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P. T. Doyle - One of the best experts on this subject based on the ideXlab platform.
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the response of broad and fine wool merino wethers to differential grazing of Annual Pastures during spring
Australian Journal of Experimental Agriculture, 2002Co-Authors: M. W. Hyder, A N Thompson, P. T. Doyle, K TanakaAbstract:Two experiments examined the effects of manipulating grazing pressure during spring on the liveweight and wool-growth response of fine- and broad-wool genotypes of Merino wethers grazing Annual Pastures. One-year-old broad- and fine-wool Merino wethers (Bungaree and Peppin; mean fibre diameter 25.4 v. 20.7 m and 22.1 v. 19.8 m before years 1 and 2, respectively) were grazed on Annual Pastures maintained near target amounts of green feed on offer (800, 1100, 1400, 2000 and 2800 kg green DM/ha), or set-stocked at the district average of 8 sheep/ha, during the spring of 1992 and 1993. Within the control-grazed treatments, there was no significant difference in the total amount of pasture produced during the experimental periods but more (P<0.05) pasture was produced under set-stocking (7900 v. 5400 kg DM/ha and 7700 v. 5600 kg DM/ha in years 1 and 2, respectively). Liveweight change was linear for most treatments over the first 90 days or so of the spring grazing period, and in both years the average rate of liveweight change was similar for both genotypes. Liveweight change increased (P 0.05) difference in liveweight change during spring for sheep grazing treatments 2000 kg DM/ha or above. Sheep from the broad-wool genotype produced more (P<0.05) wool than those from the fine-wool genotype and, as expected, the wool was also significantly broader at all feed on offer levels. For both broad- and fine-wool sheep, feed on offer and liveweight change were closely correlated with wool growth rate and fibre diameter in both years. The asymptote of the relationships with feed on offer and the intercept of the relationships with liveweight change was greater (P<0.05) for broad- than fine-wool sheep. However, there was no significant difference between genotypes in either size and shape or slope of these relationships. In other words, the wool-growth and fibre-diameter response of broad-wool sheep to decreasing feed on offer in the spring was the same as that for fine-wool sheep. For both genotypes, Annual clean-wool production (P<0.001) and mean fibre diameter (P<0.05) increased withincreasing feed on offer during spring. The total amount of wool grown per hectare during spring decreased linearly (P<0.001) with increasing feed on offer. Grazing to about 2500 kg DM/ha more-than trebled the total clean wool produced per hectare compared with set-stocking. Thus, irrespective of sheep genotype, managing feed on offer in spring is a useful tool for manipulating wool characteristics, and increasing pasture utilisation and total wool production per unit area.
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The response of broad- and fine-wool Merino wethers to differential grazing of Annual Pastures during spring
Australian Journal of Experimental Agriculture, 2002Co-Authors: M. W. Hyder, Andrew Thompson, P. T. Doyle, K TanakaAbstract:Two experiments examined the effects of manipulating grazing pressure during spring on the liveweight and wool-growth response of fine- and broad-wool genotypes of Merino wethers grazing Annual Pastures. One-year-old broad- and fine-wool Merino wethers (Bungaree and Peppin; mean fibre diameter 25.4 v. 20.7 m and 22.1 v. 19.8 m before years 1 and 2, respectively) were grazed on Annual Pastures maintained near target amounts of green feed on offer (800, 1100, 1400, 2000 and 2800 kg green DM/ha), or set-stocked at the district average of 8 sheep/ha, during the spring of 1992 and 1993. Within the control-grazed treatments, there was no significant difference in the total amount of pasture produced during the experimental periods but more (P
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strip grazing to control wool growth rate of sheep grazing green Annual Pastures
Australian Journal of Experimental Agriculture, 1999Co-Authors: P. T. Doyle, J Young, P BoothAbstract:We compared strip grazing (SG) as a means of controlling wool growth rate, reducing variation in fibre diameter along the staple, and of carrying more Merino sheep through winter on green Annual Pastures, with set stocking (SS) in 3 experiments. In experiments 1 and 2, SG involved grazing to a residual feed on offer (FOO) of 400 kg DM/ha with an estimated intake of about 0.8 kg DM/day for each sheep. Treatments commenced after pasture establishment in autumn–winter, with both treatments stocked at 20 wethers/ha until late spring. During spring, average liveweight changes were lower (P<0.01) under SG than SS (55 v. 153 g/day experiment 1; –16 v. 217 g/day experiment 2). Strip grazing, compared with SS, reduced (P<0.01) the variation in wool growth rate and fibre diameter along the staple leading to lower (P<0.01) clean wool weights (3.54 v. 3.94 and 2.97 v. 4.12 kg), but finer (P<0.01) (20.9 v. 22.0 and 19.5 v. 21.5 mm), stronger (P<0.01) (28.6 v. 25.3 and 39.9 v. 35.5 N/ktex) wool. However, there was also an increase in vegetable matter content of the wool. The effects on Annual Pastures were to increase grass (79 v. 48 and 59 v. 25%) and reduce legume (12 v. 36 and 22 v. 54%) content at the end of spring. In experiment 3, two strip grazing treatments were used: SGl with a residual FOO of about 400 kg DM/ha and a stocking rate of 28 wethers/ha; and SGh with a residual FOO of about 800 kg DM/ha and stocking rate of 14 wethers/ha. The stocking rate for SS was 12 wethers/ha. SGl, following an autumn deferment, enabled a stocking rate of 28 wethers/ha to be sustained through winter without supplementary feeding. This is substantially higher than the district average stocking rate of about 7 sheep/ha. Strip grazing reduced (P<0.01) liveweights at the completion of treatments (SGl 41.9 v. SGh 47.9 v. SS 60.3 kg), reduced (P<0.01) clean wool weights (3.40 v. 3.72 v. 4.54 kg) and mean fibre diameter (19.1 v. 19.0 v. 20.9 m), but increased staple strength (21.3 v. 19.0 v. 16.9 N/ktex). These results are discussed in relation to opportunities to utilise strip grazing in sheep production systems on Annual Pastures in south-western Australia.
