bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery of Anhydrous Ammonia‐Derived Nitrogen‐15 During Three Years of Corn Production in Iowa
Authors: Sanchez C. A. , Blackmer A. M. 
Published: July 2010

AbstractStudies were conducted at two locations to determine recovery of anhydrous ammonia‐derived 15N applied with and without nitrapyrin [2‐ehloro‐6‐(trichloromethyI) pyridine] during corn (Zea mays L.) production over a 3‐yr period in which N fertilizers were applied annually at rates commonly used in the Corn Belt. The results showed that 13 to 33% of the labeled N was removed from the plots during grain harvest in the first crop after application. Recovery of labeled N in the whole plants ranged from 29 to 45%, but the stover was returned to the plots. Nitrapyrin increased the amount of N recovered in plant tissue at only one of the six site years studied. Only small percentages (0.3‐1.5%) of the labeled N were recovered in the second and third crops after application, and nitrapyrin had negligible effects on amounts of labeled N recovered by these crops. Analysis of soil samples collected 1 yr after application of labeled N showed that 19 to 23% of this N remained in the soil. Only small portions of this N existed as exchangeable ammonium and nitrate. Most of this N was in the KMI‐N (Kjeldahl minus inorganic‐N) fraction, which includes N from both organic matter and nonexchangeable ammonium. Large portions (47‐94% of the labeled N found in the KMI‐N fraction 1 yr after application were still present 3 yr after application. The results of this study show that a substantial portion (49–64% of the labeled N was lost from the surface 1.5 m of soil during the first year by processes other than plant uptake. A probable explanation as to why the losses reported here are greater than those reported from many comparable studies is that our determinations included the amounts of fertilizer N lost during the fall‐tospring period. These losses must be considered when evaluating the long‐term efficiency of N fertilization practices and the effects of these practices on environmental quality.
Root Length Density from Minirhizotron Observations
Authors: Bland William A. , Dugas William A. 
Published: July 2010

AbstractRoot length density (L; cm root/cm3 soil) measurements are important for developing and testing many water extraction equations. Clear tubes buried in the soil (minirhizotrons) allow continuous and nondestructive observations of rooting that may be used to estimate L. In a field experiment, counts of roots at the walls of horizontally installed minirhizotrons were converted to L with L = C × (counts/ area of tube wall), using published theoretical values of C (1.0, 2.0, and 3.3). These calculated values of L were then compared to measurements of L from roots washed from soil samples. For cotton (Gossypium hirsutum L.), C = 2.0 provided the best estimate of L from the minirhizotron counts, and the data were sufficient to reject the C = 1.0 model. For sorghum [Sorghum bicolor (L.) Moench], a simple relationship between minirhizotron counts and measured root length was not found. Verification of a theoretical model for the conversion of minirhizotron observations of cotton roots to root length density increases the utility of the method.
A Comparison of pH Measurements using the Antimony Microelectrode and Glass Electrode
Authors: Conkling B. L. , Blanchar R. W. 
Published: July 2010

AbstractMicroelectrodes are useful for making in situ soil pH measurements. A study was done to compare soil pH measurements made with a standard glass pH electrode with those made using an antimony (Sb) microelectrode. Soil‐water and soil‐water‐citrate systems were prepared using soil samples from various horizons of four Missouri soils, and the pH values of the same samples were measured with glass and Sb microelectrodes. Over all soils, the average difference between pH measurements made with the Sb and the glass electrodes in the soil‐water system was 0.36 pH units. In the soil‐water‐citrate system, pH measured with the Sb electrode was consistently higher than pH measured with the glass electrode, and the average difference was 0.64 pH units.
Productivity and Water Use of Proso Millet Grown under Three Crop Rotations in the Central Great Plains
Authors: Shanahan J. F. , Anderson R. L. , Greb B. W. 
Published: July 2010

