bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Soil Texture on Alfalfa Autotoxicity
Authors: Jennings John A. , Nelson C. Jerry 
Published: July 2010

AbstractA rotation interval is recommended between alfalfa (Medicago sativa L.) stands to avoid negative effects of autotoxicity. Differences in soil properties such as texture can strongly influence allelopathic expression in plants and may explain the large variation in research results and recommended rotation intervals among states. A laboratory experiment was conducted to determine the influence of soil texture on alfalfa autotoxicity. Alfalfa extracts were passed though leaching columns filled with topsoil of either Sarpy fine sandy loam (mixed, mesic Typic Udipsamments) or Carlow silty clay loam (fine, smectitic, mesic Vertic Endoaquolls) and fractions were collected. Control columns for each soil were leached with distilled water only. Sequential fractions were added to 50 alfalfa seed in petri dishes. Radicle length and percentage germination were measured after 3 d. Active fractions reduced radicle growth more than percentage germination in both soils. The autotoxic chemical or chemicals moved through the Sarpy soil faster than through the Carlow soil. Fifty percent more water was required to move the active fraction of the extract through 10‐cm columns of the Carlow soil than the Sarpy soil. Maximum autotoxicity within a fraction was greater for the Sarpy soil, but the effects appeared in more fractions for the Carlow soil. The results indicate that similar amounts of the autotoxic factor in sandy soil will have a greater influence on alfalfa seedling growth than in the clay soil. Conversely, the same amount of rainfall will leach the autotoxic factor from a sandy soil while only diluting it in a clay soil. Soil texture and rain water throughput may interact to affect length of rotation intervals needed for successful reseeding of alfalfa. Field research is needed to determine if rotation intervals can be modified based on soil texture and irrigation or expected rainfall.
Yield and Yield Components of Corn Interseeded with Cover Crops
Authors: Abdin Omar , Coulman Bruce E. , Cloutier Daniel , Faris Mohamed A. , Zhou Xiaomin , Smith Donald L. 
Published: July 2010

AbstractThe rising costs of pesticides, soil erosion, and environmental pollution associated with corn (Zea mays L.) production have led to consideration of alternative production methods. Growing cover crops with corn could address these problems. Field experiments were conducted in 1993 and 1994 at l'Assomption and Macdonald in Quebec to determine the effects of interseeding 12 cover crops on corn yield and yield components. Fall rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), a mixture of red clover (Trifolium pratense L.) and ryegrass (Lolium multiflorum Lam.), a mixture of white clover (T. repens L.) and ryegrass, subterranean clover (T. subterraneum L.), yellow sweetclover (Melilotus officinalis Lam.), black medic (Medicago lupulina L.), Persian clover (T. resupinatum L.), strawberry clover (T. fragiferum L.), crimson clover (T. incarnatum L.), alfalfa (Med. sativa L.), and berseem clover (T. alexandrinum L.) were seeded 10 and 20 d after corn emergence. The experimental design was a splitplot, randomized complete block with four replications at each site. The mainplots were the cover crop planting dates; the subplots were the 12 cover crop treatments and 3 controls (hand weeding, chemical weeding, and no weeding). Seeding the cover crops either 10 or 20 d after corn planting did not affect corn grain yield. Chlorophyll fluorescence measurements (Fv/Fm) indicated that corn plants were stressed when interseeded with crimson clover (P < 0.05). When there was competition for moisture, crimson clover was found to be too competitive with corn at the seeding rates used in this experiment. Corn yield was less affected by the interseeded cover crops under conditions of adequate rainfall. No consistent differences in corn grain yield components were found for cover crop treatments.
Phenological Temperature Response of Maize
Authors: Stewart Douglas W. , Dwyer Lianne M. , Carrigan Lori L. 
Published: July 2010