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Strip grazing to control wool growth rate of sheep grazing green Annual Pastures
Australian Journal of Experimental Agriculture, 1999Co-Authors: P. T. Doyle, J Young, P BoothAbstract:We compared strip grazing (SG) as a means of controlling wool growth rate, reducing variation in fibre diameter along the staple, and of carrying more Merino sheep through winter on green Annual Pastures, with set stocking (SS) in 3 experiments. In experiments 1 and 2, SG involved grazing to a residual feed on offer (FOO) of 400 kg DM/ha with an estimated intake of about 0.8 kg DM/day for each sheep. Treatments commenced after pasture establishment in autumn–winter, with both treatments stocked at 20 wethers/ha until late spring. During spring, average liveweight changes were lower (P
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effects of differential grazing of Annual Pastures in spring and age of sheep on pasture and sheep production
Australian Journal of Experimental Agriculture, 1997Co-Authors: A N Thompson, M. W. Hyder, P. T. DoyleAbstract:The effects of controlled grazing through spring on the production of young (age 1 year; liveweight 38.3 ± 0.09 kg; condition score 3.0 ± 0.03) and mature (age 3 years; liveweight 61.9 ± 0.36 kg; condition score 3.1 ± 0.04) Merino wethers was examined. The grazing treatments involved adjusting sheep numbers to maintain green feed on offer near target amounts of 800, 1200, 1600, 2000, 2400 and 2800 kg dry matter/ha. Liveweight and wool growth measurements were made on 8 sheep per plot, with additional animals added or removed as necessary to maintain pasture near the target feed on offer. Changes in wool-free liveweight were linear between days 0 and 42 (period 1), and days 42 and 111 (period 2) for both classes of sheep grazing low feed on offer treatments. Hoggets lost less liveweight than mature animals while grazing low feed on offer during period 1 and gained liveweight faster (P<0.05) than mature animals for any feed on offer during period 2. Curvilinear relationships existed between feed on offer and clean wool growth rate and fibre diameter, with feed on offer accounting for 65 and 81% of the variations in wool growth rate, and 65 and 73% of the variations in fibre diameter, for hogget and mature sheep respectively. There was no significant difference in wool growth rate between animal classes. Annual clean wool production, fibre diameter and staple length increased linearly (P<0.05) with increasing feed on offer. Staple strength was higher (P<0.05) in mature sheep compared with hoggets, but was greater than 30 N/ktex for both classes of sheep irrespective of feed on offer. These results indicate that intensive grazing in spring to predetermined feed on offer is a useful tactic for manipulation of wool growth and fibre diameter, but factors other than feed on offer also contribute to liveweight change and wool growth.
L K Heng - One of the best experts on this subject based on the ideXlab platform.
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Seasonal differences in the soil water balance under perennial and Annual Pastures on an acid Sodosol in southeastern Australia
European Journal of Soil Science, 2001Co-Authors: L K Heng, K R Helyar, R Fisher, Rob White, Deli ChenAbstract:Summary Replacement of native deep-rooted grasses by shallow-rooted ones has resulted in greater losses of water and nitrogen by drainage. To counter this effect we have tested the hypothesis that liming, and the conversion of Annual grass Pastures to perennial grass Pastures, could improve the sustainability of grazing systems in the high rainfall zone (> 600 mm per annum) in southeastern Australia, through better use of water and nitrogen. A field experiment consisting of sixteen 0.135 ha (30 m × 45 m) grazed paddocks representing four pasture combinations (Annual pasture (mainly Lolium rigidum) without lime (AP–); Annual pasture with lime (AP+); perennial pasture (mainly Phalaris aquatica) without lime (PP–), and perennial pasture with lime (PP+)) was carried out from 1994 to 1997 on an acid Sodosol (Aquic Hapludalf) in southern New South Wales, Australia. Measurements were made of surface runoff, subsurface flow (on top of the B horizon) and soil water content. The results showed that perennial grass Pastures, especially PP+, extracted approximately 40 mm more soil water each year than the Annual grass Pastures. As a result, surface runoff, subsurface flow and deep drainage were at least 40 mm less from the perennial Pastures. These measurements were further supported by a simulation of soil water deficit and deep drainage for AP– and PP+ paddocks, using 10 years' past meteorological records. Overall, the results suggested that well-grown, phalaris-based Pastures could reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone.
