bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium Leaching to Increase Rooting Depth in a Brazilian Savannah Oxisol1
Authors: Ritchey K. Dale , Souza Djalma M. G. , Lobato Edson , Correa Osni 
Published: July 2010

AbstractRoot growth in subsoils of Oxisols is often precluded because the roots of many crops are sensitive to soil acidity. This increases plant stress during dry periods when available soil water in the limed surface layers is exhausted. The low soil CEC and high rainfall in Central Brazil suggest that soluble calcium salts might leach below the plow layer and reduce soil acidity. To test this possibility, soil columns, simulating field profiles, were constructed in the laboratory and various Ca salts were mixed in the 0 to 15‐cm layer. Addition of 1,200 mm water to 2,000 kg/ha Ca added as CaCl2, CaSO4, and CaCO8 caused Ca movement to 180, 75, and 25 an, respectively. Calcium sulfate decreased Al saturation and increased soil pH at depth.Several field experiments were sampled to determine the effect of previous treatments on the movement of Ca + Mg. Three to four years after application of gypsum, in ordinary superphosphate, subsoil pH and Ca + Mg status were increased, and Al saturation decreased at depths as great as 75 to 90 cm. Zea mays L. roots growing in the improved subsoil environment were able to take up water and withstand droughts.
Increased Flowering and Yield from a Bromegrass‐Timothy Meadow by Timing of Nitrogen1
Authors: Rumburg C. B. , Ludwick A. E. , Siemer E. G. 
Published: July 2010

AbstractFall application of fertilizer to irrigated meadows in the mountain and intermountain region has both utility and agronomic advantages as compared to spring applications. The objectives of these experiments was to compare the efficacy or fall and spring applied N to determine why fall applications on a bromegrass (Bromus inermis Leyss.)‐timothy (Phleum pratense L.) meadow produced higher yields and more abundant flowering of bromegrass than spring applications. Fertilizer was broadcast on the surface of small plots in either spring of fall. Yields were sampled with a sickle‐bar mower at haying stage, or at regular intervals throughout the season to estimate uninterrupted growth rates. Small plots were clipped by hand to estimate number of shoots, relative species abundance, and flowering culms. Fall fertilization with N stimulated very early, spring growth of bromegrass, which slightly preceded spring fertilization, increased relative abundance of bromegrass inflorescence, and increased dry matter yields by 15% when harvested at customary haying time. A subsequent, more detailed experiment revealed no visible evidence of floral initiation in either bromegrass or timothy in the fall, and fall fertilization had no stimulating effect on early spring growth of timothy. Unfertilized timothy produced a relative abundance of 3% reproductive culms while both spring and fall‐fertilized plots had 33% on 22 July. Relative abundance of bromegrass reproductive culms was 2% from unfertilized and spring‐fertilized plots and 25% from fall‐fertilized lots. Nitrogen fertilization increased the total number of shoots of both bromegrass and timothy, but fall applications favored bromegrass to the detriment of numbers of timothy shoots. Dry matter accumulation rates from spring and fall‐fertilized plots were nearly identical (155 kg/ha/day). Increased bromegrass inflorescences resulting from fall fertilization with N has clear implications for increasing seed yield from bromegrass. The applicability of this practice to different environments is not clear. We recommend fall applications of N to bromegrass (compared to spring applications) for dry matter production under arid conditions because fall applications will assure N is readily available to the plant when temperatures are suitable for growth. Fall‐applied N advanced the growing season by about 8 days or (1,200 kg/ha) compared to spring‐applied N. This practice will likely be detrimental to timothy in mixed bromegrass‐timothy stands.
Light Penetration in a Row‐Crop with Random Plant Spacing1
Authors: Mann Jerry E. , Curry Guy L. , DeMichele D. W. , Baker Donald N. 
Published: July 2010

