bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seeding Rate and Row Spacing Effects on Yield and Yield Components of Drill‐Seeded Rice1
Authors: Jones D. B. , Snyder G. H. 
Published: July 2010

AbstractAlthough plant population effects on crop performance have been thoroughly investigated in transplanted rice (Oryza sativa L.), less information is available for drill‐seeded rice. Previous studies evaluating the response of rice cultivars to various seeding rates and row spacings were performed before semi‐dwarf cultivars were available in areas where drill‐seeding is practiced. Two contrasting plant types, tall (cv. Lebonnet) and semi‐dwarf (cv. Bellemont and Lemont), were drill‐seeded at rates of 50, 100, and 150 kg seed ha−1 in 0.15‐, 0.20‐, and 0.25‐m row spacings in three tests conducted on an organic soil. Narrow row spacings increased grain yield for both plant types when reproductive growth occurred during a period of relatively high solar radiation and moderate temperatures. Increased seeding rates increased panicles per square meter in all tests for both plant types. This increase was compensated for by decreased filled grain number per panicle, resulting in no significant yield differences among seeding rates. It appears that seeding rates of 80 to 100 kg ha−1 are sufficient to obtain optimum stands in southern Florida.
Dry Matter, Nitrogen, Phosphorus, and Potassium Accumulation Rates by Corn on Norfolk Loamy Sand1
Authors: Karlen D. L. , Sadler E. J. , Camp C. R. 
Published: July 2010

AbstractThe maximum amount and rate of nutrient accumulation by irrigated corn (Zea mays L.) must be known so that farmers do not waste money or pollute water resources by applying excessive amounts of fertilizer. Aerial whole plant samples were therefore collected from irrigated field experiments conducted on Norfolk (Typic Paleudults) loamy sand in 1980, 1981, and 1982, to determine seasonal dry matter, N, P, and K accumulations for corn yielding 10 Mg ha−1 or more in the southeastern Coastal Plain. Rates of accumulation were derived by differentiating compound cubic polynomial equations that described seasonal accumulation patterns. Total dry matter accumulation averaged 23.1 and 24.9 Mg ha−1 for two population treatments that averaged 7 ✕ l04 or 10 ✕ l04 plants ha−1. Aerial N, P, and K accumulation respectively averaged 228, 58, and 258 kg ha−1 in 1980; 264, 37, and 372 kg ha−1 in 1981; and 225,37, and 335 kg ha−1 in 1982. Grain yields averaged 13.4, 11.7, and 10.9 Mg ha−1 in 1980, 1981, and 1982, respectively. Lower P accumulations in 1981 and 1982 were the result of lower grain yields that were apparently caused by excessive K accumulation. Calculated peak dry matter, N, P, and K accumulation rates were 650, 10, 1.6, and 28 kg ha−1 day−1 in this study, compared to rates of 247, 4.5, 0.6, and 3.2 kg ha−1, respectively, in previous midwestern studies. Peak accumulation rates during both vegetative and reproductive growth stages emphasize that cultural, nutrient, and water management practices must be coordinated to provide a minimum stress production environment for high corn yield.
Increasing Importance and Control of Mayweed Chamomile in Forage Crops1
Authors: Smith A. E. 
Published: July 2010

AbstractMayweed chamomile (Anthemis cotula L.) is a cool‐season annual weed that germinates during March and matures by mid‐May in the southeastern United States. The economic importance of this weed in the pasture ecosystem has not been determined. The objectives of this study were: (i) to determine the forage quality of mayweed chamomile foliage; (ii) to survey the potential allelopathic influence of mayweed chamomile tissue extract on the development of certain forage species; and (iii) to evaluate herbicides for the control of this weed. The in vitro dry matter digestibility of mayweed chamomile ranged from 630 to 790 g kg−1, with the highest values residing in foliage harvested during the vegetative stage of plant development. Results of laboratory bioassays and growth chamber experiments indicated that water extracts of mayweed chamomile leaf material are potentially allelopathic to alfalfa (Medicago sativa L.) and Italian ryegrass (Lolium multiflorum Lam.) seedlings. Leaf tissue mixed in potting soil significantly reduced alfalfa and Italian ryegrass plant development. The extract and tissue concentrations used in this research were estimated to be similar to concentrations expected to occur within the pasture ecosystem. Paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.6 kg a.i. ha−1 and glyphosate [N‐(phosphonomethyl) glycine] at 1.2 and 2.4 kg a.i. ha−1 controlled mayweed chamomile in sericea lespedeza [Lespedeza cuneata (Dumont) G. Don] and bermudagrass [Cynodon dactylon (L.) Pers.] forage systems.
Effect of Soil pH on Crop Yield in Northern Idaho1
Authors: Mahler R. L. , McDole R. E. 
Published: July 2010

