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Tara Simmons - One of the best experts on this subject based on the ideXlab platform.
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Phosphorus in Pasture Plants: potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, James R. Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater ( P
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phosphorus in Pasture Plants potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, J R Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater (P < 0.01; LSD05 = 117 mg kg−1) in legumes (3,480 mg kg−1) than for grasses (3,210 mg kg−1). Total plant P concentrations of grasses and legumes increased with soil Mehlich-3 P concentrations in both glasshouse and field trials with concentrations close to 6,000 mg kg−1 in arrowleaf clover at 680 mg kg−1 Mehlich-3 soil P. FRP in water extracts of plant shoots increased relative to plant total P as soil Mehlich-3 P increased, with the greatest concentrations shown by crimson clover and arrowleaf clover. Analysis of water extracts of ryegrass and clover herbage from a field trial showed that while FRP was increasing, phytase-available-P decreased significantly from about 70% of filterable unreactive P at the lowest Mehlich-3 P concentrations, to close to zero at 200 mg kg−1 Mehlich-3 P. The wide variation, and enrichment of FRP in water extracts and total P with increasing Mehlich-3 P among species, indicates that cultivar and site selection and sward management provide a potential option to mitigate P loss to surface waters.
Richard W. Mcdowell - One of the best experts on this subject based on the ideXlab platform.
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Phosphorus in Pasture Plants: potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, James R. Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater ( P
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phosphorus in Pasture Plants potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, J R Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater (P < 0.01; LSD05 = 117 mg kg−1) in legumes (3,480 mg kg−1) than for grasses (3,210 mg kg−1). Total plant P concentrations of grasses and legumes increased with soil Mehlich-3 P concentrations in both glasshouse and field trials with concentrations close to 6,000 mg kg−1 in arrowleaf clover at 680 mg kg−1 Mehlich-3 soil P. FRP in water extracts of plant shoots increased relative to plant total P as soil Mehlich-3 P increased, with the greatest concentrations shown by crimson clover and arrowleaf clover. Analysis of water extracts of ryegrass and clover herbage from a field trial showed that while FRP was increasing, phytase-available-P decreased significantly from about 70% of filterable unreactive P at the lowest Mehlich-3 P concentrations, to close to zero at 200 mg kg−1 Mehlich-3 P. The wide variation, and enrichment of FRP in water extracts and total P with increasing Mehlich-3 P among species, indicates that cultivar and site selection and sward management provide a potential option to mitigate P loss to surface waters.
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Sources of phosphorus lost from a grazed Pasture receiving simulated rainfall.
Journal of Environmental Quality, 2007Co-Authors: Richard W. Mcdowell, David Nash, F. RobertsonAbstract:Nutrients exported from grazing systems contribute to eutrophication of surface waters. In this study the contributions of soil, Pasture-Plants, and dung to P exports in overland flow were compared using simulated rainfall. The treatments were (i) grazed Pasture-Plants (isolated from soil by application of petrolatum to the soil surface), (ii) grazed Pasture-Plants and supporting soil, (iii) grazed Pasture-Plants and soil and treading, and (iv) grazed Pasture-Plants and soil and treading and dung. In general, dissolved reactive P (DRP) accounted for the majority of the P exported and P losses decreased in the order: treading and dung treatment > treading > Pasture-Plants and soil > Pasture-Plants. Very little dissolved organic P was lost in overland flow and the effects of treading diminished with time. Over a normal grazing cycle (30 d), the portion of P lost from Pasture-Plants was approximately half that lost from Pasture-Plants and soil, one-third that lost from treaded Pasture-Plants and soil, and one-quarter that lost from treaded Pasture-Plants, soil, and dung. The DRP in the Pasture-Plants treatment was approximately half that in the Pasture-Plants and soil treatment and suggests that a significant portion of the P exported from these systems is derived directly from Pasture-Plants. Due to higher proportions of particulate P (PP) in the treaded and dung treatments, DRP accounted for less of total P than in the Pasture-Plants and Pasture-Plants and soil treatments. Lower infiltration capacities probably caused by mechanical disaggregation at the soil surface are consistent with the higher proportions of PP in the treading treatments. These results were used to estimate P exports from a field trial site in Southland, New Zealand. The results suggested that P export attributable to fertilizer, dung, Pasture-Plants, and soil components were approximately 10, 30, 20, and 40%, respectively. These results suggest that since 90% of the P exports are derived from the soil–plant system and dung returns, managements to lessen P exports should continue to focus on maintaining soil P within the optimal range for Pasture-plant production and maintaining soil surface properties that maximize infiltration and minimize overland flow.
Andrew N. Sharpley - One of the best experts on this subject based on the ideXlab platform.
