bluuebunny/crossref_metadata_2025 huggingface dataset:
Microanatomical Differences of Warm‐Season Grasses Revealed by Light and Electron Microscopy1
Authors: Akin Danny E. , Burdick Donald
Published: July 2010

The warm‐season grasses, ‘Coastal’ and ‘Coastcross‐1’ bermudagrass (Cynodon dactylon (L.) Pers.) and ‘Pensacola’ bahiagrass (Paspalum notatum var. saurae Parodi), and the cool‐season species ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) were investigated for differences in lignification sites and microanatomy. Leaf samples were examined by light, transmission electron, and scanning electron microscopy. In all the grasses studied, lignin was apparent in the tissue separating xylem and phloem in all first order vascular bundles. The bermudagrasses possessed a rigid, lignified inner bundle sheath surrounding the ground tissue of first order vascular bundles; bahia possessed only a lignified, partial inner sheath in this region. The second order bundles had a single, nonlignified sheath in all warm‐season grasses examined. Tall fescue appeared to have double‐sheathed vascular bundles with the outer sheath composed of thin‐walled cells. The inner sheath in the first‐order bundles of tall fescue contained slight amounts of lignin in cells adjacent to phloem tissue. Reported differences in microanatomy could be factors responsible for digestibility variances of grasses.
Overwinter Changes in the Percent Ca, Mg, K, P, and N in Vegetation and Mulch in an Eastern South Dakota Prairie1
Authors: White E. M.
Published: July 2010

Vegetation and mulch were collected from a moist and a dry site of a native prairie in eastern South Dakota on September 3 and November 5, 1969 and April 29, 1970 to study the overwinter changes in percent Ca, Mg, K, P, and N. The percent Ca in the vegetation was similar on the three dates for both sites; the percent Mg, K, P, and N in vegetation was greatest on the first sampling date for the moist site. The percent Ca, Mg, and K in mulch tended to be greatest on November 5. The percent P and N varied from date to date. The Ca, Mg, and K leached from the decaying vegetation before November 5 may temporarily have increased the amount in the mulch but it was lost by spring.
Sorghum Growth and Nutrient Uptake in Relation to Soil Fertility: I. Dry Matter Accumulation Patterns, Yield, and N Content of Grain1
Authors: Roy R. N. , Wright B. C.
Published: July 2010

An understanding of the seasonal dry matter accumulation pattern of the sorghum [Sorghum bicolor (L.) Moench] plant under varying fertility levels is important for planning an efficient fertilization program. Field experiments were conducted to determine the effects of varying rates of N (0, 60, and 120 kg/ha) on the dry matter accumulation pattern, yield, and grain N content of a sorghum hybrid. Plant samples were collected at weekly intervals and partitioned into component parts for dry matter estimation.

The rate of dry matter accumulation in fertilized plants was rapid early in the season and continued almost linearly until maturity (91 days after sowing), but in unfertilized plants it began to drop after 70 days. In general, dry matter weight of leaves and stems reached a maximum by the 56th and 70th days, respectively, and then remained almost constant. The subsequent increase in total dry weight was due to increased head weight. Accumulation rate in the heads of fertilized plants at 70 and 77 days was very high in comparison to that of unfertilized plants. Contributions of stem, leaves, and head to the total dry matter yield with N0P0 and N120P26 treatments were 41, 23, and 36%, and 32, 18, and 50%, respectively.

Dry matter yield of whole plant, grain yield, and grain N content were higher with 60 kg N/ha than with no nitrogen by 26, 47.6, and 14.5% respectively. They were also higher (9.2, 8.8, and 10.9% respectively) with 120 N/ha. Dry matter and grain yields were higher with 26 kg P/ha than with no P by 25.6 and 46.2% respectively. N content of grain was unaffected by addition of P.
Isolated Soil Columns for Plant Research: Procedure and Uniformity Trial1
Authors: Keller Wesley , Bleak Alvin T. , Hull A. C.
Published: July 2010

Isolated soil tolumns offer one means of studying the influence on yield and other plant characteristics of different amounts of precipitation while other environmental factors are unaltered. These columns may be regarded as an inexpensive substitute for lysimeters. This study describes the establishment of 67 columns 1.22 m2 in a single row in 1967 and 79 and 88 columns in adjacent rows in 1969. The first year after establishment, a uniform crop of barley (Hordeum vulgare L.) was grown on the isolated columns as well as on two opposite sides. Coefficients of variation for total yield of barley ranged from 8.17 to 11.42%. A brief description is given of catchments to increase precipitation on the plots by 50% or to reduce it by 33%. These catchments are being used in studies with perennial forage species.
Soybean Emergence Under Field Conditions1
Authors: Fehr W. R. , Burris J. S. , Gilman D. F.
Published: July 2010

Soybean (Glyclne max (L.) Merr.) cultivars differ hypocotyl elongation and percentage seedling emergence when grown in the laboratory at certain soil temperatures and planting depths. The study reported here was conducted to determine if differences among cultivars for percentage seedling emergence also are present under different soil temperature regimes and planting depths in the field.

