bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methods of Simulating Freezing Damage during Sorghum Grain Fill
Authors: Staggenborg Scott A. , Vanderlip Richard L. , Roggenkamp Gregory J. , Kofoid Kenneth D. 
Published: July 2010

AbstractSorghum [Sorghum bicolor (L.) Moench] grain yields can be reduced if plants are exposed to freezing temperatures prior to reaching physiological maturity. Two field experiments were conducted to evaluate chemical desiccation and panicle removal as methods for simulating the loss of carbohydrate production associated with leaf death or transport tissue damage when sorghum is exposed to freezing temperatures during grain fill. In one experiment, both treatments were repeated at 3‐ to 4‐d intervals during grain fill with a range of hybrid maturities and environments to establish a relationship between caryopsis weight or test weight with heat unit accumulation after anthesis. This relationship was best described as sigmoidal in shape. A second field experiment compared these two treatments with potted field‐grown plants exposed to −2°C for 4 h. Treatments were applied four different times during grain fill. Panicle removal produced caryopsis weights 5% greater than those from freeze treatments, whereas chemical desiccation resulted in caryopsis weights 13% greater than those from freeze treatments. Test weights followed similar trends. Caryopsis weights from each treatment were similar across experiments. Panicle removal accurately simulated caryopsis weight reductions caused by exposure to freezing temperatures throughout the grain‐filling period. Chemical desiccation underestimated freeze damage during early grain fill but adequately simulated caryopsis reductions during late grain fill. Test weights from panicle removal treatments were similar in both experiments, while chemical desiccation was inconsistent across experiments. Test weight reductions caused by exposure to freezing temperatures were not adequately simulated by either treatment. The results of these experiments indicate that panicle removal is a more appropriate method for simulating freeze damage to maturing grain sorghum than is chemical desiccation; however, chemical desiccation may be utilized if appropriate adjustments are made during early grain fill.
Water Use and Yield of Dryland Row Crops as Affected by Tillage
Authors: Norwood Charles A. 
Published: July 2010

AbstractThe dryland winter wheat (Triticum aestivum L.)‐grain sorghum [Sorghum bicolor (L.) Moench]‐fallow rotation is suitable for large areas of the U.S. Great Plains. High temperatures and potential evapotranspiration limit the number of other crops that can be grown. Sunflower (Helianthus annuus L.) is drought tolerant, but crops such as corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are perceived to lack sufficient heat and drought tolerance for semiarid areas. A study was conducted near Garden City, KS, from 1991 through 1995 to compare yield and water uses of conventional tillage (CT) and no tillage (NT) corn, grain sorghum, sunflower, and soybean to determine if crops other than grain sorghum are suitable for dryland production. Conventional tillage (CT) and no tillage (NT) were included in a wheat‐row crop‐fallow rotation. Corn and soybean were similar in their depletion of soil water, as were sorghum and sunflower. Below a depth of 1.2 m, sorghum and sunflower removed the most water. Sunflower removed the most water from the last 0.3 m of the profile and probably removed deeper water. Sorghum and sunflower removed an average of 19 mm more water from the 1.8‐m soil profile than did corn and soybean. No‐till increased yields of corn in 3 yr, of sorghum and sunflower in 2 yr, and of soybean in 1 yr. Corn had the greatest yield response to NT, averaging 31%. Average yields of corn were 25% higher than sorghum yields, whereas average yields of sunflower were 83% higher than soybean yields. Other crops can be successfully grown in the wheat‐row crop‐fallow rotation, but sorghum should occupy the most acres until the other crops have been tested under different climatic conditions.
Quantitative Color Image Analysis of Agronomic Images
Authors: Ewing Robert P. , Horton Robert 
Published: July 2010

AbstractMany kinds of information that are available to our eyes in a qualitative sense require large investments of time and instrumentation to confirm quantitatively. If this information is accessible to our eyes, however, it should be possible to capture it in a color photograph and analyze it quantitatively. Our objective was to develop and make available software for enhancing and extracting quantitative information from color images. The resulting programs allow researchers to readily obtain quantitative data from color images such as photographs of plant canopies or soil with dye. The programs run in DOS and require only 512 kB of RAM, but can handle images up to 16 380 pixels across and 65 535 pixels down. The programs are designed to assist in developing an equation relating an independent parameter of interest (such as N content) to color parameters in calibration images, and then in using these equations to predict parameter values in new images. This allows one to convert, for example, an aerial photograph of a diseased wheat (Triticum sp.) field to a digital image in which the value of each pixel represents an estimated damage level. In a simple example use of the program, we show how percent canopy cover can be measured from color photographs. The programs, manual, and portions of the source code are in the public domain and are available at http://www.agron.iastate.edu/soilphysics/ewing_color.html.
Stability Analysis Using the SAS System
Authors: Piepho Hans‐Peter 
Published: July 2010