AbstractThe quantity of solar radiation penetrating a crop canopy and reaching the soil surface affects greatly the microenvironment beneath the canopy. The influence of this microenvironment upon soil radiation and evaporation as well as upon development and mortality rates of insect plant pests is well known. The development of adequate models of light penetration is an important problem associated with the characterization of the subcanopy microenvironment.In this paper, an analytical model is proposed which estimates the sunlit soil area within a row crop where plants are randomly spaced along rows. Only direct beam, parallel light is considered. The model combines both individual plant geometry and row structure. for simplicity, plant canopies are assumed to be ellipsoidal in shape. The model incorporates plant sizes, row spacings and azimuthal orientation, foliage density, planting density, leaf orientation, and solar location. Available experimental data are inadequate for a complete validation of the model; however, a relative verification was made by comparing model output to real experimental measurements. Included in the paper is a critique of available data in light of the data requirements necessary for satisfactory model validation.
Physical Characteristics of Thatch as a Turfgrass Growing Medium1
Authors: Hurto K. A. , Turgeon A. J. , Spomer L. A. 
Published: July 2010

AbstractWhere a substantial thatch layer exists, new roots and stem growth from plant crowns occurs, at least initially, within the thatch. In some turfs, very little rooting may occur in the soil underlying the thatch. Therefore, under these conditions it appears that the thatch serves a greater role as a plant‐holding matrix and a growth medium while the soil's role decreases. The objective of this study was to determine the bulk density, total porosity, moisture characteristics, and organic matter contents of thatch and surface soils of thatched and thatch‐free Kentucky bluegrass (Poa pratensis L.) sites.The evaluation methods included: 1) the core method for measuring bulk density; 2) air pycnometric determination of total porosity; 3) a modified pressure plate procedure utilizing Tempe cells for determining moisture extraction curves; and 4) organic matter content on the basis of weight loss upon ignition. Bulk density of thatch was significantly lower than soil, but varied between thatch samples depending on the amount of soil within the thatch. Total porosity of thatch samples was not significantly different, but was greater than soil porosity. Moisture retention of thatch at low water potentials was less than the surface soil from thatch‐free sites, indicating that most of these pores are macro‐size pores. This study suggests that cultural practices, such as irrigation, may need to be modified to sustain aesthetic turf where thatch is a predominant component of the edaphic environment.
Flag Leaf and Peduncle Area Duration in Relation to Winter Wheat Grain Yield1
Authors: Mohiuddin S. H. , Croy L. I. 
Published: July 2010

AbstractInformation on the photosynthetic area duration in winter wheat (Triticum aestivum L. em Thell.) is important in breeding programs for yield advancement and large numbers of data must be taken for the data to be meaningful. A 2‐year field study (1973 and 1974) was conducted at the Agricultural Experiment Station, Oklahoma State Univ., Stillwater, Okla. It was conducted to obtain information on flag leaf and peduncle area duration as selection indexes in relation to yield, tiller number, kernels/spike, and kernel weight in winter wheat and to investigate the response of five winter wheat cultivars to selected N levels and seeding rates higher than presently used for grain production. A split‐split plot design with four replications was used for the study. Nitrogen levels comprised main plots, cultivars were sub‐plots, and seeding rates were sub‐sub plots. The levels of N were 67, 134, and 202 kg N/ha, and the seeding rates were 67, 100, and 134 kg/ha. The five hard red winter wheat cultivars were ‘Tam W 101,’ ‘Palo Duro,’ ‘Danne,’ ‘Centurk,’ and ‘Caprock.’All the traits measured differed between the two crop seasons, and a significant year by cultivar interaction suggested the presence of genotype by environment interaction. Differences among N levels were not significant probably because of the high residual amounts of available nitrogen at the experimental site, the lowest level of applied N was adequate for crop growth. The highest seeding rate (134 kg/ha) reduced grain yield, kernels per spike, and flag leaf area duration. Even though the growing conditions differed between the 2 years of the study, peduncle area duration and flag leaf area duration showed a positive correlation with grain yield, kernel weight, and a negative relationship with kernels per spike. These data suggested the use of peduncle area duration and/or flag leaf area duration as selection criteria in breeding for increased grain yield potential. These readings would be more rapid than total leaf area duration; and using selected photosynthetic leaf area indexes in a breeding program for yield, data could be obtained on many more genotypes. The data also support the use of kernel weight as a selection factor for increasing grain yield.
Drought Adaptation of Cowpea. I. Influence of Drought on Seed Yield1
Authors: Turk Kenneth J. , Hall Anthony E. , Asbell C. W. 
Published: July 2010