The study was conducted on a Nicollet silt loam at Ames, Iowa for 2 years. Percentage emergence was based on the number of seedlings that emerged per 100 viable seeds planted. Percentage emergence of cultivars with short hypocotyls at 25 C in the laboratory (‘Amsoy’ and ‘Beeson’) was compared to types with intermediate (‘Chippewa 64’ and ‘l.indarin’) and long hypocotyls (‘Hawkeye’ and ‘Wayne’). Three planting dates were used each year to obtain a range of soil temperatures. Planting depths of 5 and 10 cm and seeding rates of 5 and 10 viable seeds/30 cm of row were evaluated.

Planting depth had a major influence on percentage emergence. Average emergence was 73% from 5 em and 44% from 10 em. Emergence as low as 13% was observed with the 10‐cm depth.

Seeding rates of 5 and 10 viable seeds/30 cm of row resulted in the same percentage emergence for all planting dates and planting depths studied. Seeding rate altered the number of seedlings that emerged, but not the percentage of seedlings that emerged.

Soil temperatures for date 1 were below 20 C and temperatures for dates 2 and 3 were generally between 20 and 30 C. There was no consistent difference in percentage emergence among planting dates for the 2 years. The data indicated that soil temperature did not consistently influence percentage emergence of the cultivars studied.

Hawkeye had significantly better emergence from the 10‐cm depth than the other five cultivars. Percentage emergence of the five cultivars was not significantly different. Although differences in soil temperatures among planting dates did not appear to have a consistent influence on the emergence ability of the cultivars, the emergence of the short and intermediate hypocotyl cultivars was inferior to the long hypocotyl cultivar Hawkeye. The superior emergence of Hawkeye compared to Wayne suggests that differences for ability to emerge under high soil resistance may exist among long hypocotyl genotypes. A combination of laboratory evaluation at 25 C and field testing may be needed to identify genotypes with superior emergence potential in the field.
P Uptake by Wheat and Resin‐Extractable Phosphate after Incubation in Soil Derived from Volcaninc Ash1
Authors: Zunino H. , Peirano P. , Aguilera M. , Caiozzi M.
Published: July 2010

The heavy fertilization of volcanic ash derived soils required to obtain adequate yields demands good routine methods to test availability of phosphate in these soils. Therefore a resin‐extractable P method was tested against a biological one.

Working with three selected soils, samples of each soil were fertilized with 0, 22, 66, and 132 ppm P as Ca(H2 PO4)2‐H2O and P determined after 0, 30, 60, 120 and 180 days of incubation.

A close P added/P uptake correlation is maintained in nearly all soil‐samples after any incubation period studied. However, added P and resin‐extractable P were directly related up to 60 days of incubation only. This seems to be due to the formation of new P compounds as a result of the strong P fixing properties of these soils. These P compounds may have a different relative availability to plants than to chemical extractant as compared to the Ca(H2PO4)2‐H2O initially added.
Genotypic Response of Burley Tobacco (Nicotiana tabacum L.) to Air‐curing Detached Leaves1
Authors: Gupton C. L.
Published: July 2010

Burley tobacco (Nicotiana tabacum L.) production still requires about 340 hours of labor per acre. Harvesting, barning, and preparing the leaf for market have about as intense labor requirements as 30 years ago. These operations must be mechanized to some degree to maintain production. The major objective of this study was to determine if there is a differential response of diverse burley genotypes when the leaf is cured detached from the stalk, with a view to producing cultivars whose mechanically‐harvested leaf possesses the normal characteristics of burley tobacco.

Ten burley tobacco cultivars and breeding lines that differed from each other in plant type were grown in a split‐plot design with genotypes as whole plots and methods of curing as subplots. The methods of curing consisted of conventional air‐curing on the stalk and aircuring leaves that had been detached from the stalk and strung on sticks. Yield and grade index were determined for the cured leaf of each treatment. The leaf web was sampled and analyses for percent total nitrogen, percent α‐amino nitrogen, water‐soluble acids, pH, percent ash, percent K2O, percent nicotine, percent nornicotine, and content of citric and malic acids were made.

Yield, pH, water soluble acids, percent total nitrogen, and percent α‐amino nitrogen were higher for detached than for stalk‐cured leaves. No significant differences existed between curing methods for percent K2O, percent nicotine, or percent nornicotine. Leaves cured detached were lower in percent ash and in grade index than those cured conventionally.

Certain genotypes, such as Va 509, produced much more acceptable tobacco from the standpoint of both visual and chemical characteristics than others when the leaves were cured detached. Progress may be expected in breeding for cultivars that produce burley tobacco that is acceptable when it is cured detached from the stalk.
Errors Incurred by Use of Hydrogen Peroxide Digestion in Determination of Nitrate‐Nitrogen in Plant Material
Authors: Boggero J. D. , Stromberg L. K.
Published: July 2010

Determinations of the nitrate‐nitrogen (NO3‐N) content of leaf tissue samples of sesame (Sesamum indicum L.) by two analytical methods show that erroneous results may be obtained if digestion with hydrogen peroxide is employed during the procedure. This appears to be caused by the oxidation of nonnitrate nitrogen compounds to nitrates which results in higher nitrate levels than were present in the original samples.

Nonnitrate nitrogen compounds of reagent grade, including two amino acids, were tested qualitatively for NO3‐N with negative results. These same compounds showed the presence of nitrate when tested both qualitatively and quantitatively after digestion with hydrogen peroxide.

