856 research outputs found
Right Rate, Timing, Source and Placement: More Bang for the Pasture Fertilizer Buck
As we write this paper for the conference, fall fertilizer prices continue to increase, albeit at a slower pace than earlier this fall for most materials. The latest DTN retail price survey https://www.dtnpf.com/agriculture/web/ag/crops/article/2021/10/06/fertilizerâpriceâgains-losingâsteam has urea (46â0â0) at 722/ton and potash (0â 0â60) at 0.675/lb N, 0.54/lb K2O. Compared to this time last year, urea, DAP and muriate of potash are 71, 64 and 92% higher, respectively. Other important materials used in Kentucky are also higher: ammonium polyphosphate (APP, 10â34â0); UAN (32â0â0); and anhydrous (82â0â0) are 40, 78 and 84% more expensive, respectively
Mortality of Escherichia coli O157:H7 in Two Soils with Different Physical and Chemical Properties
Wild and domesticated animals can harbor a pathogenic Escherichia coli strain designated as O157:H7. Potential health problems could occur if strain O157:H7 is a more robust survivor in defecated waste than commonly used indicator bacteria. A laboratory study was conducted to assess E. coli O157:H7 survival relative to a nonpathogenie E. coli strain in two soils with different physical and chemical characteristics. Bacteria in the inoculated soils were enumerated on a weekly basis for 8 wk using a most probable number (MPN) technique. First-order decay models were used to describe bacteria mortality in the soils. Decay series were described slightly better by a two-stage function than by a single-stage function. Strain O157:H7 exhibited similar mortality patterns to the nonpathogenic E. coli in the same soil environment. Both E. coli strains had greater mortality rates in Pope silt loam (coarse-loamy, mixed, active, mesic Fluventic Dystrudept) than Zanesville silt loam (fine-silty, mixed, active, mesic Oxyaquic Fragiudalf). Differences in available soil water probably were the overriding factor in E. coli survival. Escherichia coli O157:H7 survival could be modeled in the same way as nonpathogenic E. coli and appears to have a slightly higher mortality rate
Tropical Transpacific Shore Fishes
Tropical transpacific fishes occur on both sides of the world's largest
deep-water barrier to the migration of marine shore organisms, the 4,000- to
7,000-km-wide Eastern Pacific Barrier (EPB). They include 64 epipelagic oceanic
species and 126 species of shore fishes known from both the tropical eastern
Pacific (TEP) and the central and West Pacific. The broad distributions of 19
of 39 circumglobal transpacific species of shore fishes offer no clues to the origin
of their TEP populations; TEP populations of another 19 with disjunct Pacific
distributions may represent isthmian relicts that originated from New World
populations separated by the closure of the Central American isthmus. Eighty
species of transpacific shore fishes likely migrated eastward to the TEP, and 22
species of shore fishes (12 of them isthmian relicts) and one oceanic species
likely migrated westward from the TEP. Transpacific species constitute ~12%
of the TEP's tropical shore fishes and 15-20% of shore fishes at islands on the
western edge of the EPB. Eastward migrants constitute ~7% of the TEP's
shore-fish fauna, and a similar proportion of TEP endemics may be derived
from recent eastward immigration. Representation of transpacific species in
different elements of the TEP fauna relates strongly to adult pelagic dispersal
ability-they constitute almost all the epipelagic oceanic species, ~25% of
the inshore pelagic species, but only 10% of the demersal shore fishes. Taxa
that have multiple pelagic life-history stages are best represented among the
transpacific species. Among demersal teleosts that have pelagic larvae, pelagic
spawners are better represented than demersal spawners among transpacific
species, perhaps because offshore larval development and longer pelagic larval
durations provide the former with greater dispersal capabilities. There are
strong phylogenetic effects on representation in the transpacific fauna: (1) elasmobranchs
are proportionally better represented than teleosts, even teleosts
with more pelagic life-history stages; (2) a pelagic juvenile stage with great dispersal
potential allows tetraodontiforms that produce demersal or pelagic eggs
to be well represented; and (3) various speciose central Pacific families with
"adequate" larval dispersal characteristics lack transpacific species. El Niiios
potentially enhance eastward migration by increasing eastward flow and halving
transit times across the EPB. However, that effect may be offset by low productivity
and high temperatures in those eastbound flows. There is little clear
evidence of strongly increased migration across the EPB during El Niiios, including
recent extreme events (1982-1983 and 1997-1998). During such events
shore fishes in the TEP experience range expansions and become locally abundant at marginal areas such as the Galapagos, changes that can be confused with
increased migration across the EPB. Although there is a strong bias toward
eastward migration among the transpacific shore fishes, there likely is much
more westward migration than previously realized: 20-25% of transpacific species
may have migrated in that direction. Stronger eastbound than westbound
currents can account for this bias. Westward migrants have better developed
pelagic dispersal characteristics than many eastward migrants, suggesting that
westward migration is more difficult. Many westward migrants associate with
flotsam and flotsam-mediated migration is more likely to be westward. All
westward migrants occur at Hawai'i, but only about one-fifth of them at the
Marquesas. This bias may be due to: Hawai'i being a larger target and in the
path of most of the flotsam dispersal from the TEP; an eastward current that
impinges on the Marquesas, reducing westward arrivals; and most propagules
dispersing toward the tropical Marquesas originating in the temperate eastern
Pacific. However, the Hawaiian Islands also are much better sampled than the
Marquesas. Although the TEP reef-fish fauna may be depauperate relative to
that of the Indo-Malayan "center of diversity," it is as rich as the faunas of islands
on the western side of the EPB. Hence a preponderance of eastward migration
does not represent a response to a richness gradient across that barrier.
