bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Statistical Methods for Determining Differences between Samples from Lognormal Populations
Authors: Parkin T. B. 
Published: July 2010

AbstractSoil variables often exhibit frequency distributions that are positively skewed. When this situation exists, the assumption of normality associated with analysis‐of‐variance procedures is violated, and two common recommendations are given: (i) perform a normalizing transformation, or (ii) apply nonparametric statistical methods. Information regarding the relative efficacy of these two procedures with regard to power to detect differences between batches of samples is lacking. This study evaluates five statistical procedures for detecting differences between samples drawn from lognormal populations. The tests evaluated were (i) two‐tailed t‐test on untransformed data, (ii) twotailed t‐test on natural log‐transformed data, (iii) nonparametric Mann‐Whitney test, (iv) median confidence interval overlap method, and (v) a mean confidence interval overlap method. The tests were evaluated with regard to Type I error rate by comparing batches of samples drawn from the same lognormal population. Also, the power of the statistical tests to detect differences between two batches of samples drawn from different lognormal populations was evaluated over a range of population variances and sample sizes (n = 4 to 100). It was found that three of the tests (Tests 2, 3, and 4) were sensitive to sample differences when the underlying populations differed with regard to their medians. The other two tests (Tests 1 and 5) were sensitive to differences in population means. Test 2 is recommended when the median is the location parameter of interest; however, Test 5 should be used to detect differences in means.
Baling System for Making Laboratory‐Scale Hay Bales
Authors: Coblentz W. K. , Fritz J. O. , Bolsen K. K. 
Published: July 2010

AbstractResearch on the preservation of moist hay has long been an area of intense interest; however, such research has often been hampered by the difficulty in controlling experimental conditions luring field hay trials. The development of a laboratory‐scale baling system that would allow researchers to impose a baling treatment on a small quantity of forage would reduce the need for expensive field trials and, to a large degree, minimize weather as a factor in hay experiments. A simple system that utilizes a hinged metal baling unit and a hydraulic press to make 10.3‐ by 10.8‐ by 13.4‐cm wire‐tied hay tales over a wide range of densities (150 to 800 kg m−3) is described. The system was inexpensive to build, easy to use, and could easily be reproduced.
Residue Management Effects on Sugarcane Yield and Soil Properties in Northeastern Brazil
Authors: Ball‐Coelho B. , Tiessen H. , Stewart J. W. B. , Salcedo I. H. , Sampaio E. V. S. B. 
Published: July 2010

AbstractSugarcane (Saccharum spp.) production systems commonly include preharvest or postharvest burning to dispose of residue. In northeastern Brazil, no‐burn mulching practices are being introduced as a labor‐intensive but environmentally more friendly alternative. We examined the effect of burning crop residues on sugarcane yield and C, N, and P cycles. Carbon, N, and P losses during preharvest burning were measured for a sugarcane first ratoon crop. Postharvest burn and mulch treatments were compared for a plant crop grown on an Oxic Haplustult soil. During the preharvest burn of the first ratoon crop, 2600 kg C ha−1, 17 kg N ha−1 and 1 kg P ha−1 were lost by convection. The postharvest burn of the plant crop residue resulted in losses of 4800 kg C ha−1 and 42 kg N ha−1; P losses were undetectable in the burn. The postharvest burn of the plant crop residue had no significant effect on total C or NH4‐N plus organic N in soil during the first ratoon crop cycle. Soil pH in the top 7.5 cm layer of soil did not change after the postharvest burn, but increased 1.1 units in the top 1‐cm layer. In the unburned mulch treatment, the litter layer did not reduce tillering or N and P uptake. Harvestable cane yield of the first ratoon crop was 17 Mg ha−1 (wet wt.) greater in the mulch than the burn treatment (54 vs. 37 Mg ha−1). This yield response was attributed to increased soil water retention and reduced weed growth under the mulch. In this short‐term trial, mulching proved to be an alternative to the traditional burn system.
Simultaneous Determination of Total Sodium, Potassium, Magnesium, and Calcium in Plant Tissues Using Acid Digestion and Ion Chromatography
Authors: Goyal Sham S. , Hafez Ahmed A. R , Rains Donald W. 
Published: July 2010

