bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determining Winter Wheat Stand Densities Using Spectral Reflectance Measurements1
Authors: Aase J. K. , Siddoway F. H. 
Published: July 2010

AbstractRemote sensing would be a valuable tool to decision making and crop forecasting groups to gain knowledge of winter wheat acreage, extent of winterkill, and the potential acreage that may be reseeded to spring crop. To simulate winterkill, seven winter wheat (Triticum aestivum L.) stand variables of 0, 10, 20, 40, 60, 80, and 100% of full stand (full stand = seeding rate of 67 kg/ha) were established by seeding to stand. The plots, 20 ✕ 20 m, were located on Williams loam (fine‐loamy mixed, Typic Argiborolls) near Sidney, Mont. An Exotech Model 100‐A ground truth radiometer, corresponding to LANDSAT multispectral scanner (MSS) bands 4, 5, 6, 7, (0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, and 0.8 to 1.1µm), was used to measure reflected radiation at 0930 hours MST on clear or nearly clear days. We chose the comparatively simple, but physically meaningful normalized difference vegetation index, VI7 = (MSS7 − MSS5)/(MSS7 + MSS5), with the variant of substituting MSS6 for MSS7 to illustrate crop cover differences. In an attempt to better distinguish soil background from crops and to improve on the crop‐vegetation index relationship, we included the more complex, but also physically meaningful, perpendicular vegetation index, PVI = [(Rgg5 − Rp5)2 + (Rpp7 − Rp7)2]1/2 with the variant of substituting MSS6 for MSS7.Early in the season, VI7 delineated stands ≥40% from those <40%, allowing a judgment as to whether or not a field would need to be reseeded to spring crops. A winter wheat survival of about 40% is generally considered adequate to provide a reasonably good stand if plants are properly spaced. The 10 and 20% plots became distinguishable from the soil background at a biomass accumulation of about 30 kg/ha (LA1 ≃ 0.06).There was no advantage of using either variant of the PVI over the VI7 when plotted against leaf area index (LAI) or leaf dry matter (LDM). Both yielded a family of straight lines, with indices of determination ranging from 0.796 to 0.942, and slopes decreasing from the 10% plot to similar slopes for the 80 and 100% plots.
Yield Trends and Soil Chemical Changes Resulting from N and Manure Application to Continuous Corn1
Authors: Magdoff F. R. , Amadon J. F. 
Published: July 2010

AbstractMany Vermont dairy farms are located in a region where clay soils are common and represent much of the land topographically suited to row crops. Since these soils frequently have restricted drainage, soils are used for corn (Zea mays L.) that would be considered unsuitable in other regions. To evaluate long‐term yield trends and the effects of various treatments on crop and soil, corn silage was grown for 11 years on a somewhat poorly‐drained Panton clay soil (Typic Ochraqualf). Four rates of manure (0, 22, 44, and 66 metric tons wet weight/ha) and five rates of ammonium nitrate‐N (0, 56, 112, 168, and 224 kg N/ha) were combined factorially and applied annually to plots from 1965 through 1975.The highest yields were produced by combining 44 metric tons of manure and 224 kg N (44M to 224N). However, the 22M to 112N treatment yields were not significantly different from the highest treatment yields. The check treatment (OM‐ON) was initially 82% of the highest treatment yield, but by the end of the experiment was about 54% of the maximum yields. Annual yield fluctuations were correlated with variations in rainfall.The effect of inorganic‐N fertilizer on lowering soil pH was counteracted by manure. N application caused decreased extractable P, K, Ca, and Mg while manure application caused increased organic matter, P, Ca, and K levels. Manure did not increase soil Mg.Low yields should be expected when corn silage is grown on the Panton clay. Both manure and N applications were necessary to obtain maximum yields. Manure application at the rate of 44 metric tons/ha/year was necessary to maintain soil organic matter levels during continuous corn.
Yield, Quality, and Breeding Behavior of Pearl Millet ✕ Napiergrass Interspecific Hybrids1
Authors: Hanna Wayne W. , Monson Warren G. 
Published: July 2010