Sesame leaf samples demonstrated considerable absolute and relative errors in many cases when analyzed quantitative by two methods, one which employs hydrogen peroxide digestion and one which does not. The relative error is shown to be substantial, particularly at the lower levels of NO3‐N.
Comparative Response of Soybeans and Corn to Phosphorus and Potassium1
Authors: DeMooy C. J. , Young J. L. , Kaap J. D.
Published: July 2010

Much interest has developed concerning the comparative responses of soybeans [Glycine max (L.) Merr.] and corn (Zea mays L.) to fertilization. Grain yields of soybeans and corn grown side by side and in response to direct and residual P and K fertilizer applications were compared on an energy basis over 4 years of field experimentation. Corn was significantly more responsive than soybeans to direct and residual fertilizer P and to direct application of K. Limited nutritional requirements of soybeans were indicated by the small response from applied P and K fertilizers on land of low fertility, by the lack of response to more than a maintenance rate of P application, and by the fact that soybeans did not respond appreciably to a second cycle of P and K fertilization although the soil remained low in P and low to medium in K. The corn responded to the second increment of P and to a second cycle of P fertilization. Soybeans showed little difference between the effect of direct and residual fertilizer on yield. Corn responded to K in the year of application, but not to residual fertilizer. Differential response of corn from direct and residual P application was dependent on seasonal conditions. In the corn‐soybean cropping sequence on Webster silty clay loam where direct response from fertilizers occurred, P and K applications in alternate years were more effective for corn than for soybeans. The advantage of corn fertilization was relatively insensitive to soybean/corn price ratios.
Determinate Cotton Cultivars for More Efficient Cotton Production on Medium‐Textured Soils in the Lower Rio Grande Valley of Texas1
Authors: Namken L. N. , Heilman M. D.
Published: July 2010

The short‐season concept (early defoliation and early harvest) offers, perhaps, the greatest potential for increasing the efficiency of cotton (Gossypium hirsutum L.) production and for minimizing insect control requirements in the Lower Rio Grande Valley of Texas. Early defoliation also allows harvesting during the most optimum period in relation to expected rainfall.

The fruiting, earliness, yield, and fiber quality of three determinate cultivars of early‐maturing cotton were compared with those of a standard nondeterminate cultivar to determine the potential of these cultivars for increasing cotton production efficiency in the Lower Rio Grande Valley. The determinate cultivars, ‘Paymaster 266,’ ‘Paymaster Dwarf,’ and ‘Acco 1764,’ produced their first blooms 3 to 7 days earlier and developed a very high rate of bloom production shortly after the first blooms, as compared with the standard cultivar, ‘TPSA 110.’ The determinate cultivars set fruit over a relatively short time, making early defoliation and harvest feasible with comparable yield and only a slight reduction in fiber quality.
Low Temperature Grinding of Some High Oil Content Seeds1
Authors: Johnson J. W. , Collins F. I.
Published: July 2010

Freezing high oil seeds with liquid nitrogen and immediately grinding shortened time for required grinding considerably. Frozen seeds did not lose oil to the mill or storage container. Chemical analyses should be more accurate on samples frozen before grinding since there is no oil loss from ground material.
Comparative Effects of Nitrogen and Sulfur Fertilization and Liming on Three Crops Grown on Four Soils1
Authors: Kemper D. W. , Sorensen R. C.
Published: July 2010

Two consecutive crops of corn (Zea mays L.), soybeans (Glycine max (L.) Merrill), and bromegrass (Bromus inermis) were grown in the greenhouse on four soils to 1) compare degree of response of these three crops to nitrogen and sulfur fertilizations as affected by overall soil characteristics; 2) evaluate the effect of soil characteristics on the relationship of dry matter production and plant N content; and 3) evaluate the N/S ratio and plant N content as indicators of adequacy of N for maximum dry matter production of these crops. The crops and soils were selected to give a wide range in crop and soil characteristics which would serve as a basis for concurrent comparisons.

Dry matter production and plant N and S contents were determined. Regression procedures were used to develop response surfaces for the effect of N and S applications on these measured variables. Curves relating dry matter production with plant N content were examined for relationships among soils. Correlation was used to compare plant N content and N/S ratio as indicators of N supply for the plants.

Response to nitrogen was common for corn and brormegrass but occurred to a smaller extent for soybeans. Although the magnitudes of N responses varied with the soil type, they were not closely related to soil organic matter or nitrate levels.

Response to S was more evident during the second growing period than during the first period. Soybeans responded to S application only on the sandy Thurman soil. Interactions of N and S applications were observed primarily where large main effects of each of the fertilizers were observed. The CaCO3, had little effect on crop growth.

The curves relating dry matter production to N content of the corn plants were essentially the same for all but one soil, whereas those for bromegrass were less similar. For soybeans, these two quantities were negatively related in several cases, indicating increasing plant growth with decreasing N content in the plant.

The N content of the plant was more closely related to dry matter production than was the N/S ratio.
White Phosphorus‐Ammonia Reaction Product as a Phosphatic Fertilizer in Alkaline and Limed Acid Soils1
Authors: Hill Walter A. , Bohn Hinrich L. , Johnson Gordon V.
Published: July 2010

White phosphorus dissolved in liquid ammonia yields an insoluble, black, phosphorus‐rich material. In alkaline and limed acid soils, this substance did not inhibit germination or seedling development of sorghum (Sorghum vulgare pers.) but supplied little or no phosphate to tomatoes (Lycopersicum esculentum, var. ‘manapal’). White phosphorus injected into the ammonia zone was available to the tomatoes as phosphates.
Wind Turbulence in a Soybean Field Sheltered by Four Types of Wind Barriers1
Authors: Radke J. K. , Hagstrom R. T.
Published: July 2010

Crop yields and quality are frequently improved when the crop is sheltered by temporary, field wind barriers. To better understand the influence of temporary wind barriers on the microclimate, plant‐water relations, and crop yield, it is necessary to understand the effect of wind barriers on wind structure and turbulence.