AbstractField studies were conducted to determine cowpea [Vigna unguiculata (L.) Walp.] response to different intensities of drought at different stages of growth to guide programs for the development of improved cultivars and improved management practices for semi‐arid zones.Two cowpea cultivars were subjected to different levels of irrigation using a line‐source sprinkler system in the field on a coarse‐loamy, mixed, thermic Haplic Durixeralf soil during 2 years with contrasting weather patterns. Well‐watered plants were irrigated weekly. In other treatments, water was not supplied during either the vegetative, flowering, or pod filling stages.Dry seed yields of well‐watered treatments were negatively correlated with degree days above 35 C during flowering.Yields of both cultivars were not reduced by drought during the vegetative stage, compared with the weekly irrigated treatment, providing subsequent environmental conditions were conducive to rapid recovery of growth and efficient pod set. Drought during the flowering stage substantially reduced yields, but partial yield recovery was observed where drought caused all flowers to abscise and the subsequent environment, after irrigation was resumed, permitted a new flush of flowers to produce pods. Drought during pod filling substantially reduced yields of both cultivars in both years.Variations in yield due to environmental stresses were mainly due to variations in number of pods/m2 except for drought during pod filling which resulted in both low pod density and small seed. Yield with abundant water or drought during pod filling appeared to be partially source limited, whereas intermediate levels of drought at other stages may have resulted in sink limitations on yield because these treatments produced the heaviest seed.
Effect of Tillage on Fertilizer Requirements for Corn on a Silt Loam Soil1
Authors: Ketcheson J. W. 
Published: July 2010

AbstractCorn (Zea mays L.) yields less with no‐till or reduced tillage than with conventional tillage on medium and fine‐textured soils in Ontario, Canada. This study was undertaken to determine whether rates of N, P, or K above those normally recommended could increase the no‐till yields. Annual rates of 120 and 240 kg N/ha, and initial rates of 95, 475, and 1,260 kg P/ha and 95, 665, and 1,330 kg K/ha were applied to a silt loam soil (Albaquic Hapludalf) in combination with four different tillage treatments (fall moldboard plow, spring disc; fall mulch plow with heavy duty cultivator, spring disc; fall ridge; no‐till). Corn was grown, harvested for grain, and stover returned to the soil over a 6‐year period. Increasing N, P or K applications gave similar response patterns on each tillage treatment. There was no indication that the higher nutrient applications could overcome yield depressions associated with reduced tillage. Adequate N, P, K levels in corn tissue further substantiated an adequate nutrient supply with each tillage treatment. Resistance to penetration measurements on soil suggested that mechanical impedance might be more critical than nutrient supply in growth performance and explain the lower yields with reduced tillage. Soil tests for available P and K, combined for increments of the upper 30 cm of soil, tended to be higher with no‐till than with the plow treatment.
Toxaphene Volatilization from a Mature Cotton Canopy1
Authors: Willis G. H. , McDowell L. L. , Smith S. , Southwick L. M. , Lemon E. R. 
Published: July 2010

abstractTo fully understand the pollution potential of pesticides more knowledge concerning the mechanisms and rates of pesticide exchange between environmental compartments is needed. The momentum balance method was used in a field study to characterize toxaphene (chlorinated camphene) volatilization from cotton (Gossypium hirsutum L.) plants for 5 days following aerial application at 2.24 kg/ha. The momentum balance method uses accurate measurements of windspeed profiles, temperature gradients, and atmospheric pesticide concentration gradients above the plant canopy to provide data for calculating vertical flux densities of pesticides. The calculated volatile loss for the 5‐day period was 358 g/ha, which represented a loss of 26% of the toxaphene present in the canopy. Although typical volatile loss patterns suggested that flux densities were highest during midafternoon, there was evidence that volatility rates were also high when leaves were drying after heavy dew or light rain. Based on comparisons of the amounts of toxaphene transported from nearby cotton fields via surface runoff in earlier studies and the amounts lost by volatilization in this study, it was concluded that aerial transport is the pathway of greater loss.
Cornstalk Decomposition on a Till‐Planted Watershed1
Authors: Alberts E. E. , Shrader W. D. 
Published: July 2010