AbstractProso millet (Panicum miliaceum L.) is a shallow‐rooted, short‐season summer annual that is well adapted to the semiarid conditions of the western Central Great Plains. However, cropping systems for proso millet have not been well established in this region. Three proso millet cultivars were grown under three crop rotations, millet‐millet (M‐M), winter wheat (Triticum aestivum L.) ‐millet (W‐M) and fallow‐millet (F‐M), for five growing seasons (1973–1977) to determine water use and productivity of the second component (proso millet) in each rotation. The research was conducted on a mesic Pachic Argiustoll soil at the Central Great Plains Research Station located near Akron, CO. Precipitation during the noncropped period for the W‐M and F‐M averaged 26 and 145% more, respectively, than the M‐M rotation. The W‐M and F‐M rotations exhibited 7 and 19% more seasonal crop water use, respectively, than the M‐M sequence over the 5‐yr period of the study. These differences in water use resulted in the W‐M and F‐M rotations producing 38 and 75% more total dry matter and 50 and 116% more grain yield, respectively, than the M‐M sequence. The three cultivars responded similarly to the three crop rotations. Since grain yields were low and variable for the M‐M rotation and the noncropped period was quite long (86 wk) and inefficient in soil water storage for the F‐M rotation, the W‐M rotation appears to be the most efficient rotation of the three rotations evaluated for producing proso millet in this region.
Influence of Tillage Practices on Phosphorus Distribution and Forms in Three Ultisols
Authors: Weil R. R. , Benedetto P. W. , Sikora L. J. , Bandel V. A. 
Published: July 2010

AbstractMany studies have indicated that organic matter levels in soils tend to rise when no‐till (NT) management replaces plowing. It was hypothesized that organic P may thus play a more important role in the plant availability of P in NT soils. A laboratory study was conducted to investigate the organic and inorganic forms of P and their cycling in NT and conventionally tilled (CT) silt loams. Soils from three long‐term field experiments were sampled in the fall of 1984, obtaining core segments from 0 to 2, 2 to 4, 4 to 8, 8 to 12, 16 to 20, and 24 to 28 cm. Soil analyses indicated significant differences in the distribution with depth of macro‐nutrients between tillage systems. Total P, dilute acid‐extractable P (DA‐P), total N, and organic matter were more concentrated in the 0‐ to 2‐cm layer under NT compared to CT management. Organic P did not accumulate to the same extent as did organic N and C, resulting in a lower organic P/organic C ratio under NT than under CT management. With increased rates of P fertilization on one soil, total P and DA‐P increased dramatically in the upper soil layers, but a similar increase and stratification of organic P was not observed. Samples taken in the spring of 1985 indicated that, despite significantly higher microbial respiration in NT cores, there was no consistent change in the solubility of P over a 75‐d incubation period. Thus, it was concluded that the incubation procedure inadequately measured P mineralization in these soils. However, water‐soluble P was significantly greater in the upper 5 cm under NT, even where no P fertilizer had been applied. This may have been a result of interference with P‐adsorption reactions by accumulated organic matter. This study provided no evidence that organic P is of more importance to plant P availability under NT.
Forage Sorghum Production on a Witchweed‐Infested Soil in Relation to Cutting Height and Nitrogen
Authors: Bebawi Faiz F. 
Published: July 2010

AbstractLittle is known about forage sorghum [Sorghum bicolor (L.) Moench] and forage sorghum‐sudangrass [S. bicolor × S. sudanense] hybrid production in soil infested with witchweed [Striga hermonthica (Del.) Benth]. The objective of the present study was to evaluate the immediate effects (first harvest) and aftereffects (second and third harvest) of two cutting heights (0.1 and 0.3 m) and five N treatments (0,60 + 60,120,120 + 120, and 240 kg N ha−1) on witchweed management in forage sorghum (cv. Abu Sabeen) and forage sorghum‐sudangrass (cv. Pioneer 988) hybrid. Field studies were conducted at Shambat, Sudan, in 1984 and 1985 on a heavy alluvial clay soil (montmorillonitic, isohyperthermic Vertic Camborthid) heavily infested with witchweed. Pioneer 988 was more tolerant of witchweed than Abu Sabeen at first harvest, but less tolerant of witchweed at later harvests. The shorter cutting height resulted indirectly in a larger number of tillers (26%) and a higher forage greenchop yield (37%) at first harvest. Nitrogen increased forage tiller density approximately twofold and forage greenchop yield by approximately ten‐fold at the first harvest. There was a concurrent, approximately fivefold reduction in witchweed shoot weight. At second harvest, forage tiller density, forage greenchop yield, and witchweed shoot weight were increased with N. Both forage sorghum and witchweed were dead in the zero N plots at third harvest. No differences were detected between single and split applications of N, or between low (120 kg N ha−1) and high (240 g N ha−1) rates of N. Forage tiller density, forage greenchop yield and witchweed shoot weight were reduced at the second and third harvests compared to the first harvest.
Yield, Soil Nitrogen Uptake, and Nitrogen Fixation by Soybean from Four Maturity Groups Grown at Three Elevations
Authors: George Thomas , Singleton Paul W. , Bohlool B. Ben 
Published: July 2010

