bluuebunny/crossref_metadata_2025 huggingface dataset:
Comments on Nitrate Reduction in Unsaturated Soil
Authors: McLaren A. Douglas
Published: July 2010

Cyclic oxidation and reduction of nitrite and nitrate in soil are analysed in terms of first‐ and zero‐order microbial kinetic reactions, respectively. A reversible reaction step involving these ions can account for a low, but constant concentration of nitrate in an unsaturated field soil for long periods or for considerable depths in a laboratory soil column.
Iron‐manganese Concretions in Hydrosequences of Soils in Loess in Bavaria
Authors: Schwertmann U. , Fanning D. S.
Published: July 2010

To expand knowledge about the nature and distribution of Fe‐Mn concretions in soils, and in particular about their relation to degree of hydromorphism, the amounts and composition of concretions (0.2–0.63, 0.63–2.0, and >2.0‐mm diam) in profiles of two hydrosequences on loess in Bavaria, Germany were determined. Concretions were separated by wet sieving air‐dried soil samples. Maximum concretion formation (up to 7.5 weight percent) occurred in the upper B horizons (∼50‐cm depth) approaching the surface with increasing wetness. Maximum concretion formation (up to 40 kg/m2) also occurred under medium wetness and not in the wettest profile. Mn, Fe, and P (except not P in the wettest members) were concentrated in the concretions, Fe predominantly as goethite, Mn presumably as birnessite and P (as concluded from correlations) adsorbed to Fe‐oxides, but not to Mn‐oxides. Selected concretion and microprobe studies showed that during concretion formation Mn with Some Fe is concentrated first with Mn being essentially exhausted at a later stage where nearly only Fe accumulates. Inasmuch as P from 2,000‐year‐old bones accumulated in concretions, their formation appears to have been continuing through recent time.
Prediction of Evaporation from Columns of Soil During Alternate Periods of Wetting and Drying
Authors: Staple W. J.
Published: July 2010

This analysis was undertaken to test certain approximations in using finite difference methods to compute evaporation and soil water conservation. Analysis of four evaporation experiments showed that water movement in Wood Mountain clay loam was sufficiently repeatable during wetting and drying to permit computation of evaporation losses on the basis of predetermined soil properties. The experiments involved evaporation after the following treatments: (i) infiltration penetrating partway down columns of air‐dry soil; (ii) infiltration and 7 days' redistribution; (iii) treatment (ii) plus additional infiltration; and, (iv) repeated infiltration applied at different stages of initial drying.

In computing evaporation the Richards and Dalton flow equations were used with soil and atmospheric parameters. Temperature gradients in the soil were neglected. Hydraulic conductivity of the surface layers of soil were adjusted empirically to estimate combined liquid and vapor movement and to correct for disruptive effects such as dispersion, air blockage, and swelling near the surface. The independent domain theory was used to estimate the influence of hysteresis on capillary pressures during alternate wetting and drying. Agreement between measured and computed evaporation was satisfactory following infiltration except when water was added after > 7 days' evaporation.
No‐tillage Effects on Soil Properties under Different Crops in Western Nigeria
Authors: Lal R.
Published: July 2010

Five years of no‐tillage vs. the conventional method of tractor plowing significantly affected the physical and chemical properties of an Alfisol in western Nigeria. Continuous cropping of maize for 3 consecutive years was followed by 4 seasons of cultivation with cropping sequences of maize‐maize (Zea mays L.), maize‐cowpeas (Vigna unguiculata L. walp.), pigeon peas (Cajanus cajan Millsp.)‐maize, soybeans‐soybeans (Glycine max Merr.), maize‐soybeans, and cowpeas‐cowpeas. The no‐tillage plots had higher organic matter contents in the surface soil horizons and higher concentrations of nitrate‐nitrogen, Bray‐1 available phosphorus, and ammonium acetate extractable cations such as Ca2+, Mg2+, and K+ than the plowed plots. The infiltration rates of no‐tillage plots were higher than those of the plowed plots and, thus, runoff and erosion losses were minimal. Although maximum soil temperatures were higher in the plowed plots, the no‐tillage plots had higher soil moisture contents throughout the growing seasons. Greater earthworm activity in the no‐tillage plots reduced compaction and crust formation. Yields equal to those from the plowed plots were harvested from the no‐tillage plots under suitable crop rotations.
Anomaly and Modification of pH‐Acidity Relationship in the Double Buffer Method for Lime Requirement Determination
Authors: Yuan T. L.
Published: July 2010

A break at pH 6.2–6.3 was observed recently in the linear titration curve of the buffer used in the double buffer method (Yuan, 1974). As a result, different pH‐acidity relationships above and below this pH would have to be used in the lime requirement calculation. An attempt was made to investigate the possible cause or causes for the break. Suspected contamination of Cr2O72‐ in the K2CrO4 reagent originally used in the development of the method was investigated as was the effect of CaCl2 on buffering behavior of CrO42‐. Although a completely satisfactory explanation of the anomaly was not obtained, it appears that higher purity of currently available K2CrO4 is involved. A modification of the buffer composition was made to give a linear curve with currently available chemicals so that the soil lime requirement can be more easily calculated. A table to show the soil buffering capacity based on a linear 1:1 pH‐acidity relationship has also been added.
Soil Water Deficits Under Forested and Clearcut Areas in Northern Arkansas
Authors: Rogerson T. L.
Published: July 2010