AbstractCornstalk (Zea mays L.) residue can be used for many competing purposes including energy production and erosion control. This study was conducted to determine the rate of cornstalk decomposition and N and P release on a till‐planted watershed in the Corn Belt. Samples of cornstalk residue were periodically collected from 12 sites distributed over the watershed and analyzed for weight loss and plant nutrient content. After 12 months, 79% of the residue had decomposed. About two‐thirds of the decomposition occurred from November to April when soil temperatures were unfavorable for high microbial activity. Nitrogen and P were released from the residue during the early stages of decomposition. After 12 months, 60% of the N and 74% of the P had been lost. The percentages of N and P in the residue rapidly increased during the last 3 months of the study when soil moisture and soil temperature were favorable for optimum activity. The C/N ratio declined from 48 to 23. Narrowing of the ratio was caused by a proportionately greater decrease in C content than in N content.
Effect of Nitrapyrin and N Fertilizer on Yield and Mineral Composition of Corn1
Authors: Warren H. L. , Huber D. M. , Tsai C. Y. , Nelson D. W. 
Published: July 2010

AbstractFertilizer N applied in the fall or early spring is often used less efficiently than N applied closer to the time of maximum N demand by plants. Nitrification inhibitors make it possible to delay nitrification of applied NH4+‐N in the soil and thereby reduce overwinter and early spring N loss from leaching and denitrification. Because NH4+ absorption may induce changes in plant mineral composition, we evaluated under field conditions, the effect of inhibiting nitrification of NH4+‐N on the mineral composition of corn leaf tissue as well as on grain yield and protein content. Anhydrous ammonia with and without nitrapyrin [ 2‐chloro‐6‐(trichloromethyl) pyridine] at 0.55 kg/ha was applied in the fall and spring on soils of three types. Addition of nitrapyrin to fall‐applied NH4+ significantly increased grain yield and grain protein. Grain protein was sometimes increased when nitrapyrin was applied with NH4+ in the spring. Grain protein content was increased by N and nitrapyrin and from 10 to 33%. Protein generally continued to increase even after the maximum yield had been reached. The mineral composition of leaves was more dependent on soil type than on N treatment. The minerals K, Ba, and Mn were higher, and Ca, Mg, and A1 were lower in plants grown in Tracy sandy loam (Ultic Hapludalfs, coarse‐loamy, mixed, mesic) than in those grown in either Runnymede loam (Typic Argiaquolls, fine‐loamy, mixed, mesic) or Chalmers silty clay loam (Typic Haplaquolls, fine‐silty, mixed, mesic) soils. The concentrations of minerals in plants were similar with fertilizer treatments and time of application. Zinc was the only mineral in plants that significantly increased when nitrapyrin was added to NH4+. Nitrification inhibitors can effectively reduce N losses without adversely affecting the uptake of other minerals or the mineral composition of corn leaf tissue.
Yield, Legume Introduction, and Persistence in Permanent Pastures1
Authors: Baker Barton S. 
Published: July 2010

AbstractPermanent pasture in hill land is frequently on steep and/or rough land unsuited to frequent travel with ground equipment. Ways are needed to introduce and maintain legumes on such land. This study involved 18 treatments using P (208 kg/ha), Mo (2.2 kg/ha), lime (6.5 metric ton/ha), rototilling and white clover, Trifolium repens L. seed (2.2 kg/ha) in various combinations on two permanent pastures in central West Virginia to investigate ways of increasing yields and introducing legumes, and to determine persistence of introduced legumes. A limestone soil (Typic Hapludalf) produced higher yields when treated than a sandstone soil (Typic Dystrochrept) but the reverse was true when no treatments were applied. Legume introduction was more successful on limestone soil than sandstone soil. Phosphorus application was the most critical aspect of treatment on the limestone soil relative to legume introduction and yield increase, whereas liming was the most critical aspect of treatment on the sandstone soil.Legumes on the limestone soil accounted for over 75% of the total forage produced on some plots the year following treatment. Total legume content decreased after the 2nd year and reached a low of near 10% during the 4th year. Volunteer legumes, mostly white clover and red clover (Trifolium pratense L.), accounted for as high a percentage of the total yield as the seeded legume during the 4th and 5th years. On the sandstone soil none of the treatments resulted in enough legumes to account for more than 20% of the forage. Introduction of legumes increased yield and skewed the seasonal distribution pattern toward a higher percentage of total yields early in the season. Molybdenum did not influence legume introduction, yield, or persistence.
Response of Tropical Grasses to Stocking Rate1
Authors: Adjei M. B. , Mislevy P. , Ward C. Y. 
Published: July 2010