There is little evidence that a paucity of ecological groups in the native TEP
fauna is primarily responsible for the structure of the eastward-migrant fauna.
Rather, eastward migrants may simply represent a cross section of those in the
donor fauna, tempered by phylogenetic variation in dispersal ability. Because
few central Pacific fishes can live only on live corals and coral reefs, the rarity of
such reefs in the TEP is unlikely to strongly limit eastward migration. Differences
between oceanic and adjacent continental reef-fish faunas in the West
Pacific indicate that each is strongly tied to its respective habitat. Hence, the
rarity in the TEP of the (overwhelmingly) most abundant habitat present in the
central Pacific-tropical oceanic reefs-may strongly limit migration in both
directions across the EPB: there is little suitable habitat for eastward migrants in
the TEP and few suitable species and tiny source populations for westward migrants.
The global effects that oceanic/continental habitat differences have on
reef-fish biogeography need further assessment. Genetic data on ~18% of the
transpacific species indicate: that conspecific populations of oceanic species
(especially) and shore fishes are genetically well connected across the EPB; that
circumtropical taxa in the TEP include isolated isthmian relicts and recent
eastward migrants; that all five TEP species of one circumtropical genus (Thalassoma)
were derived by several eastward invasions after the closure of the
Isthmus of Panama; that some isolated Hawaiian central Pacific populations
were established by postisthmian invasion from the TEP; and that Indo-central
Pacific species unsuspectedly can co-occur with their endemic sibling sisters
in the TEP. Genetic data support distributional data that indicate a strong
preponderance of eastward migration across the EPB but also more westward
migration than previously thought. Future genetic studies should resolve
a question that distributional data cannot: how many widespread presumed
eastward-migrant transpacific species actually originated by westward migration
from the TEP
\u3cem\u3eEscherichia coli\u3c/em\u3e Pathogen O157:H7 Does Not Survive Longer In Soil Than A Nonpathogenic Fecal Coliform
Survival rates for individual types of fecal organisms are quite different. Although some pathogens may persist as long as 5 years in soil, most fecal pathogens from human and animal waste usually die very quickly. Two to three months is sufficient in most cases to reduce pathogens to negligible numbers once they have been excreted or land-applied in animal wastes.