AbstractMultienvironment trials are often analyzed to assess the yield stability of genotypes. Most of the common stability measures correspond to parameters of a mixed model with fixed genotypes and random environments. Analysis within a mixed model framework allows unbalanced data to be handled. This note shows how to fit the most common stability models using the MIXED procedure of the SAS system.
Vertical Phosphorus and Potassium Stratification in No‐Till Cotton Soils
Authors: Howard Donald D. , Essington Michael E. , Tyler Donald D. 
Published: July 2010

AbstractContinuous no‐till production of cotton may result in vertical stratification of nutrients similar to that observed for band fertilizer applications. If so, special soil sampling techniques may be required to adequately address the fertility status of no‐till soils. The objective of this study was to evaluate nutrient stratification relative to the planted row and with soil depth on three soils having broadcast K at various rates applied annually for 6 years to no‐till cotton (Gossypium hirsutum L.). Rows were planted within a few centimeters of the rows from the previous year; a common practice in no‐till agriculture. The selected soils were Memphis silt loam (fine‐silty, mixed, active, thermic Typic Hapludalf), Lexington silt loam (fine‐silty, mixed, thermic Ultic Hapludalf), and Loring silt loam (fine‐silty, mixed, active, thermic Oxyaquic Fragiudalf). Potassium rates of 0, 28, 56, and 112 kg ha−1 were broadcast annually beginning in 1991. Experimental design was a split plot with five replications. Samples were collected from individual plots in the planted row (IR) and between the row (BR) to a depth of 30 cm. The soil samples were divided into 0‐ to 8‐cm, 8‐ to 15‐cm, and 15‐ to 30‐cm depths and Mehlich‐1 P and K were evaluated. Mehlich‐1 P varied with soil, sampling position, and soil depth. Differences in extractable P levels due to sampling position would not affect soil test ratings; however, additional years in no‐till production may magnify position influences and so affect P fertilizer recommendations. Mehlich‐1 K was greater for the IR sampling position of the 0‐ to 8‐cm sampling depth for the three soils. Sampling only the BR position may in some instances give a lower soil test value, resulting in higher fertilizer applications. These differences varied with soil‐applied K rates and may increase with additional time in no‐till cotton.
Soil Organic Matter and Wheat Productivity in the Semiarid Argentine Pampas
Authors: Díaz‐Zorita Martín , Buschiazzo Daniel E. , Peinemann Norman 
Published: July 2010

AbstractCrop productivity under dryland conditions is largely limited by soil water availability. Soil organic matter (SOM) contents have been found to be a reliable index of crop productivity in semiarid regions because it positively affects soil water‐holding capacity. Our objectives were to explain differences in wheat (Triticum aestivum L.) yields in response to SOM levels and related properties and to quantify the contribution of a unit increment of SOM content to soil productivity during 1991, 1992, and 1994 on a total of 134 production fields in the semiarid Argentine Pampas. Wheat yields were related to both soil water retention and total organic C (TOC) contents in the top layers (0–20 cm) in years with low moisture availability (1992 [r = 0.51, P < 0.01] and 1994 [r = 0.59, P < 0.01]), and were related to both total N and available P contents in a year without water deficit stress (1991 [r = 0.58, P < 0.01]). Wheat yields over all years were linearly related to TOC (r = 0.68, P < 0.01) when these contents were <17.5 g kg−. Dependence of wheat yields on soil water retention and on TOC contents under water deficit was related to the positive effect of these soil components on plant‐available water. In the absence of water deficit (1991), nutrient availability was the limiting factor. Losses of 1 Mg SOM ha− were associated with a decrease in wheat yield of approximately 40 kg ha−. These results demonstrate the importance of using cultural practices that minimize losses of soil organic C in the semiarid Argentine Pampas.
Soil Water Dynamics after Alfalfa as Influenced by Crop Termination Technique
Authors: Bullied William J. , Entz Martin H. 
Published: July 2010

