bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Sampling Period on Nutrient Diagnostic Indices for Burley Tobacco
Authors: Evanylo G. K. , Grove J. H. , Sims J. L. 
Published: July 2010

AbstractDiagnosis and Recommendation Integrated System (DRIS) norms and critical values are two tools employed in the interpretation of plant analyses. The accuracy of these tools, especially DRIS, depends on their abilities to make diagnoses over time. Changes in values of burley tobacco (Nicotiana tabacum L.) leaf nutrient concentrations, and ratios from 35 d after transplanting (early) to postcuring (late) were examined to determine how the indices might respond as diagnostic norms over time. Total N, P, K, Ca, Mg, CI, and Mo analyses were performed on early and cured‐leaf tissue samples from a 2‐yr field study employing three N rates, four K rates, and two K sources (K2SO4 and KCI). The data were used in DRIS equations to determine the comparative abilities of early and late sampling to predict the order of nutrient limitations. Although sampling period (SP) and SP ✕ fertilizer treatment interactions significantly influenced nutrient concentrations and ratios, DRIS norms were able to make similar nutrient diagnoses on plant tissue sampled early and late. Precise diagnoses employing DRIS ratios over wide time periods can be obtained if large numbers of nutrients are considered simultaneously.
Digestion of Plant Materials for the Determination of Total Nitrogen to Include Nitrate
Authors: Silvertooth J. C. , Westerman R. L. 
Published: July 2010

AbstractMany modifications in procedures for N determination by Kjeldahl digestion exist. However, few modifications include the quantitative recovery of NO−3–N, which is essential in 15N research. A digestion procedure is described in which reduced Fe and H2SO4 pretreatment is used for the quantitative recovery of NO−3–N. The procedure utilizes an aluminum block digester with a programmable control unit. The recommended program employes a stepwise temperature ramp up to 400°C and continues digestion 1 h after clearing for a total digestion time of 7.25 h. Two other digestion programs were compared with the recommended program. One program used a temperature ramp identical to the first, but digested 2 h after clearing for a total time of 8.25 h. A third digestion program used a shortened temperature ramp, attained a final temperature of 400°C, and was completed 1 h after clearing for a total time of 5.90 h. Wheat (Triticum aestivum L.) grain samples with up to 0.5 mg additional NH+4–N and NO−3–N were used to evaluate these procedures. The recommended procedure provides complete recovery of grain N, and added N with superior levels of precision in comparison to the other digestion procedures evaluated. The digestion procedure using 5.90 h did not yield accurate analysis of grain N, indicating incomplete digestion. The 8.25‐h digestion did not result in improvement of grain N results or added N recovery.
Centipedegrass Response to Foliar Application of Iron and Nitrogen
Authors: Carrow R. N. , Johnson B. J. , Landry G. W. 
Published: July 2010

AbstractThe lawn‐care industry has interest in the use of foliar iron (Fe) to enhance the color of common centipedegrass [Eremochloa ophiuroides (Munro.) Hack.] without using excessive N. We evaluated different Fe carriers, Fe rates, and N rates in three different studies conducted on centipedegrass grown on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult). Minor differences occurred with respect to phytotoxicity but not visual quality or color from ferrous sulfate, ferrous ammonium sulfate, and Sequestrene 330 chelate. When visual quality and color ratings were made at 2 wk or more after application, the highest Fe and N rates always provided the best response. However, initial phytotoxicity [within 1 to 6 d after treatment (DAT)] from Fe and N dictated the use of much lower rates. If applied on a moderately warm day (21–33 °C), the maximum acceptable Fe rate was 2.0 kg ha−1 in combination with 0 or 9.8 kg N ha−1. Centipedegrass could receive up to 39.0 kg N ha−1 without any Fe before N burn was objectionable. On a very hot day (28–37.5 °C), only 0.73 kg Fe ha−1 could be applied with 12.2 kg N ha−1 without objectionable phytotoxicity. The maximum N rate that could be applied alone under these conditions was 24.2 kg N ha−1 before N‐induced phytotoxicity occurred. The 2.0 kg Fe ha−1 rate provided positive visual quality and color responses for up to 35 DAT, while 0.73 kg Fe ha−1 improved color for only 22 DAT. Results show that Fe can improve centipedegrass color, but that centipedegrass is very sensitive to phytotoxicity from Fe. Addition of N further reduces centipedegrass tolerance to Fe.
Nitrogen Argument for Corn Leaf Area Models
Authors: Flesch T. K. , Dale R. F. 
Published: July 2010

