bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thatch Accumulation in Bermudagrass as Influenced by Cultural Practices1
Authors: White R. H. , Dickens Ray 
Published: July 2010

AbstractExcessive thatch accumulation is a serious problem in golf course putting greens and other intensively managed turfgrass areas. More effective procedues for thatch control are needed. The relationship between different cultural practices and thatch accumulation was studied on Dothan sand loam (fine‐loamy, siliceous, thermic Plinthic Paleudult) in an experimental putting green planted to three bermndagrasses [Cynodon dactylon(L.) Pers. × C. transvaalensisBurtt‐ Davy] cultivars Tifdwarf, Tifgreen, and a selection called Dothan. Practices evaluated included N source, core aerification, vertical mowing, and sand topdressing. A multiple split plot experimental design allowed the evaluation of each individual practice in combination with all others. Effects of treatments on thatch were determined by measuring thatch depth and the compressibility of the turf surface with a thatch compression meter. Thatch accumulation, after three seasons, increased in the order: Tifgreen, Dothan, Tifdwarf. However, the effects of treatments on thatch accumulation were similar for all cultivars. Four topdressings per year reduced thatch accumulation more than a single topdressing and increased mat depth. Neither monthly aerification nor biweekly vertical mowing provided more thatch control than twice yearly application of the respective cultural practice. Fertilization with activated sewage sludge resulted in 14% more thatch than when NH4NO3was the N source. Within a given topdressing frequency, no differences in thatch accumulation occurred among N sources, levels of aerification, or vertical mowing. The regression of millimeters compressibility on thatch depth was not significant. Turf quality was not correlated with thatch depth. Tifdwarf had the greatest accumulation on thatch and also produced high turf quality ratings. Nitrogen source influenced turf quality more than other treatments. Activated sewage sludge produced superior turf quality, although more thatch was produced than when NH4NO3was applied. Cultural practices had no consistent effect on establishment of ‘Pennfine’ perennial ryegrass (Lolium perenneL.) overseeded on the experimental green. Ammonium nitrate produced better ryegrass quality than activated sewge sludge. Plots fertilized with activated sewage sludge had significantly more annual bluegrass (Poa annuaL.) than those receiving NH4NO3. Core aerification, topdressing, nor vertical mowing frequency affected ryegrass quality or annual bluegrass occurren
Sulfate Uptake Kinetics of Three Annual Range Species1
Authors: Shock Clinton C. , Williams William A. 
Published: July 2010

AbstractThe sulfate uptake rates of roots of three annual forages were found to follow different Michaelis‐Menten kinetics. Depletion of added sulfate from the nutrient medium by intact plants gave more reproduceable results than excised roots. Subclover (Trifolium subterraneumL.) showed the lowest affinity for sulfate but a high maximal rate of sulfate uptake. Soft chess (Bromus mollisL.) showed bimodal behavior either with a very high affinity and a low maximal uptake or low affinity with high maximal uptake, suggesting that two uptake mechanisms operate in this species. Sulfate uptake rates decreased with plant age for all three species. The decrease was greatest with filaree [Erodium botrys(Cav.) Bertol.] and least with soft chess. A root temperature of 4°C reduced sulfate uptake by all species implying that sulfate uptake depends on active metabolism. When returned to 20°C, sulfate uptake rates for subclover and filaree recovered immediately, but soft chess recovered only partially. Reduced O2from aeration with N2gas decreased sulfate uptake rates for subclover and soft chess but not for filaree. Subclover recovered quickly to the uptake rates observed before treatment, but soft chess did not. Selenate and molybdate interfered with sulfate uptake. Molybdate at 20 µMhad rapid deleterious effects on the root systems of all species. Selenate at the 20 µMconcentration showed no effect on soft chess, but sulfate uptake of filaree and subclover was reduced initially and plant death occurred within 24 h. The ecological significance of sulfate uptake kinetics is discussed with respect to botanical composition changes that occur with increased S supplies on deficient rangelands.
Effect of Etridiazol and Nitrapyrin Treated N Fertilizers on Soil Mineral N Status and Wheat Yields1
Authors: Liu Shyilon L. , Varsa E. C. , Kapusta G. , Mburu David N. 
Published: July 2010