Soil water under forested and cut areas on northwest and southeast aspects was measured with a neutron probe system at weekly intervals to study soil water deficit patterns under these conditions. Soil water deficits were significantly different among years, seasons, and vegetative covers. Summer deficits increased at the average rate of 2.1 mm/day on the forested and 0.6 mm/day on the cut areas. Average seasonal deficits for forested and cut areas, respectively, were: spring, 23 mm and 16 mm; summer, 104 mm and 34 mm; fall, 230 mm and 45 mm; and winter, 108 mm and 24 mm. No signficiant differences were found between soil water deficits on northwest and southeast aspects.
Calcium Retention in Response to Phosphate Sorption by Soils
Authors: Ryden J. C. , Syers J. K.
Published: July 2010

Retention of Ca increased in response to P sorption by soils, but was independent of the amounts of added Ca. Rather constant values were obtained for the molar ratio of Ca/P retained (0.19 to 0.34). Retained Ca was essentially recovered in 1M KCl washings in contrast to the fractional recovery of sorbed P. The retention of Ca in response to P sorption by soils is interpreted as arising from a sorption rather than a precipitation reaction, and results from the increase in negative charge induced by P sorption.
Soil Labile Pools of Manganese, Iron, and Zinc as Measured by Plant Uptake and DTPA Equilibrium
Authors: Rule J. H. , Graham E. R.
Published: July 2010

Labile pools of Mn, Fe, and Zn were measured on soil samples having varying pH levels at both air‐dry and field‐moist conditions using DTPA. Labile pools of Mn and Fe varied with respect to both pH and soil moisture. The effects of soil moisture and pH on Zn labile pools were slight.

Air‐dry soil samples at three pH levels were labelled with carrierfree 54Mn, 59Fe, and 65Zn, and ladino clover (Trifolium repens) and tall fescue (Festuca elatior, var. Ky 31) were grown on each in a growth chamber. Uptake of the stable isotopes and radioisotopes was determined and the data were used to calculate soil labile pools of each element.

Soil labile pools of Mn measured by ladino clover uptake were very similar to the values obtained from DTPA equilibration. Values for Fe labile pools were higher and generally in disagreement with DTPA‐measured pools. Plant measured values for Zn varied depending on soil pH with respect to DTPA‐measured pools.

Tall fescue‐measured soil labile pools of Mn, Fe, and Zn were calculated from uptake data of various combinations of cuttings. At a given pH, Mn labile pools calculated from any of the combinations were remarkably similar, but were lower than DTPA measured pools. Iron and zince labile pools were erratic with respect to both soil pH and cutting used. Uptake data suggested that a single harvest of tall fescue at ground level after a 5‐week growing period could be adequate to measure the soil labile pools of Mn, Fe, and Zn, especially if these elements were studied simultaneously.
Viscosity Measurements on Soil Humic Substances
Authors: Chen Y. , Schnitzer M.
Published: July 2010

Viscosity measurements were done on a humic acid and a fulvic acid to obtain information on particle shapes and dimensions, particle weights and polyelectroytic behavior in aqueous solutions. The pH of the humic acid solutions ranged from 7.0 to 10.5, that of the fulvic acid solutions from 1.0 to 10.0.

Humic acid at pH 7.0 and fulvic acid at pH 1.0 and 1.5 behaved like uncharged polymers. At higher pH levels, both humic and fulvic acids exhibited strong polyelectrolytic characteristics. The viscosity data fitted an equation developed by Fuoss and Strauss for linear, flexible polyelectrolytes.

In the case of fulvic acid, it was possible to assess the effect of a wide range of pH values. At very low pH, fulvic acid had the highest particle weight and particle volume. With increase in pH, the two parameters decreased to a minimum at pH 3, and then began to increase moderately. An analysis of the data for particle shapes and dimensions showed that the most likely particle configuration was rods. Viscometry offers an almost unique opportunity to study important structural characteristics of humic substances in aqueous solutions. Molecular modifications associated with drying, heating, and exposure to high vacuum can so be avoided.
A Semiautomated Procedure for Total Nitrogen in Plant and Soil Samples
Authors: Gallaher R. N. , Weldon C. O. , Boswell F. C.
Published: July 2010

This study evaluated inexpensive alternatives for the determination of total N in plant and soil samples. Plant and soil samples which varied widely in N concentration were digested in a 126‐sample‐capacity Al block digester followed by determination of total N with the ammonium electrode in a semiautomated reaction vessel assembly. The proposed Ammonium electrode semiautomated (AES) procedure was compared to standard micro‐Kjeldahl and aluminum block digested‐steam distilled‐titrated (ABDDT) procedures. Thirty to 50 more samples could be analyzed per 8‐hour day with the proposed semiautomated procedure as compared to standard micro‐Kjeldahl methods. The precision of the methods were comparable but significantly more N was found by using the ABDDT procedure.
Geography of Soil Test Results
Authors: Westin Frederick C.
Published: July 2010