AbstractWhen soil N fertility is low, it should be considered in predicting corn (Zea mays L.) leaf area index (LAI). Measurements of LAI in 1978, 1979, 1983, and 1984 were used to develop an N growth factor (NGF) to reduce daily LAI increase before silking, based on N fertilizer rate (NR) and LAI in a corn LAI model developed for non‐N limiting conditions. With the NGF there is no reduction in rate of LAI increase when LAI is below a critical value (LAICNR) determined by NR. After LAI exceeds LAICNR, NGF reduces the rate of LAI increase according to NR. After silking there was no apparent N effect on the rate of LAI decline. A LAI prediction model using NGF was tested against independent LAI measurements in 1985, including data from plots receiving no N fertilizers. The LAI prediction errors were less than 20% for most of the season. This empirical NGF is a method to lower LAI predictions for corn with low N applications in models in which N fertility has not been considered.
Planting Seed Density in Relation to Cotton Emergence and Yield
Authors: Hofmann W. C. , Kittock D. L. , Alemayehu M. 
Published: July 2010

AbstractCotton (Gossypium hirsutum L.) planting seed density has been related to seedling emergence and vigor, although its effects on yield are not clearly understood. Seed lots of the cultivar ‘DP90’ were separated into four density classes using a gravity separation table. These seed classes were evaluated along with an undivided seed sample and a sample from processed seed selected for commercial use. The seed classes were planted at three planting rates in seven tests conducted from 1983 to 1985 at Maricopa, Marana, and Safford, AZ. The soils at these locations are Typic Camborthids, Thermic Torrifluvents, and Typic Torrifluvents, respectively. The lowest density seed had significantly lower standard and cold germination test results; however, there were no differences among the other five seed classes in 2 of the 3 yr. Field emergence of the highest density seed was significantly greater than that of the other density classes for the seven tests combined, and was significantly lower for the lowest density seed. Lint yields produced by plants from the highest density seed were significantly greater than those of the four other seed classes, and the lowest density seed produced significantly lower yields. There were no significant interactions between planting seed density and planting rate for yield. The results indicate that cotton planting seed quality could be improved slightly by selecting higher density seed
Seed Reserves and Seedling Development in Winter Wheat
Authors: Peterson Curt M. , Klepper Betty , Rickman R. W. 
Published: July 2010

AbstractSeed reserves are essential for germination of cereals including wheat, but the contributions of the endosperm and its associated aleurone layer to postgermination seedling development remain to be elucidated. Winter wheat (Triticum aestivum L. em Thell. ‘Stephens’) was grown for 36 d in a controlled environment from kernels of three sizes, and from kernels where part of the endosperm had been excised prior to sowing to study the contributions of seed reserves to seedling development. Excision of endosperm delayed the first two phyllochrons, prevented outgrowth of the coleoptilar tiller, and slightly delayed the appearance of the next two tillers. Plant dry weight, leaf numbers and dimensions, number of nodal roots, and total number of tillers were all affected by endosperm excision. The combined area of the first two leaves was linearly correlated with aleurone area for all seed treatments. Areas of later‐formed leaves and final dry weight of seedlings were directly related to the areas of the first two leaves. Thus, the aleurone layer, in addition to seed reserves, is important for the enlargement of the first two leaves, with subsequent seedling development controlled by the size of the first two leaves under the conditions used in this study.
Resin‐Coated Urea Evaluation for Turfgrass Fertilization
Authors: Hummel N. W. 
Published: July 2010

