1,097 research outputs found
Report on future management options for the south west trawl limited entry fishery
As a result of community concern regarding trawling, the current management rules for the South West Trawl Limited Entry Fishery were finalised in February 1989 and the final plan was gazetted in October of that year. However, there was public disquiet about this trawling, and as a result of this disquiet, a research program was initiated by the Fisheries Department with funding received from both the Commonwealth and State Governments. The scientific report, The impact of trawling for saucer scallops and western king prawns on the benthic communities in coastal waters off south-western Australia by L J B Laurenson, P Unsworth, J W Penn and R C J Lenanton was released in July 1993. Public research seminars were held in July 1993 to discuss the report, and public submissions were called on the document. Sixteen submissions on Report 100 were received by the Fisheries Department and these were considered by a Working Group appointed by the Minister for Fisheries. The group was formed to produce draft recommendations on the future management of the South West Trawl Limited Entry Fishery, taking into account research issues, legal advice and resource sharing issues
Influence of nitrogen on atrazine and 2, 4 dichlorophenoxyacetic acid mineralization in blackwater and redwater forested wetland soils
Microcosms were used to determine the influence
of N additions on active bacterial and fungal
biomass, atrazine and dichlorophenoxyacetic acid (2,4-
D) mineralization at 5, 10 and 15 weeks in soils from
blackwater and redwater wetland forest ecosystems in
the northern Florida Panhandle. Active bacterial and
fungal biomass was determined by staining techniques
combined with direct microscopy. Atrazine and 2,4-D
mineralization were measured radiometrically. Treatments
were: soil type, (blackwater or redwater forested
wetland soils) and N additions (soils amended with the
equivalent of 0, 200 or 400 kg N ha-1 as NH4NO3).
Redwater soils contained higher concentrations of C,
total N, P, K, Ca, Mn, Fe, B and Zn than blackwater
soils. After N addition and 15 weeks of incubation, active
bacterial biomass in redwater soils was lower when
N was added. Active bacterial biomass in blackwater
soils was lower when 400 kg N ha- 1 , but not when
200 kg N ha-1, was added. Active fungal biomass in
blackwater soils was higher when 400 kg N ha-1 , but
not when 200 kg N ha-1, was added. Active fungal biomass
in redwater soils was lower when 200 kg N ha-1 ,
but not when 400 kg N ha-1, was added. After 15 weeks
of incubation 2,4-D degradation was higher in redwater
wetland soils than in blackwater soils. After 10 and 15
weeks of incubation the addition of 200 or 400 kg N
ha-1 decreased both atrazine and 2,4-D degradation in
redwater soils. The addition of 400 kg N ha-1 decreased
2,4-D degradation but not atrazine degradation in
blackwater soils after 10 and 15 weeks of incubation.
High concentrations of N in surface runoff and groundwater
resulting from agricultural operations may have
resulted in the accumulation of N in many wetland
soils. Large amounts of N accumulating in wetlands
may decrease mineralization of toxic agricultural pesticides
Management options (discussion paper) for the Shark Bay snapper limited entry fishery
At the Annual Management Meeting of the Shark Bay Snapper Limited Entry Fishery held on 22 July 1994 industry put forward a proposal that supplementary and non-transferable quota that was lost to the fishery when a licence holding non-transferable quota was transferred should be retained by the Fisheries Department and leased back to licence holders on an annual basis. As a result of this proposal and the fact that the management arrangements for the fishery are extremely complex and in need of simplification, the Minster for Fisheries approved the establishment of a Working Group to examine the lease-back proposal and other long-term management strategies for the fishery
Influence of nitrogen on cellulose and lignin mineralization in blackwater and redwater forested wetland soils
Microcosms were used to determine the influence
of N additions on active bacterial and active
fungal biomass, cellulose degradation and lignin degradation
at 5, 10 and 15 weeks in soils from blackwater
and redwater wetlands in the northern Florida panhandle.
Blackwater streams contain a high dissolved organic
C concentration which imparts a dark color to the
water and contain low concentrations of nutrients. Redwater
streams contain high concentrations of suspended
clays and inorganic nutrients, such as N and P,
compared to blackwater streams. Active bacterial and
fungal biomass was determined by direct microscopy;
cellulose and lignin degradation were measured radiometrically.
The experimental design was a randomized
block. Treatments were: soil type (blackwater or
redwater forested wetlands) and N additions (soils
amended with the equivalent of 0, 200 or 400 kg N ha- 1
as NH4NO3 ). Redwater soils contained higher concentrations
of C, total N, P, K, Ca, Mn, Fe, B and Zn than
blackwater soils. After N addition and 15 weeks of incubation,
the active bacterial biomass in redwater soils
was lower than in blackwater soils; the active bacterial
biomass in blackwater soils was lower when 400 kg N
ha', but not when 200 kg N ha-1 , was added. The active
fungal biomass in blackwater soils was higher when
400 kg N ha- 1 , but not when 200 kg N ha- 1 , was added.
