Crosby Silt Loam Research Articles

Mulching effects on phosphorus and sulfur concentrations in a Miamian soil in central Ohio, USA

AbstractIn addition to nitrogen (N), phosphorus (P) and sulfur (S) elements are also essential to conversion of biomass carbon into soil humus. Therefore, soil analyses were done on two long‐term mulching experiments initiated in 1989 and 1996 on a Crosby silt loam (Aeric Ochraqualf or Stagnic Luvisol) soil in central Ohio to assess P and S dynamics in soil for different rates of mulching. Mulch treatments were 0, 8 and 16 Mg ha−1 y−1 without any crop cultivation. Our objectives were to assess: (i) the effect of different mulch rates on P and S concentrations, and soil organic carbon sequestration; (ii) association of available and total P and S with different particle size fractions; and (iii) temporal changes in available and total P and total S concentrations within aggregate and particle size fractions with duration of mulching. Soil samples from 0 to 5 and 5 to 10 cm depths were obtained in November 2000. Mulch rate significantly increased Bray‐P in 0 to 5 and 5 to 10 cm depths but had no significant effect on total P after 4 years of mulching. Total P concentration in the 5 to 10 cm layer increased significantly with mulch application after 11 years, but the total S concentration was not affected. Total P in aggregates>2 mm size at 5 to 10 cm depth was significantly higher than whole soil after 11 years of mulching. More than 50 per cent of the total P was associated with clay fraction, and P concentration increased with duration of mulching. The enrichment factor for total P was in the order: clay>sand>silt. Total S concentration in aggregates increased with increase in aggregate size for both depths, and was in the order: clay>sand>silt. The clay fraction accounted for 48 per cent of total S after 4 years of mulching and 50 per cent after 11 years of mulching. The enrichment factor of S in clay and sand fractions increased with duration of mulching and with depth for clay, and decreased for sand. The C:P and C:S ratios decreased both with duration of mulching and particle size. Availability of P and S is essential for humification of carbon input in crop residue mulch. Copyright © 2004 John Wiley & Sons, Ltd.

Soil restorative effects of mulching on aggregation and carbon sequestration in a Miamian soil in central Ohio

AbstractSoils play a key role in the global carbon cycle, and can be a source or a sink of atmospheric carbon (C). Thus, the effect of land use and management on soil C dynamics needs to be quantified. This study was conducted to assess: (1) the role of aggregation in enhancing soil organic carbon (SOC) and total soil nitrogen (TSN) concentrations for different mulch rates, (2) the association of SOC and TSN with different particle size fractions, and (3) the temporal changes in the SOC concentration within aggregate and particle size fractions with duration of mulching. Two experiments were initiated, one each in 1989 and 1996, on a Crosby silt loam (Aeric Ochraqualf or Stagnic Luvisol) in central Ohio. Mulch treatments were 0, 8, and 16 Mg ha−1 yr−1 without crop cultivation. Soil samples from 0–5 cm and 5–10 cm depths were obtained in November 2000; 4 and 11 years after initiating the experiments. Mulch rate significantly increased SOC and TSN concentrations in the 0–5 cm soil layer only. The variation in the SOC concentration attributed to the mulch rate was 41 per cent after 4 years of mulching and 52 per cent after 11 years of mulching. There were also differences in SOC and TSN concentrations among large aggregate size fractions, up to 2 mm size after 4 years and up to 0ċ5 mm after 11 years of mulching. There were also differences in SOC and TSN concentrations among particle size fractions. Variation in the SOC concentration in relation to particle size was attributed to clay by 45–51 per cent, silt by 34–36 per cent, and to sand fraction by 15–19 per cent. Bulk of the TSN (62–67 per cent) was associated with clay fraction and the rest was equally distributed between silt and sand fractions. The enrichment of SOC and TSN concentrations in the clay fraction increased with depth. The C:N ratio was not affected by the mulch rate, but differed significantly among particle size fractions; being in the order of sand >silt >clay. Copyright © 2003 John Wiley & Sons, Ltd.