Since the factors that control soil formation and soil geography must also affect levels of soil K, P, organic matter, and pH, this study was undertaken to determine the correlations that might exist between soil geography and soil test results. Soil test results for over 80,000 farmer samples were correlated with soils classified at the series, family, subgroup, great group, suborder, and order categories of the comprehensive soil classification system. Then the regional effects of climate and native vegetation on soil test results were isolated, followed by a determination of the local effects on the soil test results of soil parent material, slope and age. Chi square statistical procedures were used to determine significance. Increasing precipitation resulted in decreased K and P and lower pH but higher organic matter. Increasing temperature lowered K and organic matter and increased P but had no effect on pH. Within a climatic zone, as sandiness increased, levels of K, P and organic matter decreased, while pH rose. When carbonate content increased, K and P decreased and pH increased, while organic matter remained constant. As slopes became steeper, levels of K, P, and organic matter decreased, while pH rose. And as soils became older, K and pH decreased, while P and organic matter remained essentially constant. Except for the influence of soil texture on organic matter, all other data were highly significant. Although precise amounts of K, P, organic matter and pH require individual field sampling, a consideration of the geography of the soils as expressed in soil taxonomic terms gives a rational starting point in plant nutrient assessment and a tool for extension of fertility‐related data.
The Evolution of Soil Properties as it Relates to the Genesis of Volcanic Ash Soils in Costa Rica
Authors: Martini J. A.
Published: July 2010

Five soil profiles developed on andesitic volcanic ash, under welldrained conditions and at various elevations associated with different climatic conditions, were studied.

These soils varied in profile development and degree of weathering from Incipient Ando soil (Umbric Vitrandept), Mature Ando soil (Typic Dystrandept), and Senile Ando soil (Hydric Dystrandept) to Incipient Latosol (Typic Humitropept) and Mature Latosol (Typic Palehumult).

Profile development associated with time of ash deposition and climate and recognized by virtue of morphological properties was closely related to progressive weathering and a consistent evolution of physical, chemical, and mineralogical properties, as well as to an increasing degradation of the native soil fertility.

This investigation served as a basis for developing a working hypothesis on the genesis of volcanic ash soils from Regosols and Ando soils to Latosols.
Effects of Various Camping Intensities on Soil Properties in Illinois Campgrounds
Authors: Young R. A. , Gilmore A. R.
Published: July 2010

Selected chemical and physical soil properties were measured at nine Illinois campgrounds, representing three major soil association groups. At each campground the following four levels of camping use were compared: unused‐control; used < 33 days per season; 34 to 66 days; and over 66 days of use per 100 day season. Differences between the interior (0 – 2.5 m radius) and exteriors (2.5 – 5.0 m) of the campsites were also investigated. There were no significant differences in any of the properties between the interiors and exteriors of the campsites. Campsites on the deep loessial soils had less compaction, more organic matter and nutrients (Mg, Ca, K, P, Na, N), and were less acid than those on fragipan or claypan soils. Most soil properties considered in the study increased with increased camping use when compared with the unused sites. The percentage of organic matter ranged from 2.57, 3.12, 3.52, and 3.18 from the unused to the most heavily used sites. Compaction for the four levels of use starting with the control sites was 3.46, 8.45, 9.14, and 9.79 kg/cm2. Soil pH was 5.1, 5.7, 6.1 and 6.3 for the same four levels of use. Ca, K, Na, P and N were also found at higher levels on heavily used sites than on the unused or lightly used sites. There was no difference in Mg levels on any of the four levels of use.
Soil Air Pressure Effects on Route and Rate of Infiltration
Authors: Linden D. R. , Dixon R. M.
Published: July 2010

One centimeter of 0.1% methylene blue solution was infiltrated into soil with various constant soil air pressures beneath the wetting surface to measure flow into and through soil macropores. Flow was increasingly impeded as soil air pressure increased from 0 to 5 mbars. Infiltration rates during the first 3 min of wetting were decreased by an order of magnitude with 5 mbars of air‐back pressure.
Nutrient Concentration in Black Spruce Foliage Immediately Following Fertilization
Authors: Salonius P. O.
Published: July 2010

Ammonium sulfate, triple superphosphate, or K sulfate were applied to plots in a 60‐year‐old black spruce (Picea mariana (Mill.) B.S.P.) stand, and seasonal changes in foliar nutrient levels on the treated plots were compared with those on the control before and after fertilization. Nitrogen was absorbed initially very quickly but there appeared to be some delay in the initial uptake of P. Both N and P were absorbed steadily throughout the remainder of the growth season. Possible methods of capitalizing on this fact and thus increasing fertilizer efficiency and decreasing losses of applied nutrients are discussed.
Soil Microbiology—It's a Small World
Authors: Clark Francis E.
Published: July 2010

Soil Microbiology—It's a Small World.

The accomplishments and personalities of some notable early American soil microbiologists are discussed. The tangled skeins of influences and interactions among them are used to justify the small world concept used in the title. In discussing the subject matter of soil microbiology, it is noted that as society becomes more concerned with population growth and world food supply, energy sources and requirements, and econology and the environment, soil microbiology is shifting its emphasis from soil and the growing plant to man and the biosphere. The soil microbiologist is becoming increasingly involved in exposing such unesthetic substrates as sewage, animal manures, and food and fiber processing and sanitary landfill organic wastes to microbial attacks. His objectives are to make such substrates less objectionable environmentally and to exploit their residual food and energy potentials. Together with these endeavors he is expanding his efforts to define the dominant roles of microorganisms in the functions of terrestrial ecosystems. Therein, microorganisms metabolize a far larger amount of the net primary productivity than do all of the higher forms of life, inclusive of man, taken collectively.
Mass Transfer Studies in Sorbing Porous Media: III. Experimental Evaluation with 2,4,5‐T
Authors: van Genuchten M. Th. , Wierenga P. J. , O'Connor G. A.
Published: July 2010