Several mathematical and statistical functions characterizing wind turbulence were determined for four types of wind barriers from hot‐film anemometer signals fed into a real‐time correlator with subsequent computer analysis. Wind barriers tested were double rows of corn (Zea mays L.), double rows of sunflowers (Helianthus annuus L.), a snowfence, and a solid board fence.

The wind structure and turbulence parameters were always different behind the solid barrier compared to the porous barriers because the wind had to go up and over the top of the solid barrier. The porous barriers broke up the larger eddies into smaller eddies, decreased the wind velocity, and reduced the amount of energy at the lower frequencies. In general, the crop barriers gave results similar to those for snowfence for velocity but were different for energy, frequency, and scale considerations. The crop barrier leaves fluttered, causing greater energy dissipation and the generation of new distinctive frequencies. The corn and sunflowers gave similar results, although the sunflower barriers tended to be like a solid barrier because of their denser canopy.
Performance of Rice Varieties in a Highly Saline Sodic Soil as Influenced by Plant Population
Authors: Dargan K. S. , Abrol I. P. , Bhumbla D. R.
Published: July 2010

It is generally recognized that increased initial plant population or increased seeding rate in saline sodic soils would compensate for decreased germination, and seedling mortality. However, there is little or no experimental evidence of the gains obtained from such a practice. In present investigation the performance of seven rice (Oryza sativa L.) varieties at three plant populations in a highly saline sodic soil was studied in the field at the Central Soil Salinity Research Institute, Karnal, India. Varieties tested were the tall indica types ‘Jhona 349,’ ‘Jhona 351,’ ‘Basmati 217,’ and ‘Basmati 370’ and the semidwarf types ‘IR 8,’ ‘IR 8–68’ and ‘Jaya.’ Plant populations used were 2, 4, and 6 transplants/hill. Variety IR 8–68, a local selection from IR 8, with 6 transplants/hill gave the significantly highest grain yield at 57.33 quintals/ha. Variety IR 8 at 6 transplants/hill and Jhona 349 at 4 transplants/hill yielded next in order. Increase in plant population from 2 to 4 and 6 transplants/hill resulted in significantly higher grain yield in all varieties except Jhona 349 where there was a decrease at 6 transplants/hill. Increased yield resulted from increased survival of hills and greater number of panicle‐bearing tillers per hill.
Construction of Welded ‘Wet Loop’ Thermocouple Psychrometer Junctions1
Authors: Spomer L. Arthur
Published: July 2010

The construction and performance of a welded wire, wet loop (Richards') thermocouple psychrometer measuring junction are described. This junction is simpler to construct, not subject to the incomplete wetting error probable with previous designs, and more sensitive and stable than the silver ring junctions.
Overseeding Small Grain in Standing Soybeans vs Conventional Planting Methods1
Authors: Clapp J. G.
Published: July 2010

Rye (Secale cereale L.) and wheat (Triticum aestivum L.) were overseeded in a soybean (Glycine max (L.) Merrill) crop on both Coastal Plain and Piedmont soils. This method of seeding enables the small grain crop to be planted at an optimum time rather than being subjected to a possible delay in planting caused by a late soybean harvest and/or wet fields. Rye and wheat grain yields were 53 and 75% higher, respectively, for overseeding than for late plantings.
Effect of Root Pruning on Water Relations and Growth of Cotton1
Authors: Stansell J. R. , Klepper Betty , Browning V. Douglas , Taylor H. M.
Published: July 2010

To investigate changes in plant water use and growth rates brought about by the loss of a part of a root system, an experiment was conducted to determine quantitatively the effects of removing pan of a cotton (Gossypium hirsutum L.) root system. Approximately one‐fourth of the total root length was severed by forcing a sharp‐edged plate horizontally through the soil from front to rear of a rhizotron compartment. Root length was estimated from the number of roots appearing at the glass viewing surface of the compartment. Stem diameters were monitored continuously with linear variable differential transformers. Plant height was measured daily. Growth reductions after root pruning were greater when the root system was small and concentrated in the upper 25 cm of soil than when the root system was larger and confined to the upper 50 cm of soil. Consequently, effects of root damage by cultivation or by root pathogens may, in part, depend on the size and extent of the root system at the time of damage.
Lint Yield of Hill‐Dropped and Drill‐Planted Pima Cotton1
Authors: Kittock D. L.
Published: July 2010

Cotton (Gossypium sp.) growers in recent years have been changing from planting cotton by drill‐planting and thinning to planting to a stand. Much planting to a stand is done by hill‐dropping seed. This study was initiated to compare lint yield of ‘Pima S‐4’ cotton (G. borbadense L.) when drill‐planted and thinned and when hill‐dropped at 23‐cm spacing. There were three population levels, 1, 2 and 3 plants/hill, for hill‐dropped and comparable plant populations for drill‐planting and thinning. There were no significant differences in lint yield between hill‐dropping and drill‐planting in 3 years.
Differential Response of Oats to Manganese Stress1
Authors: Brown J. C. , Jones W. E.
Published: July 2010

Oat (Avena sativa L.) varieties differ in their susceptibility to Mn deficiency. A Mn‐efficient plant utilizes a limited supply of Mn, whereas a Mn‐inefficient plant, grown under identical conditions, develops Mn‐deficiency symptoms. The objective of this study was to characterize these differences.