AbstractSodium, K, Mg, and Ca in plant tissue were measured by single column ion chromatography (SCIC) as an alternative to traditional methods such as atomic absorption spectrophotometry (AAS) or inductively coupled plasma–atomic emission spectrophotometry (ICPAES). Interference of the NH4 peak on the Na peak in SCIC was eliminated by removal of NH4 ions by drying the nitric‐perchloric acid plant digest at 350 °C. Cations were separated using an IC‐Pack CM/D column with 0.1 mM EDTA + 3 mM HNO3 as eluent. Inclusion of 10% (v/v, = 1.89 M) acetonitrile in the eluent shortened the retention time of divalent cations by 22% compared with the time without acetonitrile. The Na, K, Mg, and Ca content of plant samples analyzed with this technique agreed closely with certified values provided by the National Institute of Standards and Technology (NIST). The lower limit of detection of SCIC for Na, K, Mg, and Ca were 0.05, 0.2, 0.025, and 0.05 mg L−1, respectively, using a 100‐μL sample. The response of peak areas as a function of solute concentration was linear up to 10 mg L−1 of each cation. The SCIC method was cheaper than AAS or ICP, and faster than AAS, mainly due to simultaneous analyses of all four cations. SCIC did not generate hazardous and toxic waste and thus did not require special disposal procedures.
WAS: Computer Software for Wheat Quality Data Management
Authors: Morris Craig F. , Raykowski James A. 
Published: July 2010

AbstractWheat (Triticum aestivum L.) cultivar development programs benefit from the efficient assessment of end‐use quality of experimental lines. Efficiency of assessment is enhanced when quality testing data are accurately collected, recorded, interpreted, and reported. The Wheat Analysis System (WAS) software specifically addresses this management need by providing a user‐friendly, menu‐driven system that generates data collection forms and reports, structures data entry, and maintains a cumulative database which is amenable to statistical analysis and interpretation. Data are managed in two master files according to a nursery‐sample system of organization. Quality tests and analyses are grouped into processes that accommodate all of the common methodologies used for soft and hard wheat evaluation, including grain and flour analyses, milling, and baking. A supplemental process, in addition to user‐defined variables, provides flexibility and broad applicability. The WAS software is compiled in Borland C, version 3.0, and operates on DOS‐based computers with 640K RAM, hard and floppy disk drives, and a printer. A color monitor, though not required, greatly enhances the use of the menu‐driven features. WAS is simple to use, requires no programming, and directly and specifically addresses the needs of wheat quality testing and evaluation programs—thereby aiding the overall cultivar development process.
Nitrogen and Carbon Dynamics in No‐Till and Stubble Mulch Tillage Systems
Authors: Christensen Neal B. , Lindemann William C. , Salazar‐Sosa Enrique , Gill L. R. 
Published: July 2010

AbstractSoil nitrogen and organic carbon differences between no‐till and conventional tillage systems are often dramatic and well documented, but these differences between no‐till and stubble mulch tillage systems are more subtle. Our objective was to evaluate changes in soil inorganic N, organic N, organic C, surface soil moisture and grain yield on the southern High Plains as affected by stubble mulch and no‐till tillage systems from 1988 to 1992. The cropping system was a sorghum (Sorghum bicolor (L.) Moench)‐sorghum‐fallow‐wheat (Triticum aestivum L.) rotation conducted on a Pullman sandy clay loam (fine, mixed, thermic Torrertic Paleustoll) under dryland conditions near Clovis, NM. Tillage treatments were main plots and N fertilization treatments were subplots. Averaged over 5 yr and 37 sampling dates, the no‐till treatment had 2.0 mg kg−1 less inorganic N, 40 mg kg−1 more organic N, and 617 mg kg−1 more organic C than the stubble mulch treatment. Although differences between tillage systems were generally small, they were most noticeable during sorghum planting and development. No‐till unfertilized treatments often showed N deficiency symptoms during development. Nitrogen fertilization was more important than tillage system in determining sorghum and wheat yields in wet years. In dry years, N‐fertilized stubble mulch treatments had the lowest yields. Since conversion to either stubble mulch or no‐till in 1987, organic C levels under both systems have continually increased.
Growth Regulator and Seed Storage Effects on Switchgrass Germination
Authors: Zarnstorff Mark E. , Keys Robert D. , Chamblee Douglas S. 
Published: July 2010

