bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disk Meter for Rapid Estimation of Herbage Yield in Grazing Trials1
Authors: Bransby D. I. , Matches A. G. , Krause G. F. 
Published: July 2010

AbstractA rapid, indirect, in situ technique for making accurate estimates of pasture dry matter (DM) yield would be of great benefit in grazing trials to insure sound grazing management and meaningful interpretation of results. A disk meter, designed to estimate pasture DM, was constructed and evaluated on tall fescue (Festuca arundinacea Schreb.) pastures which were grazed by yearling steers. Fifty paired observations of bulk‐height readings with the disk meter and DM yields were used to establish the regression relationship between meter reading and yield. Separate calibrations were made for four different size disks. Area and diameter of disks, respectively, were 0.2 m2, 0.50 m; 0.4 m2, 0.71 m; 0.6 m2, 0.87 m; and 0.8 m2, 1.0 m. Relative to a constant weight per unit area of 5 kg/m2, actual disk weights were 1, 2, 3, and 4 kg, respectively, for the 0.2, 0.4, 0.6, and 0.8 m2 disks. Also, additional calibrations were made for the 0.2 m2 disk with weights of 2 and 3 kg. Correlation coefficients (r) for bulk‐height and DM yield ranged from 0.79 to 0.94, and all were significant at the 1% level of probability. Neither size nor weight of disks had any significant effect on residual standard deviation or r, although the heavier weights did alter the regression coefficient (b). Tall fescue pastures changed from reproductive growth in June to a vegetative phase in September, and this also affected b values. This study indicates that the disk meter can be useful for monitoring herbage‐on‐offer in grazing experiments which have a pure stand of tall fescue.
Influence of Seed Size on Yield and Yield Components of Rape1
Authors: Major D. J. 
Published: July 2010

AbstractThis study was initiated because previous research had indicated that large rapeseed produced higher yielding plants than small rapeseed and because this had not been studied in the rape‐growing area of western Canada. Seed of two rape species (Brassica campestris L. cultivar ‘Span’ and B. napus L. ‘Zephyr’), was screened to provide lots of small, medium, and large seeds (expressed as mg/seed), and grown in the field at Lethbridge, Canada, with an ungraded sample. A randomized complete block design was used with 4 replications in 1974 and 8 in 1975. The soil was a Brown Chernozemic (Typic Haploboroll) silty clay loam (Lethbridge series) developed on alluvial‐lacustrine material. In a laboratory study, 500 seeds of each cultivar were weighed and date of germination recorded. In a greenhouse study, 200 seeds of each cultivar were weighed individually and dates of emergence recorded. Thirty days after planting, 50 plants were chosen at random, transplanted, and grown to maturity. The remaining plants were dried and weighed for an estimate of seedling vigor. Planted seed size in the field did not significantly affect plant height, final population density, pods per plant, seeds per pod, seed size, or seed yield. In the laboratory and greenhouse studies, some small seeds produced smaller or slower growing plants. Seed size was positively related to seedling vigor but not consistently related to final seed yield or its components. Grading rapeseed, therefore, would be of little or no economic value to the farmer.
Potential of Sunflowers for Silage in Double‐Cropping Systems Following Small Grains1
Authors: Sheaffer C. C. , McNemar J. H. , Clark N. A. 
Published: July 2010