AbstractEtridiazol[5‐ethoxy‐3‐(trichloromethyl)‐1,2,4‐thiadiazole] and nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine] are two nitrification inhibitors that offer potential for reducing N losses in soils from denitrification and leaching, thereby improving N utilization by crops. The objective of this study was to evaluate the ability of these two compounds to reduce nitrification of applied N fertilizers in soils and influence wheat (Triticum aestivumL.) yields. Experiments were conducted in 1977, 1979, and 1980 on Weir (fine, montmorillonitic, mesic Typic Ochraqualfs) and Stoy (fine‐silty, mixed, mesic Aquic Hapludalfs) silt loam soils, typical for wheat production in southern Illinois. Anhydrous ammonia, urea, and urea‐ammonium nitrate (UAN) solutions were applied without and with the two inhibitors at 0.56 and 1.12 kg/ha. Nitrogen rates varied incrementally from 0 to 150 kg/ha. Fertilizers with the inhibitors were applied in the fall prior to wheat seeding. Mineral N forms in soils were determined periodically after application. Etridiazol and nitrapyrin were equally effective in reducing nitrification of ammonium N in soils up to 160 days following application when compared to nontreated fertilizers. Above normal precipitation and temperature tended to reduce inhibitor effectiveness. Both inhibitors at the higher rate generally had greater amounts of NH+4‐N present in soils on any date following application than the lower rate. Treating N fertilizers increased wheat yields from zero up to 32% above nontreated comparisons applied in the fall. Greatest responses were always associated with climatic and soil conditions that favored N losses by denitrification. No yield benefits accrued from the use of inhibitors when the applied N was not subject to loss conditions. Nitrification inhibitors added to fallapplied N resulted in wheat yields that were similar to and occasionally greater than those obtained from spring N topdressings.
Multistrain vs. Single Strain Rhizobium japonicum Inoculants for Early Maturing (00 and 000) Soybean Cultivars: N2Fixation Quantified by 15N Isotope Dilution1
Authors: Rennie R. J. , Dubetz S. 
Published: July 2010

AbstractEarly maturing soybean cultivars (groups 00 and 000) adapted to western Canada are now available but since the soils contain no indigenous Rhizobium japonicum, it is important to determine if strains selected for efficient N2fixation with American soybean cultivars are also efficient with Canadian cultivars and if single strain are superior to multistrain inoculants. Accordingly, a 2‐year evaluation was made of the effect of up to eight single strains and two commercial multistrain combinations of R. japonicumgranular inoculants on maturity, seed yield, oil and protein content, and N2fixation (as determined for the first time by 15N isotope dilution) for three promising soybean lines. Rhizobium japonicumstrains 61A148 (USDA 142) and 61A118 (USDA 138) were consistently superior in N2fixation with all soybean cultivars, resulting in seed yields and seed protein higher than those of the other strains. Strain 61A101 was consistently an inefficient N2fixer. These differences in efficiency between strains were not related to documented ability to take up H2evolved by nitrogenase because, although strain 61A148 is considered Hup+, strain 61A118 is Hup–. Several strains resulted in percent plant N derived from the atmosphere exceeding 50% with N2fixed as high as 151 kg N ha−1for strain 61A148 on King Grain line X005. However, over all strains, Maple Amber was superior for supporting N2fixation, averaging 91 kg while X005 had 83 kg and Maple Presto 60 kg N fixed ha−1. Line strain combinations resulting in lower levels of N2fixation assimilated more soil N such that total N yields averaged over lines and strains were generally similar. These strains selected for U. S. soybean cultivars are also acceptable for Canadian soybeans. Interstrain competition occurred with one multistrain inoculant, to the detriment of plant yield. A commercial mix containing four strains (61A101, 61A118, 61A124, 61A148) had low N2fixation similar to that of strain 61A101. This suggested that strain 61A101 was highly competitive and may have formed a majority of the nodules thereby excluding the highly efficient strains 61A118 and 61A148. However, a new commercial mix containing three strains which were clones of 61A101, 61A118, and 61A124 did not exhibit any detrimental interstrain competition. Thus, the new multistrain soybean inoculant can be recommended for Canadian soybean cultivars.
Microclimate of a Rainfall Shelter1
Authors: Dugas W. A. , Upchurch D. R. 
Published: July 2010