Four Mn‐inefficient oat varieties (‘Star,’ ‘Maelor,’ ‘Cayuse,’ and ‘Vicland’) and four Mn‐efficient oat varieties (‘S171,’ ‘Avon,’ ‘Park,’ and ‘Golden Rain’) were grown in nutrient solution containing increasing amounts of Mn. All of the Mn‐inefficient varieties except Star developed Mn‐deficiency symptoms when grown at 0.005 mg/liter Mn. None of the Mn‐efficient varieties developed the symptoms. Concentration of Ca was consistently greater in tops of the Mn‐efficient than in those of Mn‐inefficient oat varieties. Where the concentration of P was increased in the nutrient solution, Vicland contained more P and less Ca than Golden Rain. It is suggested that Ca may physically substitute for Mn at nonspecific sites in the plant, thus making more Mn available for specific chemical reactions that require it.
Nonionic Surfactant Effects on Growth and Porosity of Barley Roots1
Authors: Luxmoore R. J. , Valoras N. , Letey J.
Published: July 2010

Nonionic surfactant materials were applied in both solution and soil culture to assess the direct surfactant and the soil‐surfactant interaction effects on root dry weight and root porosity (gas space volume per unit root volume) of barley (Hordeum vuigare L.).

Plants were grown for 28 days in solution culture with nonionic surfactant Soil Penetrant 3685 up to 100 ppm. Root dry weight was significantly reduced at 40 ppm and was further reduced to 32% of control plant root weight at 100 ppm. Root porosity, determined by the pycnometer method decreased from 13% (control) to 9% with 20 to 80 ppm surfactant. At 100 ppm, porosity was 4.5%. These results suggest that surfactant penetrated the root at concentrations above 20 ppm and caused flooding of intercellular gas spaces. At a high concentration (> 40 ppm) root growth decreased and the surfactant inhibited root tip meristematic processes. Soil Penetrant was more toxic to roots than Water In surfactant and this more toxic than Aqua Gro surfactant in a soil having little water repellency. Adsorption of surfactants by soil reduced the toxicity to roots. In a water repellent soil, root growth at 28 days was greatly enhanced with a 5,000 ppm addition of either Aqua Gro or Water In indicating more favorable soil‐plant water relations. In both soils root dry weight was reduced at high surfactant concentration, however, there were no significant effects on root porosity (mean value 5.7%) suggesting that root tip physiology was more affected by surfactants than internal root morphology.
Effect of Plant‐Available Stored Soil Moisture on Corn Yields. I. Constant Climatic Conditions1
Authors: Leeper R. A. , Runge E. C. A. , Walker W. M.
Published: July 2010

Agronomists have long been interested in how variation in soils and climate are related to crop yields. An experiment was conducted to quantify the effect of weekly plant available stored soil moisture (PASSM) during 10 weeks of the growing season on corn (Zea mays L.) yield under constant and variable climatic conditions. The objective of this study was to determine how soils, varying in the amount of water supplied to corn, affect corn yield under constant climatic conditions. Plot yields from four Illinois locations (farms) for 3 years (1969–1971) were correlated with weekly PASSM, rooting depth, and available water‐holding capacity in the rooting zone. Experimental plots had high fertility and management levels. Approximately six sites to various depths to a root‐restricting glacial till or natric horizon, giving a wide range in independent variables, were established at each location. The PASSM values were calculated from weekly gravimetric moisture samples that were adjusted for rooting depth, bulk density, and 1/3 and 15 bar water retentions. The PASSM values were summed by a method similar to Fisher's polynomial technique as previously modified.

The average R2 value of quadratic regression calculated for each year location was 58%. Above average PASSM was most beneficial either during tasseling or grain‐filling stages depending on the season. Quadratic regressions for each year‐location were calculated using rooting depth and available water‐holding capacity instead of weekly PASSM as the treatment variable, with average R2 values of 73 and 71%, respectively. The effect of each centimeter of rooting depth or available water‐holding capacity, as estimated from linear regression coefficients, varied considerably with the favorableness of the season. The lower precision of the weekly PASSM models, when compared with the rooting depth and available water‐holding capacity models was due to weekly sampling variation and possibly water movement above and below the soil surface. It was concluded that with adequate fertility and a high level of management, the potential of a soil to produce corn was largely determined by the soil's capacity to store and supply water.
Effects of Herbicides in a Crop‐Herbicide Rotation on Sulfur Oxidation in Tifton Soil1
Authors: Jones L. S. , Anderson O. E. , Dowler Clyde
Published: July 2010