AbstractSunflowers (Helianthus annus L.) are a drought tolerant and high dry matter producing crop. Due to these properties, sunflowers might find use as a silage crop in double‐cropping systems where moisture supplies are limited. The objective of this study was to evaluate cultural practices and sunflower cultivars which would enhance forage quality and yield.Oil and confectionary sunflower cultivars were handplanted in a factorial experiment at populations of 71.8, 143.6, and 287.2 thousand plants/ha in 1973; and 86.1, 172.1, and 344.3 thousand plants/ha in 1974. Fertilizer was applied at rates of 56‐49‐93 (low) and 112‐98‐186 (high) kg N‐P‐K/ha. The experiment was conducted in the field on a Chester silt loam (fine‐loamy, mixed mesic Typic Hapludults) in 1974 and an Elsinboro loam (fine‐loamy mixed mesic Typic Hapludults) in 1975. In a second field experiment conducted from 1973 to 1975, sunflowers, corn (Zea mays L.), and sorghum (Sorghum bicolor L. Moench) were no‐tillage planted into barley (Hordeum vulgare L.) stubble using conventional farm machinery following the removal of the small grain. Populations of sunflowers, corn, and sorghum were 128, 46, and 366 thousand plants/ha, respectively. In 1973 and 1974, the experiment was located on a Delanco silt loam (fine‐loamy, mixed mesic Aquic Hapludults) and in 1975 on a Chester silt loam (fine‐loamy, mixed mesic Typic Hapludults).Confectionary cultivars produced more dry matter/ha than oil cultivars. All sunflowers had low forage quality. Dry matter yields were greater at higher populations up to 344.4 thousand plants/ha, but at higher populations lodging occurred. Fertilizer application had no effect on silage yield or forage quality. In the second experiment sunflowers were found to be as productive as corn and matured in a shorter period of time.Results from these experiments indicate that sunflowers can be competitive with corn in terms of dry matter production when planted in a double‐cropping system; however, low‐forage quality is a limiting factor in potential use of sunflowers for silage in the northeast.
Sampling Distribution of Nitrates in Irrigated Fields1
Authors: Reuss J. O. , Soltanpour P. N. , Ludwick A. E. 
Published: July 2010

AbstractThe object of this study was to determine the components of variability encountered in sampling farmers' fields for soil nitrates. This information is required for formulating recomendations for sampling plan and intensity. Twenty‐four irrigated farm fields in northeastern Colorado and Western Nebraska were sampled on 61 ✕ 61 m grids. One soil core was taken in 30‐cm increments from each grid to a depth of 120 cm. Duplicate cores were obtained from each third grid to allow determination of within grid variability. The laboratory‐induced variability was also estimated. The results indicated that within and among grid standard deviations increased as the means increased. The standard errors of laboratory determinations (subsampling plus analytical errors) also increased as the means increased. A logarithmic transformation produced histograms that approximated a normal distribution better than the untransformed values. Therefore, the geometric mean represented the nitrate content of a sampled field better than an arithmetic mean. Regression analyses showed that geometric mean could be estimated by multiplying the arithmetic mean of nitrates by 0.91. The nitrate values changed significantly in parallel and perpendicular directions with respect to the crop rows in a nonpredictive manner, indicating that a systematic sampling plan will lead to a more representative sample than a random sampling plan. By separation of a spatial component of variance it was calculated that for the average field sampled to a depth of 120 cm, 7% of the area had nitrate levels below 67% of the geometric mean while on 9% of the area the nitrates exceeded 150% of the geometric mean. In the most variable 10% of the fields 20% or more of the area had nitrate levels below 67% of the geometric mean while on 21% of the area the nitrate exceeded 150% of this value. The laboratory standard deviation was consistently 5% of the mean, indicating a lognormal distribution. With this laboratory precision doubling laboratory variability will not significantly increase the confidence interval of the geometric mean at a low level of sampling intensity, but it will have much larger effect as sampling intensity increases. The number of cores required for a 90% confidence interval of about ± 15% and ± 26% of the geometric mean was calculated to be 82 and 20 per field, respectively.
Water Relations of Cotton. II. Continuous Estimates of Plant Water Potential from Stem Diameter Measurements1
Authors: Huck Morris G. , Klepper Betty 
Published: July 2010

AbstractInformation about plant water potential is often required at very frequent intervals in studies with small numbers of plants. Two methods for inferring plant water potential continuously and nondestructively are described for cotton (Gossypium hirsutum L.) plants. Both methods require continuous monitoring of stem diameter and occasional destructive sampling of tissue for determination of water potential by conventional methods. The computed results are compared with experimental measurements of plant water potential.The shrinkage modulus method requires calibration points obtained from conventional water potential measurements in early morning and mid‐afternoon in order to relate a measured diameter change to a corresponding measured water potential difference. The dynamic flux method requires an initial estimate of tissue conductivity (between 0.7 and 1.4 ✕ 10−6 cm2 sec−1 bar−1 for cotton) and a half‐time for xylem‐phloem equilibration (30 min for cotton). These parameters are used to calculate the stem xylem water potentials which would have been required to bring about measured changes in stem diameter. Both techniques permit plant water status to be monitored continuously in either field or laboratory experiments with minimum destructive sampling of tissue; once accurate parameter estimates are available, the dynamic flux method requires less frequent field calibration.
Element Concentration of Forage and Non‐soluble Cell Wall Fraction of Coastal Bermudagrass1
Authors: Edwards J. H. , Jackson W. A. , Beaty E. R. , McCreery R. A. 
Published: July 2010