AbstractTo induce water stress on crops grown in areas where extended periods without precipitation during the growing season are infrequent, rainfall shelters are increasingly being used. Shelters are moved over plots during or previous to precipitation. The microclimatic effects of a large (18 ✕ 48 m) fiberglass shelter near Temple, TX were investigated. Air temperature, solar radiation, wind speed, and relative humidity measurements were made throughout two growing seasons to determine the effect of the shelter on the canopy microclimate (relative to the microclimate outside the shelter) when the shelter was off and over the plots. When the shelter was over the plots, the effects upon wind speed and radiation, which were affected most, were consistent; radiation was reduced from 30 to 40% and, because of shelter design, wind speed was reduced to nearly zero. Generally, air temperature and humidity effects were dependent upon temperature and radiation levels. Air temperature differentials greater than 6°C developed within an hour after movement of the shelter over the plots, while radiation and wind effects occurred instantaneously. When off the plots, the shelter's microclimatic effects were not detectable. Under certain conditions, however, the shelter may significantly affect the microclimate. Therefore, researchers using shelters need to investigate the microclimate under a shelter for proper interpretation of plant responses to the environment.
Climate, Management, and N Effect on Corn Leaf N, Yield, and Grain N1
Authors: Asghari M. , Hanson R. G. 
Published: July 2010

AbstractTwo field corn (Zea mays L.) N response experiments, with previous cropping of alfalfa (Medicago sativa L.) and wheat (Triticum aestivum L.), were conducted for 4 years (1977 to 1980) on Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf). The study was conducted to relate the climatic factors of air temperature in June, July, and August, expressed as heat units, and precipitation during the same months to corn yield response to fertilizer N. A previous evaluation utilized grain N (a quantitative measurement) as measure of plant N sufficiency to develop a model integrating these climatic factors to predict total Nand fertilizer N requirements. The objective of this study is to integrate the variables of fertilizer N application by leaf N (a relative plant nutrient measurement) concentration with climatic parameters to predict N requirements for maximum yield. Regression analyses related relative yield to monthly precipitation, heat units, and their products of leaf N or applied N and the square of leaf N or applied N. The primary N source affecting leaf concentrations was from fertilizer N when corn followed wheat and from the previous crop residue when corn followed alfalfa. The critical leaf N concentration of 2.09 mol kg−1 was selected when relative yield of 97% was achieved, because additional increases in leaf N had little effect on yield. Precipitation and heat units accounted for 32 and 62% of the ear leaf N concentration when corn followed wheat and alfalfa, respectively. Including linear and quadratic terms of fertilizer N explained 98 and 92% variability, respectively, in the leaf N, and the fertilizer N requirements for yield maximization were calculated to be 152 and 66 kg ha−1 where corn followed wheat and alfalfa, respectively. This corresponded to 137 and 48 kg N ha−1 fertilizer requirements when 1.09 mol kg−1 grain N was used as the criterion for maximum yield. The summation of precipitation and heat units into the monthly periods of June, July, and August were significantly related to leaf N and grain N. Results indicate that leaf N concentration as well as grain N, can be used as a tool to quantify the N sufficiency and N fertilizer requirements for maximum corn yield.
Influence of Soybean Pubescence Type on Radiation Balance1
Authors: Nielsen D. C. , Blad B. L. , Verma S. B. , Rosenberg N. J. , Specht J. E. 
Published: July 2010

AbstractIncreasing the density of pubescence on the leaves and stems of soybeans (Glycine max L.) should influence the radiation balance of the soybean canopy and affect the evapotranspiration and photosynthetic rates. This study was undertaken to evaluate the influence of increased pubescence density on various components of the radiation balance. Near‐isogenic lines of two soybean cultivars (Clark and Harosoy) were grown in four adjacent small plots (18 ✕ 18 m) during the 1980, 1981, and 1982 growing seasons near Mead, Nebr. The soil at this site is classified as a Typic Argiudoll. The isolines of each cultivar varied only in the amount of pubescence (dense vs. normal pubescence). Measurements of albedo, reflected photosynthetically active radiation (PAR), emitted longwave radiation, and net radiation were made over the crop surfaces with instruments mounted on a rotating boom located at the intersection of the four plots. Radiative canopy temperatures were measured with a handheld infrared thermometer (IRT). Results show that dense pubescence increased reflection of shortwave radiation and PAR by 3 to 5% and 8 to 11%, respectively. Emitted longwave radiation and radiative canopy temperature were not significantly affected by increased pubescence, although there was a slight tendency for the dense pubescent canopy to be cooler. Increased pubescence decreased net radiation over the canopy by 0.5 to 1.5%. These results suggest that soybeans with dense pubescence may be slightly better adapted to the high radiation, high temperature, and limited moisture conditions of the eastern Great Plains than are those with normal pubescence.
Timing and Rate of K Application for Wheat‐Soybean Double Cropping on a Sandy Soil1
Authors: Elwali A. M. O. , Gascho G. J. 
Published: July 2010