AbstractSwitchgrass (Panicum virgatum L.) is a warm season perennial grass that shows potential as a forage in the southeastern USA. Problems with switchgrass establishment from seed are often due to inherent seed dormancy from seeds harvested in fall and seeded the following spring. The objectives of this study were to determine (i) the effects of wet prechill (PC) treatment (5°C for 14 d) and scarification (8 M H2SO4 for 5 min) on germination of five switchgrass cultivars and (ii) the effect of plant growth regulators (ethylene, gibberellin, and kinetin), CO2, PC, and influence of storage temperature and duration on germination of four selected lots of Blackwell (BW) and Cave‐in‐Rock (CIR) seeds. Storage treatments were initiated 1 February using seeds harvested the previous fall. Early germination percentage (7 d) was increased between 22 and 73 by PC, while final germination percentage (28 d) was increased between 2 and 40. Germination of BW 6086 was increased from 60 to 63% by ethylene, and from 59 to 65% by gibberellin (ɑ = 0.05). Seeds stored at −8°C showed little change in early or final germination with time of storage (90 d to 4 yr). Dormancy of BW 1198, BW 6086, and CIR 6012 was largely broken after 90 d of storage at 23°C. Germination of seeds stored at 23°C generally started to decline after 180 d to 2 yr. Postharvest storage of seeds at 23°C from January to April (90 d) should ensure adequate germination at time of seeding.
Floral Asynchrony and Kernel Set in Maize Quantified by Image Analysis
Authors: Bassetti Paolo , Westgate Mark E. 
Published: July 2010

AbstractA delay in the onset of silk emergence relative to pollen shed often decreases kernel set in maize (Zea mays L.). Lack of pollen, failure of silks to emerge, and loss of silk receptivity all are probable causes for kernel loss. To date, it has not been possible to distinguish between these possibilities, due to the lack of quantitative information on the intensity of pollen shed and progress of silk emergence under field conditions. Using a computer‐aided image analysis system, we measured the daily progress of silk emergence and the intensity of pollen shed in the field. Kernel set also was measured on plants whose silk emergence varied from 8 d before to 13 d after anthesis (DAA). About 200 silks emerged on the first day silks appeared and >90% of the florets had silks exposed within 3d. Pollen shed followed a normal distribution with time, peaked 3 DAA, and ended 13 DAA. On ears with silks exposed to pollen for only one d, nearly all florets set kernels when pollen was shed at intensities greater than ≈ 100 grains cm−2 d−1mm; however, percent set in apical floret positions decreased when the onset of silk emergence was delayed >3 DAA, despite pollen shed at a rate sufficient to ensure high kernel set. These results indicate that asynchrony between silk emergence and pollen shed decreases kernel set because silks emerge after pollen amount becomes limiting. In the current experiment, the intensity of pollen shed limited kernel set only beyond 7 DAA. Also, silks emerged prior to anthesis remained receptive to pollen for at least 5 d. This finding suggests that selection for silk emergence prior to pollen shed (protogyny) may improve kernel set in maize under conditions known to delay silk emergence.
Nitrogen Utilization of Selected Cropping Systems in the U.S. Northeast: II. Soil Profile Nitrate Distribution and Accumulation
Authors: Guillard Karl , Griffin Gary F. , Allinson Derek W. , Yamartino William R. , Rafey M. Moosa , Pietrzyk Stephen W. 
Published: July 2010

AbstractHigh rates of N fertilizers and limited crop uptake of N during the growing season can result in excessive accumulation of soil nitrate (NO−3). Soil NO−3 can be decreased with efficient cropping systems. Experiments were conducted in Connecticut from 1987 through 1990 on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept) to determine the effects of N rate and cropping system on soil NO−3. Orchardgrass (Dactylis glomerata L.), red clover (Trifolium pratense L.), a double‐crop system of oat (Avena sativa L.) followed by tyfon [Brassica rapa L. × B. pekinensis (Lour.) Rupr.], maize (Zea mays L.) followed by a cover crop of winter rye (Secale cereale L.), and a fallow system received preplant N at 0, 112, 224, 336, and 448 kg ha−1. Each system was evaluated for two consecutive growing seasons and repeated three times. Nitrogen was applied only in the first growing season. Soil NO−3 at the first autumn sampling generally increased for all systems as N rate increased. Mean spring soil NO−3 levels were only 23% of previous autumn NO−3 levels. By the second autumn sampling, soil NO−3 values were near background levels except in the fertilized fallow system. At the two highest N rates, oat‐tyfon produced the smallest overwinter change in soil NO−3 storage. An oat‐tyfon double crop, orchardgrass, or red clover system should decrease soil NO−3 more effectively than maize or a noncropped fallow when soil NO−3 accumulations are greater than those produced from N inputs equivalent to 224 kg ha−1.
Rhizobia1 Inoculation and Phosphorus and Zinc Nutrition for Annual Medics Adapted to Mediterranean Environments
Authors: Materon Luis A. , Ryan John 
Published: July 2010