AbstractHigh quality forage production is needed in late summer and fall until frost. The pearl millet (Pennisetum americanum ✕ napiergrass (P. purpureum Schum.) interspecific hybrids have potential for producing high quality forage during this period but more than 1 year's data on a number of hybrids using different female parents is limited. In 1976, 1977, and 1978, 20 pearl millet ✕ napiergrass interspecific hybrids were seeded in the field in a Fuquay soil (Arenic Plinthic Paleudults : loamy, siliceous thermic) and evaluated for dry‐matter yield percent in vitro dry‐matter digestibility (IVDMD), percent crude protein, agronomic characteristics (seed Production, pest resistance, yield distribution), and breeding behavior (effects of male and female parents on dry matter yield). Most of the interspecific hybrids were equal to the best pearl millet hybrids in yield, IVDMD, and protein. In 1977 and 1978, six and two interspecific hybrids, respectively, were significantly (P = 0.05) higher in dry matter yield. One hybrid, Tift 23A ✕ N23, yielded 34 and 27% more dry matter in 1977 and 1978, respectively, than the best pearl millet hybrid. Hybrids with ‘Tift 23A1’ yielded over 25% more dry matter than hybrids with ‘Tift 23D2A1 when the same male parents were used on both female parents. One of the major advantages of the interspecific hybrids is that they produced almost 50% of their forage from after the middle of August until early December.This study also showed that of the three female parents tested, Tift 23A1 produced the highest yielding hybrids and that much variability for maximizing yield exists among the napiergrass clones used as male parents in the interspecific hybrids.
Thatch Influence on Mobility and Transformation of Nitrogen Carriers Applied to Turf1
Authors: Nelson K. E. , Turgeon A. J. , Street J. R. 
Published: July 2010

AbstractThatch frequently exists as part of the edaphic environment of a turfgrass community and thus, should be considered when attempting to determine the fate of topically applied fertilizers in turf. The purpose of these investigations was to determine the influence of a thatch layer on the vertical mobility and transformation of soluble and slowly soluble N carriers following application.Measurements of N leaching, retention, and volatilization were made using cores of thatch and Flanagan silt loam (Aquic Argiudoll) soil extracted from fieldgrown turf of Kentucky bluegrass (Poa pratensis L.). Urea was selected as the soluble N carrier, and isobutylidene diurea (IBDU) was the slowly soluble N carrier. Application of urea resulted in 2.5 times as much N leaching and correspondingly lower N retention, in thatch than in soil. Where IBDU was used as the N source, leaching from the thatch was reduced from 81 to 5% of the applied N, and leaching from the soil was reduced from 32 to 23% compared to urea‐treated cores. In the volatilization studies, 39% of the applied N from urea was lost as ammonia from thatch cores compared to only 5% from the soil cores. Where IBDU was the N source, little N volatilization (4% from thatch, 2% from soil) occurred. In conclusion, where a substantial thatch layer exists, and turfgrass rooting is largely confined to the thatch layer, use of a slowly soluble N carrier might be preferable over soluble urea for reducing N losses due to leaching and volatilization. As an alternative, effective measures for controlling the thatch may result in greater efficiencies in the use of fertilizer N by the turfgrass community.
Effects of Plant‐Water Stress on Root Distribution of Corn, Soybeans, and Peanuts in Sandy Soil1
Authors: Robertson W. K. , Hammond L. C. , Johnson J. T. , Boote K. J. 
Published: July 2010

AbstractThe efficient recovery by crops of added nutrients and water is influenced by plant rooting characteristics. Published data on the relationship of irrigation water and root distribution of certain crops grown on sandy soils in humid regions are lmited and needed. This field study was a part of an investigation on three soil types to determine the effect of plant‐water stress and irrigation on root distribution of corn (Zea mays L.), soybeans [Glycine max (L.) Merr.], and peanuts (Arachis hypogaea L.). The basic irrigation plan was to replenish the water deficit in only the top 30 to 60 cm of the soil profile. Depth of wetting and the degree of soil water depletion below the irrigated soil layer varied with irrigation frequency and amount of water per application. Although treatments were not the same in the four experiments reported, the major part of the study involved four water management treatments: 1) no irrigation; 2) light, infrequent irrigation; 3) light, frequent irrigation; and 4) medium, infrequent irrigation. Seed yields were obtained at maturity and root length measurements were made at full canopy. Root lengths per unit volume of soil were measured by the Line intercept method. Yields of corn and peanuts increased with total amount of irrigation water used, but there was no yield response to irrigation in the soybean experiment. Peanut and soybean root growth (root length per unit area to a depth of 150 cm) was not affected by water management. In the corn experiments, irrigation increased the length of roots in the 150 cm soil profile. The largest root length value was found in the light, infrequent irrigation treatment. Crops vary in rooting response to plant‐water stress and irrigation strategy. Limited rooting of corn under water stress very likely decreases the efficiency of water and fertilizer use.
Water Status of Cotton as Related to Taproot Length1
Authors: Meyer Wayne S. , Ritchie Joe T. 
Published: July 2010