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Phosphorus in Pasture Plants: potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, James R. Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater ( P
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phosphorus in Pasture Plants potential implications for phosphorus loss in surface runoff
Plant and Soil, 2011Co-Authors: Richard W. Mcdowell, Andrew N. Sharpley, J R Crush, Tara SimmonsAbstract:Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from Pasture Plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater (P < 0.01; LSD05 = 117 mg kg−1) in legumes (3,480 mg kg−1) than for grasses (3,210 mg kg−1). Total plant P concentrations of grasses and legumes increased with soil Mehlich-3 P concentrations in both glasshouse and field trials with concentrations close to 6,000 mg kg−1 in arrowleaf clover at 680 mg kg−1 Mehlich-3 soil P. FRP in water extracts of plant shoots increased relative to plant total P as soil Mehlich-3 P increased, with the greatest concentrations shown by crimson clover and arrowleaf clover. Analysis of water extracts of ryegrass and clover herbage from a field trial showed that while FRP was increasing, phytase-available-P decreased significantly from about 70% of filterable unreactive P at the lowest Mehlich-3 P concentrations, to close to zero at 200 mg kg−1 Mehlich-3 P. The wide variation, and enrichment of FRP in water extracts and total P with increasing Mehlich-3 P among species, indicates that cultivar and site selection and sward management provide a potential option to mitigate P loss to surface waters.
Brian Dear - One of the best experts on this subject based on the ideXlab platform.
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the search for new Pasture Plants to achieve more sustainable production systems in southern australia
Australian Journal of Experimental Agriculture, 2008Co-Authors: Brian Dear, Mike EwingAbstract:Increasing the proportion of the landscape planted to deep-rooted perennial Pasture species is recognised as one of several remedial actions required for the control of dryland salinity in southern Australia. The widespread use of perennials in farming systems is limited at present by the lack of well-adapted perennials that can be grown to reduce recharge in a landscape where drought, soil acidity, temporary waterlogging, infertile soils and unrestricted grazing prohibit the use of many species. The range of Plants adapted to salinity also needs to be expanded to stabilise and ameliorate soils already degraded by rising watertables and to increase the profitability of grazing discharge regions within the landscape. This paper describes the steps involved in a national forage screening and breeding program initiated by the Cooperative Research Centre (CRC) for Plant-based Management of Dryland Salinity1, seeking to expand the range of perennial and or salt-tolerant forage Plants that can be incorporated into farming systems of southern Australia. It describes the target environments, soil constraints, farming systems and the criteria being considered when assessing the potential of new Plants, including assessment of the weed risk posed by introducing new species. This paper forms an introduction to a special issue which presents the outcomes of the Pasture species field evaluation and plant breeding program conducted by the CRC.
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outcomes of the search for new perennial and salt tolerant Pasture Plants for southern australia
Animal Production Science, 2008Co-Authors: Brian Dear, Kevin Reed, Andrew D CraigAbstract:The potential adaptation of a range of perennial Pasture species to recharge environments in southern Australia is reviewed based on their performance in 20 field nurseries in a nationally coordinated project. Species were also evaluated for their suitability to discharge sites where salt and waterlogging are major restraints. Species are ranked according to their potential to be incorporated into farming systems and the scope for further breeding and selection. Medicago sativa L. (lucerne) was the most persistent of the perennial legumes across a diversity of recharge environments. Lotus corniculatus L. (birdsfoot trefoil) showed the most promise on soils prone to waterlogging. Other legumes that showed potential included Cullen australasicum (Schltdl.) J.W. Grimes (tall verbine) and Lotononis bainesii Baker (lotononis). The herb Chicoriyum intybus L. was superior to M. sativa on more acid soils. Phalaris aquatica L. (phalaris) and summer dormant cultivars of Dactylis glomerata L. (cocksfoot), Festuca arundinacea L. (tall fescue) and Lolium perenne L. (perennial ryegrass) were among the most persistent and productive of the perennial grasses. Further exploitation of temperate perennial grass germplasm with increased summer dormancy should be a priority to increase the role of these grass species in lower rainfall, summer-dry environments. Although difficult to establish, the indigenous grasses Austrodanthonia caespitosa (Gaudich.) H.P. Linder (wallaby grass) and A. richardsonii (Cashmore) H.P. Linder were persistent and showed good recruitment. They should be a priority for low rainfall, low input environments. Other grasses that showed promise were Chloris gayana Kunth (Rhodes grass), Secale montanum Guss. (mountain rye), Microlaena stipoides (Labill.) R. Br. (weeping grass), Ehrhata calcycina Sm. (veldt grass) and Bromus stamineus E. Desv. (grazing brome). For discharge environments, Melilotus siculus (Turra) Vitman ex B.D. Jacks. was one of the most salt tolerant legumes and should be a priority for further development. Medicago polymorpha L. (burr medic) appears underutilised in discharge environments. Increasing the waterlogging tolerance of this moderately salt tolerant species would further enhance its potential. Trifolium michelianum Savi. (balansa clover) owed its success in discharge areas more to ‘salt avoidance’ rather than salt tolerance per se. Melilotus sulcatus Desf., T. tomentosum L. and Lotus tenuis Waldst. & Kit. ex Willd. also had traits that may prove advantageous for discharge environments. Within the Pasture grasses, Puccinellia ciliata Bor (pucinellia) was superior at sites prone to waterlogging whereas T. ponticum performed better in moderately drained saline sites.