AbstractElements contained in forage, the primary feed of beef cattle, are extremely important in animal nutrition. However, lack of knowledge concerning the release of elements in the forage during digestion has hampered effective research on the biological value of forage elements. The research reported here was concerned with measuring some of the major elements contained in (a) coastal bermudagrass (Cynodon dactylon L. Pers.) and (b) in the non‐soluble cell wall fraction of this forage. The experiments were done in the field on a Cecil sandy loam soil (a Typic Hapludult). Coastal bermudagrass fertilized with 0, 165, 336, and 504 kg/ha of N and clipped at 2, 4, 6 and 8 weeks after first clipping was analyzed for Ca, K, Mg, Mn, Na, Fe, Zn, and Cu. The nonsoluble cell wall fraction of the same forage samples was analyzed for Ca, K, Mg, Mn, Cu, and Zn. The cell wall extraction removed about 90% of the Cu and from 97 to 99% of the Ca, K, Mg, and Mn contained in the forage. However, from 80 to 100% of the Zn contained in the forage remained in the non‐soluble cell wall fraction. Increasing N rates increased the K, Mn, and Cu concentration in the forage, but did not influence the concentration retained in the non‐soluble cell wall fraction. Clipping frequency and growth cycle did not affect the concentration of the elements in the forage or the non‐soluble cell wall fraction.
Nitrate‐N Percolation through Irrigated Sandy Soil as Affected by Water Management1
Authors: Smika D. E. , Heermann D. F. , Duke H. R. , Bathchelder A. R. 
Published: July 2010

AbstractFertilizer N has been considered as a source of groundwater pollution because of NO3‐N mobility in soil. This study was conducted on a Torripsammet soil (Valent fine sandy loam) during three consecutive growing seasons to determine the magnitude and differences in NO3‐N losses below corn (Zea mays L.) roots from two different, but current, farmer‐used fertilizer management practices. Three farmer‐owned and ‐operated center pivot sprinkler irrigation systems (designated A, B, and C) near Crook, Colo. were used each year. Nitrate‐N percolation losses were measured in water samples collected at 150 cm below the soil surface in vacuum extractors located in a line 91, 182, and 372 m for the pivot in each field. The A, B, and C systems were managed so that 4.8, 2.5, and 10.2% respectively, of the growing season water (irrigation plus rain) percolated to the 150‐cm depth. Three‐year average annual NO3‐N collected in the extractors was 30.4, 19.0, and 59.7 kg/ha for the A, B, and C systems, respectively. Nitrate‐N and water percolating to the 150‐cm depth were highly correlated (r = 0.95), with each centimeter of water carrying an average 10.2 kg/ha NO3‐N. Average annual total dry matter production for the systems, in the same order, was 20,763, 21,876, and 18,858 kg/ha, respectively, and was negatively related to NO,‐N percolating to the 150‐cm depth (r = −0.99), showing that production was highly related to NO3‐N loss. Total dry matter production decreased 65 kg/ha for each kg/ha of NO3‐N percolating to the 150‐cm depth. Soil NO3‐N changed very little from spring to fall in each of the systems but the soil under the A and B systems contained more than 250 kg/ha NO3‐N to a depth of 180 cm, whereas soil under the C system contained only 20 kg/ha to this depth.
Plowsole Placement of Fertilizer for Soybeans and Response to Tillage of Plowsole1
Authors: Camper H. M , Lutz J. A. 
Published: July 2010