AbstractBecause of their deep roots and high water demand, alfalfa (Medicago sativa L.) hay crops can reduce water available to crops following in the rotation. Recharging the soil water profile after alfalfa is, therefore, a high priority in dryland cropping systems. The objective of this study was to investigate effects of alfalfa crop termination date (late June, early August, and in spring immediately before spring wheat seeding) and method (herbicides, tillage, and herbicides plus tillage) on soil water conservation, and establishment, yield, and water use efficiency (WUE) of a following spring wheat (Triticum aestivum L.) crop. Experiments were conducted over 5 site‐years in a subhumid region of western Canada. Herbicide termination resulted in greater total water recharge and a faster rate of water recharge than treatments involving tillage. Greater efficiency of soil water recharge for herbicide termination after the first hay harvest (late June) appeared to cause deep water percolation at one site. Delaying termination until after the second hay harvest (early August) did not reduce soil water availability at spring seeding of the following wheat crop, but increased reliance on overwinter soil water recharge. Delaying herbicide treatment until spring reduced water at seeding and wheat yields in some cases. Compared with treatments involving tillage, herbicide treatments resulted in higher levels of groundcover (i.e., greater soil erosion control), higher WUE, and higher grain yields. Herbicide termination after the second hay harvest produced the most favorable overall outcome; better than the traditional approach of tillage after the first hay harvest.
Growth Analysis of Five Spring and Five Winter Triticale Genotypes
Authors: Royo Conxita , Blanco Ricardo 
Published: July 2010

AbstractLittle is known about the pattern of growth and biomass partitioning of spring and winter triticale (×Triticosecale Wittmack), although such information can aid in interpreting the results of field experiments and is an essential step in the development of crop simulation models. This study was conducted to analyze and compare the growth of five winter and five spring triticale genotypes over two years in northeast Spain. Plants were sampled at the main stages of the Zadoks scale, and biomass, LAI and their components, and stem elongation were determined. The relationships between all the growth traits studied and accumulated growing degree‐days from sowing (GDD) were described by the same asymmetric logistic peak curve. Genotypic variability could be mainly associated with plant phenology. On average, winter triticale types needed 165 more GDD than spring types to reach maximum LAI. Also, winter triticale genotypes needed 190 more GDD to complete their main stem elongation, and 109 more GDD to reach their maximum rate of dry weight accumulation in the stems than spring genotypes did. The length of the first tiller was closer to the length of the main stem in winter types than in spring types. Both types of triticale had similar patterns of biomass accumulation. The asymmetric logistic peak curve used in this work fitted asymptotic and peak‐type relationships, and can be a useful tool for growth studies.
Chemical Dwarfing and the Response of Cool‐Season Grass Seed Crops to Spring‐Applied Nitrogen
Authors: Young William C. , Chilcote David O. , Youngberg Harold W. 
Published: July 2010

AbstractSeed yield response of cool‐season grasses to spring‐applied N is usually limited because of lodging. This study investigated whether chemical dwarfing of these crops improves their seed yield response to spring‐applied N. Chewing's fescue [Festuca rubra L. subsp. fallax (Thuill.) Nyman; syn. F. rubra var. commutata Gaudin], tall fescue (Festuca arundinacea Schreb.), and orchardgrass (Dactylis glomerata L.) were established in September 1983 near Corvallis, OR. Treatments were all combinations of 90, 120, 150, 180, and 210 kg N ha−1 applied at the double‐ridge stage of development, followed by paclobutrazol [(2RS,3RS)‐l‐(4‐chlorophenyl)‐4,4‐dimethyl‐2‐(1H1,2,4‐triazol‐1‐yl)‐pentan‐3‐ol] at 0, 0.25, 0.5, and 1 kg a.i. ha−1 applied at floret initiation stage in 1985 and 1986. Averaged across years and N rates, the 1 kg ha−1 rate reduced Chewing's fescue height by 23% and tall fescue and orchardgrass heights by 30%. In the absence of paclobutrazol, Chewing's fescue and tall fescue seed yields were the greatest at 90 kg N ha−1. Paclobutrazol did not affect seed yield response of Chewing's fescue to N rates, but tall fescue seed yield in 1986 was the greatest at 150 kg N ha−1 when only 0.25 kg a.i. paclobutrazol ha−1 was applied. Averaged across N rates, the 0.5 kg ha−1 rate increased Chewing's fescue seed yield by 32% in 1985 and 18% in 1986, and also increased tall fescue seed yield by 32% in 1985 and 23% in 1986. Orchardgrass seed yield was the greatest at 180 kg N ha−1 in both years. Paclobutrazol did not affect orchardgrass seed yield in 1985, and the 1 kg ha−1 rate decreased seed yield in 1986. We concluded that in western Oregon paclobutrazol application at floret initiation does not improve seed yield response of these crops to spring‐applied N, but it would significantly improve Chewing's fescue and tall fescue seed yield, regardless of the N rate applied. Results did not indicate any advantage for applying paclobutrazol on orchardgrass seed crop.
Nature of the Reactions of Monocalcium Phosphate Monohydrate in Soils: III. Studies with Metastable Triple‐Point Solution
Authors: Lindsay W. L. , Lehr J. R. , Stephenson H. F. 
Published: July 2010