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nitrate leaching loss under Annual and perennial Pastures with and without lime on a duplex texture contrast soil in humid southeastern australia
European Journal of Soil Science, 2001Co-Authors: A M Ridley, K R Helyar, L K Heng, G R Morrison, Rob White, R FisherAbstract:Mineral N accumulates in autumn under Pastures in southeastern Australia and is at risk of leaching as nitrate during winter. Nitrate leaching loss and soil mineral N concentrations were measured under Pastures grazed by sheep on a duplex (texture contrast) soil in southern New South Wales from 1994 to 1996. Legume (Trifolium subterraneum)-based Pastures contained either Annual grass (Lolium rigidum) or perennial grasses (Phalaris aquatica and Dactylis glomerata), and had a control (soil pH 4.1 in 0.01 M CaCl 2 ) or lime treatment (pH5.5). One of the four replicates was monitored for surface runoff and subsurface flow (the top of the B horizon), and solution NO 3 - concentrations. The soil contained more mineral N in autumn (64-133 kg N ha -1 to 120cm) than in spring (51-96 kg N ha -1 ), with NO 3 - comprising 70-77%. No NO 3 - leached in 1994 (475 mm rainfall). In 1995 (697 mm rainfall) and 1996 (666 mm rainfall), the solution at 20 cm depth and subsurface flow contained 20-50 mg N l -1 as NO 3 - initially but < 1 mg N l -1 by spring. Nitrate-N concentrations at 120 cm ranged between 2 and 22 mg N l -1 during winter. Losses of NO 3 - were small in surface runoff (0-2 kg N ha -1 year -1 ). In 1995, 9-19 kg N ha -1 was lost in subsurface flow. Deep drainage losses were 3-12 kg N ha -1 in 1995 and 4-10 kg N ha -1 in 1996, with the most loss occurring under limed Annual pasture. Averaged over 3 years, N losses were 9 and 15 kg N ha -1 year -1 under control and limed Annual Pastures, respectively, and 6 and 8 kg N ha -1 year -1 under control and limed perennial Pastures. Nitrate losses in the wet year of 1995 were 22, 33, 13 and 19 kg N ha -1 under the four respective Pastures. The increased loss of N caused by liming was of a similar amount to the decreased N loss by maintaining perennial pasture as distinct from an Annual pasture.
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soil factors affecting the sustainability and productivity of perennial and Annual Pastures in the high rainfall zone of south eastern australia
Australian Journal of Experimental Agriculture, 2000Co-Authors: R E White, K R Helyar, A M Ridley, Deli Chen, L K Heng, J Evans, R Fisher, J R Hirth, Pauline M Mele, G R MorrisonAbstract:A field study was carried out in the high rainfall zone (HRZ, >600 mm p.a.) of southern Australia from March 1994 to August 1997 to test the hypothesis that sown perennial grasses and liming could make the existing Pastures more sustainable through better use of water and nitrogen. The site, on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales, was typical of much of the HRZ grazing country in southern New South Wales and north-east Victoria. The experiment consisted of 4 replicate paddocks (each 0.135 ha) of 4 treatments: Annual pasture (mainly ryegrass Lolium rigidum, silver grass Vulpia spp., subterranean clover Trifolium subterraneum and broadleaf weeds) without lime, Annual pasture with lime, perennial pasture (phalaris Phalaris aquatica, cocksfoot Dactylis glomerata and subterranean clover T. subterraneum) without lime, and perennial pasture with lime. Soil pH (0–10 cm) in the limed treatments was maintained at 5.5 (0.01 mol/L CaCl2), compared to 4.1 in the unlimed treatments. The Pastures were rotationally grazed with Merino ewe or wether hoggets at a stocking rate which varied with the season, but was 10–25% higher on the limed Pastures [14.8–17.3 dry sheep equivalent (dse)/ha] than the unlimed Pastures. One replicate set of pasture treatments was intensively monitored for surface runoff, subsurface flow (at the top of the B horizon), water potential gradients and ammonium volatilisation. Other measurements of nitrogen inputs, transformations and losses were made on all paddocks. In a normal to wet year, surface runoff, subsurface flow and deep drainage (>180 cm depth) were about 40 mm less from the perennial than the Annual Pastures. The reduction in deep drainage under the perennials was about one-third to one-half (20–29 mm/year). The smaller loss of solution NO3– from the perennial Pastures (up to 12 kg N/ha.year) suggested soil acidification under perennials was reduced by about 1 kmol H+/ha.year. Denitrification and volatilisation losses of N were small (1–12 kg N/ha.year). Nitrogen fixed by subterranean clover (above ground parts) ranged from 2–8 kg N/ha in the drought of 1994–95 to 128 kg N/ha in a normal year (1996). The soil-pasture nitrogen balance was positive for all treatments and averaged 76 kg N/ha.year over 2 years. The abundance of introduced and native earthworms increased from 85 to 250/m2 in the limed Pastures between 1994 and 1997. Introduced species, such as Aporrectodea trapezoides, were especially responsive to lime. Animal production per hectare was 10–25% higher on Pastures with lime. Critical gross margins per dse were lowest ($16/ha) for a long-lived perennial pasture (>15 years), and highest ($20/ha) for a short-lived perennial (5 years). Overall, there were substantial benefits in animal production, improved soil quality and water use from establishing perennial grass Pastures with lime on these strongly acid soils.