Carbon budget study using CO 2 flux measurements from a no till system in central Ohio

Enhancing carbon sequestration in soil is an important means to reduce net emissions of carbon dioxide (CO 2) to the atmosphere. The soil organic carbon (SOC) pool is the net result of carbon (C) input in the form of crop residue and biomass, and output including CO 2 flux and other losses. The objectives of this study were to: (1) determine the influence of known additions of crop residue in a no till system on CO 2 flux measured with the static chamber alkali-absorption method, and (2) calculate the C budget from the CO 2 flux and C added in crop residue. The experiment was started on a Crosby silt loam (Stagnic Luvisol) in 1989. Annually 0, 2, 4, 8 and 16 Mg ha −1 wheat straw ( Triticum aestivum L.) was applied. Noon soil temperature and daily CO 2 flux were determined in 1997. Residue application rate had a significant impact on soil temperature as measured at noon, especially early in the growing season. Noon soil temperature was up to 14°C higher under unmulched compared with that of mulched treatments. Measured CO 2 flux ranged from 0.4 to 4.2 g C m −2 per day. Differences in CO 2 flux between crop residue treatments were not significant on most sampling dates, probably due to the presence of undecomposed residue in the soil which did not contribute to the CO 2 flux, and to variability in sampling. Average daily soil temperature at 5 cm depth determined on a nearby weather station explained 60% of the variation in CO 2 flux from bare plots. The C budget calculated from CO 2 flux measurements indicated a net depletion of SOC in all treatments. However, measured SOC contents indicated an increase of SOC over time in some treatments. It is likely that the annual CO 2 flux measured with the static chamber alkali-absorption method is overestimated due to omission of CO 2 measurements when soil water content is high, and perhaps other, as yet unknown factors. A comparison of the static chamber technique and improved dynamic chamber techniques and micrometeorological methods is recommended.

Geographic Information Systems Show Impact of Field Placement on sh2 Sweet Corn Stand Establishment

The objective of this study was to ascertain if stand establishment of sh2 sweet corn (Zea mays L.) would benefit from variable planting depths determined by the use of geographic information systems (GIS). Spring and fall research plots were established in a field [80 × 20 m (262 × 66 ft)] containing Crosby silt loam and Kokomo silty clay loam soil series in Columbus, Ohio. Three sh2 sweet corn cultivars (Starship, Skyline, and Confection) were planted at three depths on the two soil types in the fall study, with an additional transition soil added in the spring. Emergence counts as well as soil moisture and temperature were monitored. In the spring, sites were also sampled for nutrient levels and soil compaction. Significant variability was found within the field with respect to soil moisture, temperature, nutrient levels, and compaction. Seedling emergence fluctuated with average soil moisture increasing in blocks with up to 24% moisture and then leveling off. Daily minimum soil temperatures impacted stand establishment. Although heat units accumulated faster on the Crosby soil, emergence was slower and less complete on these soil series than on Kokomo soil series. Further investigation determined that although temperatures of the Crosby soil were 3 to 4.5 °C (5.4 to 8.1 °F) warmer during the day than the Kokomo soil, temperatures on the Crosby soil averaged 2 °C (3.6 °F) cooler at night. Analysis of emergence patterns and field variability was performed on ArcView mapping software. Although `Skyline' planted at 2 cm (0.8 inches) had the best emergence overall, final stand would have been increased with `Skyline' planted variably at 2 and 4 cm (1.6 inches). Mapping the field under these different scenarios showed that although area with less than 70% stand would exist with a 2-cm uniform planting depth, the entire field would have a stand of 70% or greater with variable planting depth using a high vigor seedlot.