AbstractVariability of development rate estimates across locations and years using the current heat unit system of growing degree‐days (GDD) with maximum and minimum temperature thresholds of 30 and 10°C (GDD30,10) limits predictability of maturity in hybrid maize (Zea mays L.). Data sets of daily maximum and minimum air temperatures and dates of maize development stages were collected for a range of hybrids at locations in Canada and the northern USA (39° to 45° N lat). Data were analyzed to improve the temperature response functions for maize at different stages of development. Results indicate that during vegetative growth, phenological response to mean daily air temperature followed a sigmoidal curve beginning below 5°C, with maximum response to temperatures between 25 and 30°C. During reproductive growth, the temperature response function was flat from 0 to 12°C and rose significantly only with mean daily air temperatures greater than this range. A general thermal index (GTI) based on these two response functions improved estimation of maturity dates by 50% over estimates made using GDD30,10 (SE of 6.7 d for GTI and 13.6 d for GDD30,10 in estimating time from planting to maturity). The greatest improvement using GTI occurred for the reproductive period (SE of 5.8 d using GTI, compared with 12.1 d using GDD30,10). These results suggest that incorporating the temperature response function reported in this paper would improve prediction of maize development.
Contribution of Rice Tillers to Dry Matter Accumulation and Yield
Authors: Wu Guowei , Wilson Lloyd T. , McClung Anna M. 
Published: July 2010

AbstractA rice (Oryza sativa L.) crop functions as a population of tillers produced at different times and possessing specific growth characteristics. The objective of this study was to characterize the contribution of cultivar tillering ability to dry matter accumulation, yield components, and grain yield. Field experiments were conducted over a 2‐yr period using a completely randomized plot design at Beaumont, TX, grown under a pin‐point flood system, with a China clay soil (fine, smectitic, hyperthermic Oxyaquic Dystrudert). Three cultivars were chosen (Gulfmont, Rosemont, and Teqing), to represent moderate to high tillering abilities, and three plant densities were chosen (56, 112, and 169 plants m−2), to produce differential competition for light and nutrients. Teqing had the highest tillering ability and partitioned more mass to tillers, especially at the lowest plant density, with 77% of the total mass represented by tillers, compared with 71 and 69% for Gulfmont and Rosemont, respectively. However, total dry mass per unit area at harvest was not significantly different, contrasting the plant density treatments (1618, 1725, and 1744 g m−2 for the 56, 112, and 169 plants m−2 treatments, respectively, when averaged across cultivars). Both cultivar and plant density significantly affected a number of yield components, but not kernel weight. The higher yield of Teqing (918 g m−2), contrasted with the lower‐yielding Gulfmont (791 g m−2) and Rosemont (729 g m−2), appears largely to have resulted from its greater tillering ability, higher spikelet density, and longer maturation period, which makes greater use of the relatively long growing season length at Beaumont.
Soybean Leaf Morphology and Defoliation Tolerance
Authors: Haile Fikru J. , Higley Leon G. , Specht James E. , Spomer Stephen M. 
Published: July 2010

AbstractPlant tolerance to pest injury is an ideal component of integrated pest management (IPM) programs, because it places no selection pressure on pest populations, but tolerance is little understood and its use in pest management is limited. In field experiments in 1994, 1995, and 1996, we characterized tolerance to defoliation in ‘Clark’ soybean [Glycine max (L.) Merr.] isolines differing in leaf morphology: 3‐ and 5‐leaflet, narrow and wide leaflet. Sequential defoliation was imposed manually at the R2 stage (full flowering), based on an insect consumption model. In 1994 and 1996, with ample rainfall, all isolines expressed yield compensation or overcompensation for defoliation as high as 75%, due to compensatory regrowth and delayed leaf senescence; in 1995, however, when rainfall was marginal, defoliation caused significant yield reduction. Equal amounts of leaf tissue removed resulted in different leaf area indices (LAIs). Wide‐leaflet isolines had higher LAI than narrow‐leaflet isolines, but the narrow‐leaflet isolines, particularly Clark‐3N, had greater light interception capacity for a given LAI level and had a higher light extinction coefficient in 1995. This shows that light was available to leaves in the lower canopy in the narrow‐leaflet isoline. Both low and high defoliation treatments caused significant yield reductions in all isolines, except that low defoliation did not significantly affect the yield of Clark‐3N in 1995. The narrow‐leaflet isolines apparently tolerated defoliation better than the wide‐leaflet isolines because the narrow‐leaflet isolines had greater light interception and maintained equal or better yields, despite similar defoliation. In addition to LAI, both canopy light interception and light extinction coefficient are important criteria for selecting cultivars tolerant to defoliation.
Water Distribution in a Fragipan Soil during the Growing Season
Authors: Rhoton Fred E. , Römkens Mathias J. M. 
Published: July 2010