AbstractNew resin coatings have been developed for producing slow‐release fertilizers for turfgrasses. It is important that new fertilizer materials be evaluated so that recommendations can be made for their use. Four experimental resin‐coated ureas (RCU) were evaluated for maintenance fertilization of Merion Kentucky bluegrass (Poa pratensis L.) turf grown on an Arkport sandy loam (coarse‐loamy, mixed, mesic Psammentic Hapludalfs). The RCUs had an analysis of 41% N and laboratory release rates of 270 d (RCU‐270), 100 d (RCU‐100), and 70 d (RCU‐70). A mixture of the RCU materials (RCU‐M), sulfur‐coated urea (SCU), urea, a 22–1.8–6.6 with 10% by weight dicyandiamide (DCD), and oxamide were included for comparison. The fertilizers were applied at an annual rate of 196 kg N ha−1, as single‐spring or split‐spring, and fall applications. The most rapid response to fertilization as measured by fresh weight yields and color ratings was produced by urea, followed in order by SCU, RCU‐70, and RCU‐100. The release rate of RCU‐270 was too slow to produce acceptable color ratings through much of the test at both fertilization times. The most uniform response was produced by RCU‐100 at both the single‐spring and split treatments. The highest N recovery in the leaf tissue was obtained from oxamide (24 and 59%), the single‐spring application of SCU (27 and 58%), and the split applications of RCU‐100 (21 and 52%) and RCU‐70 (25 and 54%). Nitrogen recovery from SCU was highest in growth periods immediately following fertilization, while recovery was more uniform across growth periods with the RCU‐100. Certain RCU fertilizers are well suited for turfgrass fertilization.
WEEDER: an Advisory System for the Identification of Grasses in Turf
Authors: Fermanian T. W. , Michalski R. S. 
Published: July 2010

AbstractTo effectively control weeds found in a turf it is first necessary to correctly identify them. A computer program, WEEDER, was built using the artificial intelligence system AGASSISTANT to provide a means for effectively identifying grass weed and turf species through the recognition of selected variables. WEEDER has a rule‐based, non‐hierarchical knowledge base concerning 37 grass species commonly found in turfs throughout the USA. Each species is represented by 11 or fewer variables. In order to measure the value of WEEDER for identifying unknown grasses in comparison to a commonly used method, the dichotomous identification key, 41 volunteers were assigned to one of two groups; (i) those with any previous experience in plant diagnosis or any formal training in plant science; and (ii) those with no experience or training. Each individual identified four unknown grasses; creeping bentgrass (Agrostis palustris Huds.); perennial ryegrass (Lolium perrene L.); zoysiagrass (Zoysia japonica L.); and large crabgrass (Digitaria sanguinalis [L.] Scop.) using WEEDER or a printed identification key. The maximum mean of either group to identify a grass species was 55% of the specimens, which were examined by participants with plant science training using WEEDER. Participants with some plant science training had a higher mean identification of each species (23% identified) than participants with no training (18%) when using the identification key. Little difference in their ability to identify the unknown species was found between the two groups when they were using WEEDER. There was a significant increase in the mean ability of all participants to identify an unknown grass using WEEDER (50%) rather than the identification key (20%) after rules for the four species were modified. A demonstrated advantage of WEEDER over the printed key was its ability to be easily modified to increase its usefulness. The mean percentage of correctly identified grasses by all participants increased from 11 to 50% after rules pertaining to the unknown grasses were modified to reflect variable values most consistently selected. No significant dependency on a participant group was found for correctly identifying a grass species when using WEEDER after the rules were modified. Further testing of WEEDER is required to determine if the modified rules are consistent with additional grass sample and user populations.
Soil Properties' Role in Stem Canker Infection of Soybean
Authors: Rhoton Fred E. 
Published: July 2010

AbstractStem canker [Diaporthe phaseolorum (Cke & Ell.) Sacc. var. caulivora Athow and Caldwell] is a destructive disease of soybean [Glycine max (L.) Merr.] that can unpredictably increase from negligible amounts to near total infestation within a year. An understanding of the soil environment's contribution to these outbreaks is essential to any comprehensive stem canker research program. This study was designed to assess the relationship between several soil properties and different disease levels occurring over a range of soil conditions. Experimental plots were established at six sites that differed in depth of past erosion. A high‐fertility status (P, 140 kg ha‐1; K, 280 kg ha‐1) was maintained on one half of the plots at each site. The remaining plots were left unamended. Visual estimates of stem canker infection levels in 1986 equalled 72 and 86% for the fertilized and unfertilized treatments, respectively, at the slightly eroded site. Estimates for similar treatments at the most severely eroded site were 3 and 2%, respectively. Regression analysis indicated that soil organic matter content, pH, and soil water accounted for 66% of the variability in infection levels among the differentially eroded sites; whereas, plant residues from the previous crop year had no influence. Higher infection levels associated with the unfertilized plots were significantly correlated (P < 0.01) with lower concentrations of K in the soybean plants. These results indicate that greater stem canker infection levels can be expected on soils with higher organic matter, pH, and soil water content, and on soils that contain lower amounts of potassium.
Growth, Grain Yield, and Tissue Mineral Concentration of Corn Treated with Ethephon
Authors: Bullock D. G. , Raymer P. L. 
Published: July 2010