Comparisons are made between observed and calculated effluent concentration distributions for the movement of 2,4,5‐T (2,4,5‐trichlorophenoxyacetic acid) through 30‐cm long unsaturated soil columns. The comparisons are made using both analytical and numerical solutions of a previously published model, which included the effects of intra‐aggregate diffusion and adsorption. The results in this study indicate that intra‐aggregate diffusion and adsorption/desorption are the main mechanisms responsible for effluent tailing. An estimated 60% of the adsorption. Was found to occur in the stagnant region of the soil. When intra‐aggregate diffusion was included in the model, the observed adsorption/desorption hysteresis phenomenon found to be significant in several earlier studies, was shown to be much less important in describing the observed concentration distributions.
Effects of Trace Elements on Phosphatase Activity in Soils
Authors: Juma N. G. , Tabatabai M. A.
Published: July 2010

Studies to evaluate the effects on the activity of acid and alkaline phosphatases of 20 trace elements showed that all trace elements inhibit the activity of phosphatases in soils. Results showed that the relative effectiveness of the trace elements in inhibition of phosphatase activity depends on the soil. When the trace elements were compared by using 25 µmole/g soil, the average inhibition of acid phosphatase in three soils showed that Hg(II), As (V), W(VI), and Mo(VI) were the most effective (average inhibition >50%) and that Ba(II), Co(II), and As(III) were the least effective (average inhibition <10%) inhibitors. Other elements that inhibited acid phosphatase activity in soils were: Cu(I), Ag(I), Cd(II), Cu(II), Zn(II), Mn(II), Sn(II), Ni(II), Pb(II), Fe(II), Cr(III), Fe(III), B(III), Al(III), V(IV), and Se(IV); their degrees of effectiveness varied in the three soils used.

The most effective inhibitors of alkaline phosphatase activity in soils were Ag(I), Cd(II), V(IV), and As(V). All the trace elements that inhibited acid phosphatase activity also inhibited alkaline phosphatase activity. The order of effectiveness of the trace elements in inhibition of acid phosphatase activity was different from that of inhibition of alkaline phosphatase activity. Generally, the inhibitory effect of trace elements was less in the presence of 2.5 µmole/g soil than in the presence of 25 µmole/g soil. In addition to the effect of trace elements, phosphate ion inhibited acid and alkaline phosphatase activities in soils. Related anions such as NO2‐, NO3‐, Cl‐, and SO42‐ were not inhibitory in the presence and absence of buffer.
Phosphorus Fertility of Some Tropical Soils in Sierra Leone
Authors: McKenzie E. , Kurtz L. T. , Melsted S. W.
Published: July 2010

Chemical fractions and profile distributions of native phosphorus were determined in some soils of Sierra Leone, West Africa. Total P in the horizons of eight profiles ranged from 70 to 420 pp2m. Distributions within profiles were usually rather uniform, with concentrations tending to be somewhat greater in the surface and deepest horizons. Phosphorus fractions extracted by NH4F and NaOH were typically between 18 and 30 pp2m (6 to 12% of the total P), while the acid‐soluble fraction was virtually absent. On the average, 15% of the total P was in the reductant‐soluble form. Bray P‐1 values ranged from 5 to 25 pp2m P in the surface horizons, but were often < 3 pp2m at depths below 40 cm. A very low proportion of the native P in these soils would be expected to be readily utilized by crops.

Estimates were also made of P retention capacities, P equilibrium concentrations in solution, and recovery with the Bray P‐1 extractant of added P after different periods of incubation. Behavior of P in Sierra Leone soils in these procedures was not greatly different from that in some Illinois soils where the management of P fertility has become routine. Attaining and maintaining adequate levels of P in Sierra Leone soils by fertilization would not appear to be difficult, assuming phosphate fertilizers can be obtained.
Pyrite and Pyritic Mill Tailing as a Source of Iron in a Calcareous Iron‐deficient Soil
Authors: Barrau E. M. , Berg W. A.
Published: July 2010

Mill wastes from ore processing, particularly acid‐forming pyrites, often pose disposal problems. This greenhouse study evaluated pyrite and a pyritic mill tailing as Fe sources on an Fe‐deficient calcareous soil.

Pyrite and tailing < 0.1 mm in diameter were applied at rates of 45 and 135 metric ton/ha. Controls, 200 and 600 ppm Fe as Fe2(SO4)3 and 5 and 15 ppm Fe as FeEDDHA, were used as standards. The treatments were seeded with sudangrass (Sorghum vulgare sudanense) and six successive crops were harvested. Sudangrass yields increased 160 to 200% with pyrite and tailing treatments; these yields were significantly greater than the control and were comparable to yields from the other Fe sources. The 5 ppm FeEDDHA treatment, however, increased yield for only the first two crops.

Plant‐available soil Fe measured by DTPA extraction increased with all Fe treatments, while the levels of DTPA‐extractable Zn and Mn remained the same or increased slightly. DTPA‐extractable Cu doubled with the high rate of pyrite addition. The concentration of Fe in the plants remained the same or increased slightly with the Fe treatments, while concentrations of Zn, Cu, and Mn all decreased.
Row Spacing and Direction Effects on Water Uptake Characteristics of Peanuts
Authors: Chin Choy E. W. , Stone J. F. , Garton J. E.
Published: July 2010

Peanuts (Arachis hypogaea L.) grown in 30‐cm wide, north‐south rows, lost less water to evapotranspiraton than those grown in 90‐cm rows or than east‐west rows of these spacings. Plants grown in 90‐cm wide, north‐south rows tended to have the highest water losses. The reason for this phenomenon was not determined, although there is reason to believe net radiation is lower in narrow rows than wide.

Yield of peanuts was enhanced by the narrow rows and no orientation effect on yield was noted. Thus, water‐use efficiency was increased by both yield effect and water conservation effect. Peanut quality was the same for all treatments.