AbstractThe resistance to penetration developed during the formation of fragipan horizons effectively excludes plant roots from the water stored in this zone. Thus, plant roots are believed to be restricted to the use of water stored in the profile between the fragipan and soil surface. This study was conducted to determine if fragipan horizons contribute water to plant rooting zones during the growing season. Twelve experimental field plots were installed at each of three sites situated on Grenada silt loam (fine‐silty, mixed, active, thermic Glossic Fragiudalfs). Based on relative depths to the fragipan horizon, these three sites represented slight, moderate, and severely eroded phases of the soil. Access tubes were inserted to a depth of 30.5 cm below the fragipan surface on six of the plots at each site. Water contents were measured weekly by a combination of gravimetric and neutron probe methods from the 1984 through the 1987 growing seasons. Results indicate that the fragipan horizons contributed water to the overlying profile each growing season at all three sites. The extent of water loss from the fragipan was determined by its proximity to the soil surface. For the four growing seasons, the fragipan horizon contributed on average 15.6% of the water lost at the severely eroded site, compared with 5.5 and 6.1% at the slightly and moderately eroded sites, respectively. These results suggest that plants grown on soils with fragipan horizons have indirect access to water stored in that zone. Consequently, yield data from such studies must be carefully interpreted when comparing sites with a range of depths to fragipan.
Estimating Cotton Canopy Ground Cover from Remotely Sensed Scene Reflectance
Authors: Maas Stephan J. 
Published: July 2010

AbstractMany agricultural applications require spatially distributed information on growth‐related crop characteristics that could be supplied through aircraft or satellite remote sensing. A study was conducted to develop and test a methodology for estimating plant canopy ground cover for cotton (Gossypium hirsutum L.) from scene reflectance. Previous studies indicated that a relatively simple relationship between ground cover and scene reflectance could be developed based on linear mixture modeling. Theoretical analysis indicated that the effects of shadows in the scene could be compensated for by averaging the results obtained using scene reflectance in the red and near‐infrared wavelengths. The methodology was tested using field data collected over several years from cotton test plots in Texas and California. Results of the study appear to verify the utility of this approach. Since the methodology relies on information that can be obtained solely through remote sensing, it would be particularly useful in applications where other field information, such as plant size, row spacing, and row orientation, is unavailable.
Potato Yield, Petiole Nitrogen, and Soil Nitrogen Response to Water and Nitrogen
Authors: Meyer Roland D. , Marcum Daniel B. 
Published: July 2010

AbstractDetection of high NO3 concentrations in domestic wells has led to concern about excessive fertilizer N use in crop production. A potato (Solanum tuberosum L. cv. Russet Burbank) experiment was initiated to examine the effect of water and N on potato yield and quality, tuber N concentrations, petiole NO3 concentrations, and N distribution in the soil. The field trial consisted of a line‐source irrigation system with six water rates (0.33, 0.66, 1.00, 1.10, 1.20, and 1.30 times crop evapotranspiration ETc) each having six planting‐time N rates (0, 56, 112, 168, 224, and 448 kg ha−1) replicated four times with treatments applied to the same plots in two successive years on a Pittville sandy loam (fine‐loamy, mixed, mesic Typic Argixerolls). Yields were significantly increased with water, averaging 14.1 to 54.4 Mg ha−1 in 1992 and 20.8 to 46.5 in 1993. Nitrogen rate significantly increased yield in 1993, averaging 28.7 to 44.1 Mg ha−1, but not in 1992. Residual soil profile NO3‐N (1040 mg kg−1) present at planting time in the first cropping season was utilized, denitrified, or leached from the top 150 cm of soil by above‐normal winter rainfall before the beginning of the second season. At the end of the second season, low NO3−N concentrations were observed in soil profiles receiving 0, 112, and 224 kg N ha−1, whereas a concentration of 1050 mg kg−1 was found in the 0‐ to 60‐cm depth of soil with the 448 kg N ha−1 rate. High residual soil N in 1992 resulted in N use efficiency (NUE) for tubers of >200 g kg−1; in the 1993 season, however, NUE was > 300 g kg−1. Nearmaximum yields were obtained with 1.10 to ETc applied water and 0 to 56 kg N ha−1 in 1992 and with 1.10 to 1.30 ETc applied water and 168 to 224 kg N ha−1 in 1993.
Integrated Root System Age in Relation to Plant Nutrient Uptake Activity
Authors: Gao Shiyu , Pan William L. , Koenig Richard T. 
Published: July 2010