AbstractCereal production in the Mediterranean region (where rainfall averages 200 to 600 mm yr−1) has traditionally used fallowing in alternate years to conserve crop‐limiting soil moisture. Self‐regenerating pasture medics (Medicago spp.) were introduced to provide forage for livestock in the alternate year and to reduce the cereal's need for fertilizer N; their adaptation depends on compatible Rhizobium meliloti bacteria for N2 fixation and on climatic conditions. In addition, nutrients such as P and Zn are potentially limiting factors. Therefore, in a greenhouse experiment (60 d) using a P‐deficient, air‐dried, nonsterilized clay soil (Calcixerollic Xerochrept) treated with P (0, 15, 45, and 135 mg kg−1) and Zn (0 and 5 mg kg−1, we assessed growth of four annual medic species with and without rhizobial inoculation and fertilizer N: Medicago polymorpha L., M. rotata Boiss., M. rigidula (L.) All., and M. noeana Boiss. Except for M. noeana, growth of all species responded significantly to applied P and to Zn only with adequate P and N levels (or rhizobial inoculation). Pod number and root biomass were also increased by P application, with differences occurring between species. Thus, when a medic species is newly introduced, inoculation has a role to play where no compatible rhizobia exist. Phosphorus fertilization and medic seed inoculation can easily be done, while the use of adapted biotypes in low‐Zn soils is more problematic
An Algorithm for Predicting Crown Root Axes of Annual Grasses
Authors: Rickman Ronald W. , Klepper Betty , Ball Daniel A. 
Published: July 2010

AbstractRoot formation by any plant determines its success or failure for creating seed for its next generation. Those interested in managing plants for optimum harvestable yield require information about effects of their practices on root growth. Crop growth models can be convenient summarizations of such knowledge. Models of plants and environment currently describe the plant shoot more completely than they describe the root. The morphologically based root formation algorithm presented in this paper provides opportunities for improving both the description of root formation and the response of roots to their environment. The equation relating shoot and root development will be convenient for crop modeling. It can also be used as a standard for comparison of field rooting observations, as environmental effects on rooting are quantified. The equation predicts the number of root axes on a plant from the plant phyllochron interval, the timing of nodal root appearance relative to leaf appearance, and the effect of environmental stresses that reduce tillering. A comparison of algorithm predictions with observed root formation by wheat (Triticum aestivum L.) from a warm, dry seedbed revealed that fewer roots were formed during the early tillering stage of development than predicted for unstressed plants. Correction for observed tillering did not reduce predicted root numbers to those observed. Observed early‐season root observations were matched by using one‐half of possible tillering as a stress correction.
Allelopathy in Forage Crop Systems
Authors: Miller Darrell A. 
Published: July 2010

AbstractSecondary plant metabolites and their degradation products are important in all agroecosystems including those with forage crops. Allelopathy affects cropping systems and interseeding of one species into established sods of another. Autotoxicity and heterotoxicity are types of allelopathy. Alfalfa (Medicago sativa L.) has been investigated as both an autotoxic and heterotoxic species. Reestablishment of alfalfa immediately after alfalfa has usually resulted in poor stands due to autotoxicity, and several other forage species also exhibit autotoxicity. Many forage species have shown heterotoxicity, both between forage species and weed species. Several investigators have identified various allelochemicals and/or families of allelochemicals as being responsible for allelopathic reactions. Identifying such chemicals would aid in developing resistant forage cultivars and in maintaining a productive and profitable crop. Crop rotation, cover‐crop management, interplanting, double cropping, no‐till planting, and nonrotational cropping systems are involved with allelopathic effects. Some alfalfa cultivars possess some resistance to these allelochemicals. Therefore, a breeding program could provide resistant germplasms. Various forage grasses and some weed species have demonstrated allelopathic effects on alfalfa, and alfalfa has allelopathic effects on some weed species. This alone may provide an insight for herbicide studies in alfalfa production.
Canopy Light Reflectance and Field Greenness to Assess Nitrogen Fertilization and Yield of Maize
Authors: Ma B. L. , Morrison Malcolm J. , Dwyer Lianne M. 
Published: July 2010