AbstractIn dryland crop areas it is common for plants to depend on subsoil water for some part of the growing season. In this situation, water moves through a considerable length of root axis to reach the plant top. Resistance to this movement of water (axial resistance) can become significant. This experiment was designed to assess the interaction of root geometry and plant water status and to compare values of root resistance calculated for two contrasting cotton (Gossypium hirsutum L.) root systems. Cotton plants were grown in a greenhouse either in pots (26‐cm‐deep) or in soil‐filled tubes (120 cm‐long) supported in base pots. After initial watering of the soil in tubes, only the base pots were watered, so that plants developed long taproots and depended on water in the base pots.Except for the strong development of the taproot with in the tube, little other root growth occurred there because of soil drying. The taproots of pot‐grown plants were not well defined 20 cm from the plant base because of extensive branching. Rooting density in the base pot of plants with long taproots was 5.2 ± 0.7 cm cm−3 and compared with 13.7 — 5.6 cm −3 for plants grown in pots. Plants of the two treatments had similar leaf area, rate of water uptake, and value of both covered and exposed leaf water potential. Within the long taproots many secondary xylem vessels had been laid down. Individual xylem vessel size tended to increase with distance from the plant base. Calculated values of axial resistance (0.0097 cm−3 day bar) for long taproot were less than for the taproot of pot‐grown plants (0.0153 cm−3 day bar) because the increase in equivalent xylem vessel size more than offset the effect of the increased length. Values of total root resistance were calculated from the potential difference between covered leaf water potential and soil water potential divided by the water uptake rate. Total root resistance values were similar, and so, by difference, radial root resistance was larger for the long‐rooted plants. This difference is explained by the difference in rooting density. We concluded that a balance was apparently maintained between the absorbing length of the root system and the longitudinal transport system.
Evaluation of Commercial Soybean Inoculants by Various Techniques1
Authors: Hiltbold A. E. , Thurlow D. L. , Skipper H. D. 
Published: July 2010

AbstractMuch of the expanding production of soybeans (Glycine max L.) in the southeastern United States and in other countries is on soils without naturalized populations of Rhizobium japonicum. Effective inoculation is essential where soybeans are planted for the first time. Considering the frequency of inoculation failures and the variety of inoculant products available to growers, research was initiated, to determine relative effectiveness of inoculants and to compare evaluation techniques. Commercial soybean inoculants sold in Alabama in 1976, 1977, and 1978 were evaluated by rhizobial plate counts in two laboratories, most probable number (MPN) determination, greenhouse pot test and acetylene reduction assay, and by field experiments in R. japonicum free soil. Serial dilution and standard plating techniques, along with MPN by soybean nodulation, provided measures of viability in the inoculants. Products were applied in greenhouse and field experiments according to manufacturer's instructions. Nodulation, N fixation, and yield of soybeans were measured relative to numbers of rhizobia applied per seed by various products.More than 1,000‐fold differences were found among products in viable rhizobia content. Plate counts adequate discriminated products when 107 rhizobia per gram was considered to be the lower limit for acceptability. The close correlation of plate counts and MPN (soybean nodulation) indicated reliability of plate counts despite the difficulty of enumerating rhizobia among numerous contaminants. Nodulation of soybeans in greenhouse and field plantings in soil free of R. japonicum was directly related to the number of rhizobia applied per seed, with no nodulation produced by products supplying fewer than 108 rhizobia per seed, and generally abundant nodulation by products providing 105 to l06 rhizobia per seed. Some products performed poorly despite apparent adequate viability; for example, where a fungicide was added at planting. Various strains of R. japonicum and formulation processes, as well as number of rhizobia applied, may account for differences in nodulating effectiveness. In no case, however, was a product of low plate count found to be an effective inoculant. Plate count provides a relatively rapid, inexpensive evaluation that is supported by other techniques involving soybean nodulation response.
Phosphorus Influx and Growth Characteristics of Corn Roots as Influenced by Phosphorus Supply1
Authors: Anghinoni I. , Barber S. A. 
Published: July 2010

