74 research outputs found
Phosphorus forms and extractability from three sources in a recently exposed calcareous subsoil
Irrigation-induced erosion and land leveling have decreased crop
yields on - 800 000 ha of south-central Idaho silt loam soils because
of topsoil removal. Phosphorus availability is a known production
problem after topsoil removal. This study evaluated the effect of three
P sources on soil P solubility by three standard methods for calcareous
soils. A long-term study was initiated on a Portneuf silt loam (Coarse-silty,
mixed, superactive, mesic Durinodic Xeric Haplocalcid) by removing
the surface 0.3 m of topsoil from strips between undisturbed
topsoil strips. Phosphorus treatments applied across all strips were
conventional fertilizer (applied according to soil test), dairy manure,
and cheese whey. All treatments increased the freshly exposed subsoil
bicarbonate extractable ortho-P concentrations up to or greater than
the topsoil concentrations, which were more than adequate for economical
crop production. The high-whey and manure treatments increased
the subsoil saturation paste and 0.01 M CaCl2 extractable
ortho-P concentrations up to or greater than the untreated topsoil
ortho-P concentrations. The initial topsoil ortho-P solubility was along
the ?-tricalcium phosphate (?-TCP) isotherm and the initial subsoil
was well below the ?-TCP isotherm. The ortho-P solubility of the
subsoil monocalcium phosphate (MCP) treatment remained just below
the ?-TCP isotherm. The cottage cheese whey treatment increased
subsoil P solubility up to the ?-TCP isotherm and the manure treated
subsoil ortho-P solubilities were between the ?-TCP and octacalcium
phosphate (OCP) isotherms. Most subsoil ortho-P concentrations by
all three extraction methods decreased from spring to fall and then
increased over winter in the subsequent spring samples. Soil solution
ortho-P concentrations decreased with time in the subsoil treatments
except immediately following treatment applications. The topsoil ortho-P
extract concentrations by all three methods varied among samplings
but remained about the same during the study period
Improving exposed subsoils with fertilizers and crop rotations
Irrigation-induced erosion and land leveling have decreased crop
yields on approximately 800 000 ha of south-central Idaho silt loam
soils. Previous attempts to increase subsoil productivity to that of
the topsoil have not been successful on these soils. This study was
conducted to find a method(s) for increasing the productivity of freshly
exposed subsoil to that of the topsoil and to determine the factor(s)
limiting subsoil production. A 4-yr study was initiated by removing
the surface 0.3 m of topsoil from strips between undisturbed topsoil
strips of a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic
Calciorthid). Different crop rotations were established within the
strips and fertility treatments were applied across the strips. The
fertilizer treatments were conventional fertilizer application according
to soil test, dairy manure, and two cottage cheese (acid) whey rates.
During the fourth year, dry edible bean (Phaseolus vulgaris L., cv.
Viva) were grown on the entire plot area as a test crop. The application
of 44 Mg manure ha-1 in the spring and 93 Mg manure ha-1 in the
fall of 1991 (first year of study) was the only treatment that restored
subsoil bean production to that of the topsoil plots. Plant Zn and
soil organic C concentrations were the only measured factors that
correlated with bean yield increases on the subsoil
Organic phosphorus source effects on calcareous soil phosphorus and organic carbon
The loading, solubility, mobility, and plant availability of P is a
growing environmental concern to regulators and planners of nutrient
management plans, confined animal feeding operations, and wastewater
land application permit sites. Insufficient information is available
on how P reacts from different organic sources when applied to calcareous
soils. A field study was conducted to determine the interactions
among P application rate, source, extractability, and soil organic carbon
(OC) concentration. A Portneuf silt loam (Coarse-silty, mixed,
superactive, mesic Durinodic Xeric Haplocalcids) topsoil and freshly
exposed subsoil were fertilized with monocalcium phosphate (MCP),
cheese whey, and dairy manure. Organic matter added with the whey
did not influence soil OC concentrations whereas organic matter
added with the manure doubled the subsoil OC and increased the
topsoil OC concentrations. Bicarbonate and saturation paste extractable
ortho- and organic-P concentrations were linearly related to soil
OC concentrations but were not related to the amount of ortho- or
organic-P added. All forms of P increased more per unit of added P
in the order manure > whey > MCP and were correlated with the soil
OC concentrations. These results suggest organic waste applications
should be managed from :oil P test data rather than on P application
rates
Bio-analytical Assay Methods used in Therapeutic Drug Monitoring of Antiretroviral Drugs-A Review
A comunicação na articulação agroindustrial entre uma cooperativa central, suas cooperativas singulares e cooperados