It is expensive and time- consuming to test for individual pathogens. Consequently, nonpathogenic fecal indicator bacteria, which are easily and inexpensively detected, are often used to study pathogen survival in soil and water. Current methods for rapidly detecting fecal indicator bacteria use the capacity of fecal coliforms (e.g. Escherichia coli) to metabolize a fluorescent indicator compound, 4-methylumbelliferyl Ă-D-glucuronide (MUG) as evidence for fecal contamination
It Takes More Than Calcium to Neutralize Soil Acidity
Proper pH management is the foundation to a good soil fertility program. Soil pH influences nutrient availability and root growth and function. Just because an agricultural product contains calcium does not mean that it will change soil pH. The effectiveness of three calcium products in raising soil pH was compared to an untreated check in acid soils. A field trial was conducted at 16 locations across Kentucky and a laboratory incubation study was conducted at the University of Kentucky Research and Education Center. The same application rates were used for the three products, whether in field trials or laboratory incubations. The rates were 46.8 L ha-1 for the liquid calcium and 4.5 Mg ha-1 for the pelletized and ag limes. The field studies exhibited higher soil pH at 3-month and 12-month sample dates with ag lime and pelletized lime treatments than with the check and liquid calcium treatments. The lab study exhibited higher soil pH values at each sample date (1, 3, 6 and 12 month) with ag lime and pelletized lime than with check and liquid calcium. The soil pH was not improved with the addition of liquid calcium (chloride) and results of this study are supported by the chemical foundations of soil acidity neutralization reactions - calcium chloride does not neutralize acidity and calcium carbonates do
Mortality of Escherichia coli O157:H7 in Two Soils with Different Physical and Chemical Properties
Wild and domesticated animals can harbor a pathogenic Escherichia coli strain designated as O157:H7. Potential health problems could occur if strain O157:H7 is a more robust survivor in defecated waste than commonly used indicator bacteria. A laboratory study was conducted to assess E. coli O157:H7 survival relative to a nonpathogenie E. coli strain in two soils with different physical and chemical characteristics. Bacteria in the inoculated soils were enumerated on a weekly basis for 8 wk using a most probable number (MPN) technique. First-order decay models were used to describe bacteria mortality in the soils. Decay series were described slightly better by a two-stage function than by a single-stage function. Strain O157:H7 exhibited similar mortality patterns to the nonpathogenic E. coli in the same soil environment. Both E. coli strains had greater mortality rates in Pope silt loam (coarse-loamy, mixed, active, mesic Fluventic Dystrudept) than Zanesville silt loam (fine-silty, mixed, active, mesic Oxyaquic Fragiudalf). Differences in available soil water probably were the overriding factor in E. coli survival. Escherichia coli O157:H7 survival could be modeled in the same way as nonpathogenic E. coli and appears to have a slightly higher mortality rate
Orientation and symmetries of Alexandrov spaces with applications in positive curvature
We develop two new tools for use in Alexandrov geometry: a theory of ramified
orientable double covers and a particularly useful version of the Slice Theorem
for actions of compact Lie groups. These tools are applied to the
classification of compact, positively curved Alexandrov spaces with maximal
symmetry rank.Comment: 34 pages. Simplified proofs throughout and a new proof of the Slice
Theorem, correcting omissions in the previous versio
Assessing the Nutrient Status of Alfalfa Stands in Kentucky
Alfalfa (Medicago sativa L.) is a perennial forage legume and is sometimes referred to as the âQueen of Foragesâ due to its high nutritional value. Alfalfa is commonly produced as hay for use in the dairy and equine industries. Alfalfa yield increased exponentially from the 1950s to the1980s due to new breeding and management innovations. However, during the 1980s yields plateaued at around 7.5 Mg/ha and remain there today. The overarching goal of this study was to determine the role of soil fertility in the observed yield plateau. Fifty alfalfa stands in Kentucky were sampled to gather information about their macro and micronutrient status. Samples were taken, when the stand reached the late bud to early flower stage of maturity, from a 6 x 6 m2 area that was representative of the entire stand. Soil samples were collected to 10 and 15 cm depths and were sent to the University of Kentucky soil testing lab for analysis. The top 15 cm of 30 stems were dried, ground, and sent to Kansas State University for tissue analysis. In 2022, soil and tissue data from the alfalfa stands sampled indicated that potassium, sulfur, and magnesium were the nutrients most commonly reported to be below established sufficiency ranges. In addition, pH was low in just under half of the sampled stands. Tissue analysis indicated that soil testing overestimated potassium deficiencies in alfalfa stands in Kentucky. Even so, potassium levels were below the sufficiency range in nearly one-fourth of the alfalfa stands sampled
Fragipan Horizon Fragmentation in Slaking Experiments with Amendment Materials and Ryegrass Root Tissue Extracts
Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5-18.8 mm compared to the 44.2-47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress
Soil Health â It\u27s Not All Biology
Soil Health research tends to bias to a biology/microbiology emphasis. We believe this bias neglects important physical and chemical interactions in soil that are crucial to soil function. We offer several examples illustrating this bias, and how it may misrepresent management practices that have the greatest influence on Soil Health. Four suggestions are given as approaches to mitigate this bias. By appreciating soil structure as a foundation for Soil Health and its microbial community, we believe better recommendations can be made to assist the farm community in its stewardship of soil as a critical natural resource
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