K R Helyar - One of the best experts on this subject based on the ideXlab platform.
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Pasture and sheep responses to lime application in a grazing experiment in a high-rainfall area, south-eastern Australia. I. Pasture production
Australian Journal of Agricultural Research, 2006Co-Authors: K R Helyar, S. J. Welham, Mark Conyers, Ljc. Castleman, R.p. Fisher, C. M. Evans, Brian R. Cullis, Peter CreganAbstract:‘Managing Acid Soils Through Efficient Rotations (MASTER)’ is a long-term pasture–crop rotation experiment commenced in 1992. One of the objectives was to demonstrate the extent of crop, pasture, and animal responses to lime on a typical acidic soil in the 500–800 mm rainfall zone in south-eastern Australia. Two types of Pastures (perennial v. Annual Pastures) with or without lime application were established in 1992. This paper presents the results of the pasture dry matter (DM) responses to lime application over 6 years from 1992 to 1997. Results showed that both perennial and Annual Pastures responded positively to lime on a highly acidic soil on the south-west slopes of New South Wales. Averaged across pasture types and 5 growing seasons, the limed Pastures produced 18% more pasture DM (520 kg/ha, P < 0.05) than the unlimed Pastures. Significant responses to lime were detected on perennial Pastures (610 kg DM/ha, P < 0.05), but not on Annual Pastures, although the limed Annual Pastures produced more DM (420 kg/ha, P = 0.20) than the unlimed Annual Pastures. There was a large seasonal variation in pasture growth rate with the significant lime responses in winter and spring on both perennial Pastures (P < 0.05) and Annual Pastures (P < 0.10 in winter and P < 0.05 in spring), but no responses in autumn and summer on either perennial or Annual Pastures. The extra growth in winter is of importance as winter is the period when feed is normally inadequate and limits stocking rates. It is recommended that perennial-based Pastures should be promoted for the purposes of productivity, in terms of increasing pasture production and improving feed quality, and for the environmental benefits in terms of alleviating the soil acidity problem and reducing the risk of dryland salinity in the high-rainfall zone in south-eastern Australia.
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Effects of lime on the botanical composition of pasture over nine years in a field experiment on the south-western slopes of New South Wales
Australian Journal of Experimental Agriculture, 2003Co-Authors: K R Helyar, Ljc. Castleman, R.p. Fisher, C. M. Evans, Brian R. Cullis, M. C. Wilson, Mark ConyersAbstract:Two permanent Pastures (Annual pasture v. perennial pasture) were established in 1992 as part of the long-term field experiment, MASTER — Managing Acid Soils Through Efficient Rotations. The primary objective of the experiment was to develop an agricultural system that is economically viable and environmentally sustainable on the highly acidic soils in south-eastern Australia. This paper reports on the effects of lime on the botanical composition changes of Annual and perennial Pastures over 9 years. In general, lime increased the proportion of the desirable species, such as phalaris (Phalaris aquatica) in perennial pasture and subterranean clover (Trifolium subterraneum) in Annual Pastures, and decreased the proportion of the undesirable species, such as Vulpia spp., in both Annual and perennial Pastures, ultimately improving the quality of feed-on-offer to animals. As a result, the limed Pastures carried 24% more sheep than the unlimed Pastures, while maintaining individual animal performance similar for both limed and unlimed Pastures. The phalaris-based perennial pasture was more stable in terms of maintaining the sown species than the Annual pasture. Lime improved the persistence of phalaris and the longevity of the phalaris-based pasture should be at least 10 years. Lime changed the direction of plant succession of Annual Pastures. Without lime, Vulpia spp. gradually became more dominant while ryegrass and subterranean clover became less dominant in Annual Pastures. With lime, barley grass (Hordeum leporinum) gradually invaded the sward at the expense of ryegrass, thus reducing the benefits of lime, but this effect was less for the perennial Pastures than for Annual Pastures. Liming perennial Pastures should be more beneficial than liming Annual Pastures because of the beneficial effects on pasture composition. In addition, previously published work reported that liming perennial Pastures improved sustainability through better use of water and nitrogen.