Crop residue and tillage effects on carbon sequestration in a Luvisol in central Ohio

Soils play a key role in the global carbon cycle. They can be a source or a sink of carbon and influence CO 2 concentrations in the atmosphere. In order to calculate the carbon budget of a region, the effect of soil management practices on carbon sequestration in soils needs to be quantified. Objectives of this experiment were to determine: (i) the effects of ridge till, plow till and no-till on the soil organic carbon (SOC) pool; (ii) the SOC loss or sequestration for mulch rates of 0–16 Mg ha −1 year −1 wheat ( Triticum aestivum L.) straw applied in combination with each tillage method, and (iii) impacts of tillage and crop residue treatments on soil physical quality, including aggregation and porosity. The experiment was initiated in 1989 on a Crosby silt loam (Stagnic Luvisol) in Central Ohio. Seven years after initiation of the experiment, there was a positive, linear effect of residue application rate on SOC contents in all tillage treatments. In the eighth year of the experiment these trends were confirmed for plow and no-till, but not for ridge till. Linear-regression equations, relating SOC content for the 0–10 cm soil depth to mulch rate, were: for no-till: SOC (Mg ha −1) = 15.21 + 0.32 [Residue (Mg ha −1 year −1)] ( r = 0.68) and for plow till: SOC = 11.95 + 0.27 [Residue] ( p = 0.72). The carbon conversion efficiencies were 8% per year for plow till and 10% per year for no-till. Detailed sampling at different depths revealed that increases in SOC content were only significant for the 0–5 cm depths of plow and no-till treatments. Effects of crop residue application on water stable aggregation in the 0–10 cm layer were most pronounced with plow till and ridge till but not with no-till. Water retention characteristics, a measure of pore size distribution, was not influenced by tillage system, but crop residue application had a significant effect on water retention in the 0–10 cm layer at matric suctions of 30–300 kPa. This means that residue application increased macropores of diameters 1–10 μm. It is concluded that, depending on the amount of crop residue returned to the soil, the large numbers of farmers converting from plow to no-till cultivation in the Corn Belt may create an important sink for atmospheric CO 2.

Integrating the mehlich‐3 extractant into existing soil test interpretation schemes

Abstract Nutrients were extracted from samples of two Ohio soils derived from Wisconsin‐age glacial till, a Crosby silt loam (Aerie Ochraqualfs, fine, mixed, mesic) and a Hoytville silty clay (Mollic Ochraqualfs, fine, illitic, mesic) using the Mehlich‐3 extractant, and also using Bray‐1 for phosphorus (P) and ammonium acetate (NH4OAc) for potassium (K), calcium (Ca), and magnesium (Mg). Mehlich‐3 removed more P from the soils than did Bray‐1, and determining P in the Mehlich‐3 extracts by ICP revealed more P than when determination was made using molybdate‐blue colorimetry. All relationships between quantities of P extracted by Bray‐1 and Mehlich‐3 were linear. Both Mehlich‐3 and NH4OAc removed similar quantities of K, Ca, and Mg from the Crosby soil, but results from the Hoytville soil were considerably more variable. On these and similar soils, P‐fertilizer recommendation schemes based on Bray‐1 could be adapted to Mehlich‐3 using simple linear relationships; however, relationships involving exchangeable cations may require further evaluation.

Effect of Soil Type and pH on Persistence and Carryover of Imidazolinone Herbicides

Field studies were conducted in 1988 through 1990 to determine the effect of soil pH, over a 4.5 to 6.5 range, on imazethapyr persistence and on imazaquin and imazethapyr carryover to ‘Pioneer 3377’ corn in a Crosby silt loam (1.6% organic matter) and a Hoytville clay (3.3% organic matter). Imazethapyr appeared to be more persistent in Hoytville clay than in Crosby silt loam. In Crosby silt loam, imazethapyr persistence increased as pH decreased, whereas soil pH did not affect persistence in Hoytville clay. Imazaquin or imazethapyr did not affect corn grown the year following application to Crosby silt loam. Imazethapyr applied to Hoytville clay did not cause significant injury or yield reduction to corn. Carryover of imazaquin in Hoytville clay caused corn injury and yield reduction, increased as pH decreased, and was more evident at 280 g ai ha−1than at 140 g ha−1.