There is no reason to believe that the water conserving effect is unique to peanuts. Research on other crops in similar geometries is to be encouraged.
Fate of Urea Fertilizer Added to a Boreal Forest Pinus banksiana Lamb. Stand
Authors: Morrison I. K. , Foster N. W.
Published: July 2010

Distribution of N in various components of a 45‐year‐old, relatively pure Pinus banksiana (jack pine) ecosystem on a sandy outwash site, was estimated at various times during the first three growing seasons following fertilization with 300‐kg urea‐N/ha. At the end of the third growing season, N, equivalent to that applied, was distributed as follows: in trees, 23%, in ground vegetation, 1%, in soil organic layers, 26%; and in mineral soil, 10%. An estimated 30% was lost into the atmosphere through volatilization, while the remaining 10% was unaccounted for. Negligible nitrification suggested little likelihood of ground‐water contamination following urea fertilization.
Automatic Feedback Control to Maintain Constant Soil Moisture Tension in the Study of Drought Tolerance in Rice
Authors: Alvarez E. I. , De Datta S. K.
Published: July 2010

We have developed a greenhouse technique by which a chosen soil moisture tension can be maintained continuously. The setup for supplying water at relatively constant soil moisture tension in pots includes five major components—water tank, W‐tube, water distribution system, soil moisture tension sensors, and pots. The W‐tube, which contains a predetermined amount of Hg, controls the soil moisture tension in the pots. Water can flow freely from the tank to the pots through the distribution system whenever the soil moisture tension exceeds that desired. Response to the sensors' demand for water is rapid.

We have successfully used this setup to compare relative drought tolerance of rice (Oryza sativa L.) varieties and breeding lines. Another use of this setup might be to measure evapotranspiration (ET) almost instantaneously; the technique might be useful in some soil‐plant‐atmosphere‐water relationship studies.
A Possible Model for the Surface‐induced Hydrolysis of Organophosphorus Pesticides on Kaolinite Clays
Authors: Mingelgrin U. , Saltzman Sarina , Yaron B.
Published: July 2010

A model for the hydrolysis of organophosphorus pesticides on clay surfaces is proposed; organophosphate ester molecules are susceptible to hydrolysis of the phosphate ester bond, whereby they are rapidly degraded on the kaolinite surfaces. It is suggested that the organophosphorus molecules undergo hydrolysis by the ligand water associated with the counter ions. Consequently, the degradation process is dependent on the nature of the saturating cation and its hydration status.
Evaluating Weathering Characteristics of Water‐harvesting Catchments from Rainfall‐runoff Analyses
Authors: Fink D. H. , Frasier G. W.
Published: July 2010

Better ways are needed to evaluate the weathering properties of water‐repellent and membrane‐covered water‐harvesting field catchments. Normally, only the ratio of runoff to precipitation from natural storms (percentage of runoff) is calculated, which provides useful information on treatment efficiency and durability, but little about why or how a treatment actually failed. We used linear regression analyses of precipitation vs. runoff‐yield data collected over several years (storms with no runoff omitted) to obtain (i) threshold values, i.e., the minimal rainfall needed to produce runoff, and (ii) the runoff‐efficiencies of treatments after threshold. These analyses showed that silicone and wax‐treated water‐repellent catchments weathered quite differently. The silicone treatment showed a uniform deterioration throughout the treated zone while the wax treatment showed a progressive deterioration beginning at the top of the treated profile. A gravel‐covered membrane catchment gradually increased runoff threshold from 1‐ to 2‐mm water, which was ascribed to a gradual accumulation of dust entrapped in the gravel. The weathering properties of several other common type catchments were evaluated using the technique. A brief discussion is included on the application of the technique to evaluate the accuracy of precipitation‐ and runoff‐measuring devices in water‐harvesting systems.
Biomass and Nutrient Accumulation in a Cottonwood Plantation—the First Growing Season
Authors: Baker James B. , Blackmon B. G.
Published: July 2010

During their first growing season, eastern cottonwood (Populus deltoides Bartr.) planted at a 3 by 3 m spacing on a slackwater clay soil (Vertic Haplaquept) in western Mississippi produced 3,680 kg/ha of dry matter. Of this, 900 kg/ha was in leaves, 700 in branches, 820 in stems, and 1,260 in roots. Seventy‐six percent of the aboveground biomass was accumulated during August and September. At the end of September, just prior to leaf fall, the trees contained 43.5 kg/ha of N, 4.7 kg P, 34.7 kg K, 36.5 kg Ca, and 6.4 kg Mg. From 62 to 79% of these elements was accumulated in August and September.

Foliar N and P concentrations peaked in early summer, then steadily decreased until leaf fall in November. Branch and stem N and P decreased from a maximum in early summer to a low in September, then increased during October and November. Seasonal patterns of Ca and Mg were similar to those of N and P, except that foliar concentrations steadily increased throughout the summer to a maximum at time of leaf fall. Trends in foliar K were similar to those of N and P; however, K concentrations in branches and stems declined through the summer to a low at time of leaf fall.