AbstractMetastable triple‐point solution (MTPS), the solution saturated with respect to Ca(H2PO4)2·H2O and CaHPO4·2H2O, was reacted with a series of soil samples in order to simulate the initial reaction zone that occurs adjacent to a dissolving granule of superphosphate in soil.As this acidic solution (initially pH 1.48) contacted successive soil increments, appreciable quantities of Al, Fe, Mn, K, and Ca were dissolved or exchanged from the soil. The solution formed during this series of reactions gradually became supersaturated with respect to certain Ca and Fe‐Al phosphate compounds. As the pH rose above 2.3, more rapid precipitation of phosphates occurred and was accompanied by the simultaneous removal of Ca, Al, Fe, and K from solution. The crystalline compound, CaHPO4·2H2O, CaHPO4, and H6K3Al5(PO4)8·18H2O, were identified petrographically and by X‐ray as precipitates that later formed in solutions filtered during the reaction sequence. The results are compared to those of a previous study in which soil was reacted with TPS (the stable equilibrium solution saturated with respect to Ca(H2PO4)2·H2O and CaHPO4).
Degradation of Structure of Yolo Loam by Compaction
Authors: Vomocil J. A. , Flocker W. J. 
Published: July 2010

AbstractField compaction of Yolo loam soil over 6 years resulted in marked changes in several physical characteristics of the soil. The degradation of structure was more than temporary in that air drying, crushing, and sieving of the soil did not remove all evidence of the deliberate compaction. Remolded briquets of crushed and sieved soil from the plots receiving supplemental compactive effort had a modulus of rupture of 3,300 millibars, while briquets of soil from plots receiving only the minimum traffic necessary for cultivation over the 6‐year period had a modulus of rupture of 1,200 millibars. The water stability of aggregates by wet sieving was reduced from 9% to 2%. Unconfined compressive and tensile failure tests on remolded samples showed that the soil from compacted plots reconsolidated after wetting and drying into stronger casts. Increased mechanical strength of remolded soil from the compacted plots was demonstrated by compression and penetrability measurements. The changes in strength were taken as evidence of reduction of water stability of soil aggregates by compaction. A residual effect of the compaction was definitely detected.
Effect of Method of Incorporation of Zinc in Fertilizer on Zinc Uptake and Yield of Pea Beans (Phaseolus Vulgaris)
Authors: Ellis B. G. , Davis J. F. , Judy W. H. 
Published: July 2010

AbstractIncorporation of either ZnO or ZnSO4 into fertilizer reduced the water solubility of Zn, the Zn uptake by pea beans, and the final yield as compared to the same rate and carrier of Zn hand mixed with fertilizer at planting time. Zn‐EDTA chelate remained 100% water‐soluble when coated on the fertilizer granule in conjunction with MnSO4; however, it was only 40% water‐soluble if coated in conjunction with MnO, and only 10% water‐soluble if incorporated into the fertilizer granule. The reduced water solubility was reflected in the uptake of Zn and the yield of pea beans.
Seasonal Variation in Soil Nutrients Under Six Rocky Mountain Vegetation Types
Authors: Weaver T. , Forcella F. 
Published: July 2010