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Seasonal differences in the soil water balance under perennial and Annual Pastures on an acid Sodosol in southeastern Australia
European Journal of Soil Science, 2001Co-Authors: L K Heng, K R Helyar, R Fisher, Rob White, Deli ChenAbstract:Summary Replacement of native deep-rooted grasses by shallow-rooted ones has resulted in greater losses of water and nitrogen by drainage. To counter this effect we have tested the hypothesis that liming, and the conversion of Annual grass Pastures to perennial grass Pastures, could improve the sustainability of grazing systems in the high rainfall zone (> 600 mm per annum) in southeastern Australia, through better use of water and nitrogen. A field experiment consisting of sixteen 0.135 ha (30 m × 45 m) grazed paddocks representing four pasture combinations (Annual pasture (mainly Lolium rigidum) without lime (AP–); Annual pasture with lime (AP+); perennial pasture (mainly Phalaris aquatica) without lime (PP–), and perennial pasture with lime (PP+)) was carried out from 1994 to 1997 on an acid Sodosol (Aquic Hapludalf) in southern New South Wales, Australia. Measurements were made of surface runoff, subsurface flow (on top of the B horizon) and soil water content. The results showed that perennial grass Pastures, especially PP+, extracted approximately 40 mm more soil water each year than the Annual grass Pastures. As a result, surface runoff, subsurface flow and deep drainage were at least 40 mm less from the perennial Pastures. These measurements were further supported by a simulation of soil water deficit and deep drainage for AP– and PP+ paddocks, using 10 years' past meteorological records. Overall, the results suggested that well-grown, phalaris-based Pastures could reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone.
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nitrate leaching loss under Annual and perennial Pastures with and without lime on a duplex texture contrast soil in humid southeastern australia
European Journal of Soil Science, 2001Co-Authors: A M Ridley, K R Helyar, L K Heng, G R Morrison, Rob White, R FisherAbstract:Mineral N accumulates in autumn under Pastures in southeastern Australia and is at risk of leaching as nitrate during winter. Nitrate leaching loss and soil mineral N concentrations were measured under Pastures grazed by sheep on a duplex (texture contrast) soil in southern New South Wales from 1994 to 1996. Legume (Trifolium subterraneum)-based Pastures contained either Annual grass (Lolium rigidum) or perennial grasses (Phalaris aquatica and Dactylis glomerata), and had a control (soil pH 4.1 in 0.01 M CaCl 2 ) or lime treatment (pH5.5). One of the four replicates was monitored for surface runoff and subsurface flow (the top of the B horizon), and solution NO 3 - concentrations. The soil contained more mineral N in autumn (64-133 kg N ha -1 to 120cm) than in spring (51-96 kg N ha -1 ), with NO 3 - comprising 70-77%. No NO 3 - leached in 1994 (475 mm rainfall). In 1995 (697 mm rainfall) and 1996 (666 mm rainfall), the solution at 20 cm depth and subsurface flow contained 20-50 mg N l -1 as NO 3 - initially but < 1 mg N l -1 by spring. Nitrate-N concentrations at 120 cm ranged between 2 and 22 mg N l -1 during winter. Losses of NO 3 - were small in surface runoff (0-2 kg N ha -1 year -1 ). In 1995, 9-19 kg N ha -1 was lost in subsurface flow. Deep drainage losses were 3-12 kg N ha -1 in 1995 and 4-10 kg N ha -1 in 1996, with the most loss occurring under limed Annual pasture. Averaged over 3 years, N losses were 9 and 15 kg N ha -1 year -1 under control and limed Annual Pastures, respectively, and 6 and 8 kg N ha -1 year -1 under control and limed perennial Pastures. Nitrate losses in the wet year of 1995 were 22, 33, 13 and 19 kg N ha -1 under the four respective Pastures. The increased loss of N caused by liming was of a similar amount to the decreased N loss by maintaining perennial pasture as distinct from an Annual pasture.