Effect of Soil pH on Adsorption and Persistence of Imazaquin

Laboratory and field studies were conducted in 1988 through 1990 to determine the effect of soil pH on imazaquin adsorption and persistence in a Crosby silt loam (1.6% organic matter) and a Hoytville clay (3.3% organic matter). Above a pH of 6, 6 to 7% of the total imazaquin present was adsorbed to both soils. Adsorption increased as pH decreased from about 7 to 4.5, with a maximum of 16.5 and 31% adsorbed on Crosby and Hoytville soils, respectively. Imazaquin was more persistent in the Hoytville clay than in the Crosby silt loam. Herbicide dissipated more slowly in both soils in 1988 than in 1989 due to dry soil conditions immediately prior to and following herbicide application in 1988. In both soils, imazaquin persistence increased as soil pH decreased, over a pH range from 6.5 to 4.5. Increased persistence with decreasing pH was attributed in part to increased adsorption and decreased availability for microbial degradation.

Interrill Erodibility of Some Ohio Soils Based on Field Rainfall Simulation

AbstractPrediction of soil erodibility and an understanding of erosion processes are vital to sustained productive use of agricultural land. Interrill erodibilities (Ki) of five Ohio soils were assessed and compared with predicted Ki using the Water Erosion Prediction Project equation (WEPP‐K). A portable rainfall simulator was used to apply ∼ 70 mm h‐1 intensity rain for 1 h on 0.75‐m2 field plots representing crop row sideslopes. The soils studied included Miamian (fine, mixed, mesic Typic Hapludalf) and Riddles (fine‐loamy, mixed, mesic Typic Hapludalf) silt loams, Crosby silt loam (fine, mixed, mesic Aeric Ochraqualf), Kokomo silty‐clay loam (fine, mixed, mesic Typic Argiaquoll) and Mechanicsburg loam (fine‐loamy, mixed, mesic Ultic Hapludalf). The value of Ki determined for each soil was related to selected physical and chemical properties. Values of Ki varied significantly between soils and ranged from 1.23 ± 0.09 to 1.97 ± 0.60 × 10‐6 kg s m‐4. Interrill erodibility was negatively correlated with water‐stable aggregates (WSA) >0.25 mm (r2 = 0.50), WSA > 0.5 mm (r = 0.49), and organic C (r2 = 0.61), and positively correlated with Middleton's dispersion ratio (r2 = 0.84) and the ratio of water‐dispersible clay to total clay (r2 = 0.70). The WEPP‐Ki differed from measured values by ∼ 10 to 40%, ranging from 1.1 to 2.0 kg s m‐4. There was no correlation between WEPP‐Ki and measured Ki.

Long-Term Tillage Effects on Seed Banks in Three Ohio Soils

Soils from long-term tillage plots at three locations in Ohio were sampled to determine composition and size of weed seed banks following 25 yr of continuous no-tillage, minimum-tillage, or conventional-tillage corn production. The same herbicide was applied across tillage treatments within each year and an untreated permanent grass sod was sampled for comparison. Seed numbers to a 15-cm depth were highest in the no-tillage treatment in the Crosby silt loam (77 800 m–2) and Wooster silt loam (8400 m–2) soils and in the grass sod (7400 m–2) in a Hoytville silty clay loam soil. Lowest seed numbers were found in conventional-tillage plots in the Wooster soil (400 m–2) and in minimum-tillage plots in the Crosby (2200 m–2) and Hoytville (400 m–2) soils. Concentration of seeds decreased with depth but the effect of tillage on seed depth was not consistent among soil types. Number of weed species was highest in permanent grass sod (10 to 18) and decreased as soil disturbance increased; weed populations were lowest in conventional tillage in the Hoytville soil. Common lambsquarters, pigweeds, and fall panicum were the most commonly found seeds in all soils. Diversity indices indicated that increased soil disturbance resulted in a decrease in species diversity. Weed populations the summer following soil sampling included common lambsquarters, pigweeds, fall panicum, and several species not detected in the seed bank.