AbstractThe age of a root segment is inversely related to its nutrient uptake activity (uptake rate per unit root length). It is uncertain how this information should be incorporated into nutrient uptake models, due to our inability to characterize the age of a whole root system. A method of calculating an integrated root system age (IRSA) was defined, and two solution experiments were conducted to relate the N uptake activity of spring wheat (Triticum aestivum L.) to root age. Literature data also were analyzed to characterize the relationship between IRSA and nutrient uptake activity of whole plant root systems. Integrated root system age was defined as the summation of the mean ages of root segments produced during each growth period weighted by the ratio of the root length generated during each growth period to total root length. The NH4 and NO3 uptake activity of spring wheat decreased with plant age as IRSA increased, while plants with similar IRSA at 14 and 21 d had similar N uptake activity. These relationships between IRSA and the uptake activity of N, P, K, Ca, and Mg of corn (Zea mays L.) were also revealed from an analysis of published data. In young root systems, nutrient uptake activity declined rapidly as IRSA increased, while older root systems (IRSA >10 to 15 d) maintained a relatively low and gradually declining nutrient uptake activity with increasing IRSA. The IRSA is a useful parameter for characterizing nutrient uptake activity of an entire root system, providing a potential tool for modeling nutrient uptake.
SAS Code for Recovering Intereffect Information in Experiments with Incomplete Block and Lattice Rectangle Designs
Authors: Federer Walter T. , Wolfinger Russell D. 
Published: July 2010

AbstractEfficient use of resources and time requires optimal planning of designed experiments and optimal recovery of information from them. Selection of an appropriate experiment design and selection of an appropriate statistical analysis are mandatory for efficient experimentation. It is known that using a random effects model is more efficient than using a fixed effects one, as in the analysis of variance, meaning that fewer experimental units (plots) will be necessary to obtain the same precision. The question of transformation of data prior to analysis, of using standard textbook analyses, or of using a form of spatial analysis arises with each experiment. To obtain these analyses, it is desirable that computer programs (code) be available to the experimenter. Computer programming to recover the information from random effects is not well or widely understood. In light of recent developments of software for performing the needed calculations, a description of SAS programs is presented. Code is described for recovering interblock, interrow, intercolumn, intergradient, and interregression information in incomplete block and lattice rectangle (row‐column arrangement within each complete block) designed experiments. These are illustrated with a numerical example.
Starter Nitrogen and Growth Habit Effects on Late‐Planted Soybean
Authors: Starling Michael E. , Wood C. Wesley , Weaver David B. 
Published: July 2010

AbstractIn the Gulf Coast region of the southeastern USA, soybean [Glycine max (L.) Merr.] is often planted in a double‐cropped system following corn (Zea mays L.). In this system, soybean planting date is delayed from the optimal range (mid‐May to mid‐June) to late July, causing a substantial yield reduction. Potential grain yield response has led to increased interest in indeterminate growth habit and N application for late‐planted, double‐cropped soybean systems. Our objective was to determine the interactiv effects of growth habit (determinate and indeterminate stem termination types) and starter N (0 and 50 kg ha−1) on soybean growth and yield when planted following corn in a double‐crop system. Three Maturity Group VIII soybean genotypes [the near‐isolines Au86‐2397I (Dt1Dt1, indeterminate) and Au86‐2397D (dt1dt1, determinate) and a determinate check cultivar, Cook] were planted in late July in seven Alabama environments during 1995 and 1996. Starter N increased R1 dry matter for both Au86‐2397D and Au86‐2397I by 0.50 Mg ha−1. Au86‐2397I had 1 cm greater average plant height at the R1 developmental stage and 14 cm greater height at R8 than Au86‐2397D. Au86‐2397I yielded 0.16 Mg ha−1 more than its determinate near‐isoline. Application of starter N decreased the number of nodules per root, but increased plant N concentration and dry matter yield. Grain yield was increased on average by 0.15 Mg ha−1 with addition of starter N. In this study, an indeterminate genotype soybean coupled with application of starter N promoted greater soybean growth and yield in a late‐planted, double‐cropped system.
Phytotoxicity of Banded Urea Amended with Triple Superphosphate and Potassium Chloride
Authors: Ouyang Duosheng , MacKenzie Angus F. , Fan Mingxian 
Published: July 2010