AbstractCorn (Zea Mays L.) lodging limits grain yield (yield) in the southeastern USA. Ethephon (2‐chloroethyl‐phosphonic acid) can reduce lodging, but its effect on tissue mineral concentration is unknown. The objectives of this study were to measure the effect of ethephon application rate and time on mineral concentration of tissue, yield, and lodging of corn. Field experiments were conducted during 1986 and 1987 on a Dothan loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudults). Three corn hybrids were planted as a four ✕ three factorial of rate (0, 0.14, 0.28, and 0.56 kg ethephon ha−1 and application time (1 to 2 cm long developing tassel as Time 1; Time 1 + 6 d; Time 1 + 12 d). Yield and grain moisture decreased as rate increased. Plant and ear height decreased as rate increased, and the magnitude of the inhibition increased as application time was delayed. Earleaf concentration (ELC) of N, P, K, Ca, S, B, and Cu; and grain concentration of N, P, K, and Mg increased (7 to 20%) as rate increased. Except for Zn ELC and K ELC, time did not affect mineral concentration.
Tillage Effects on Grain Yields in a Wheat, Double‐Crop Soybean, and Corn Rotation
Authors: Wagger M. G. , Denton H. P. 
Published: July 2010

AbstractCrop rotations in conjunction with the appropriate tillage system can be an important means for enhancing crop yields in the southeastern USA. The objective of this study was to determine the grain yield response in a wheat (Triticum aestivum L.), double‐crop soybean [Glycine max. (L.) Merr.), corn (Zea mays L.) rotation for different tillage sequences of conventional tillage (CT) and no‐tillage (NT). The four tillage sequences were; (i) continuous NT for all three crops; (ii) wheat CT, soybean NT, corn NT; (iii) wheat CT, soybean NT, corn CT; and (iv) continuous CT for all three crops. A field experiment was conducted for 3 yr on a Pacolet sandy clay loam (clayey, kaolinitic, thermic Typic Hapludult) and an Aycock fine sandy loam (fine‐silty, siliceous, thermic Typic Paleudult) at North Carolina Piedmont and Coastal Plain locations, respectively. Notillage corn and soybean yields were greater than those in CT systems every year at the Piedmont location. Averaged over a 3‐yr period, these yield increases due to NT were 32 and 43% for corn and soybean, respectively. Corn and soybean yields were less affected by tillage at the Coastal Plain location, with NT yields greater than CT yields in only one year out of three for each crop. In general, wheat yields tended to be lower in a NT system at the Piedmont location, averaging 9% lower than CT wheat over a 2‐yr period. Yield increases for NT corn and soybean were attributed primarily to greater soil moisture availability as a result of reduced runoff. Tillage in the previous crop/year had little effect on grain yields.
Soil Potassium Distribution in Grazed K‐31 Tall Fescue Pastures as Affected by Fertilization and Endophytic Fungus Infection Level
Authors: Wilkinson S. R. , Stuedemann J. A. , Belesky D. P. 
Published: July 2010