AbstractSoils under vegetation types dominated by Festuca idahoensis, Artemisia tridentata, Populus tremuloides, Pseudotsuga menziesii, and Abies lasiocarpa were sampled at monthly intervals during 1974 and 1975 to determine the magnitude of seasonal variation in nutrient availability. Results may be summarized by expressing minimal values observed in 1974 as a percentage of maximum values: nitrate 27%, ammonium 30%, phosphorus 45%, potassium 65%, calcium 77%, magnesium 82%, sodium 60%, and organic matter 80%. Nutrients were most available in the early fall (September — October) and least available at midwinter (January — April). Rates of change in nutrient availability were smallest in winter and spring. Seasonal variation in Abies forests was notably less than in other vegetation types.
Nitrous Oxide Production and Reduction during Denitrification as Affected by Redox Potential
Authors: Letey J. , Valoras N. , Focht D. D. , Ryden J. C. 
Published: July 2010

AbstractNitrous oxide evolution from soils may contribute to partial destruction of the ozone layer in the stratosphere. Knowledge of factors affecting the N2O/N2 evolution ration from soils is important in properly assessing the hazard associated with N2O evolution. Previous investigations demonstrated that air‐dry soils incubated in the laboratory under conditions to cause denitrification had an initial high N2O/N2 evolution ratio which rapidly decreased and approached zero. It was not possible to determine whether the observed time effect on the gaseous evolution was related to concurrent changes in the redox potentials in the soil. Experiments were conducted to measure the production, reduction, or both, of N2O at various redox potentials in incubation containers. Equal weights of soil and KNO3 solution were added to the incubation containers which were placed in a temperature‐controlled waterbath shaker. The container was evacuated and refilled with helium. Small amounts of oxygen were periodically injected into the container to achieve the desired redox potential. Gas samples were withdrawn daily and analyzed for N2O, N2, O2, and CO2 on a gas chromatograph. Nitrate‐nitrogen concentrations in solution were analyzed at the beginning and end of the incubation and were found to range from approximately 200 to 400 mg/liter during the incubation. There was essentially no denitrification at redox potentials of 300, 350, or 400 mV as determined by gas analyses and measurement of nitrate‐nitrogen. When no oxygen was added to the system, the redox potential decreased and poised at approximately 200 mV throughout the incubation. At a redox potential of 200 mV, the N2O concentration increased, reaching a maximum at approximately 3 days, and decreased thereafter, reaching zero in 5 to 7 days after initiation of incubation. Thus, the previously observed time dependency of N2O evolution was repeated in these experiments and the results cannot be attributed to change in redox potential with time. The data also demonstrate that N2O can be reduced more rapidly than NO3‐, even in the presence of relatively high NO3‐ concentrations.
The Mechanism of Copper(II) Binding by Humic Acid: An Electron Spin Resonance Study of a Copper(II)—Humic Acid Complex and Some Adducts with Nitrogen Donors
Authors: Boyd Stephen A. , Sommers Lee E. , Nelson Darrell W. , West Douglas X. 
Published: July 2010

AbstractElectron spin resonance (ESR) spectroscopy was used to study the mechanism of Cu2+ binding by humic acid (HA) extracted from a Chalmers silt loam soil. The Cu‐HA complex and some adducts with nitrogen donors were examined. The ESR data presented showed that the addition of pyridine (py) and 1,10‐phenanthroline (phen) to the Cu‐HA complex resulted in the substitution of coordinated H2O ligands by the nitrogen donor ligands without displacement of HA oxygen donor ligands also coordinated to the Cu2+ center. The addition of a more basic nitrogen donor, ethylenediamine (en), resulted in the displacement from Cu2+ of both coordinated H2O ligands and HA oxygen donors, forming Cu(en)22+. The g‖ and A‖ values obtained for the py and phen adducts revealed that there were two HA oxygen donors coordinated equatorially to the Cu2+ center in the original Cu‐HA complex. The characterization of the adducts with phen and en was consistent with the formation of a Cu2+ chelate in the original Cu‐HA complex, where the two equatorial Cu‐HA oxygen bonds would occupy cis‐ positions. The crystal field strength of HA oxygen donor ligands coordinated to the Cu2+ center was stronger than that of H2O.