. Concentrated superphosphate (49% P2O5 tagged with P32) mixed with the organic soils was very effective in increasing the growth of corn, but less benefit was noted with field beans and sudan grass.The phosphorus content of plants was progressively depressed by successive increments of CaCO3. Distinct phosphorus deficiency symptoms were evident on corn grown in soil receiving the highest lime rate. The use of superphosphate eliminated all signs of phosphorus starvation in corn and significantly increased the phosphorus content of each crop at all lime levels. It is suggested that the depression in percent plant phosphorus caused by liming was due to a decrease in the proportion of H2PO4‐ to HPO4= ions in the soil solution.The percent of plant phosphorus derived from fertilizer was generally progressively reduced by increasing amounts of lime. At the rate of 50 pounds of P2O5 per acre, this percentage was approximately ½ that found in plants receiving the 200‐pound P2O5 per acre application. Though the amount of fertilizer phosphorus absorbed by corn was many times that by field beans, the percent of fertilizer derived phosphorus in the two crops was quite similar at any given lime‐superphosphate level.Laboratory studies indicated that liming followed by 6 months of moist incubation had little effect on the amount of phosphorus extractable in a dilute hydrochloric acid‐ammonium fluoride solution.