Of the total quantity of N, P, K, Ca, and Mg in the foliage in September, 26% of the N, 33% of the P, 28% of the K, 62% of the Ca, and 51% of the Mg fell with abscised leaves in November. Sixty‐one percent of the foliar N and 53% of the foliar P were translocated to other tissue prior to leaf fall. Potassium, calcium, and magnesium were not involved in internal nutrient cycles since they were not translocated and retained in support tissue. A large portion of the foliar K was apparently leached or lost through root exudation or other means.
Surface Morphology of Quartz and Age of Soils
Authors: Douglas Lowell A. , Platt David W.
Published: July 2010

The surface morphology of quartz sand grains from soils developed from Wisconsin, Illinoian, and Kansan age glacial material and on residual parent materials were studied using scanning electron microscopy. Both solution and precipitation surfaces were observed. Quartz surfaces showed an amount of chemical alteration proportional to the water holding capacity and the age of the parent material. More alteration was found in the A horizons than in the B horizons of the youngest soils studied, while little difference between A and B horizons of very old soils was observed. The surface morphology of quartz sand grains may be used to estimate the age of a soil relative to the glacial periods within the Quaternary.
Oxygen Content of Soil Air By a Field Method
Authors: Patrick W. H.
Published: July 2010

A field method was developed that allows rapid, accurate measurement of soil oxygen at various depths in the soil profile. A small sample of soil air is withdrawn from permanently installed air reservoirs or diffusion chambers into a cell containing a polarographic oxygen electrode that is connected to a portable oxygen meter.
Programmable Pocket Calculator vs. Computer: A Comparison of Relative Efficiency for Small Jobs in the Soil Characterization Laboratory
Authors: Parker J. C. , Amos D. F.
Published: July 2010

A time and cost comparison was made for three methods of performing computations for pipette particle size distribution, clod bulk density, Atterberg limits, and potential volume change (FHA‐PVC Meter). The programmable calculator was more efficient than either a nonprogrammable calculator or a computer using Fortran with card input. The nonprogrammable calculator costs were 1.6 to 5.3 times those using the programmable machine. The computer costs were 2.8 to 10.4 times those of the programmable calculator. In this particular lab, $200 per year was saved using a programmable calculator on these four analyses alone.
Assessing Phosphorus Fertilizer Needs Based on Intensity‐Capacity Relationships
Authors: Lee Yong S. , Bartlett R. J.
Published: July 2010

Phosphorus in a pH 4.8 NH4OAc soil extract, through crop response correlation work, may indicate the degree to which a level of P in a given soil is optimum. But, being an intensity measurement, this NH4OAc‐P value does not indicate the amount of P fertilizer needed to bring a soil, which has a particular P sorption capacity, to its optimum level.

The relationship between added P and the square root of the NH4OAc‐P, measured after incubation of a given acid or limed soil, was a straight line with a characteristic slope for that soil. The value of this slope, termed the Phosphorus Fertilizer Index (PFI), showed a high correlation with the amount of Al extracted by pH 4.8 NH4OAc (r2=0.94). Inclusion of soil chemical characteristics other than Al in the calculation did not improve the P intensity‐capacity relationships significantly.

The usefulness of these relationships in determining P fertilizer needs was verified in an incubation study with 50 acid Ap horizon samples of Vermont soils. This study showed excellent correlations (r2=0.90 and 0.92 for unlimed and limed soils, respectively) between NH4OAc‐P measured in the soils after fertilizer addition and the NH4OAc‐P calculated from the PFI slopes estimated from the Al measured in the same NH4OAc extract.
Microbial Epimerization of Myo‐inositol to Chiro‐inositol in Soil
Authors: L'Annunziata Michael F. , I. Juan Gonzalez , Olivares O. Luis A.
Published: July 2010

14Carbon‐(1,2,3,5/4,6)‐inositol (14C‐myo‐inositol) was incorporated into an Andosol sandy loam soil and incubated for a 12‐day period at 70% field moisture capacity under sterile and nonsterile soil conditions. Comparison by thin‐layer chromatography of an isolated metabolite with an authentic standard and infrared spectrometry were used to identify the metabolite as 14C‐(1,2,4/3,5,6)‐inositol (14C‐chiroinositol) of unknown optical activity. The 14C‐chiro‐inositol was identified in the biologically active soil. No epimerization of 14C‐chiroinositol was observed in sterile soil. The abundance of the 14C‐chiroinositol was approximately 4% relative to that of the parent compound, as determined by liquid scintillation counting of the two chromatographically separated compounds.
A Survey of the Fertility Status of Surface Soils Under “Cerrado” Vegetation in Brazil
Authors: Lopes A. S. , Cox F. R.
Published: July 2010

Agriculture is becoming more intensive in central Brazil, but there is little information available on the fertility status of most of the soils. To determine this status a total of 518 topsoil samples were collected from a 600,000‐km2 area in central Brazil. Laboratory characterization included pH, exchangeable Al, cation exchange capacity, nutrient levels (including micronutrients), organic matter, texture, and color. The results, presented as frequency distributions, indicate the following general conditions: a pH of 4.8 to 5.2, an organic matter level of 1.5 to 3.0%, extremely low levels of effective CEC and extractable Ca, Mg, P, and Zn, a high level of Fe, a high degree of Al saturation, and a broad range in textural class. Organic matter was the most important soil fraction in relation to effective CEC in these soils. The data suggest that problems associated with fertilizer inputs needed to bring these soils under more intensive agriculture are generally similar, but may vary in degree.
Effect of Soil Shear Strength on Soil Detachment due to Raindrop Impact
Authors: Cruse R. M. , Larson W. E.
Published: July 2010