Comparison of Solid vs. Liquid Dairy Manure Applications on Corn Yield and Soil Composition

AbstractA 6‐yr field experiment was conducted to determine the effects of liquid and solid dairy (Bos taurus) manure applications on a Crosby silt loam (Aerie Ochraqualfs) soil cropped to corn (Zea mays L.). Liquid manure at rates of 112, 224, and 336 Mg ha−1 and solid manure at rates of 34, 67, and 101 Mg ha−1 were spread annually for 5 yr. No manure was applied the 6th yr, but the soil was cropped to determine residual nutrient effects. Check and inorganic fertilizer treatments were also included in the study. Manure addition increased corn yields when compared to the check (no fertilizer). There were variable weather conditions and nutrient concentrations of the manure sources, and the manure application rates were relatively high. Corn yields were as great or greater from plots supplied with manure and manure slurries as those supplied with commercial fertilizer. Over the 5 yr of manure application, the 224 Mg ha−1 rate of liquid manure and the 67 Mg ha− rate of solid manure results in maximum corn yields that were 1% higher than commercial fertilizer. Accumulations of nutrients in the soil from high liquid manure application rates (224 and 336 Mg ha−1) increased corn yields during the residual cropping year. Corn leaf N and P concentrations tended to reflect N and P rates applied with the manures and the fertilizer treatment compared to the check, but not consistently each year. Source of manure had little affect on corn leaf composition. Soil P, K, and Na increased with each additional year of manure application and tended to increase with higher application rates. Extractable P accumulated in the upper profile of soil, whereas exchangeable K and Na increased at lower depths in the soil profile, especially with the highest manure application rates. Based on this study, both solid and liquid dairy manures are valuable sources of nutrients for corn production; however, they are less efficient than commercial fertilizers when comparing equivalent nutrient levels and when they are applied to the soil surface. Excessive application of either manure source causes potential for considerable groundwater pollution.

Continuous Tillage and Rotation Combinations Effects on Corn, Soybean, and Oat Yields1

AbstractFew studies report long‐term effects of various tillage and crop rotation practices. Studies were conducted to compare the relative ability of various tillage and crop rotation combinations (3 ✕ 3 factorial) to sustain corn (Zea mays L.), soybean (Glycine max L.), and oat (Avena sativa L.) yields. The tillage and rotation combinations were continuously applied for more than 20 years to a well‐drained Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudalf), an imperfectly drained Crosby silt loam (fine, mixed, mesic Aeric Ochraqualf), and a very poorly drained Hoytville silty clay loam (fine, illitic, mesic Mollic Ochraqualf). Tillage treatments were no‐tillage; plow and then plant; and plow, disk, and plant. Rotation treatments on the Wooster and Hoytville soils included continuous corn, corn and soybean in a 2‐year rotation, and corn‐oats‐meadow in a 3‐year rotation. Only continuous corn was grown on the Crosby soil. Corn yields were always positively influenced by no‐tillage on the Wooster soil and negatively influenced on the Hoytville soil. The results obtained for the Crosby soil were mixed. The average yearly corn yield increase and decrease due to no‐tillage on the Wooster and the Hoytville soils were 1070 kg ha−1 and 503 kg ha−1, respectively. The negative response to no‐tillage on the Hoytville soil was primarily due to the large decrease in yield obtained as a result of the continuous corn rotation treatment (average annual yield decrease, 880 kg ha−1). Yield responses of soybean and oats on the Wooster and the Hoytville soils were similar to those observed for corn. When Phytophthora root rot resistant (tolerant) soybean cultivars were grown on the Hoytville soil with the standard cultivars which had been used during most of the experimental period, yield differences between the no‐tillage and plow treatments were essentially eliminated. This study suggests that yield reductions of corn and soybean associated with no‐tillage on heavy clay, very poorly drained soils may be reduced by rotating crops and/or by the use of disease resistant cultivars.

Potassium Fertilization Effects on Phomopsis Seed Infection, Seed Quality, and Yield of Soybeans1