AbstractBanded urea can result in toxicity to corn (Zea mays L.) germination and growth, due to accumulation of NH3 and NO‐2s as a result of urea hydrolysis. Delaying urea hydrolysis through addition of acidic materials may reduce urea toxicity. Laboratory and field experiments were conducted to study phytotoxicity of banded urea amended with triple superphosphate (TSP) or KCI. A Ste. Rosalie clay (fine, mixed, frigid Typic Humaquept), an Ormstown silty clay loam (fine‐silty, mixed, frigid Typic Humaquept), and a Chicot sandy clay loam (fineloamy, mixed, frigid Typic Hapludalf) were used in the laboratory to investigate corn germination and growth across distances of 2.0 and 4.0 cm from the fertilizer band with four rates of TSP (0, 0.11, 0.22, and 0.33 g P kg−1), two rates of KCI (0 and 0.42 g K kg−1), 0.50 g urea‐N kg−1 and an unfertilized control. Field experiments were conducted on a Ste. Rosalie clay and an Ormstown silty clay loam with two rates of urea (60 and 120 kg N ha−1) and three rates of TSP (0, 26, and 52 kg P ha−1), either compacted or blended. In the laboratory experiment, NO‐2‐N, and pH decreased with TSP and KCI, due to delayed urea hydrolysis. Soil electrical conductivity (EC) increased with KCI, but was not affected by TSP. Corn growth decreased with increased soil NH3 concentration and EC. In the field, corn germination decreased with banded urea and increased with banded TSP at Day 10 after planting, but no difference was found at Day 20. Compacted mixtures of urea‐TSP increased corn germination, growth, N uptake, and yield compared with blended mixtures for the same rate of P. Compaction of urea and TSP may provide an effective way to improve efficiency of banded urea for corn production.
Acidic Soil Amendment with a Magnesium‐Containing Fluidized Bed Combustion By‐Product
Authors: Stehouwer Richard C. , Dick Warren A. , Sutton Paul 
Published: July 2010

AbstractRemoval of SO2 from the emissions of coal‐fired boilers produces by‐products that often consist of CaSO4, residual alkalinity, and coalash. These by‐products could be beneficial to acidic soils because of their alkalinity and the ability of gypsum (CaSO4·2H2O) to reduce AI toxicity in acidic subsoils. A 3‐yr field experiment was conducted to determine the liming efficacy of a fluidized bed combustion boiler by‐product (FBC) that contained 129 g Mg kg−1 as CaMg(CO3)2 and MgO and its effects on surface and subsurface soil chemistry. The FBC was mixed in the surface 10 cm of two acidic soils (Wooster silt loam, an Oxyaquic Fragiudalf, and Coshocton silt loam, an Aquultic Hapludalf) at rates of 0, 0.5, 1, and 2 times each soil's lime requirement (LR). Soils were sampled in 10‐cm increments to depths ranging from 20 to 110 cm, and corn (Zea mays L.) and alfalfa (Medicago sativa L.) were grown. Application of Mg‐FBC increased alfalfa yields in all six site‐years, whereas it had no effect on corn grain yield in five site‐years and decreased grain yield in one site‐year. Plant tissue concentrations of Mg, S, and Mo were increased by Mg‐FBC, while most trace elements were either unaffected or decreased. Application of Mg‐FBC at one or two times LR increased surface soil pH to near 7 within 1 wk. Although surface soil pH remained near 7 for 2 yr, there was minimal effect on subjacent soil pH. Application of Mg‐FBC increased surface soil concentrations of Ca, Mg, and S, which promoted downward movement of Mg and SO4. This had different effects on subsoil chemistry in the two soils: in the high‐Ca‐status Wooster subsoil, exchangeable Ca was decreased and exchangeable Al was increased, whereas in the high‐Al‐status Coshocton subsoil, exchangeable Al was decreased and exchangeable Mg was increased. The Mg‐FBC was an effective liming material and, because of the presence of both Mg and SO4, may be more effective than gypsum in ameliorating subsoil Al phytotoxicity.