AbstractKnowledge of the effect of P status of corn (Zea mays L.) plants and P distribution in the toot zone on P influx and root growth is important for simulation modeling of P uptake by corn. Only limited information is available. The objective of this research was to determine the relation between plant P status and the portion of the roots supplied with P on plant P influx and root growth and morphology. Two solution culture experiments were conducted in controlled climate facilities. Phosphorus influx was measured on 18‐day‐old corn plants that had been starved for P for 1 to 6 days. Split‐root experiments were used to measure the effect of P distribution on root growth and P uptake. Starving the plant for P reduced P concentration in the shoot and root and this resulted in a 55% increase in the maximum P influx, Imax. Supplying P to only part of the root system also resulted in a lower plant P concentration and higher Imax by the roots in P solution. When less than 50% of the roots were supplied with P, root growth rate in the P solution was 25% greater than in the minus P solution. Phosphorus uptake was correlated with root surface exposed to P (R2 = 0.88).
Design and Testing of a Microlysimeter for Wetland Rice1
Authors: Tomar V. S. , O'Toole J. C. 
Published: July 2010

AbstractAssessment of water loss as transpiration and evapotranspiration for each hour or for each day in the field is difficult because the available methods are either very expensive or inaccurate. This paper introduces a simple, sensitive, and accurate microlysimeter for wetland rice (Oryza sativa L.) fields.The microlysimeter was designed and tested to measure transpiration and evapotranspiration in wetland rice fields. It consists of a poly‐vinyl‐chloride cylinder, sealed at the lower end and connected to a water reservoir/manometer through flexible tubing. A constant water level is maintained in the microlysimeter with a Mariotte system and water loss from the reservoir/manometer is measured. Total water loss as evaporation from free water surface in the cylinder and transpiration from canopy was measured as evapotranspiration. To measure transpiration, the cylinder was covered to stop evaporation from free water surface in the cylinder.The microlysimeters were laboratory‐calibrated and compared in the field with large square tanks. Water use pattern as evapotranspiration per unit land area was essentially the same with both the units. The microlysimeter is accurate even for time intervals as short as 1 hour and can be fabricated locally.
Comparison of Sprinkler, Trickle, Subsurface, and Furrow Irrigation Methods for Row Crops1
Authors: Sammis Theodore W. 
Published: July 2010

AbstractTrickle, subsurface, and sprinkler irrigation have been attributed to higher yields and water‐use efficiencies than the conventional furrow irrigation method.The purpose of this study was to determine the extent to which these irrigation systems could be used to increase water‐use efficiency while maintaining reasonable yields, compared to furrow irrigation, and to determine what effect the frequency of irrigation would have on resulting yields and water‐use efficiency.Potatoes (Solaneum tuberosum) ‘Kennebec’, and lettuce (Lactuca sativa) ‘GL‐659’ were watered by sprinkler, trickle, subsurface, and furrow irrigation to maintain a minimum soil‐water potential of −20 kPa and −60 kPa.When potatoes were grown on a Glendale clay‐loam soil (mixed calcareous thermic family of Typic Torrifluvent) at a location where rainfall did not supply a significant portion of their water requirements the highest yield and water‐use efficiency were achieved using a subsurface irrigation system with water applications occurring when the soil‐water potential at the 15 cm depth reached −20 kPa.When potatoes were grown on a Pedrick sandy‐loam soil (coarse‐loamy, mixed calcareous, Mesic Ustic Torriorthent) and rainfall contributed a significant portion of the water requirements throughout the growing season, the highest water‐use efficiency was obtained with trickle and subsurface systems with water applications occurring when the soil‐water potential at the 15 cm depth reached −60 kPa. Differences in yields at this study site were non‐significant for all irrigation methods.The subsurface irrigation method appears to offer the best method of supplying uniform soil moisture in the root zone to the plant throughout the growing season, resulting in highest yields and high water‐use efficiencies.Comparable lettuce yields and water‐use efficiencies were achieved by trickle, sprinkler, and frequent subsurface irrigation treatments due to good stand establishment and avoidance of moisture‐stress conditions. Infrequent sprinkler irrigations reduced yields due to moisture stress. Furrow irrigation, using proper management and short furrow runs, resulted in yields and water‐use efficiencies as high as those of the other irrigation methods. Yield and water‐use efficiency were reduced when flooding of the beds occurred at germination.
Effect of Field Weathering on the Viability and Vigor of Soybean Seed1
Authors: TeKrony D. M. , Egli D. B. , Phillips A. D. 
Published: July 2010