Soil strength was altered in three different ways to test the hypothesis that soil splash from raindrop impact is related to soil strength parameters. Bulk density changes were used to alter direct solid particle‐to‐particle contact; changes in matric potential were used to change contact relationships between solid particles and liquid films; and additions of polyvinyl alcohol (PVA) provided a direct bonding mechanism between solid particles. The amount of soil detached by a single simulated 4.8‐mm raindrop falling from a height of 177 cm was closely correlated with the shearing strength as measured by a triaxial compression test.
Field‐measured Spectroradiometric Reflectances of Disked and Nondisked Soil With and Without Wheat Straw
Authors: Gausman H. W. , Leamer R. W. , Noriega J. R. , Rodriguez R. R. , Wiegand C. L.
Published: July 2010

Our objective was to compare field‐measured spectroradiometric reflectances of nondisked bare soil with or without littered wheat (Triticum aestivum L.) straw and bare soil that was disked directly or after littering with wheat straw. This information is needed to develop a procedure for predicting potential soil erosion using aircraft or satellite multispectral scanner reflectance measurements.

A ground‐based spectroradiometer was used to measure reflected radiation from six soil‐tillage‐wheat straw treatments: disked and nondisked soil with and without two wheat straw rates—equivalent to 2.24 and 4.48 metric tons/ha, respectively.

The near‐infrared region (0.75 to 1.3 µm), exemplified by the 1.05‐µm wavelength, seemed to be better than the visible region (0.45 to 0.75 µm) or water absorption wavebands (1.5 to 1.8 µm and 2.0 to 2.5 µm) for distinguishing among reflectances of the soil‐tillage‐straw treatments.

Results indicated that LANDSAT multispectral scanner's band 7 (0.8 to 1.1 µm) might be used to distinguish nondisked bare soils from those with different amounts of straw on their surface, but not to distinguish reflectance of nondisked bare soils, disked bare soils, and disked soils with small amounts of straw incorporated in them.

Further research is needed on the interacting effects on reflectance of other soils, soil moisture contents, kinds and amounts of plant residue, tillage operations, and their interactions on reflectance.
Chiseling Influences on Soil Hydraulic Properties
Authors: Allmaras R. R. , Rickman R. W. , Ekin L. G. , Kimball B. A.
Published: July 2010

Chiseling is now more frequently used for primary tillage in the drylands of eastern Oregon and Washington. Improved measures of chiseling effects on soil water relations are needed to evaluate water intake and infiltration benefits, especially as related to depth of chiseling. Hydraulic conductivity (K) and soil water desorption characteristic (SWDC) were field measured in the 120‐cm soil profile of a Walla Walla (mesic typic Haploxeroll) silt loam before and after chiseling 43‐cm deep.

The test Walla Walla soil is layered. Cation exchange capacity, exchangeable Ca2+, clay content, and organic matter all changed at the 30‐cm depth; dry bulk density decreased with depth above 45 cm and was constant below 45 cm; K was 10 to 1,000‐fold lower in depths above 30 cm; water contents in the SWDC (−50 to −200 mbar range) were lower in upper 30‐cm layer.

Chiseling affected both the SWDC and K in the upper 30 cm, especially at 10 and 20‐cm depths, but had no influence on these measurements at 40 cm. Both water potential at constant water content in the SWDC and K were increased especially in the −50 to −300 mbar range. Failure of chiseling to improve water relations in the mild duripan extending from 30 to 45 cm suggests the need for addition of plant residue or chemical amendments into the chisel slots.

Water contents and hydraulic heads during drainage showed that chiseling could reduce evaporation by reducing water content and diffusivity. Overall soil profile hydraulic resistances showed relative average K up to 15 times greater as a result of chiseling 43 cm deep, but nearly similar accelerated internal drainages were projected for simulated chiseling to 25‐cm depth vs. chiseling to 43 cm.
Response of Yellow‐Poplar and Red Oak to Fertilization in West Virginia
Authors: Auchmoody L. R. , Smith H. Clay
Published: July 2010

Fertilization tests with small sawlog‐size yellow‐poplar (Liriodendron tulipifera L.) and red oak (Quercus rubra L.) were begun in the northern mountain section of West Virginia in the spring of 1970. Treatments were made with N, P, N‐P, and N‐P‐K. During the first year, N was broadcast at 336 kg/ha, P at 97 kg/ha, and K at 93 kg/ha. Second season application included 112 kg/ha of N and 97 kg/ha of P. Basal‐area response to N over a 3‐year period amounted to a 47% increase for yellow‐poplar and a 29% increase for red oak. There was no response to P, either alone or in combination with N. Negative effects on basal‐area growth were observed where KCl was applied. Foliar response in leaf weight and color was attributed mostly to N, although P in combination with N produced slightly heavier and darker green leaves than N only. Foliar N in yellow‐poplar corresponding to the best basal‐area growth was about 3.0% N.
A New Approach to Determination of Cation Exchange Capacity
Authors: Fernando M. J. , Burau R. G. , Arulanandan K.
Published: July 2010

The dielectric dispersion (Δε0), defined as the difference in the dielectric constant of a sample measured at 3 × 106 Hz and at 75 × 106 Hz, was linearly related to CEC of the sample. One linear relationship between Δε0 and CEC was obtained for clay‐silica flour mixtures where CEC was varied by changing the proportion of clay in the sample as well as by using clays with different CEC (kaolinite, illite, montmorillonite). A second linear relationship, with somewhat different slope, was obtained between the Δε0 and the CEC of natural soil samples.
A Field Procedure for Base Saturation Using KCl‐Triethanolamine, pH 8.
Authors: Holmgren George G. S. , Nelson Reuben E.
Published: July 2010

Base saturation as determined by BaCl2‐triethanolamine acidity (pH 8.1) and NH4OAc‐extractable bases is closely approximated by analysis of acidity and bases extracted by KCl‐triethanolamine (0.0375N triethanolamine in 1N KCl, pH 8.1). One gram of soil is extracted with 20 ml of this reagent and titrated sequentially for acidity and calcium plus magnesium. Sodium and potassium are not included in the analysis.