AbstractHeavy application of ammonium‐based N fertilizers on cereal crops has resulted in the acidification of soils in northern Idaho. The objective of this 5‐yr study initiated in 1981 was to determine the effect of soil pH on the yield of lentil (Lens culinaris, cv. Tekoa and Chilean), spring pea (Pisum sativum, cv. Columbia and Alaska), winter wheat (Triticum aestivum, cv. Daws, Hill 81, and Stephens), and spring barley (Hordeum vulgare, cv. Advance and Steptoe). Data were compiled from 39 field studies conducted on Mollisols and Alfisols to produce mathematical models to describe soil pH‐yield relationships. Linear‐plateau regression models consisting of intersecting straight lines were fitted to percent maximum yield data for each crop or crop cultivar. The point where the two lines intersected was called the minimum acceptable pH for maximum yield. Lentil and pea were least tolerant to acid conditions, with minimum acceptable pH values required for maximum yields of 5.65 and 5.52, respectively. Cereals were more tolerant, with a minimum acceptable pH value of 5.23 for spring barley. The three winter wheat cultivars reacted differently to soil pH, as Daws, Hill 81, and Stephens had minimum acceptable pH values of 5.19,5.37, respectively. Even though Hill 81 did not have the lowest minimum acceptable pH value, it was considered the most acid‐tolerant winter wheat cultivar because the slope of the line describing the relationship between pH and yield in the limiting region was less than those of the other two cultivars.
Soil Coring Machine for Microplots and Large Soil Cores1
Authors: Swallow C. W. , Kissel D. E. , Owensby C. E. 
Published: July 2010

AbstractA self‐contained, hydraulically operated soil coring machine was constructed that can push large open‐ended cylinders or boxes into the soil to establish microplots or obtain large soil cores. This machine reduces the time required to create microplots by inserting open‐ended tubes into the soil profile with minimum disturbance to surrounding areas. The equipment is mounted on two wheels and can be towed across the plot area by any small vehicle. The machine has been successfully used to establish undisturbed microplots up to 760 mm in diameter by pushing cylinders up to 1 m deep into the soil. This machine can also remove soil cores of 250 mm in diameter and 900 mm deep from the soil profile.
Asymptotic and Parabolic Yield and Linear Nutrient Content Responses to Rice Population Density1
Authors: Counce Paul A. 
Published: July 2010

AbstractKnowledge of optimum rice (Oryza saliva L.) population densities and the response of rice nutrient status to population density is necessary for rice producers and researchers to achieve maximum productivity. The objectives of this study were to determine (i) the responses of rice yield to population, (ii) critical populations for experiments with asymptotic yield responses to population, (iii) optimum populations for experiments with parabolic yield responses to population, and (iv) Y‐leaf (youngest mature rice leaf of a plant) nutrient content responses to population. Seeding rates were used to obtain broad ranges of populations over 2 yr for three rice cultivars at three Arkansas locations. Asymptotic and parabolic area yield equations were determined for area yield and population data. In 11 experiments, asymptotic yield responses to population were found; in five experiments, parabolic yield responses were found; in three experiments, linear responses were found; and in three experiments there was no significant relationship between yield and population. Critical and optimum populations were 87 to 308 plants m−2, with most in the range of 159 to 270 plants m−2. In some experiments, the effects of population on N, P, K, and Fe contents were negative. The effect of population was positive for Mn in six of 14 experiments. Reductions in yield at excessive populations appeared to be associated with population‐dependent stresses such as water deficits, disease, and nutrient deficiencies.
Effect of Subsoiling a Compacted Clay Loam Soil on Growth, Yield, and Yield Components of Wheat1
Authors: Oussible Mohamed , Crookston R. Kent 
Published: July 2010

