The effects of grazing on the phosphorus requirement of an annual pasture

1971 ◽  
Vol 22 (1) ◽  
pp. 81 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Subterranean Clover ◽  
Growing Season ◽  
Maximum Growth ◽  
Grazing Pressure ◽  
Light Interception ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Phosphorus Requirement ◽  
Root Size

The applied phosphorus requirement of a pasture sown to subterranean clover was measured with and without grazing. Under moderate grazing pressure, in the year of establishment, the pasture required about 50 % more phosphorus than when ungrazed. In the following season, at a higher stocking rate, the grazed areas needed twice as much phosphorus as the ungrazed to make 90% of their maximum growth. In both years this difference in requirement between stocked and unstocked treatments was present throughout the growing season. Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation. It does not appear to be due to effects of defoliation on root size. Nor does it depend on differential light interception or on changes in botanical composition.

Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 1. Botanical composition, sward characteristics and availability of components of annual temperate pastures

2010 ◽  
Vol 50 (2) ◽  
pp. 138 ◽  
Author(s):  
B. A. McGregor
Keyword(s):  
Subterranean Clover ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Bare Ground ◽  
Pasture Production ◽  
Weed Invasion ◽  
Merino Sheep ◽  
Grazed Pastures ◽  
Temperate Pastures ◽  
Angora Goats

The effects of animal species (AS; Angora goats, Merino sheep or goats and sheep mixed grazed together at ratio 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on the availability, botanical composition and sward characteristics of annual temperate pastures under continuous grazing were determined in a replicated experiment from 1981 to 1984. AS and SR had significant effects on pasture availability and composition and many AS × SR interactions were detected. The pastures grazed by sheep had significantly reduced content and proportion of subterranean clover and more undesirable grasses compared with those grazed by goats. There were no differences in dry matter availabilities between goat- and sheep-grazed pastures at 7.5/ha, but at 10 and 12.5/ha goat pastures had significantly increased availabilities of green grass, dead and green clover and less weeds compared with sheep pastures. There was a significant AS × SR interaction for the density of seedlings in May following pasture germination. Between July and January, the height of pastures was greater under goats than sheep but from January to March pasture height declined more on goat-grazed than on sheep-grazed pastures. There was an AS × SR interaction for incidence of bare ground. Increasing the SR increased bare ground in pastures grazed by sheep but no change occurred on pastures grazed by goats. Changes in pasture characteristics due to increased SR were minimised on pastures grazed by goats but the grazing of sheep caused larger and faster changes and the pastures were damaged at the highest SR. Goats did not always select the same herbage material as sheep, changed their selection between seasons and were not less selective than sheep. Angora goats were flexible grazers and continually adapted their grazing behaviour to changing herbage conditions. Goat grazing led to an increase in subterranean clover, an accumulation of dead herbage at the base of the sward, reduced bare ground, taller pastures in spring and a more stable botanical composition. Mixed-grazed pasture characteristics were altered with SR. With careful management Angora goats on sheep farms may be used to manipulate pasture composition, to speed up establishment of subterranean clover, to decrease soil erosion and to reduce weed invasion.

Effect of fertilizer nitrogen, stocking rate and autumn deferment of grazing in association with hay cutting on the root structure of annual pasture species

1976 ◽  
Vol 16 (78) ◽  
pp. 110 ◽  
Author(s):  
JJ Doyle ◽  
MJ Sharkey
Keyword(s):  
Nitrogen Fertilizer ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Root Structure ◽  
Root Branching ◽  
Grass Roots ◽  
Hordeum Leporinum ◽  
Main Components

Length, weight, branching and chemical composition of roots of barley grass (Hordeum leporinum) and subterranean clover, (Trifolium subterraneum), the main components of a non-irrigated pasture were measured in the fourth year of an experiment on pastures grazed by Corriedale wethers. The grazing treatments were in a factorial design (2 x 2 x 3) replicated three times, with three stocking rates, two levels of nitrogen fertilizer and two methods of management. Grass and clover density was reduced progressively as stocking rate was increased from 10 to 12 to 17 wethers ha-1 but the surviving plants at maturity had vigorous root systems. This performance of annual species contrasts with that of perennial pasture species where root development and root branching may be expected to decline with increase in grazing pressure. Applications of nitrogen fertilizer annually at rates of 0 or 67 kg ha-1 had little effect on density of grasses or clovers but clover roots were lighter and had fewer rhizobia nodules where nitrogen fertilizer had been applied. The management of pasture by deferment of grazing during regeneration was beneficial to clover plants in that their root structure was larger at maturity; similar effects were not evident in grass roots.