Crop production on light‐textured soils is often dependent on the microbial oxidation of sulfur from soil organic matter or S‐amended fertilizers. Because of the recognized influence of some herbicides on microbial activity, we investigated possible effects of herbicides on the oxidation of S. To study the possible relationship between S availability and herbicides, a field of Tifton Is was selected where herbicides had been applied for 3 years to soil on which corn, soybeans, cotton, and peanuts were grown continuously and in rotation. Recommended rates and methods of application were used in applying the chemicals. During the third year, soil samples were collected from the 0 to 15 cm layer of all plots. Samples were amended with elemental S, incubated at 32C, and sulfates were determined at 10‐day intervals. Oxidation of added S proceeded in all samples, and though the accumulation of sulfates was slowed during the first 10 days, never was it completely inhibited. Irrespective of treatment, the added S was completely oxidized to sulfate by the 40th day of incubation. Though the effect was minor, the combinations of herbicides applied to soybeans and peanuts tended to affect sulfofication more than those applied to corn and cotton.
Evaluation of Computational Methods for an Exponential Regression Model1
Authors: Carmer S. G.
Published: July 2010

Several computational methods are available for the estimation of parameters A and K in the exponential regression model Y = NAKN relating yield of corn (Zea mays L.), Y, per unit area to plant density, N. From estimates of A and K two additional parameters may be estimated: Nopt, the agronomic optimum plant density, and Ymax, the maximum yield of corn which is obtained at the optimum plant density.

Objectives in this study were to compare three methods of computing estimates of A, K, Nopt, and Ymax and to determine if the effects of computational methods vary with treatment design, random error magnitude, and random error structure. One computational method involves linearization of the model through logarithmic transformation, whereas the other methods retain the non‐linearity of the model and utilize iterative least squares procedures.

Estimates of the four parameters were obtained from each of 100 simulated experiments for each of 270 combinations of nine treatment designs, two random error structures, five random error magnitudes, and three computational methods. Little of the variation in the 270 average values of each parameter was due to the effects of computational method, random error structure, or their interaction. Effects of treatment design, magnitude of random error, and then‐ interaction, however, accounted for 85 to 94% of the variation, depending on the parameter being estimated. Computational methods had only slight effects on coefficients of determination, average residual variances, and the range and bias of average parameter estimates.
Estimating Millability of Sugarcane From Small Samples
Authors: James Norman I. , Miller J. D.
Published: July 2010

A method was developed for estimating variety correction factor (VCF), a measure of millability in sugarcane (Saccharum sp.), from % primary juice extraction. We can obtain 4,000 to 5,000 estimates of milling quality per year with this method compared to a few hundred estimates of milling quality with other methods. Clones with poor milling quality can be discarded during early stages of selection in breeding programs.

When samples were processed with a cutter‐grinder and 3‐roller mill, the association between % primary juice extraction and VCF (r = 0.922** and 0.856**) was as close as the association between % fiber and VCF (r = −0.852** and −0.846**). The regression equation for predicting VCF from % primary juice extraction was developed for samples processed with a 3‐roller mill.

Distribution of fibervascular bundles within stalks did not influence milling quality as measured by VCF.
Chemical and Cultural Methods for Downy Brome Control and Yield of Winter Wheat1
Authors: Swan D. G. , Oveson M. M. , Appleby A. P.
Published: July 2010

Downy brome (Bromus tectorum L.) is difficult to control with stubble mulch fallow. Herbicides effectively control this weeds so combinations of herbicides and stubble mulch fallowing were evaluated. Winter wheat (Triticum aestivum L.) yields from chemical, stubble mulch, and chemical plus stubble mulch fallow systems were obtained from 1960 to 1966 at nitrogen levels of 45, 90, and 134 kg/ha.

In the summer fallow year, vegetation was controlled in the chemical plots with a winter treatment of atrazine [(2‐chloro ‐4‐(ethylamino‐)‐6‐(isopropylamino)‐s‐triazine] plus amitrole (3‐amino‐s‐triazole), and the use 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] in the summer. Wheat was seeded directly into nontilled soil. Conventional stubble‐mulch tillage was used for tilled plots. Tillage was initiated in early June in the chemical + stubble mulch plots.

Effect of nitrogen rate and fallowing method on wheat yield was inconsistent over the study period. Chemical + stubble mulch fallow was the most consistent treatment. Yields from this treatment were significantly higher than from chemical alone 3 of the 5 years, indicating that tillage often is beneficial in this soil type even when weeds are not a factor.
Simple Method for Growth of Small Plants in Nutrient‐Sand Culture1
Authors: Mazur A. R. , Hughes T. D.
Published: July 2010

A simple and inexpensive, yet controllable system for growing small plants in nutrient‐sand cultures was designed and constructed. The system was devised for large volumes of nutrient solution, as well as for accurate control of frequency and duration of wetting cycles necessary for comparing absorption and utilization of NH+4 and NO‐3. The system uses subirrigation to flush and renew the root‐zone nutrient solution and is, thus, especially useful for studies involving small plants, such as grass seedlings, which are easily dislodged by other methods. This method has been used successfully in turfgrass nutrition studies.
Prediction of Winter Wheat Yield From Short‐Term Weather Factors1
Authors: Pochop L. O. , Cornia R. L. , Becker C. F.
Published: July 2010

Crop production is often severely limited by a lack of moisture during critical periods of the growing season. In the semi‐arid regions of the Great Plains, in particular, the time distribution of rainfall is usually thought to be as important as the total amount. Precipitation management promises one means of alleviating the problem of moisture deficiencies during critical growth periods of crops.