The active fungal biomass in redwater wetland soils was
lower when 200 kg N ha- 1 , but not when 400 kg N ha- 1 ,
was added. Cellulose and lignin degradation was higher
in redwater than in blackwater soils. After 10 and
15 weeks of incubation, the addition of 200 or 400 kg N
as NH4NO3 ha-1 decreased cellulose and lignin degradation
in both wetland soils to similar levels. This study
indicated that the addition of N may slow organic matter
degradation and nutrient mineralization, thereby
creating deficiencies of other plant-essential nutrients
in wetland forest soils
Matrix-based fertilizers: A new fertilizer formulation concept to reduce nutrient leaching
We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO 3 -,
NH4+ , and total phosphorus (TP) leaching, with Osmocoate® 14-14-14, a conventional
commercial slow release fertilizer (SRF), and with an unamended control in greenhouse
column studies. The MBF formulations covered a range of inorganic N and P in compounds
that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly
bound compounds (MBF3) mixed with Al(SO 4)3 H2O and/or Fe2(SO4 )3 and with high ionic
exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals
containing these nutrients in the MBF temporarily bind N and P to a Al(SO4 )3 H2O and/or
Fe2(SO4 )3 starch- chitosan- lignin matrix. One milligram (8000 spores) of Glomus intradices
was added to all formulations to attempt to enhance nutrient uptake. In this first series of
experiments, soil columns were planted to white soft spring wheat (Triticum aestivum L.cv.
Frame).
Three soils were used, a sand, a loam and a loamy sand. In several studies, SRF leachate
contained higher amounts of NH4+ , NO3 " and TP than leachate from all other fertilizers.
Although plant biomass and yield with MBF was reduced in the first series of experiments,
follow-up studies have shown that formulation adjustments allow comparable plant responses
among SRF and MBFs. There were no consistent differences in the amount of NH4+ , NO3 -
and TP in the MBF leachates compared to the control leachate. Arbuscular mycorrhizal
infection in plant roots did not consistently differ among plants growing in soil receiving SRF,
MBFs and control treatments. The efficacy of MBF fertilizer strategy to reduce N and P
leaching to surface has been verified and with continued work to optimize formulations this
technology is expected to provide a new approach for groundwater protection, especially in
easily drained soils. The approach has been submitted for patenting
Matrix based fertilizers reduce nitrogen and phosphorus leaching in greenhouse column studies
We tested the efficacy of matrix based
fertilizer formulations (MBF) that reduce NH4, total
phosphorus (TP), total reactive phosphorus (TRP) and
dissolved reactive phosphorus (DRP) in leachate. The
MBF formulations cover a range of inorganic N and P
in compounds that are relatively loosely bound
(MBF1) to more moderately bound (MBF2) and more
tightly bound compounds (MBF3) mixed with Al
(SO4)3 H2O and/or Fe2(SO4)3 and with the high ionic
exchange compounds starch, chitosan and lignin.
Glomus interadicies, a species of arbuscular mycorrhizal
fungal spores that will form mycorrhizae in
high nutrient environments, was added to the MBF
formulations to increase plant nutrient uptake. When
N and P are released from the inorganic chemicals
containing N and P the matrix based fertilizers likely
bind these nutrients to the Al(504)3 H2O and/or
Fe2(504)3 starch–chitosan–lignin matrix. We tested
the efficacy of the MBFs to reduce N and P leaching
compared to Osmocote® 14-14-14, a slow release
fertilizer (SRF) in sand filled columns in a greenhouse
study. SRF with and without Al and Fe leached 78-
84% more NH4, 58-78% more TP, 20-30% more
TRP and 61-77% more than MBF formulations 1, 2,
and 3 in a total of 2.0 liters of leachate after 71 days.
The concentration and amount of NO3 leached among
SRF and MBF formulations 1 and 2 did not differ.