AbstractThe exploitation of the soybean [Glycine max (L.) Merr.] ‐Bradyrhizobium juponicum symbiosis in varied environments requires an understanding of factors that may affect fixed and soil N assimilation. Temperature affects both soybean maturity and N requirement, and soil N availability. Five soybean varieties belonging to four maturity groups (00, IV, VI, and VIII) and their respective nonnodulating isolines were planted at three sites along an elevational transect in Hawaii to study the effect of elevation‐associated changes in temperature on yield, soil N uptake, and N2 fixation. The mean soil/air temperatures during the experiment were 24/23,23/21, and 20/18°C, with 7, 8, and 9°C differentials between mean maximum and mean minimum air temperatures at elevations of 320,660, and 1050 m, respectively. The soils of the two lower sites were Humoxic Tropohumults and that of the highest site was Entic Dystrandept. The seeds were inoculated at planting with B. japonicum. Plants were harvested at physiological maturity. Average dry matter yield and N accumulation at the highest site was only 48 and 41%, respectively, of that at the lowest site. Early maturing varieties were relatively more affected by high elevation than were later varieties. Within each site, late‐maturing varieties produced greater yield and accumulated more N than did the early varieties. Nitrogen fixation contributed 80, 66, and 97% to total plant N at the lowest, intermediate, and highest sites, respectively. Differences between sites in the proportion of N from fixation were due to differences in the availability and uptake of soil N. Although total N assimilation between varieties differed in some cases by more than 400%, the proportions of N derived from fixation were similar within a site. On a per‐day basis, N accumulation was similar among varieties at a site. Since the different maturity groups had similar average N assimilation rates per day within a site, and since soil N mineralization rate per day at a site can be assumed to be constant, the proportion of total N derived from N2 fixation is necessarily constant. Since the proportion of N derived from fixation is yield independent at a site, it may be possible to predict the relative contributions of soil N and symbiotic N2 fixation to soybean through characterization of the processes that affect N availability at a site. Data from in vitro soil N mineralization and a greenhouse pot test indicated that low temperature may have decreased root growth and uptake of soil N, or soil N availability more than it reduced N2 fixation.
Effect of Salinity on Grain Yield and Quality, Vegetative Growth, and Germination of Triticale
Authors: Francois L. E. , Donovan T.J. , Maas E. V. , Rubenthaler G. L. 
Published: July 2010

AbstractDevelopment of high yielding triticale (X Triticosecale Wittmack) cultivars may promote an increased acreage of this crop on irrigated soils in the western United States. Often these soils are, or have the potential to become, highly saline. Because of the lack of information on salinity effects on vegetative growth and seed yield of triticale, the salt tolerance of two cultivars (Beaguelita ‘s’ and Cananea 79) was determined in a 2‐yr field plot study. Six salinity treatments were imposed on a Holtville clay [clayey over loamy, montmorillonitic (calcareous), hyperthermic Typic Torrifluvent] by irrigating with waters salinized with NaCl and CaCl2, (1:1 by weight). Electrical conductivities of the irrigation waters were 1.8,2.6, 5.1, 7.5,9.6, and 12.2 dS/m the first year, and 1.4, 3.9, 7.9, 12.0,16.0, and 20.3 dS/m the second year. Grain yield, vegetative growth, and germination were measured. Relative grain yield for both cultivars was unaffected by soil salinity up to 7.3 dS/m (electrical conductivity of the saturated‐soil extracts in the rootzone). Each unit increase in salinity above 7.3 dS/m reduced grain yield by 2.8%. These results place triticale in the salt‐tolerant category. Yield reduction resulted primarily from a reduction in spike number rather than from lower weight per spike or lower weight per individual seed. Salinity reduced vegetative growth less than grain yield in Cananea 79 but more in Beaguelita ‘s’. Both cultivars were slightly less salt tolerant at germination than they were after the three‐leaf stage of growth.
Effect of Incrementing Nitrogen Application on Sucrose Yield of Sugarbeet
Authors: Anderson Frank N. , Peterson Gary A. 
Published: July 2010