AbstractDuring favorable growing conditions tropical stargrasses (Cynodon spp.) are highly productive, producing more forage than is utilized by cattle under normal stocking rates, and resulting in large amounts of low quality, standing residue. Therefore, grazing trials were conducted to study the effects of three stocking rates (SR) (7.5, low; 10, medium; and 15 cattle/ha, high) on forage yield, quality, utilization and animal performance of three stargrasses: ‘UF‐5’ and ‘McCaleb’ (Cynodon aethiopicus Clayton and Harlan) and ‘UF‐4’ (Cynodon nlemfuensis Vanderyst var. nlemfuensis). Additionally, the medium SR was imposed on “Transvala” digitgrass (Digitmia decumbens Stent.) and “Pensacola” bahiagrass (Paspalum notatum Flugge). The average annual dry matter (DM) yields of stargrasses at low, medium, and high SR and of digitgrass and bahiagass at medium SR were 17.0, 18.3, 20.1, 15.0, and 10.0 metric tons/ha, respectively. In 1976, the in vito organic matter digestibility of digitgrass (51%) and UF‐5 (49%) was superior to that of UF‐4 and McCaleb (46%) stargrass with bahiagrass averaging 46% and 50% in 1976 and 1977, respectively. Crude protein in all entries was similar, averaging 9.9%. Seasonal DM utilization (75 to 95%) of stargrass by cattle was directly related to SR. However, forage intake of 7.6 kg DM/animal/day at the high SR was lower than at the medium (9.3) and low SR (10.2). Forage DM consumed annually (168‐day period) at the medium SR averaged 16.7 metric tons/ha For stargrasses, 14.9 for digitgrass and 9.9 for bahiagrass. Cattle average daily gain (ADG) over seasons ranged from 0.18 to 0.56 kg/dayfor stargrasses, and was an inverse linear function of SR. The ADG measured at a 6‐week interval was a curvilinear function of grazing pressure (GP) with an optimum GP of 6 to 8 kg available forage DM/100 kg body weight/day at 7.5 cm height of cut. Seasonal (168 days) beef gains (2‐year average) on stargrasses were 470, 617, and 576 kg/ha at the high, medium, and low SR, respectively. The ADG and beef product/ha at the medium SR in 1976 on stargrass, digitgrass, and bahiagrass averaged 0.35, 0.28, 0.22, kg/day, 580, 461, and 396 kg/ha, respectively. These data indicated that although ADG is low, high yields of total beef/ha can be obtained with proper stocking rates and correct grazing pressure on stargrass pastures.
Magnesium in Grasses of Three Selected Regions in the United States and its Relation to Grass Tetany1
Authors: Kubota Joe , Oberly G. H. , Naphan E. A. 
Published: July 2010

AbstractGrass tetany, a conditioned Mg deficiency, is a serious nutritional disease in cattle in various parts of the United States. While year to year variability is high, disease incidence is notably higher in some areas than others, indicating that soils, species of grasses, and temperature may be contributing factors. The Mg concentrations in grasses were determined to identify regional patterns and factors that affect them. Attention was focused on three distinctly different regions: 1) western U.S. from southern Nevada to Oregon, 2) eastern U.S. from North Carolina to Maine, and 3) central U.S. including the Lake states. In the West, the Mg concentration was low in grasses grown on droughty soils formed in volcanic ash. In the eastern U.S., the Mg concentration in grasses decreased from North Carolina to Maine, indicating the dominance of temperature over soils. In the North Central Region, the dominance of dolomitic till (Wisconsin) over calcitic till (Michigan) as sources of soil parent material was evident in the production of Mg adequate grasses for livestock. Regional patterns of tetany incidence seemed more closely associated with grasses having less than 0.2% Mg than with grasses having K/(Ca+Mg) ratios of 2.2 or more.