The objective of this study was to assess the potential effects of precipitation augmentation on agricultural production in the Great Plains area of Wyoming. The influence of added rainfall on winter wheat production in eastern Wyoming has been estimated. The results are limited to winter wheat, the major crop of the region. The influence of precipitation augmentation on winter wheat production was shown to be largely dependent upon the time at which added rainfall occurs. The benefits of added rainfall to increased winter wheat production were shown to be greatest during the middle portion of the growing season, relatively negligible early in the season, and negative late in the season.
Fate of Fall and Spring Applied 15N‐Labeled Aqueous Ammonia in Porous, Buried Bags1
Authors: Chalk P. M. , Keeney D. R.
Published: July 2010

Application of nitrogen fertilizers, particularly anhydrous NH3 is frequently practiced in the northern sections of the Corn Belt to spread out the work load and take advantage of lower fertilizer prices. However, nitrogen losses through nitrification of the fertilizer followed by leaching or denitrification have been a continuing concern. The work described here was designed to evaluate the fate of Fall and Spring applied NH3 under field conditions using 15N labeled fertilizer. Because of limitations in the amount of labeled fertilizer available, and to minimize sampling problems, small porous bags (125 cm3) were filled with soil, injected with 15N aqueous NH3 and were placed either under fallow or under corn (Zea mays L.) on a Plano silt loam soil. The bags were retrieved at intervals and the soil and plants analyzed for 15N. Recovery of Spring applied NH3 in the corn plants was between 58 and 69%, and about 7% remained in the soil, primarily as organic N and fixed NH4. Recovery decreased with an increase in the amount of N applied. About half of the Fall applied fertilizer N incorporated into the organic‐N fraction was released the following spring, but fertilizer‐derived organic‐N from Spring‐applied NH3 was largely unavailable to soil microorganisms. From 60 to 80% of the Spring applied fertilizer N fixed by day was released during cropping. The major pathway for loss of fertilizer N was presumed to be either leaching or denitrification. Some fertilizer‐derived (NO2 + NO3)‐N was leached as much as 60 to 75 cm below the point of placement by the following Spring. At this depth it would be unavailable to the following crop until the roots had penetrated deeply. The results suggest that fall application of NH3 is not desirable, from an agronomic or an environmental point of view, because of potential N fertilizer losses, particularly by leaching. At least in the soil studied, Fall application has an advantage in that less fertilizer N is retained in an unavailable form.
Irrigation Border Effects in Pima Cotton1
Authors: Kittock D. L.
Published: July 2010

The purpose of this study was to determine if two border rows on each side of yield rows were necessary to prevent border effects in irrigation tests on American Pima cotton (Gossypium barbadense L.). Individual rows were harvested in 6‐row plots on first harvest (67% to 89% of total harvest) in Pima cotton irrigation, cultivar, plant‐population tests. Tests were conducted for 4 years. Analyses of these data indicate that lint yield of outside‐border rows (rows 1 and 6 of 6‐row plots) was significantly affected by adjacent irrigation treatment for the three methods of irrigation tested. Border effects on lint yield of inside‐border rows (rows 2 and 5) were much lower, but significant at the 0.05 or 0.50 level. Difference in lint yield between inside‐border rows and yield rows (rows 3 and 4) ranged from 2.7 to 4.7% for the three irrigation methods.

Need for more than one pair of border rows is indicated. However, border effects on inside‐border rows were small in most comparisons. In one instance, absolute yields of inside‐border rows were affected by the adjacent treatments, but relative yield levels of different irrigation treatments were not affected.
Shade‐cloth Microclimate of Soybeans1
Authors: Allen L. H.
Published: July 2010

A shade cloth tent was erected over a crop of soybeans [Glycine max (L.) Merr.], in a micrometeorological CO2 enrichment experiment, to restrict eddy diffusivity and vertical turbulent transport. This barrier was tried because earlier studies had shown that CO2 released in crops under natural conditions was rapidly dispersed by turbulence. The objectives were to evaluate plant response to the modified microclimate and the effectiveness of the shade cloth tent in reducing losses of applied CO2. Profiles of air temperature, CO2 concentration, water vapor concentration, and wind were measured both above and below the shade cloth and in an adjacent open field. Total solar, visible, and net radiation were also measured.

Less light reached the shaded crop, but the plants grew larger and gave about the same dry‐matter yield. However the shaded crop lodged severely. Soil water was extracted at a slower rate by the shaded crop for two reasons: a) because less radiation reached the crop to supply energy for evapotranspiration and b) because a “humidity blanket” developed under the cloth barrier giving a smaller leaf‐to‐air vapor pressure gradient. The “humidity blanket” resulted from lower turbulent transport under the shade cloth. The shade cloth wind screen decreased water stress and water use, increased the amount and improved the distribution of diffuse irradiance, and increased the diffuse to direct‐beam irradiance ratio. Therefore shade culture might have potential beyond present‐day tobacco (Nicotiana tubacum L.) culture, for high value crops with low light saturation of photosynthesis, especially in arid climates with high solar radiation.