AbstractNitrogen fertilization of sugarbeet (Beta vulgaris L.) usually increases root yields but decreases sucrose concentration. Therefore, management strategies must aim at an optimization of both that leads to maximum sucrose yield and not root yield. This study explored the value of applying N in increments to increase sucrose production and decrease top growth and impurities of the sugarbeet crop. The soil was depleted of N by cropping with corn (Zea mays L.) each year prior to the sugarbeet production year. Total N rates from 30 to 300 kg ha−1 N were applied in increments of 30,60, and 90 kg ha−1 over a time span of 16 wk each year of the experiment for 3 yr on a Tripp very fine sandy loam (coarse‐silty, mixed, mesic Typic Haplustoll). A series of hail storms in the second year of the experiment caused the N requirement to be higher for that year, as N in the leaves removed by the hail did not recycle. The first and third years demonstrated a normal pattern of greater top growth, lower sucrose concentration, and lower purity as N rates increased. Optimum N rates were 50 kg ha−1 higher for root yields than for maximum sucrose production. Delaying N supply by incrementing fertilizer applications favored root development and sucrose production but did not affect top growth.
Yield, Lodging, and Growth Characteristics in Sweet Corn as Influenced by Ethephon Timing and Rate
Authors: Gaska J. M. , Oplinger E. S. 
Published: July 2010

AbstractSummer storms frequently lodge sweet corn (Zea mays L.), making harvest difficult while reducing yields. Ethephon (2‐chloroethylphosphonic acid), a plant growth regulator, has the potential to be an anti‐lodging agent in sweet corn. Field research was conducted on a Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) at the Arlington Research Station near Arlington, WI, in 1985 and 1986 to determine the effect of ethephon timing and rate on sweet corn. Four rates (0, 140, 280, and 420 g ha−1) of ethephon were applied at three application timings [tassel elongation (TE), TE + 4 to 6 d, and TE + 9 to 13 d] to two plant densities of ‘Jubilee’ sweet corn. In 1985, plant densities of 49 400 and 66 700 plants ha−1 were used. In 1986, an additional ethephon rate of 70 g ha−1 and plant densities of 59 200 and 73 900 plants ha−1 were used. In hand‐harvested plots, ethephon altered yield and plant growth both years. High rates of ethephon reduced lodging by 87%, plant and ear height by 16 and 13%, respectively, and increased brace root development by 50%. High plant densities increased yields 8% and lodging 23%. Timing of ethephon application on yield had variable results. Yields were reduced 13% with the high rate of ethephon at the early and middle application times, but were not altered at the late application time. When the potential for lodging is high, ethephon at the higher rates and late application times may be effective in preserving sweet corn yields.
Interactive Water and Nitrogen Effects on Senescence of Maize. II. Photosynthetic Decline and Longevity of Individual Leaves
Authors: Wolfe D. W. , Henderson D. W. , Hsiao T. C. , Alvino A. 
Published: July 2010