AbstractIn Virginia, most of the soybean [Glycine max (L.) Merrill] are grown on the light‐textured soils of the Coastal Plain. Because of tillage operations, a traffic pan has developed over the years in some of these soils. This pan may reduce water infiltration and root penetration with a subsequent reduction in crop yields. During droughty periods, the traffic pan may be beneficial by reducing the percolation rate of water through the rooting zone. At any rate, the effect of the pan on soybean production is unknown and should be investigated. Also, the effect of incorporating P and K into the traffic pan on the production of soybeans should be determined.In order to evaluate the importance of the traffic pan in soybean production, an experiment was conducted for 6 consecutive years on Sassafras sandy loam (Typic Hapludults; fine‐loamy siliceous, mesic) at Warsaw, Va. Comparisons were made of rates of P, K, and/or lime tilled and not tilled into the traffic pan after the surface 15‐cm soil layer had been removed.Tillage of the plow sole increased plant height in 1 year, reduced it in 2 years, but the average heights for 6 years with and without tillage were identical. Tillage did not affect maturity but increased yields in 1 of 6 years. Soybean seed weight, shattering, and pod and stem blight were unaffected by tillage but purple seed stain was increased by tillage.Fertility treatments had a significant effect on plant height, maturity, yield, seed size, disease, and shattering.
Growth and Nutrient Uptake by Rice in a Flooded Soil under Controlled Aerobic‐Anaerobic and pH Conditions1
Authors: Jugsujinda Aroon , Patrick W. H. 
Published: July 2010

AbstractA number of studies have shown that soil redox conditions and pH are important factors in determining the growth and nutrient uptake of lowland rice (Oryza sativa L.), but no studies report the interaction between these two conditions. A study was made of growth and nutrient uptake of rice plants grown in soil suspensions maintained under either aerobic or anaerobic conditions and at several pH values.Different redox and pH conditions caused marked differences in the uptake of some nutrients and smaller differences in growth of rice. Fe and Zn uptakes were especially affected by redox‐pH interaction. Uptake of the two elements decreased markedly as the pH was increased. The two elements reacted differently to redox conditions, however, with Fe showing greater uptake and Zn showing lower uptake under anaerobic conditions. P uptake was affected more by pH than by redox conditions, with a general decrease in uptake resulting as pH increased. Increasing pH also resulted in lower uptake of labelled ammonium‐N with redox conditions showing little effect.
Screening Corn for Al Tolerance Using Different Ca and Mg Concentrations1
Authors: Rhue R. Dean , Grogan C. O. 
Published: July 2010

AbstractCations such as Ca and Mg can protect roots from the toxic effects of Al. However, little use of this fact has been made in screening for Al tolerance. This study was undertaken to determine the effects of Ca and Mg concentrations in screening solutions on the toxicity of Al in roots of corn inbreds (Zea mays L.). Two‐day‐old corn seedlings were grown for 12 days in dilute nutrient solutions containing 0.25 mM Al. Treatments consisted of Ca or Mg at concentrations of 0.5, 1.0, and 2.0 mM. The pH was adjusted to 4.60 initially with no further adjustments. The large solution: root volume ratio resulted in only small pH changes during the 12‐day screening. These small pH changes had little or no effect on the toxicity of Al in corn roots. Increasing the concentration of Ca decreased the severity of Al toxicity in roots of corn inbreds. However, there were marked differences among inbred lines in the ability of their roots to grow in these screening solutions at all levels of Ca. For example, roots of the inbred lines W153R and Va17 were susceptible and tolerant, respectively, to Al at all three levels of Ca, whereas A239 showed symptoms of severe Al toxicity at 0.5 mM and 1.0 mM Ca but produced good root growth at 2.0 mM Ca. Thus, a wide range in tolerance to Al was observed in these screening solutions by varying the concentration of Ca. At equal concentrations, Mg was as effective as Ca in protecting corn roots from Al. This technique could be utilized for screening species where a knowledge of the range in tolerance among individual genotypes is desired.
Yield, N, and S Content of Corn as Affected by N and S Fertilization on Coastal Plain Soils1
Authors: Rabuffetti Armando , Kamprath Eugene J. 
Published: July 2010