AbstractThe wheat [Triticum aestivum (L.) em. Thell.] and soybean (Glycine max (L.) Merr.] double cropping sequence is an important cropping system in the Southern Coastal Plain of the USA. A study was conducted for two crop cycles to determine the optimum timing of supplying adequate K on a Bonifay sand (loamy, siliceous, thermic grossarenic, Plinthic Paleudult). Treatment variables consisted of five K application timings at two Mg rates (0 and 40 kg ha−1) in the first crop cycle, and four K application timings at four rates of K (90,135,180, and 225 kg ha−1) in the second crop cycle. Significant leaching of K from the 0 to 15 and 15 to 30 cm depth was measured when all of the K fertilizer was applied at wheat planting. Potassium uptake and grain yield of wheat were significantly greater for treatments in which one‐half of the total K fertilizer was applied at wheat planting and the remainder in February or as one‐fourth at wheat planting, one‐half in February and the remainder at 6 to 8 weeks after soybean planting compared with the application of all of K fertilizer at wheat planting, application of K at planting of both crops or split application of K in four equal increments on both crops. However, soybean yields were not significantly affected by the treatments in either cropping cycle. Application of Mg in the first cycle increased both soil and plant Mg concentrations but had no significant effect on yields. Increasing rates of K linearly increased wheat yield and soil K at soybean planting but had no significant effects on soybean yield or soil K at the end of the season. We concluded that delaying the application of at least one‐half of the K fertilizer until spring is essential for maintaining adequate K in the rhizosphere of wheat plants on deep sands.
Growth of ‘Braxton’ Soybeans as Influenced by Irrigation and Intrarow Spacing1
Authors: Ramseur E. L. , Wallace S. U. , Quisenberry V. L. 
Published: July 2010

AbstractAchievement of maximum crop yields necessitates the study of factors influencing yields. The influence of irrigation regime and plant population on growth of a Group VII determinate soybean [Glycine max (L.) Merr.] was measured to determine if a particular growth pattern would result in increased yield. In 1980 and 1981, ‘Braxton’ soybeans were grown in 0.91‐m rows on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludults) under full‐season irrigation (FSI), irrigation beginning at bloom (BI), and no irrigation (NI). Intrarow spacings ranged from 43 or 61 to 457 mm. At growth stage R2, FSI, BI, and NI plants had attained 72, 66, and 75%, respectively, of maximum height and 38, 35, and 55%, respectively, of maximum vegetative dry weight. Height, stem diameter, and dry weight were greater in the irrigated treatments than in NI. Fullseason irrigated plants were generally taller than BI and NI plants and had 1.7 times more dry weight at R2. With increasing spacing, height decreased while stem diameter increased. Vegetative weight was maximized at spacings of 76 mm or less. Development of canopy cover and LAI was more rapid with decreasing spacing and with irrigation. At least 90% canopy closure was obtained in all spacings of FSI and BI, whereas only 59% was achieved in NI. Yields were the same for FSI and BI, and, within irrigation treatments, there were no yield differences among spacings of 305 mm or less. We conclude that comparable yields can be obtained within a wide range of growth patterns, and that severe reductions in vegetative growth at R2 may have little influence on yield if water is supplied thereafter.
Row Spacing and Seeding Rate Effects on Yield and Yield Components of Soft Red Winter Wheat1
Authors: Joseph K. D. S. M. , Alley M. M. , Brann D. E. , Gravelle W. D. 
Published: July 2010