AbstractOver the past three decades, soil compaction, especially of subsurface horizons, has become a serious problem in irrigated areas of Morocco. This study was designed to determine if subsurface compaction of a clay loam soil in Morocco could be effectively alleviated by subsoiling–to the extent that grain yields of wheat (Triticum aestivum L.) would be improved. A second objective was to document the nature of any resulting yield improvement in terms of changes in root and shoot growth, as well as in the standard components of grain yield. Field experiments were conducted in 1983 and 1984. A single‐tooth subsoiler was pulled through the soil at 0.4‐m intervals, to a depth of 0.7 m. Within the zone through which the tooth passed, soil bulk density was reduced by 11%, while soil porosity and air‐filled porosity were increased by 17 and 50%, respectively. Soil mechanical resistance of subsoiled plots was decreased by 19 to 33% at the 0.2‐ to 0.35‐m depth. At this same depth, roots were 54% longer per unit weight in subsoiled plots. Throughout the growing season, plants grown on subsoiled plots were consistently and significantly taller. These taller plants had more reproductive shoots, each with more and larger kernels. This resulted in an average yield increase of 48% for grain, and 28% for straw.
Herbage Intake Rates of Beef Cattle Grazing Alfalfa1
Authors: Dougherty C. T. , Bradley N. W. , Cornelius P. L. , Lauriault L. M. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.), a forage crop unique in that it has high potential in terms of both yield and quality, has considerable capacity for animal production when grazed under management that is based on its growth and development. Two grazing experiments, using balanced change‐over designs, were set up to measure the ingestive behavior of beef heifers (Bos taurus) during the first, second, and third hours of grazing sessions on alfalfa pastures established on Maury silt loam (fine, mixed, mesic Typic Paleudalfs). In Exp. I where the herbage mass, in terms of dry matter (DM), was 3.06 Mg ha−1 and the herbage DM allowance was 6.1 kg h−1 per heifer, animals ingested DM at 2.96, 1.88, and 1.56 kg h−1 during their first, second, and third hours of grazing, respectively. The mean rates of biting were 26, 21, and 19 bites min−1 for the same periods. Herbage DM intake per bite declined linearly from 1.96 to 1.54 to 1.36 g for each hour increment in grazing time. Forage utilization was 51, 32, and 27% for the same increments. In Exp. II where the herbage mass (DM) was 1.74 Mg ha−1 and the allowance was 3.4 kg h−1, heifers ingested 2.35, 1.47, and 1.20 kg h−1 during their first, second, and third hours of grazing, respectively. The mean rates of biting were 34, 22, and 18 bites min−1 during the same periods within the grazing session. Herbage DM intake per bite averaged 1.17 g and did not vary within the grazing session. Forage utilization was 75, 47, and 37% during the three consecutive hours within the grazing session. Maximum rates of herbage intake were characterized by larger bites and relatively slow rates of biting. Rates of herbage intake were considerably higher during the first hour of grazing than during the second and third hours. In a 3‐h grazing session, animals consumed 47, 29, and 24% of their intake during the first, second, and third hours, respectively.
Animal Evaluation of Forages Following Several Methods of Field Renovation1
Authors: Koch D. W. , Holter J. B. , Coates D. M. , Mitchell J. R. 
Published: July 2010