AbstractSoybeans [Glycine max (L.) Merr.] are often damaged by the seedborne fungi Phomopsis sp. and Diaporthe phaseolorum (Cke. and Ell.) Sacc. in regions where the climate is warm and humid during and after maturation. Incidence of these fungi is sometimes decreased by soil application of K fertilizer to improve crop growth. This study was designed to determine if high levels of soil available K, or K fertilizer applications beyond that necessary to maximize yield, would have a significant effect on seed‐borne fungi and seed quality.Soybeans were grown on Granby loamy fine sand (sandy, mixed, mesic Typic Haplaquoll), on Canfield silt loam (fine‐loamy, mixed, mesic Aquic Fragiudalf), and on Crosby silt loam (fine, mixed, mesic Aerie Ochraqualf). Potassium fertilizer was applied at various rates to establish a range of available K in soil. Potassium concentration of leaves closely paralleled K fertilizer treatments and the soil K levels. Seed was harvested from mature plants, and seed‐borne fungi were identified on samples cultured on potato‐dextrose agar. Phomopsis sp. was the most common fungus isolated from soybeans, ranging up to a 63% incidence. Diaporthe phaseolorum occurred with much less frequency, rarely exceeding a 10% incidence.Potassium fertilization nearly always decreased moldy seed, but increased seed germination and yield somewhat less frequently. Where germination was increased by K fertilization, the incidence of Phomopsis sp. and D. phaseolorum nearly always remained unchanged. Thus, K fertilization usually does not influence Phomopsis sp. and D. phaseolorum infection of seed, but possibly limits fungal growth after infection has occurred. Fertilizer rates in excess of that necessary to maximize yield had little influence on germination or moldy seed.Occurrence of Phomopsis sp. was greater in seeds from lower nodes than from upper nodes; whereas, the reverse was true of D. phaseolorum. Even though K deficiency symptoms occurred only on upper fruits and leaves, K fertilization decreased Phomopsis sp. 23 percentage points in lower seeds in contrast to 14 percentage points in upper seeds. Infection of seed by Phomopsis sp. within a plant does not appear to be related to K deficiency symptoms.

Applying Liquid Dairy Waste to Silt Loam Soils Cropped to Corn and Alfalfa‐Orchard Grass

AbstractThree‐year and 2‐year field experiments were conducted to study the effects on crop yield and soil and plant composition of applying dairy slurry to Kokomo silt loam cropped to corn (Zea mays L.) and Crosby silt loam fallowed and subsequently planted to alfalfa (Medicago sativa)‐orchard grass (Dactylis glomerata), respectively. Anaerobic dairy slurry (6.4 to 9.1% dry matter) was applied at rates 112, 224, and 336 metric tons/ha, providing an average of 304, 609, and 914 kg N/ha; 60, 121, and 181 kg P/ha; 293, 587, and 880 kg K/ha; and 61, 121, and 181 kg Na/ha, respectively, per year. A check treatment was also included.Maximum corn grain and silage production was obtained with the 224‐metric ton slurry rate. Plant composition was not affected by waste applications except total N levels in corn leaves increased with increasing waste rates during the second year. Except for NH4+‐N, the concentrations of soil constituents measured (NO3−‐N, P, K, Na, EC) were increased by waste applications, especially with the 224‐ and 336‐metric ton rates, compared to the check. Similarly, as compared to the check, all soil constituents measured were increased by waste applications on the fallow soil. One year of alfalfa‐orchard grass cropping, however, reduced the levels of all measured soil components except P and K to concentrations similar to or lower than the initial values. Alfalfa‐orchard grass growth was variable, but the 112‐metric ton application rate appeared to support maximum yields. In general, the concentrations of P and K in forage tissue tended to increase with increasing waste application rate. Under the climatic conditions of this study, annual dairy slurry applications of <224 metric tons/ha to soil cropped with corn and 112 metric tons/ha to fallow soil subsequently planted with alfalfa‐orchard grass had no detrimental effects on the chemical composition of two silt loam soils or on plant composition.

Influence of Long Term Tillage, Crop Rotation, and Soil Type Combinations on Corn Yield