AbstractStress‐induced senescence is frequently alluded to, but interactive effects of water and N deficits on leaf longevity and on physiological changes associated with leaf aging have received little attention. A 2‐yr field experiment with maize (Zea mays L.) was conducted on Yolo loam (fine‐silty, mixed, nonacid, thermic Typic Xerorthents) with four treatments: N fertilized (180 kg N/ha) with (NI) and without (ND) irrigation; and no N applied with (OI) and without (OD) irrigation. Size and longevity measurements were made of leaves at all nodal positions, and leaves 5, 11, and 15 (counting up from stem base) were monitored for changes in photosynthetic capacity (PC), N concentration, and chlorophyll content (CHL). Leaf PC was correlated with percent N during senescence in all treatments (r2 = 0.86), but an occasional midday depression in PC, unrelated to leaf N status, was observed in severely water stressed plants. Chlorophyll and percent N were also correlated (r2 = 0.80), but initial onsets of decline in these two parameters often differed by several days. Nitrogen deficits were less severe in 1983 than 1982, but in both years lack of applied N had an early impact and reduced longevity of lower leaves. In 1982, N deficiency caused a 50% reduction in leaf peak values of percent N, CHL, and PC, and the decline in leaf 5 was most rapid in low N plants. Water stress intensified as stored soil water was gradually depleted, and the most rapid decline and earliest complete senescence of upper leaves (11 and 15) occurred in the ND treatment. These results indicate that early stress effects on leaf area and ear development affected subsequent demands for water and N, which in turn altered patterns of leaf senescence.
Response of Field Grown Alfalfa to Root Waterlogging and Shoot Removal. II. Nitrogen and Fermentation Metabolism
Authors: Barta A. L. 
Published: July 2010

AbstractShoot removal and root hypoxia are two stresses to which alfalfa (Medicago sativa L.) roots are often exposed. Because shoots are the primary energy source for all higher plant metabolism, clipping may have severe consequences on anoxic root metabolism. The objective of this study was to characterize aspects of N metabolism, especially polyamine accumulation, and fermentation metabolism when waterlogged roots are further stressed by shoot removal 2 or 12 d before soil saturation. Experiments were conducted on a fine, loamy, mixed mesic Typic Fragiudalf soil water‐saturated for up to 14 d. Seedling plants of ‘Vernal’ and ‘Answer’ alfalfa were used at the flowering stage of growth. There was no relationship between flooding injury and root N content or amino‐N concentration, although both were significantly affected by flooding. Putrescine concentrations increased significantly with flooding, but there was no correlation with flooding injury among the shoot treatments. Root ethanol concentrations increased in all flooded treatments but were not correlated with root injury. Glucose‐6‐P concentration increased under hypoxia and did not appear rate limiting for fermentation. Root ATP concentrations were significantly reduced by both clipping and root flooding, while the ATP/ADP ratio was affected only by flooding. Because both the ATP concentrations and the ATP/ADP ratios were similar in tissues with differing flooding injury, a quantitative relationship between energy availability and flooding tolerance is not a probable characteristic of the tolerance mechanism.
Winter Wheat Response to Nitrogen and Irrigation
Authors: Eck Harold V. 
Published: July 2010

AbstractWinter wheat (Triticum aestivum L.) is grown on the Southern Great Plains under dryland conditions and under varying irrigation regimes. Relationships between water and fertilizer needs are not well defined. Field studies were conducted to determine: (i) the interacting effects of N fertilization and irrigation on N and P needs, wheat yields, and yield components; and (ii) the effects of riming of water deficit periods on N and P needs, wheat yields, and yield components. Studies were conducted on a Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Respective N and P rates ranged from 0 to 210 kg ha−1 and 0 to 40 kg ha−1. Irrigations were applied or withheld to allow the crop to be nonstressed (I‐1), stressed during heading and grain filling (I‐2), stressed during tillering and jointing (I‐3), and stressed throughout spring (I‐4). Two‐year average data showed that 140 kg N ha−1 was sufficient for maximum grain yields on treatment I‐1, while 70 kg N ha−1 was sufficient on treatments on I‐2 and I‐3, and no N response occurred on treatment I‐4. Compared to treatment I‐1, grain yields were 27, 32, and 52% less on treatments I‐3, I‐2, and I‐4, respectively. Water use efficiency (WUE) increased with increments of N through 140 kg ha−1 on treatment I‐1, and through 70 kg ha−1 on treatments I‐2, and I‐3 but applied N did not affect WUE on treatment I‐4. In 1981, WUE was highest on treatment I‐1 and lowest on treatment I‐4; in 1982, however, WUE was highest on treatment I‐4 and lowest on treatments I‐1 and I‐3. For limited irrigation, irrigating during tillering and jointing would be preferable to allowing stress then, and irrigating during heading and grain filling, because there is still potential for high yields if precipitation occurs during heading and grain filling.