The extraction apparatus is constructed from two 20‐cm3 syringes, one acting as extraction tube and the other providing vacuum and volumetric measurement of the extractant. Titration is conveniently performed by calibrated syringes mounted in the caps of reagent bottles.
Soil Thermal Diffusivity Determination from Overspecification of Boundary Data
Authors: Singh S. R. , Sinha B. K.
Published: July 2010

The heat conduction equation has been solved for evaluating thermal diffusivity of soils by overspecifying the usual boundary conditions in terms of the thermal gradient at the boundary surface. Solutions have been obtained for different Dirichlet‐type boundary conditions describing the boundary temperature. These were (i) linearly rising/falling, (ii) exponentially rising, (iii) exponentially falling, and (iv) sinusoidal. The thermal gradient in the soil profile was evaluated using a cubic spline. Field data were analyzed firstly by representing the surface temperature as linearly rising and secondly as sinusoidal. More consistent results were obtained with the help of the first approximation which represented the boundary data closely. This shows that a close approximation of boundary condition by an appropriate function is essential to get reliable values of the thermal diffusivity.
Flow from a Line Source above a Shallow Water Table
Authors: Warrick A. W. , Lomen D. O.
Published: July 2010

An analytical solution is developed for a buried line source with an underlying constant potential surface. The geometry is appropriate to describe flow from a trickle or subsurface irrigation system of porous pipe or emitters spaced closely in a line above a shallow water table or in a lysimeter. Assumptions include steady‐state conditions and a hydraulic conductivity exponentially related to the pressure head.

The soil water pressure head distribution is calculated for two geometries, one for which the water table dominates over the line source throughout the flow medium, and a second for which most of the flow region is as if the source were above an infinitely deep lower boundary.
Retention of Soil Water Following Forest Cutting
Authors: McColl J. G.
Published: July 2010

Eucalyptus globulus (Labill.) forests in the Oakland‐Berkeley hills, California, were clearcut in 1973–74 following severe damage from freezing in December 1972. The soil water regimes in clearcut and adjoining uncut areas, were compared during the two years following cutting.

During the wet winter season (Dec.–May), surface drying and evapotranspiration by annual grasses were the only losses in the clearcut; more soil water was retained in the clearcut due to lack of evapotranspiration by the forest trees.

Soil water rapidly decreased in both the clearcut and forest during the long, dry summer periods, and differences between the two areas widened. By midsummer soil matric suctions in the clearcut dropped below 15 bars (22.4% Pv, volumetric water content), and in the forest to below 70 bars (8.5% Pv). During the summer, Pv increased with profile depth in the clearcut, but in the forest, soil water was depleted uniformly with depth in the profile.

Although volumetric water contents of soil (Pv) were significantly different between clearcut and forest areas, rates of water loss (k) during summer were not clearly related to forest cover. In the clay‐loam soil, k was dependent on the soil water storage at the beginning of the dry summer period, on the ability of trees in the uncut forest to withdraw water from parent material and from fractured bedrock in excess of that available in the soil profile, and on Pv which decreased during summer.
Occurrence Of Lepidocrocite And its Association With Goethite in Natal Soils
Authors: Schwertmann U. , Fitzpatrick R. W.
Published: July 2010

Hydromorphic soils (pseudogleys) in a highland‐montane climate of Natal (South Africa) contain appreciable amounts of lepidocrocite. Its occurrence appears to be restricted to imperfectly drained lower positions on southern (cooler) slopes at an altitude between 1,300–1,900 m. In these positions, Fe is reduced under anaerobic Conditions leading to lepidocrocite formation on reoxidation. Goethite is closely associated with lepidocrocite and increases on approaching better aerated microzones such as root channels and textural boundaries where it usually forms crusts. Both FeOOH forms were determined quantitatively by XRD. Simultaneous formation of the two Fe‐oxides is inferred from synthesis experiments in which an increasing partial pressure of CO2 in an O2‐CO2 gas mixture to oxidize a FeCl2 solution favored goethite at the expense of lepidocrocite. The crystallinity of lepidocrocite (as measured by XRD line broadening) decreased when approaching root channels. This is attributed to a decreased in pH and agrees again with synthesis experiments where the same effect was observed. Goethite is generally less crystalline than lepidocrocite.
Phosphate Adsorption on an Oxisol
Authors: Parfitt R. L.
Published: July 2010

Adsorption isotherms for phosphate on the A and B horizon of an oxisol from Papua New Guinea showed high affinity adsorption at low solution concentrations and a linear increase in adsorption at higher solution concentrations. Adsorption increased with decrease in pH in the range 3 to 8. Comparison with data obtained under similar conditions with synthetic goethite (α‐FeOOH) and gibbsite [Al(OH)3] suggested that phosphate reacted with FeOH and FeOH2+ groups on soil iron oxide surfaces to form a binuclear bridging FeOP(O2)OFe complex and with exposed Al(OH)H2O on kaolinite edges and on hydroxy‐aluminum species to form a binuclear or bidentate phosphate complex. At higher phosphate concentrations isotherms showed continued adsorption which may be due to a further reaction involving hydroxy‐aluminum groups.