AbstractInformation to determine optimum row spacing and seeding rates for soft red winter wheat (Triticum aestivum L. em Thell.) in high‐yielding environments in the mid‐Atlantic Coastal Plain region is not available. Three field experiments were conducted in the Coastal Plain of Virginia (on Typic Hapludult and Aquic Quartzipsamments soils) to evaluate row spacing and seeding rate influences on grain yield of winter wheat grown with intensive management. Seeding rates ranging from 186 to 558 seeds m−2 were studied in row spacings of 10 and 20 cm with additional treatments of 744 and 1116 seeds m−2 in 10‐cm row spacings. Intensive management included adequate supplies of P, K, and micronutrients as preplant fertilizer, insecticide, and fungicide use, and split‐spring N applications. Measurements included wheat grain yield and yield components. Ten‐centimeter row spacings produced 0.6 to 0.8 Mg ha−1 higher grain yields than 20‐cm row spacings at similar seeding rates. Yield levels ranged from 5.0 to 8.1 Mg ha−1. Heads m−2 and kernels head−1 varied with seeding rate to a greater extent than weight kernel−1. Yields did not vary over a wide range of plant populations, but were reduced with low (469 heads m−2) or high (897 heads m−2) harvest populations. Seeding rates of 372 to 744 seeds−2 in 10‐cm rows were sufficient to produce high yields with the ‘Tyler’ cv. grown under intensive management.
Grain Sorghum Response to Tillage Method Used during Fallow and to Limited Irrigation1
Authors: Baumhardt R. L. , Zartman R. E. , Unger P. W. 
Published: July 2010

AbstractIn the Southern High Plains, grain sorghum [Sorghum bicolor(L.) Moench] is grown under various irrigation regimes from full irrigation to dryland. Continued water depletion from the Ogallala Aquifer and increasing expense of pumping water have resulted in a need for developing more water‐efficient irrigated crop production systems for this area. An experiment was conducted to determine the response of grain sorghum to limited irrigation and fallow management. Winter wheat (Triticum aestivumL.) residue was managed during fallow by either no‐tillage or disk‐tillage practices. The sorghum was grown dryland or received one well‐timed growing‐season irrigation. Precipitation stored as soil water during an 11‐month fallow period was significantly higher with no‐tillage than with disk‐tillage where 1.1 kg residue m‐2 was present, but not where only 0.2 kg m‐2 was present. Dryland no‐tillage yields were greater than disk‐tillage due to greater stored water at planting. A significant irrigation × tillage interaction was found for grain yield and water use efficiency only when water stress was severe at the time of irrigation. The combination of no‐tillage during fallow after wheat and a single, well‐timed irrigation for a succeeding sorghum crop was found to be a suitable transition system from an irrigation‐on‐demand to a dryland production system.
Interactive Effects of Pot Geometry, Water Management, Salinity, and Growing Medium on Growth and Yield Components of Snapbean in the Greenhouse1
Authors: Campbell W. F. , Wagenet R. J. , Jones A. 
Published: July 2010

AbstractResults of greenhouse experiments vary with pot size and shape, i.e., surface area/depth ratio (S/D), even when genetic, environmental, and nutritional factors are held constant. This paper demonstrates the importance of the S/D ratio on snapbeans (Phaseolus vulgarisL.) as influenced by salinity, water management, growing medium, and soil surface mulch. In the first experiment, plant dry weight, pod and seed number, and seed weight of ‘Blue Lake’ snapbean (bush‐type) were significantly reduced as the S/D ratio and electrical conductivity (EC) of the irrigation water increased. Plant dry weight was also affected by changes in watering interval (WI). With the exception of the EC × WI interaction, all of the interactions significantly affected plant dry weights. The S/D × EC interaction significantly affected seed number and seed weight per plant. In the second experiment, plant dry weight and pod and seed number per ‘Earliwax’ snapbean plant were significantly affected by S/D, water quantity (WQ), substrate type (ST), and WI. Substrate type and WI significantly affected seed weight per plant. Interactions involving S/D ratios, WQ, and WI significantly affected yield components. Soil surface mulches alone did not significantly influence individual yield components, but had significant effects in combination with S/D and WQ. Both of these experiments demonstrated the importance of S/D ratio on plant yield and provide further proof that the results of greenhouse experiments are not likely to correspond to those in the field.