Eddy diffusivity was reduced to about 16% at the height of the shade cloth, but CO2 concentration increases at the crop's top during releases were only about twice as large with the shade cloth in place as they were with the shade cloth removed. Therefore the shade cloth was moderately effective in trapping released CO2 but much still escaped.
Cottonseed Density: Associated Germination and Seedling Emergence Properties1
Authors: Krieg D. R. , Bartee S. N.
Published: July 2010

Recent studies have indicated that separation of cottonseed (Gossypium hirsutum L.) for improvement in seed quality should be based on seed density rather than seed size or weight. Seed density is closely related to embryo maturity and is more independent of genotype than are other seed properties.

The primary objective of this study was to determine the effect of seed density on some of the processes associated with cottonseed germination and seedling establishment of several cultivars. Acid delinted seed were separated into four density groups using a pneumatic separator. Rate of imbibition, quantity and quality of material leached from the seed, rate of radicle elongation, germination and seedling emergence percentages were measured as indicators of seed quality and seedling vigor potential.

Germination percentages were directly related to both seed density and seed weight, with the better correlation existing with seed density. The rates of imbibition and radicle elongation were related to seed density within a cultivar with differences existing between cultivars. A slower rate of radicle elongation was observed for the highest density class during the first 2 to 3 days of germination, which was related to a decreased rate of imbibition during the first 8 hours of contact with water. The quantity of soluble sugars, Ca, and K leached from the seed during imbibition was inversely related to seed density, suggesting interferences existed during seed development or deterioration had occurred in the low density seed. Seed density was highly related to rate of emergence, total emergence, and seedling survival under both growth chamber and field conditions.

The results obtained suggest that seed density is the best predictor of cottonseed germination, emergence and potential seedling vigor. Seed separation for improvement in seed quality should be based on density rather than other seed properties.
Effect of Irrigation and Nitrogen on the Dry Matter and Crude Protein Yields of ‘Pangola’ Digitgrass1
Authors: Byam L. , Gumbs F. A.
Published: July 2010

In Trinidad, West Indies, a dairy industry is being developed on Piarco fine sand/fine sandy loam soil, classified as Aquoxic Tropudults. The soil is physically and chemically poor. The cattle obtain most of their food supply by grazing ‘Pangola’ digitgrass (Digitaria decumbens Stent.). There is an urgent need to increase grass production on this soil type. Inadequate water supply in the dry season limits grass production. Previous fertilizer trials with Pangola digitgrass on this soil type have indicated that N fertilizer is likely to give better yield response than P, K, or Ca. This trial was therefore conducted to determine the irrigation‐N management for wet and dry season production of Pangola digitgrass on this soil at adequate levels of P and K.

The dry matter and crude protein yield responses of the grass to irrigation and N were studied in the field on established pastures. A split plot design was used with irrigation levels as the main plots and N levels as subplots. There were three levels of irrigation (irrigation back to field capacity at soil water deficits of 1.25, 2.50, and 3.50 cm per 30 cm of soil) and a control (no irrigation); and three levels of N, 224, 448, and 672 kg/ha.

In the moderately dry year of 1972 in Trinidad, irrigation had little effect on the dry matter yields or the percentage or total crude protein of Pangola but in the severe dry season of 1973, dry matter yield was essentially doubled even when the soil was allowed to dry to a maximum water deficit of 3.75 cm per 30 cm.

In the dry season of 1972, dry matter and crude protein yields increased with an increase in N fertilization from 224 kg to 672 kg N/ha/year but this was reversed in the wet season. The total annual dry matter production was best at 224 kg N/ha and irrigation back to field capacity at 1.25 cm deficit.

The best irrigation‐N management for Pangola depended on the season of the year as well as on the severity of the dry season. In the moderately dry season, N substituted for irrigation and 672 kg/ha of N without irrigation was best. In a severe dry season, 224 kg N/ha/year and irrigation at the 1.25 or 2.50 cm deficit gave the best yields; and in the wet season, the management should be 224 kg N/ha and irrigation at the 1.25 cm deficit. The fertilizers were applied as split applications; N was applied after every 6‐week harvest and phosphate and potash, after every third harvest.
Effects of B Application on Soybean Yield, Chemical Composition, and Related Characteristics1
Authors: Touchton J. T. , Boswell F. C.
Published: July 2010

Soybeans (Glycine max L. Merr.) are generally considered not to respond to B applications. A few responses to B application on soybeans have been reported for soils similar to those reported here. In addition, toxicities have been reported but not related to methods of application with current recommended cultivars. The purpose of these studies was to compare the effects of broadcast and foliar applications of B at rates of 0 to 2.24 kg/ha for soybeans (‘Hutton’) grown on two Coastal Plains soils and a Piedmont soil. The parameters evaluated were B accumulation and distribution in the soil and plants and the effects of B on yield, elemental concentration in leaves and mature seed, plant maturity, seed size and quality, and nodule formation. A significant positive correlation was found between applied B and water‐soluble soil B and total plant B. Broadcast applications of B caused no apparent vegetative damage but the 1.12 and 2.24 kg/ha foliar applications resulted in leaf burn, malformed leaves, and delayed maturity. On the Coastal Plain soils, yields were influenced by rate of applied B, but not by method of application. There was a beneficial effect from the 0.28, 0.56, and 1.12 kg/ha rates of B at one site and a detrimental effect from the 2.24 kg/ha rate at both sites. Yields on the Piedmont soil were not influenced by B applications. Protein and oil percentages, seed size, and nodule formation were not affected by method or rate of B. The B concentration in the mature seed increased with increased B rates but there were no differences between methods of application.