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soil factors affecting the sustainability and productivity of perennial and Annual Pastures in the high rainfall zone of south eastern australia
Australian Journal of Experimental Agriculture, 2000Co-Authors: R E White, K R Helyar, A M Ridley, Deli Chen, L K Heng, J Evans, R Fisher, J R Hirth, Pauline M Mele, G R MorrisonAbstract:A field study was carried out in the high rainfall zone (HRZ, >600 mm p.a.) of southern Australia from March 1994 to August 1997 to test the hypothesis that sown perennial grasses and liming could make the existing Pastures more sustainable through better use of water and nitrogen. The site, on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales, was typical of much of the HRZ grazing country in southern New South Wales and north-east Victoria. The experiment consisted of 4 replicate paddocks (each 0.135 ha) of 4 treatments: Annual pasture (mainly ryegrass Lolium rigidum, silver grass Vulpia spp., subterranean clover Trifolium subterraneum and broadleaf weeds) without lime, Annual pasture with lime, perennial pasture (phalaris Phalaris aquatica, cocksfoot Dactylis glomerata and subterranean clover T. subterraneum) without lime, and perennial pasture with lime. Soil pH (0–10 cm) in the limed treatments was maintained at 5.5 (0.01 mol/L CaCl2), compared to 4.1 in the unlimed treatments. The Pastures were rotationally grazed with Merino ewe or wether hoggets at a stocking rate which varied with the season, but was 10–25% higher on the limed Pastures [14.8–17.3 dry sheep equivalent (dse)/ha] than the unlimed Pastures. One replicate set of pasture treatments was intensively monitored for surface runoff, subsurface flow (at the top of the B horizon), water potential gradients and ammonium volatilisation. Other measurements of nitrogen inputs, transformations and losses were made on all paddocks. In a normal to wet year, surface runoff, subsurface flow and deep drainage (>180 cm depth) were about 40 mm less from the perennial than the Annual Pastures. The reduction in deep drainage under the perennials was about one-third to one-half (20–29 mm/year). The smaller loss of solution NO3– from the perennial Pastures (up to 12 kg N/ha.year) suggested soil acidification under perennials was reduced by about 1 kmol H+/ha.year. Denitrification and volatilisation losses of N were small (1–12 kg N/ha.year). Nitrogen fixed by subterranean clover (above ground parts) ranged from 2–8 kg N/ha in the drought of 1994–95 to 128 kg N/ha in a normal year (1996). The soil-pasture nitrogen balance was positive for all treatments and averaged 76 kg N/ha.year over 2 years. The abundance of introduced and native earthworms increased from 85 to 250/m2 in the limed Pastures between 1994 and 1997. Introduced species, such as Aporrectodea trapezoides, were especially responsive to lime. Animal production per hectare was 10–25% higher on Pastures with lime. Critical gross margins per dse were lowest ($16/ha) for a long-lived perennial pasture (>15 years), and highest ($20/ha) for a short-lived perennial (5 years). Overall, there were substantial benefits in animal production, improved soil quality and water use from establishing perennial grass Pastures with lime on these strongly acid soils.
R Fisher - One of the best experts on this subject based on the ideXlab platform.
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Seasonal differences in the soil water balance under perennial and Annual Pastures on an acid Sodosol in southeastern Australia
European Journal of Soil Science, 2001Co-Authors: L K Heng, K R Helyar, R Fisher, Rob White, Deli ChenAbstract:Summary Replacement of native deep-rooted grasses by shallow-rooted ones has resulted in greater losses of water and nitrogen by drainage. To counter this effect we have tested the hypothesis that liming, and the conversion of Annual grass Pastures to perennial grass Pastures, could improve the sustainability of grazing systems in the high rainfall zone (> 600 mm per annum) in southeastern Australia, through better use of water and nitrogen. A field experiment consisting of sixteen 0.135 ha (30 m × 45 m) grazed paddocks representing four pasture combinations (Annual pasture (mainly Lolium rigidum) without lime (AP–); Annual pasture with lime (AP+); perennial pasture (mainly Phalaris aquatica) without lime (PP–), and perennial pasture with lime (PP+)) was carried out from 1994 to 1997 on an acid Sodosol (Aquic Hapludalf) in southern New South Wales, Australia. Measurements were made of surface runoff, subsurface flow (on top of the B horizon) and soil water content. The results showed that perennial grass Pastures, especially PP+, extracted approximately 40 mm more soil water each year than the Annual grass Pastures. As a result, surface runoff, subsurface flow and deep drainage were at least 40 mm less from the perennial Pastures. These measurements were further supported by a simulation of soil water deficit and deep drainage for AP– and PP+ paddocks, using 10 years' past meteorological records. Overall, the results suggested that well-grown, phalaris-based Pastures could reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone.