AbstractThe quality of soybean [Glycine max (L.) Merr.] seed at harvest is dependent on the field production environment during development, maturation, and storage on the plant. These investigations were conducted to evaluate the effects of field weathering after physiological maturity (maximum dry seed weight) on seed viability and vigor. Five production environments were compared for two cultivars (‘Cutler 71’ ‐ 1973, ‘Kent’ and Cutler 71 ‐ 1974 and 1975). Seed was hand‐harvested at physiological maturity, harvest maturity (first time the seed dried to less than 14% moisture content), and at regular intervals for up to 3 months after harvest maturity. All seed were evaluated for viability (standard germination test) and vigor (accelerated‐aging germination test).Physiological maturity occurred at a seed moisture content of approximately 55% for both cultivars. The time interval from physiological maturity to harvest maturity (desiccation period) ranged from 10 to 20 days and was closely related (R2 = 0.88) to the mean open pan evaporation during the period. Seed viability and vigor were highest at physiological maturity and remained high (>80% germination) until harvest maturity for all but one production environment. Viability was maintained at these high levels for 1 to 2 months following harvest maturity for four of five production environments. However, seed vigor declined rapidly, reaching levels that were significantly (α = 0.05) less than those at harvest maturity within 4 to 39 days after harvest maturity. In four of the production environments, seed vigor reached a level of less than 50% germination within 1 month of harvest maturity. The time required for seed vigor to significantly decline following harvest maturity was closely related to mean air temperature (R2 = 0.90), mean minimum relative humidity (R2 = 0.94), and precipitation per day (R2 = 0.75). The wide range in seed vigor observed shortly after harvest maturity emphasizes the importance of timely harvest of seed fields and evaluation of seed viability and vigor soon after harvest.
Gaseous N Losses from Winter Wheat1
Authors: Hooker M. L. , Sander D. H. , Peterson G. A. , Daigger L. A. 
Published: July 2010

AbstractResearch monitoring N uptake by various agricultural crops has shown total N accumulations in the plant to increase prior to the growth stages around heading to flowering with a subsequent decrease in total N occurring after flowering. Volatilization of N from the plant may account for much of this loss as well as account for some of the deficits exhibited in N balance studies. Experiments were conducted in a gas‐tight growth chamber to determine what role plants alone may play in the overall loss of N from the soil‐plant system. Winter wheat (Triticum aestivum L.) was established, vernalized, and grown to maturity in the growth chamber. At first internode elongation, the chamber was closed and sealed for the duration of the experiment. Air supplied to the chamber during this period was bubbled through 1 N H2SO4 to remove ambient NH3 and through a reagent specific to NO and NO2 to remove these gases. Air samples were continuously drawn from the chamber and bubbled through 0.2 N H2SO4 to trap evolved NH3. These samples were collected weekly and analyzed using steam distillation. A second portion of the air sample was washed through the NO‐NO2 specific reagent and analyzed colorimetrically. Only trace amounts of NO and NO2 could be found at any time during the experiment leading to the conclusion that volatilization of these gases does not contribute significantly to the loss of N from the plant. Ammonia volatilized from the system at the rate of 0.34 to 0.89 ✕ 10−1 mg NH3‐N/m2/day prior to flowering. After flowering the rate of NH3‐N evolution increased to 1.03 to 1.32 ✕ 10−1 mg/m2/day. This dramatic increase in the rate of NH3‐N evolution at flowering coincides with the plant growth stage that researchers have begun to observe deficits in total N accumulations in the above ground portion of the plants. This data supports the hypothesis forwarded here, that volatilization of NH3 from plant tissue can partially account for the deficits in total N accumulation observed in plant tissue following flowering.