AbstractFertilizer requirements of grazed pastures may be influenced by the spatial distribution of nutrients in animal excreta. This experiment was conducted to determine the effect of two levels of fertilization and endophytic fungus (Acremonium coenophialum Morgan‐Jones et Gams) infection of Kentucky‐31 tall fescue (Festucu arundinacea Shreb) on the lateral and vertical distribution of soil K after 3 yr of grazing. Each pasture consisted of 0.7 ha of a Cecil sandy clay loam (clayey, kaolinitic, thermic Typic Hapludult,) and was grazed using the put‐and‐take method. Forage was removed only by grazing. Endophytic fungus levels were 20% (Low endophytic fungus, LE) and 52% (high endophytic fungus HE), and fertilizer rates were 134‐15‐56 kg N‐P‐K (Low fertilizer LF), and 336‐37‐139 kg N‐P‐K ha−1 yr (high fertilizer HF) in a 2 ✕ 2 factorial replicated twice in a randomized block design. Each pasture was divided into 12 zones with each zone sampled separately to a depth of 122 cm before the grazing experiment began and then annually for 3 yr. Potassium did not accumulate in the majority of the pasture area at either fertility level except near the waterer, mineral feeder, and shade. Potassium accumulation rates in this area, determined by linear regression, were 7, 23, 23, and 46 kg K yr‐1 for LELF, LEHF, HELF, and HEHF treatments, respectively. These amounts were equivalent to 18, 24, 59, and 47% of the fertilizer K applied to the 0.7 ha pastures for the LELF, LEHF, HELF, and HEHF treatments, respectively. This accumulation was a result of animal grazing and resting behavior. Much of the K accumulated below 15 cm. Transfer of K by grazing steers to camping zones and subsequent leaching increased with fertility level and endophyte infection level. This redistribution reduces effectiveness of K recycling under grazing, and increases fertilizer K requirements in non‐camping zones.
Response of Five Food Legume Crops to an Irrigation Gradient Imposed During Reproductive Growth
Authors: Senthong Chuckree , Pandey R. K. 
Published: July 2010

AbstractFood legumes, an excellent source of protein and soil fertility improvement, offer small farmers a means of intensifying cropping on rice lands in semiarid and tropical regions. Unfortunately food legume productivity is often limited by variation in the amount and distribution of rainfall. The study was conducted to compare differential responses of mungbean (Vigna radiata L.), soybean [Glycine max (L.) Merr.], cowpea [Vigna unguiculata (L.) Walp.], peanut (Arachis hypogaea L.), and pigeonpea (Cajanus cajan L.) to a soil water gradient imposed during the reproductive growth phase. Field studies were conducted on Lipa clay loam, an isohyperthemic Typic Hapludoll silt loam soil, using a line source sprinkler irrigation system at the International Rice Research Institute, Philippines, from January to May during 1985 and 1986. Among the five species, peanut yielded significantly higher across the irrigation regimes in both years. Lack of water in the driest regime (50% water deficit replacement) reduced the seed yield of mungbean, soybean, cowpea, and peanut by an average of 43, 39,34, and 32%, respectively. However, pigeonpea seed yield increased by an average of 31% in the driest regime. Seed yield increases per mm of total irrigation water plus rainfall were 3.46 and 5.61 kg ha−1 in soybean, and 3.55 to 5.67 kg ha−1 in peanut in 1985 and 1986, respectively. However, pigeonpea yield per mm of total irrigation water plus rainfall declined 1.53 and 1.27 kg ha−1 in 1985 and 1986, respectively. Peanut performed best in irrigated as well as in rainfed environments, followed by cowpea, soybean, and mungbean. Pigeonpea was suitable only for the relatively dry, rainfed environment. Results indicate the need to match the suitable food legumes to maximize the rice land use.
Apparent Recovery and Physiological Efficiency of Nitrogen in Sesbania Incorporated before Rice
Authors: Furoc R. E. , Morris R. A. 
Published: July 2010

AbstractWhen incorporated for lowland rice (Oryza sativa L.), the agronomic efficiency of green manure N exceeding 100 kg ha−1 is low. Apparent N recovery and physiological efficiency of green manure N, ranging to 200 kg N ha−1 were determined on a fine, mixed, isohyperthermic Aerie Tropaqualf in the Philippines. Sesbania sp. accumulated 100 kg N ha−1 in 48 d and 160 kg N ha−1 in 60 d. Nitrogen uptake (NU, kg N ha−1) from green manures flooded during the last 25 d before incorporation was a linear function of incorporated N (NU = 49 + 0.23N). Uptake from green manures that were not flooded diminished as incorporated N increased (NU = 35 + 0.51N – 0.0012N2). The flooding effect was attributed to inhibition of NO−3 accumulation on submerged control plots. Nitrogen uptake was linearly related to extractable NH+4‐N determined 7 d after green manure incorporation. As N uptake increased, however, physiological efficiency declined. Dry‐season rice recovered only 6% of the green manure N not recovered by wet‐season rice. Because both apparent recovery and physiological efficiency are low, and residual green manure N recovery is minor, the advantage to growing Sesbania sp. for more than 48 d to accumulate N in excess of 100 kg ha−1 is limited.