AbstractSod‐seeding is the only practical method to introduce improved forage species on many fields. Animal data are needed to adequately evaluate the viability of sod‐seeding. This study determined animal responses to changes in forage composition following several methods of renovation. Two fields with fine, sandy loam soils were used. Bradford Field (Typic Dystrochrepts) was dominated by smooth brome (Bromus inermis L.). Walker Field (Typic Fragiochrepts) was low in fertility and had a diverse sward. Treatments consisted of an N‐fertilized control and sod‐seeding of legumes following either paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) or glyphosate [N‐(phosphonomethyl)glycine] application. Additionally, red clover (Trifolium pratense L.) and timothy (Phleum pratense L.) were seeded conventionally at the Walker site. Nutritive value of three harvests from Bradford Field and one harvest from Walker Field was determined in feeding trials with 250‐kg dairy heifers (Bos primigenius). Greater legume content of renovated swards (avg. 720 g kg−1 the year following seeding) compared to N‐fertilized controls (avg. 230 g kg−1) resulted in greater forage crude protein (CP) content (all four harvests) and greater dry matter (DM) intake (two of four harvests), greater N intake (NI) (all four harvests), and greater body tissue retention of N (three of four harvests) by dairy heifers. Metabolizable and digestible energy were similar for all harvests and improvement methods. There were no differences in animal response to forages from sod and conventional seedings, except that NI was greater from sod‐seedings. The year following seeding, there was an average 48 and 75% increase in digestible DM and CP yield, respectively, from treatments introducing legumes compared to N‐fertilized controls. These results show that when existing species are not highly responsive to N, improved forage species can be seeded without tillage and without N, and result in improved forage quality and animal performance.
Characteristics of Exposed Subsoil—At Exposure and 23 Years Later1
Authors: Eck Harold V. 
Published: July 2010

AbstractThe effects of topsoil removal on subsoil characteristics and productivity are usually studied at or soon after removal, with little attention to changes with time. The objective of this study was to evaluate the effects of 23 yr of exposure on the chemical and physical characteristics and productivity of various layers of Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls). An area on a 1% slope was leveled in 1960, giving plots with 0, 0.10, 0.20, 0.30, and 0.41 m of topsoil removal. The area was cropped to grain sorghum [Sorghum bicolor (L.) Moench] in fertility studies for 6 yr, fallowed for 2 yr, then planted to tall wheatgrass (Agropyron elongatum) and left undisturbed until 1983. The study was then reactivated with grain sorghum being grown without fertilizer 1 yr to determine fertilizer residual effects. In 1984 the previous N fertilizer treatments were reinstituted. During the 23 yr, organic matter (OM) and total N decreased in uncut surface soil but increased in exposed subsoil where initial levels were low. Extractable P levels and particle size distribution remained essentially unchanged. The proportion of large water‐stable aggregates (4.0–12.7 mm) decreased, especially in the surface soil where OM decreased with time. Decreases in large aggregates were accompanied by increases in the 0.25‐ to 1.0‐mm size range. Productivity of exposed subsoil layers increased over time. In relation to yields on similarly treated surface soil, yield reductions from soil removal (avg 0.10, 0.20, 0.30, and 0.41 m) in 1960 to 1962 and 1984 were as follows: unfertilized, 55 and 33%; P fertilized, 52 and 38%; N fertilized, 31 and 16%; N and P fertilized, 2 and 14%. Productivity increases were associated with increases in both N and P supplying capacity.
Particle Size and Soil Texture Effects on Elemental Sulfur Oxidation1
Authors: McCaskill M. R. , Blair Graeme J. 
Published: July 2010

AbstractMost previous experiments examining factors affecting the conversion of elemental S into plant‐available forms have used indirect methods, such as measuring sulfate accumulation, and have at times resulted in exaggerated estimates of elemental S oxidation rates. Direct measurement of residual elemental S offers a more reliable estimate of conversion rate, but only some of the factors known to affect conversion rate have been investigated by direct methods. A pot experiment was conducted over 238 days to measure conversion rates under a range of elemental S particle sizes (0.1–2.0 mm) and soil textures, and with and without inoculation with sulfur‐oxidizing bacteria. Conversion rates were measured by two indirect methods—S uptake by plants and 35SO4 dilution‐and one direct method—acetone extraction of remaining elemental S. Initial surface area of elemental S was the prime determinant of conversion rate, but three other factors had to be considered to fully explain observed release characteristics. These were (i) a gradual particle disappearance in 0.1‐ and 0.2‐mm particles, which caused a reduction in conversion rate with time, (ii) a depression in conversion rate for particle sizes ≧ 0.4 mm on noninoculated treatments, and (iii) shape considerations that were imputed to the observed lower conversion rates for the more spherical 2.0‐mm size. Three of the four soils—an Arenic Haplustult, a Plinthic Haplustult, and a Typic Torrert—showed increased conversion rates in response to inoculation, with inoculation responses most marked for the larger (> 0.4 mm) particle sizes. The other soil—a Udic Ustochrept—was not responsive to inoculation. No relationship was detected between soil texture and elemental S conversion rate over a range of clay contents from 9 to 52%.
Market Grade Effects on Fatty Acid Composition of Five Peanut Cultivars
Authors: Mozingo R. W. , Coffelt T. A. , Wynne J. C. 
Published: July 2010