Phosphorus forms and extractability from three sources in a recently exposed calcareous subsoil
Irrigation-induced erosion and land leveling have decreased crop
yields on - 800 000 ha of south-central Idaho silt loam soils because
of topsoil removal. Phosphorus availability is a known production
problem after topsoil removal. This study evaluated the effect of three
P sources on soil P solubility by three standard methods for calcareous
soils. A long-term study was initiated on a Portneuf silt loam (Coarse-silty,
mixed, superactive, mesic Durinodic Xeric Haplocalcid) by removing
the surface 0.3 m of topsoil from strips between undisturbed
topsoil strips. Phosphorus treatments applied across all strips were
conventional fertilizer (applied according to soil test), dairy manure,
and cheese whey. All treatments increased the freshly exposed subsoil
bicarbonate extractable ortho-P concentrations up to or greater than
the topsoil concentrations, which were more than adequate for economical
crop production. The high-whey and manure treatments increased
the subsoil saturation paste and 0.01 M CaCl2 extractable
ortho-P concentrations up to or greater than the untreated topsoil
ortho-P concentrations. The initial topsoil ortho-P solubility was along
the ?-tricalcium phosphate (?-TCP) isotherm and the initial subsoil
was well below the ?-TCP isotherm. The ortho-P solubility of the
subsoil monocalcium phosphate (MCP) treatment remained just below
the ?-TCP isotherm. The cottage cheese whey treatment increased
subsoil P solubility up to the ?-TCP isotherm and the manure treated
subsoil ortho-P solubilities were between the ?-TCP and octacalcium
phosphate (OCP) isotherms. Most subsoil ortho-P concentrations by
all three extraction methods decreased from spring to fall and then
increased over winter in the subsequent spring samples. Soil solution
ortho-P concentrations decreased with time in the subsoil treatments
except immediately following treatment applications. The topsoil ortho-P
extract concentrations by all three methods varied among samplings
but remained about the same during the study period
Improving exposed subsoils with fertilizers and crop rotations
Irrigation-induced erosion and land leveling have decreased crop
yields on approximately 800 000 ha of south-central Idaho silt loam
soils. Previous attempts to increase subsoil productivity to that of
the topsoil have not been successful on these soils. This study was
conducted to find a method(s) for increasing the productivity of freshly
exposed subsoil to that of the topsoil and to determine the factor(s)
limiting subsoil production. A 4-yr study was initiated by removing
the surface 0.3 m of topsoil from strips between undisturbed topsoil
strips of a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic
Calciorthid). Different crop rotations were established within the
strips and fertility treatments were applied across the strips. The
fertilizer treatments were conventional fertilizer application according
to soil test, dairy manure, and two cottage cheese (acid) whey rates.
During the fourth year, dry edible bean (Phaseolus vulgaris L., cv.
Viva) were grown on the entire plot area as a test crop. The application
of 44 Mg manure ha-1 in the spring and 93 Mg manure ha-1 in the
fall of 1991 (first year of study) was the only treatment that restored
subsoil bean production to that of the topsoil plots. Plant Zn and
soil organic C concentrations were the only measured factors that
correlated with bean yield increases on the subsoil
Organic phosphorus source effects on calcareous soil phosphorus and organic carbon
The loading, solubility, mobility, and plant availability of P is a
growing environmental concern to regulators and planners of nutrient
management plans, confined animal feeding operations, and wastewater
land application permit sites. Insufficient information is available
on how P reacts from different organic sources when applied to calcareous
soils. A field study was conducted to determine the interactions
among P application rate, source, extractability, and soil organic carbon
(OC) concentration. A Portneuf silt loam (Coarse-silty, mixed,
superactive, mesic Durinodic Xeric Haplocalcids) topsoil and freshly
exposed subsoil were fertilized with monocalcium phosphate (MCP),
cheese whey, and dairy manure. Organic matter added with the whey
did not influence soil OC concentrations whereas organic matter
added with the manure doubled the subsoil OC and increased the
topsoil OC concentrations. Bicarbonate and saturation paste extractable
ortho- and organic-P concentrations were linearly related to soil
OC concentrations but were not related to the amount of ortho- or
organic-P added. All forms of P increased more per unit of added P
in the order manure > whey > MCP and were correlated with the soil
OC concentrations. These results suggest organic waste applications
should be managed from :oil P test data rather than on P application
rates
The ionic mechanism of action of GABA and l-glutamate on a crustacean striated muscle (vas deferens of the crayfish)
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