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nitrate leaching loss under Annual and perennial Pastures with and without lime on a duplex texture contrast soil in humid southeastern australia
European Journal of Soil Science, 2001Co-Authors: A M Ridley, K R Helyar, L K Heng, G R Morrison, Rob White, R FisherAbstract:Mineral N accumulates in autumn under Pastures in southeastern Australia and is at risk of leaching as nitrate during winter. Nitrate leaching loss and soil mineral N concentrations were measured under Pastures grazed by sheep on a duplex (texture contrast) soil in southern New South Wales from 1994 to 1996. Legume (Trifolium subterraneum)-based Pastures contained either Annual grass (Lolium rigidum) or perennial grasses (Phalaris aquatica and Dactylis glomerata), and had a control (soil pH 4.1 in 0.01 M CaCl 2 ) or lime treatment (pH5.5). One of the four replicates was monitored for surface runoff and subsurface flow (the top of the B horizon), and solution NO 3 - concentrations. The soil contained more mineral N in autumn (64-133 kg N ha -1 to 120cm) than in spring (51-96 kg N ha -1 ), with NO 3 - comprising 70-77%. No NO 3 - leached in 1994 (475 mm rainfall). In 1995 (697 mm rainfall) and 1996 (666 mm rainfall), the solution at 20 cm depth and subsurface flow contained 20-50 mg N l -1 as NO 3 - initially but < 1 mg N l -1 by spring. Nitrate-N concentrations at 120 cm ranged between 2 and 22 mg N l -1 during winter. Losses of NO 3 - were small in surface runoff (0-2 kg N ha -1 year -1 ). In 1995, 9-19 kg N ha -1 was lost in subsurface flow. Deep drainage losses were 3-12 kg N ha -1 in 1995 and 4-10 kg N ha -1 in 1996, with the most loss occurring under limed Annual pasture. Averaged over 3 years, N losses were 9 and 15 kg N ha -1 year -1 under control and limed Annual Pastures, respectively, and 6 and 8 kg N ha -1 year -1 under control and limed perennial Pastures. Nitrate losses in the wet year of 1995 were 22, 33, 13 and 19 kg N ha -1 under the four respective Pastures. The increased loss of N caused by liming was of a similar amount to the decreased N loss by maintaining perennial pasture as distinct from an Annual pasture.
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soil factors affecting the sustainability and productivity of perennial and Annual Pastures in the high rainfall zone of south eastern australia
Australian Journal of Experimental Agriculture, 2000Co-Authors: R E White, K R Helyar, A M Ridley, Deli Chen, L K Heng, J Evans, R Fisher, J R Hirth, Pauline M Mele, G R MorrisonAbstract:A field study was carried out in the high rainfall zone (HRZ, >600 mm p.a.) of southern Australia from March 1994 to August 1997 to test the hypothesis that sown perennial grasses and liming could make the existing Pastures more sustainable through better use of water and nitrogen. The site, on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales, was typical of much of the HRZ grazing country in southern New South Wales and north-east Victoria. The experiment consisted of 4 replicate paddocks (each 0.135 ha) of 4 treatments: Annual pasture (mainly ryegrass Lolium rigidum, silver grass Vulpia spp., subterranean clover Trifolium subterraneum and broadleaf weeds) without lime, Annual pasture with lime, perennial pasture (phalaris Phalaris aquatica, cocksfoot Dactylis glomerata and subterranean clover T. subterraneum) without lime, and perennial pasture with lime. Soil pH (0–10 cm) in the limed treatments was maintained at 5.5 (0.01 mol/L CaCl2), compared to 4.1 in the unlimed treatments. The Pastures were rotationally grazed with Merino ewe or wether hoggets at a stocking rate which varied with the season, but was 10–25% higher on the limed Pastures [14.8–17.3 dry sheep equivalent (dse)/ha] than the unlimed Pastures. One replicate set of pasture treatments was intensively monitored for surface runoff, subsurface flow (at the top of the B horizon), water potential gradients and ammonium volatilisation. Other measurements of nitrogen inputs, transformations and losses were made on all paddocks. In a normal to wet year, surface runoff, subsurface flow and deep drainage (>180 cm depth) were about 40 mm less from the perennial than the Annual Pastures. The reduction in deep drainage under the perennials was about one-third to one-half (20–29 mm/year). The smaller loss of solution NO3– from the perennial Pastures (up to 12 kg N/ha.year) suggested soil acidification under perennials was reduced by about 1 kmol H+/ha.year. Denitrification and volatilisation losses of N were small (1–12 kg N/ha.year). Nitrogen fixed by subterranean clover (above ground parts) ranged from 2–8 kg N/ha in the drought of 1994–95 to 128 kg N/ha in a normal year (1996). The soil-pasture nitrogen balance was positive for all treatments and averaged 76 kg N/ha.year over 2 years. The abundance of introduced and native earthworms increased from 85 to 250/m2 in the limed Pastures between 1994 and 1997. Introduced species, such as Aporrectodea trapezoides, were especially responsive to lime. Animal production per hectare was 10–25% higher on Pastures with lime. Critical gross margins per dse were lowest ($16/ha) for a long-lived perennial pasture (>15 years), and highest ($20/ha) for a short-lived perennial (5 years). Overall, there were substantial benefits in animal production, improved soil quality and water use from establishing perennial grass Pastures with lime on these strongly acid soils.