AbstractPeanut (Arachis hypogaea L.) seeds are sized into market grades before processing into manufactured products. Therefore, manufacturers need to consider the effect of market grade and cultivar on fatty acid composition and storage quality. Previous studies have not considered the effect of market grade on oil quality. Sized seed of five Virginia‐type peanut cultivars grown in field plots at the Peanut Belt Research Station in Lewiston, NC, on a Norfolk sandy loam soil (Typic Paleudults), and at the Tidewater Agricultural Experiment Station in Suffolk, VA, on an Eunola loamy fine sand soil (Aquic Hapludults) for 3 yr (1982–1984) were evaluated for fatty acid composition. Seed of ‘NC 7’, ‘VA 81B’, ‘NC 6’, ‘Florigiant’, and ‘GK 3’ were sized into three shelled market grades (extra large, medium, and No. 1) for analysis. Significant differences were observed among cultivars for all fatty acids, oleic/linoleic (O/L) ratio, and computed iodine value. A change in market grades from No. 1 to medium to extra large resulted in a significant increase in the percentage of stearic, oleic, and arachidic acids and a significant decrease in the percentage of palmitic, linoleic, eicosenoic, behenic, and lignoceric acids. Significantly lower computed iodine values and significantly higher O/L ratios were recorded for the larger size seed. Significant environment × cultivar interactions were recorded for iodine value, O/L ratio, and all fatty acids except palmitic and oleic. Environment × market grade interactions were significant for all fatty acids, O/L ratio, and iodine value. Significant cultivar × market grade interactions were obtained for palmitic, oleic, and linoleic acids, iodine value, and O/L ratio. These results show market grade, cultivar, and environment affect fatty acid composition, computed iodine value, and O/L ratio. Larger size seed produced fatty acid distribution, iodine values, and O/L ratios that indicated better stability and longer shelf‐life of the peanut.
Alterations in Plant Growth and Dry Matter Distribution in Soybean
Authors: Egli D. B. 
Published: July 2010

AbstractThe partitioning of assimilate between vegetative and reproductive plant parts of soybean [Glycine max (L.) Merrill] during flowering and fruit set could be related to fruit and seed number, and yield. Experiments were conducted in the field (cv. Cumberland) for 2 yr to investigate the effect of alterations in plant growth on the distribution of dry matter during flowering and fruit set. Alterations in plant growth were created by reducing the insolation (63%) during flowering and fruit set by using commercial shade cloth and by low density plantings (spaced plants, approximate equidistant spacing with 0.9 m between plants). The control and shade treatments were grown in 0.76‐m rows (0.71‐m in 1984), and conventional cultural practices were used. Partitioning ratios (reproductive mass/total biomass) were calculated from four samples collected between R1 and R6. Leaves (uppermost fully expanded leaf and the leaf four nodes below it) were sampled during flowering and fruit set for carbohydrate and N analysis. Shade reduced crop growth rate (R1‐R5), vegetative mass at R5, seed number per square meter, and yield. The spaced plants were much larger and had nearly 80% of their reproductive mass on the branches at R6 compared with 5% for the control plants. Leaf starch and soluble sugar concentrations tended to be reduced by the shade treatment and increased in the spaced plants. There were no treatment effects on leaf N concentration. The treatments had a minimal effect on the partitioning ratios, indicating that distribution of dry matter between vegetative and reproductive plant parts was relatively constant across large differences in plant size and growth rate. This suggests that the fruit and seed numbers may be more closely related to crop growth rate than to the partitioning of assimilate.