The SRF treatment leached 34% less NO3 , than
MBF3. Total plant weight did not differ among
fertilizer treatments. Arbuscular mycorrhizal infection
did not differ among plants receiving SRF and MBF
formulations 1, 2 and 3. Although further greenhouse
and field testing are called for, results of this initial
investigation warrant further investigation of MBFs
Matrix-based fertilizers reduce nutrient leaching while maintaining Kentucky bluegrass growth
Abstract We tested the efficacy of matrix-based
fertilizers (MBFs) to improve Kentucky bluegrass
(Poa pratensis L.) growth while reducing NH, NO3,
dissolved reactive phosphorus (DRP), and total
phosphorus (TP) compared to commercial slowrelease
fertilizer (SRF) Polyon®, ESN®, and Avail®
in greenhouse column studies. The MBFs covered a
range of inorganic N and P in compounds that are
relatively loosely bound (MBF6) and more tightly
bound compounds (MBF7) with Al(SO4)318H2O
and/or Fe2(SO4)33H2O and with high ionic exchange
compounds starch, cellulose, and lignin. The total
amount of NO3 and NH4 leached was greater from
columns receiving Polyon® and ESN® fertilizers than
all other treatments. The MBF6+Avail® or MBF7+
Avail® fertilizers leached 64–68% less NO3 than
Polyon® (43-0-0) and ESN® (46-0-0), and 73–76%
less TDP and TP than Avail® (10-34-0). A greater
amount of NO3 was leached from the MBF6+Avail®
and the MBF7+Avail® treatments than the other MBF
fertilizer treatments. Shoot and root biomass were
greater when plants received the Avail®, MBF6+
Avail®, and MBF7+Avail® fertilizer treatments than
the other fertilizer treatments. When combined with
small quantities of commercial SRFs, these new MBFs
were able to maintain plant growth while reducing N
and P leaching. These new MBF formulations do not
depend on organic or inorganic coatings to reduce N
and P leaching and with further testing and development
could be effective commercial fertilizers
Influence of polyacrylamide application to soil on movement of microorganisms in runoff water
Polyacrylamide (PAM) use in irrigation for erosion control has increased water infiltration and reduced soil erosion. This has
improved runoff water quality via lower concentrations of nitrogen, phosphorous, and pesticides, and decreased biological oxygen
demand. Since non-toxic high molecular weight anionic PAMs removed clay size sediment particles in flowing water, we hypothesized
that PAM would effectively remove or immobilize microorganisms in flowing water. In an agricultural field, we determined
the efficacy of PAM-treatment of furrow irrigation water to remove several categories of microorganisms in the inflow and runoff.
Treatments were: (I) PAM application and a control; (2) three flow rates; (3) two distances from the inflow point; and (4) three
times during each irrigation. After water traveled 1 m at 7.5 and 15.5 1 min-1 , PAM-treatment reduced total bacterial and microbial
biomass and total fungal biomass relative to the control treatment. After water traveled 40 m at 7.5, 15.5, and 22.5 1 min-1
PAM-treatment reduced algae, the numbers active and total bacteria, active and total fungal length, and total bacterial biomass,
total fungal and microbial biomass relative to the control treatment. Although specific organisms were not identified or monitored
in this study, the results clearly have implications for controlling the spread of soil-borne plant pathogens and other classes of
harmful organisms within and among fields via irrigation water and in re-utilized return flows. Beyond furrow-irrigated agriculture,
new methods to manage overland transmission of harmful microorganisms could potentially help control transport of pathogens
from animal waste in runoff and groundwater
Matrix based fertilizers reduce nitrogen and phosphorus leaching in three soils
We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO3-, NH4+, and total phosphorus (TP) leaching, with Osmocoate 14-14-14, a conventional commercial slow release fertilizer (SRF) and an unamended control in three different soil textures in a greenhouse column study. The MBFs covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF 1) to more moderately bound (MBF 2) and more tightly bound compounds (MBF 3) mixed with Al(SO4)3H2O and/or Fe2(SO4)3 and with high ionic exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals containing these nutrients in the MBF bind N and P to a Al(SO4)3H2O and/or Fe2(SO4)3 starch-chitosan-lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soil textures the SRF leachate contained a higher amount of NH4+, NO3- and TP than leachate from all other fertilizers. In all three soils there were no consistent differences in the amount of NH4+, NO3- and TP in the MBF leachates compared to the control leachate. Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBFs regardless of Al(SO4)3H2O or Fe2(SO4)3 additions. Arbuscular mycorrhizal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. Although the MBFs resulted in less plant growth in this experiment they may be applied to soils growing plants in areas that are at high risk for nutrient leaching to surface waters
The efficacy of polyacrylamide to reduce nutrient movement from an irrigated field
Irrigation-induced erosion contributes to elevated sediment and nutrient concentrations in irrigation return-flow
water. Polyacrylamide (PAM) is an effective flocculent widely used to reduced soil erosion. We hypothesized PAM would
reduce transport of sediment and nutrients in surface irrigation water flowing over soil. We measured nutrients in irrigation
inflow and runoff water and total and extractable nutrients in sediment transported from agricultural fields. Treatments
were: (1) PAM application and no PAM (control), (2) three flow rates (7.5, 15.0, and 22.5 L min- 1), (3) distance along the
furrow (1 m below the inflow point and 40 m down furrow), and (4) time during irrigation (0.5, 3.5, and 6.5 h after initial
inflow). After irrigation water flowed 40 m, water flowing in furrows receiving PAM treatments reduced the NO3-
concentration in runoff by 85% and the total P concentration in water by 90% compared to runoff water in furrows without
PAM, regardless of flow rate. Mass export of NH4 +, NO3-, dissolved reactive phosphorus (DRP), total P, K, Ca, Mg, Fe, Mn,
Cu, B, and Zn in untreated irrigation runoff water increased as the flow rate increased from 7.5 to 22.5 L min- 1. Export of
these nutrients, via sediment carried by untreated irrigation runoff water, increased from 2 to 5 fold as the flow rate increased
from 7.5 to 22.5 L min-1. After water flowed 40 m, transport of these extractable nutrients was reduced from 10 to 40 fold in
PAM-treated furrows. With proper application, PAM reduces nutrient loss from furrow-irrigated agricultural fields,
protecting surface water and groundwater quality
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