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Seasonal differences in the soil water balance under perennial and Annual Pastures on an acid Sodosol in southeastern Australia
European Journal of Soil Science, 2001Co-Authors: L K Heng, K R Helyar, R Fisher, Rob White, Deli ChenAbstract:Summary Replacement of native deep-rooted grasses by shallow-rooted ones has resulted in greater losses of water and nitrogen by drainage. To counter this effect we have tested the hypothesis that liming, and the conversion of Annual grass Pastures to perennial grass Pastures, could improve the sustainability of grazing systems in the high rainfall zone (> 600 mm per annum) in southeastern Australia, through better use of water and nitrogen. A field experiment consisting of sixteen 0.135 ha (30 m × 45 m) grazed paddocks representing four pasture combinations (Annual pasture (mainly Lolium rigidum) without lime (AP–); Annual pasture with lime (AP+); perennial pasture (mainly Phalaris aquatica) without lime (PP–), and perennial pasture with lime (PP+)) was carried out from 1994 to 1997 on an acid Sodosol (Aquic Hapludalf) in southern New South Wales, Australia. Measurements were made of surface runoff, subsurface flow (on top of the B horizon) and soil water content. The results showed that perennial grass Pastures, especially PP+, extracted approximately 40 mm more soil water each year than the Annual grass Pastures. As a result, surface runoff, subsurface flow and deep drainage were at least 40 mm less from the perennial Pastures. These measurements were further supported by a simulation of soil water deficit and deep drainage for AP– and PP+ paddocks, using 10 years' past meteorological records. Overall, the results suggested that well-grown, phalaris-based Pastures could reduce recharge to groundwater and make pastoral systems more sustainable in the high rainfall zone.
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soil factors affecting the sustainability and productivity of perennial and Annual Pastures in the high rainfall zone of south eastern australia
Australian Journal of Experimental Agriculture, 2000Co-Authors: R E White, K R Helyar, A M Ridley, Deli Chen, L K Heng, J Evans, R Fisher, J R Hirth, Pauline M Mele, G R MorrisonAbstract:A field study was carried out in the high rainfall zone (HRZ, >600 mm p.a.) of southern Australia from March 1994 to August 1997 to test the hypothesis that sown perennial grasses and liming could make the existing Pastures more sustainable through better use of water and nitrogen. The site, on an acid duplex soil at Book Book near Wagga Wagga in southern New South Wales, was typical of much of the HRZ grazing country in southern New South Wales and north-east Victoria. The experiment consisted of 4 replicate paddocks (each 0.135 ha) of 4 treatments: Annual pasture (mainly ryegrass Lolium rigidum, silver grass Vulpia spp., subterranean clover Trifolium subterraneum and broadleaf weeds) without lime, Annual pasture with lime, perennial pasture (phalaris Phalaris aquatica, cocksfoot Dactylis glomerata and subterranean clover T. subterraneum) without lime, and perennial pasture with lime. Soil pH (0–10 cm) in the limed treatments was maintained at 5.5 (0.01 mol/L CaCl2), compared to 4.1 in the unlimed treatments. The Pastures were rotationally grazed with Merino ewe or wether hoggets at a stocking rate which varied with the season, but was 10–25% higher on the limed Pastures [14.8–17.3 dry sheep equivalent (dse)/ha] than the unlimed Pastures. One replicate set of pasture treatments was intensively monitored for surface runoff, subsurface flow (at the top of the B horizon), water potential gradients and ammonium volatilisation. Other measurements of nitrogen inputs, transformations and losses were made on all paddocks. In a normal to wet year, surface runoff, subsurface flow and deep drainage (>180 cm depth) were about 40 mm less from the perennial than the Annual Pastures. The reduction in deep drainage under the perennials was about one-third to one-half (20–29 mm/year). The smaller loss of solution NO3– from the perennial Pastures (up to 12 kg N/ha.year) suggested soil acidification under perennials was reduced by about 1 kmol H+/ha.year. Denitrification and volatilisation losses of N were small (1–12 kg N/ha.year). Nitrogen fixed by subterranean clover (above ground parts) ranged from 2–8 kg N/ha in the drought of 1994–95 to 128 kg N/ha in a normal year (1996). The soil-pasture nitrogen balance was positive for all treatments and averaged 76 kg N/ha.year over 2 years. The abundance of introduced and native earthworms increased from 85 to 250/m2 in the limed Pastures between 1994 and 1997. Introduced species, such as Aporrectodea trapezoides, were especially responsive to lime. Animal production per hectare was 10–25% higher on Pastures with lime. Critical gross margins per dse were lowest ($16/ha) for a long-lived perennial pasture (>15 years), and highest ($20/ha) for a short-lived perennial (5 years). Overall, there were substantial benefits in animal production, improved soil quality and water use from establishing perennial grass Pastures with lime on these strongly acid soils.