Richard J Simpson - One of the best experts on this subject based on the ideXlab platform.
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Pasture Plants and soil fertility management to improve the efficiency of phosphorus fertiliser use in temperate grassland systems
Crop & Pasture Science, 2014Co-Authors: Richard J Simpson, Alan E Richardson, S N Nichols, J R CrushAbstract:Phosphorus (P) fertilisers are important for productivity in many grassland systems. Phosphorus is a non-renewable and finite resource, and there are environmental and economic reasons for using P more effectively. We review the P balance of temperate Pastures to identify the factors contributing to inefficient use of P fertiliser and discuss ways to improve P-balance efficiency. Immediate gains can be made by ensuring that P fertiliser inputs are managed to ensure that the plant-available P concentrations of soil do not exceed the minimum concentration associated with maximum Pasture production. Unnecessarily high soil P concentrations are associated with greater potential for P loss to the wider environment, and with higher rates of P accumulation in soils that have a high P-sorption capacity. Soil microorganisms already play a crucial role in P cycling and its availability for Pasture growth, but are not amenable to management. Consequently, Plants with lower critical P requirements, particularly because of better root foraging, will be an important avenue for improving the P-balance efficiency of fertilised Pastures. Traits such as long fine roots, branching, root hairs, and mycorrhizal associations all contribute to improved root foraging by Pasture Plants; some of these traits are amenable to breeding. However, progress in breeding for improved P efficiency in Pasture Plants has been minimal. It is likely that traditional plant breeding, augmented by marker-assisted selection and interspecific hybridisation, will be necessary for progress. There are practical limits to the gains that can be made by root foraging alone; therefore, Plants that can ‘mine’ sparingly available P in soils by producing organic anions and phosphatases are also needed, as are innovations in fertiliser technology.
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utilization of phosphorus by Pasture Plants supplied with myo inositol hexaphosphate is enhanced by the presence of soil micro organisms
Plant and Soil, 2001Co-Authors: Alan E Richardson, P A Hadobas, Julie Hayes, C P Ohara, Richard J SimpsonAbstract:A range of Pasture grass (Danthonia richardsonii and Phalaris aquatica) and legume (Medicago polymorpha, M. sativa, Trifolium repens and T. subterraneum) species showed limited capacity to obtain phosphorus (P) from inositol hexaphosphate (IHP), when grown in either sterile agar (pH 5.0 or 5.5) or sand-vermiculite media (pH 5.0). The total P content of shoots from IHP-supplied Plants grown in agar was between 20% and 34% of that for seedlings supplied with an equivalent amount of P as inorganic phosphate (Pi), while in sand-vermiculite, the total P content of IHP-grown Plants was between 5 and 10% of control Plants. The poor ability of Plants to utilize P from IHP resulted in significantly lower tissue P concentrations and, in general, reduced plant dry weight accumulation. In contrast, the P nutrition of Plants supplied with IHP was significantly improved by inoculating media with either a cultured population of total soil micro-organisms or with a specific isolate of Pseudomonas sp., selected for its ability to release phosphate from IHP (strain CCAR59; Richardson and Hadobas, 1997 Can. J. Micro. 43, 509-516). In agar and sand-vermiculite media, respectively, the P content of IHP-grown Plants increased with inoculation by up to 3.9- and 6.8-fold, such that the dry weight and P content of the plant material were equivalent to those observed for control Plants supplied with Pi. However, the response to inoculation was dependent on the growth medium and the source of micro-organisms used. In sand-vermiculite, the cultured population of soil micro-organisms was effective when IHP was supplied at an equivalent level of Pi required for maximum plant growth. By comparison, inoculation of Plants with the Pseudomonas strain was only effective at very high levels of IHP supply (×36), whereas in agar a response to inoculation occurred at all levels of IHP. The ability of Pasture Plants to acquire P from phytate was, therefore, influenced by the availability of IHP substrate, which was further affected by the presence of soil micro-organisms. Our results show that in addition to having an effect on the sorption characteristics of the growth media, soil micro-organisms also provided a source of phytase for the dephosphorylation of phytate for subsequent utilization of Pi by Plants.