AbstractStudies to compare the relative ability of a wide range of tillage and crop rotation combinations (3×3 factorial) to sustain corn (Zea mays L.) production on several soils typical of Ohio were initiated in 1962. Soils were a well‐drained Wooster silt loam (Typic Fragiudalf), an imperfectly drained Crosby silt loam (Aeric Ochraqualf), a very poorly drained Hoytville silty clay loam (Mollic Ochraqualf), and a very poorly drained Toledo clay (Mollic Haplaquept). Tillage treatments were no‐tillage; plow and then plant; and plow, disk, and plant. Rotations were continuous corn, corn‐soybeans, (Glycine max L.) (2 year), and corn‐oats (Avena sativa L.)‐meadow (3 year) with each crop appearing each year in each rotation. Results are reported only for plots having equal plant density within a site‐year combination, and adequate weed control.Corn yields were remarkably insensitive to tillage. The two plowed treatments had equal yield for virtually all years at each site within the same rotation. The no‐tillage treatment averaged 975 kg/ha or 13% lower yield than the average of plowed treatments on the Mollic Ochraqualf soil for 10 years of continuous corn, but had the same yield as the plowed treatments for the other two rotations. The no‐tillage treatment averaged 750 kg/ha or 10% greater yield than the average of plowed treatments on the Typic Fragiudalf soil for 11 years of continuous corn or corn‐soybeans rotation. Otherwise tillage treatments generally produced the same corn yield within site‐rotation combinations.

BHC Translocation from Treated Soil and the Effect on Growth of Red Clover1

Greenhouse-grown 5-month-old Kenland red clover from Brookston clay loam Crosby silt loam treated with 0.1, l.0, 10, and 100 p.p.m. BHC was analyzed for BHC content by the Schechter-Hornstein method. Averages of 0.08, 0.16, 0.91, 13.84 p.p.m. BHC and 0.10, 0.24, 2.07, 14.53 p.p.m. BHC for the respective soils and concentrations were found in the clover hay. BHC dosages of 200p.p.m. in Brookston soil and 100 p.p.m. in Crosby did not affect germination. Brookston soil required twice the BHC concentration present in Crosby to produce an identical effect on growth. Stunting, malformation, and mortality of young plants was proportionate to BHC dosage. Complete recovery from phytotoxic manifestations occurred in plants surviving beyond the ninth week.

A Chlorite‐Like Mineral in Indiana Soils

AbstractA clay mineral with basal spacing of approximately 14Å is a constituent of many Indiana soils. The properties of a sample of this mineral separated from Crosby silt loam were studied.During the weathering of the soil profile, the pH decreased and the 14Å mineral replaced illite as the dominant clay mineral. In similar size fractions of clay, the potassium content decreased from the C to the A horizon, while the cation‐exchange capacity remained practically unchanged.X‐ray diffraction and other procedures were used to determine the properties of the 14Å mineral and the effect of various treatments on these properties. Many of its characteristics were found to be similar to those reported for dioctahedral vermiculite. Several of the reactions suggested positively charged, partially hydrated aluminum hydroxide rather than hydrated exchangeable aluminum ions as the interlaying material.It was concluded that during weathering of illite, aluminum can replace potassium between the clay plates. The form of this interlayer aluminum is probably influenced by soil pH. A suggested general formula is: urn:x-wiley:03615995:saj2sssaj195703615995002100010005x:equation:saj2sssaj195703615995002100010005x-math-0001 where x varies with soil pH. Dioctahedral vermiculite and dioctahedral chlorite could thus form a continuous series.

Separation of Organic Acids from Several Dormant and Incubated Ohio Soils

AbstractThe objectives of this study were to determine the organic acid content of several of the Grey‐Brown Podzolic soils in Ohio and to study changes in the acids occurring as a result of short period aerobic incubatious of the soil materials at constant temperature and moisture.The soil materials used in this investigation, Brookston silty clay loam, Crosby silt loam, Miami silt loam, and Wooster silt loam, were obtained from naturally wooded areas in the state.A chromatographic column containing silica gel was employed for the separation of the organic acids. This procedure permitted the separation and quantitative estimation of the organic acids extracted with ether from the soil material. The identities of the organic acids were indicated by a comparison of their positions on an elution calibration chart with those of known pure organic acids. The chromatographically separated acids were not chemically characterized.It was found that of the organic acids separated by this procedure, only two occurred in significant amounts, namely acetic and formic acids. In addition, very small quantities of other acids, including succinic and lactic acids and what are thought to be a group of high‐molecular weight fatty acids, were also separated. The latter probably resulted from alkali hydrolysis of the fats extracted from the soil materials.A 1% glucose treatment of the several soil materials apparently did not appreciably change the organic acid make‐up either qualitatively or quantitatively. Preliminary data are presented concerning the effect of incubation on phosphorus solubility.