AbstractAssessment of crop N requirements is necessary to develop production systems with optimal N input. A field experiment with six maize (Zea mays L.) hybrids grown at three N fertilizer rates (0, 100, and 200 kg N ha−1) was conducted on a well‐drained sandy loam of the Grenville series (coarse‐loamy, mixed, mesic Typic Eutrochrepts) on the Central Experimental Farm at Ottawa, ON, in Canada (45°23' N, 75°43' W) for 3 yr (from 1991 to 1993) to evaluate whether canopy reflectance and greenness can measure changes in maize yield response to N fertility. Canopy reflectance, leaf area and greenness were measured on 11 dates from 4 wk before to 4 wk after anthesis. Grain yield at harvest was also measured. Direct radiometer readings at the 600‐ and 800‐nm wavelengths or a derived normalized difference vegetation index [NDVI = (800 nm − 600 nm)/(800 nm + 600 nm)] best differentiated N and hybrid treatments at most sampling dates. Canopy light reflectance was strongly correlated with field greenness at almost all growth stages (field greenness being a product of plant leaf area and leaf greenness measured with a chlorophyll meter, in this case a SPAD‐502). Both canopy light reflectance and field greenness measured preanthesis were correlated with yield at harvest. Light reflectance measured after anthesis differentiated hybrid differences in leaf senescence. Our data suggest that light reflectance measurements prior to anthesis may predict grain yield response and provide in‐season indications of N deficiency.
Ammonia Transport in a Temperate Grassland: II. Diurnal Fluctuations in Response to Weather and Management Conditions
Authors: Bussink D. Wim , Harper Lowry A. , Corré Wim J. 
Published: July 2010

AbstractAmmonia emission into the atmosphere is of concern because of its potential impact on atmospheric aerosol chemistry and fertilizer N use efficiency. The purpose of this study was to evaluate the effects of N surplus and deficit on soil‐plant‐atmosphere NH3 exchange in a temperate humid grassland. Plant and soil N measurements were made along with NH3 fluxes using flux‐gradient techniques. Ammonia flux was related to the plant ammonia compensation point (NH3 CP), which was controlled by plant N concentration and management practices (such as harvest and fertilization). The measured fluxes were generally much larger during daytime than during nighttime. The daily variation in flux was apparently caused by higher diffusive resistance at night. Generally, there were no significant differences between daytime and nighttime NH3 CP. Ammonia was absorbed in dew and released during dew evaporation; however, nighttime absorption exceeded daytime release, with some of the N apparently being captured by the crop.
Simulating Forage Sorghum Yields with SORKAM
Authors: Fritz John O. , Vanderlip Richard L. , Heiniger Ronnie W. , Abelhalim Ahmed Z. 
Published: July 2010

AbstractA validated crop model can be a valuable tool for evaluating new production and management practices, particularly for crops routinely grown in environments that produce large variation in field performance tests. Previous work has been done to validate SORKAM a crop growth model for grain sorghum [Sorghum bicolor (L.) Moench]. The purpose of this study was to determine the ability of SORKAM to simulate forage sorghum yields for a wide range of environmental conditions. Data for the simulations used in the validation process were taken from performance tests for four cultivars (‘Early Sumac’, ‘Atlas’, ‘Sugar Drip’, and ‘Canex’) conducted at two sites in Kansas over 25 yr. Simulated bloom date, grain, stover, and total dry matter yields were regressed on measured data. The SORKAM model simulated bloom dates without bias; however, the root mean square error (RMSE) was 8 d, and the model tended to overestimate bloom date under conditions of water deficit. The model generally overpredicted yields of the four cultivars for grain (bias = 3.2 Mg ha−1), stover (bias = 2.0 Mg ha−1), and total dry matter (bias = 5.2 Mg ha−1). In addition to overestimation of total dry matter production, weaknesses in the SORKAM model in simulating forage sorghum growth included inability to simulate phenological development accurately under moisture deficit stress and to partition dry matter into grain and stover. These problems must be resolved before SORKAM can be used to address management decisions.