AbstractSince there is an increasing use of high analysis fertilizers containing very little sulfur, two field experiments were conducted to evaluate the S requirements of corn (Zea mays L.) grown on Coastal Plain soils under present management practices. The soils used were Goldsboro loamy sand (Aquic Paleudult) and Wagram loamy sand (Arenic Paleudult). Experiments consisted of a complete factorial arrangement of nitrogen rates (which varied from 56 to 224 kg/ha) and S rates (which varied from 0 to 66 kg/ha). Gypsum was used as the source of S. The hybrid ‘Pioneer 3369A’ was grown at both sites. Nitrogen fertilization had the largest effect on yield and N content of corn grain. The effects of S fertilization depended on the N supply. With 56 or 112 kg N/ha, S additions had no effect or depressed grain yields and N content. With 168 or 224 kg N/ha, S fertilization significantly increased grain yields and N content of corn grain. Total amounts of S accumulated by corn varied from 7 to 20 kg/ha depending on soil type, N, and S rates. Nitrogen fertilization had a larger effect than S fertilization in determining total S accumulation in grain and stover. This study indicated that additions of 30 to 60 kg S/ha to adequately N‐fertilized corn crops are likely to improve grain yield and quality of corn grown on Coastal Plain soils, particularly on those having deep sandy A horizons.
Evaluation of Wild Oat Straw as a Soil Erosion Retardant Using Simulated Rainfall1
Authors: Singer Michael J. , Blackard John 
Published: July 2010

AbstractSoil cover is recognized as an important factor in soil erosion control. This study was made to determine the qantitative relationship between cover percent for one cover type and soil loss under simulated rainfall. Data from this experiment are used to calculate a cover coefficient for wild oat (Avena barbata Brot.) straw similar to the “C” factor in the Wischmeier Universal Soil Loss Equation (USLE). The R, K, L, S, and P factors were kept constant during the experiment.A rainfall simulator was used in the laboratory to produce 30 min rainfall events of 76 mm/hour (3 in/hour) intensity on soil material at 9% slope. Under these conditions, wild oat straw significantly reduced sediment loss at cover levels of 50% or more. A significant reduction in runoff volume was observed for cover percentages exceeding 90%. A parabolic regression model Y = 158.4 − 0.051X − 0.014X2 which describes the relationship between Y sediment loss and X percent cover (0 to 100) was highly significant R2 = 0.81. The effect of the straw was to 1) reduce splash, 2) reduce soil crust formation, 3) block sediment movement, 4) delay runoff initiation, and 5) reduce total runoff loss. A cover coefficient (CC) can be calculated as a ratio of soil loss under any straw cover percent to soil loss under no straw cover. The relationship needs to be tested for other cover types before it is used with cover types different than straw mulch, or substituted for the C factor of the Wischmeier equation.
Critical Zinc Levels Related to Early Growth and Development of Determinate Soybeans1
Authors: Ohki K. 
Published: July 2010

AbstractEvidence of Zn deficiency in determinate soybeans [Glycine max (L.) Merr.] has appeared. Critical deficiency levels of Zn relating leaf concentration and growth are needed to provide reference values associated with maximum growth. The objective was to determine reference values needed to aid in the Zn fertilization program. Soybeans were grown in the greenhouse for 41 days in modified Hoagland solution with total Zn rates of 0, 5, 10, 20, 50, 100, 200, 300, 400, 500, 700, and 1,000 μg/liter Zn. Leaf blades were sampled at harvest and analyzed for Zn by atomic absorption. The critical nutrient deficient levels for Zn were 15, 15, and 14 μg/g dry weight in blades 1 (young developing leaf), 2, and 3 (recently matured leaf), respectively. For purposes of evaluating the Zn status, the recently matured leaf (blade 3) is suggested as the tissue to sample. The critical Zn levels in blade 4 and 5 were 17 and 21 μg/g, respectively. Blade 1 had the sharpest transition zone. Zinc deficiency reduced top and root dry weights, plant height, flower number, and branching; however node development was not affected by Zn deficiency stress. Symptoms similar to Mn toxicity were induced by very low Zn supply. High Mn concentrations were associated with low Zn in blade 3 of plants supplied with 5 μg Zn/liter.