Tactical versus continuous stocking in perennial ryegrass-subterranean clover pastures grazed by sheep in south-western Victoria. 2. Ryegrass persistence and botanical composition

2001 ◽  
Vol 41 (8) ◽  
pp. 1109 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale ◽  
G. R. Saul ◽  
G. A. Kearney
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Summer Rainfall ◽  
Grazing Pressure ◽  
Botanical Composition ◽  
Average Mass ◽  
Gravelly Soil ◽  
Western Victoria

A 4-year field experiment was carried out in south-western Victoria to determine whether tactical stocking might improve perennial ryegrass (Lolium perenne L.) persistence and prime lamb production, compared with the more common practice of continuous stocking. Tactical stocking consisted of variable-length summer, autumn and winter rotations and continuous stocking in spring. The 2 grazing strategies were compared on 2 contrasting pastures: an upgraded pasture, sown with newer cultivars of perennial ryegrass and subterranean clover (Trifolium subterraneum L.) with 26 kg phosphorus/ha.year, and a more typical naturalised perennial ryegrass pasture receiving 6 kg phosphorus/ha.year. Paddocks were grazed by Border Leicester x Merino ewes, which were mated to a terminal sire to lamb in September. The effects of the grazing systems and pasture treatments on ryegrass persistence and pasture botanical composition are presented in this paper. The perennial ryegrass component of the sward decreased from an average mass of 1000 kg dry matter/ha on the upgraded pasture and 400 kg dry matter/ha on the typical pasture in spring 1996 to 100 kg dry matter/ha and <50 kg/ha for the 2 pasture types, respectively, in spring 1998. This occurred irrespective of the grazing system imposed. The decline of ryegrass was attributed to several factors including the very dry 3-year period, summer rainfall events that caused ryegrass buds to break dormancy then die when dry conditions resumed, the gravelly soil type where the experiment was located, and the high grazing pressure used. A number of species became more prevalent in the pastures as the ryegrass disappeared. Silver grass (Vulpia spp.) increased 4–5-fold on all treatments. By the fourth year, barley grass (Hordeum leporinum) and Bromus spp. had increased significantly with tactical stocking compared with continuous stocking. Capeweed (Arctotheca calendula L.) and Erodium spp. increased on both the continuously stocked and upgraded pastures. The subterranean clover component was maintained across all treatments over the 4 years, indicating that tactical stocking did not adversely affect clover persistence. Since ryegrass declined irrespective of treatment, the tactical stocking system used in this study cannot be recommended for improving ryegrass persistence.

Evaluation of natural annual pastures of Trangie in central western New South Wales, 2. Botanical composition changes with particular reference to Hordeum leporinum

1973 ◽  
Vol 13 (65) ◽  
pp. 662
Author(s):  
RJ Campbell ◽  
JA Beale
Keyword(s):  
New South ◽  
Grazing Pressure ◽  
Relative Importance ◽  
Botanical Composition ◽  
Stocking Rate ◽  
South Wales ◽  
Hordeum Leporinum ◽  
Germination And Growth ◽  
Composition Changes ◽  
Total Soil Nitrogen

The botanical composition of natural pastures stocked at 2.5, 3.7, and 4.9 Merino wethers per hectare was examined over a number of years. Several experiments were conducted in conjunction with the main grazing experiment to determine the relative importance of factors that might be influencing the composition of the pastures. In particular, the importance of nitrogen and sulphur, grazing pressure, and surface mulch were studied. Increased grazing pressure throughout the growing season reduced the proportion of Hordeum leporinum (barley grass) in the pasture. Total soil nitrogen, as affected by stocking rate, did not appear to be important in determining the percentage of barley grass in the pasture. A layer of surface mulch stimulated the germination and growth of barley grass, but not the germination of Erodium crinitum (crowfoot), one of the major broadleaf components of this pasture type.

Limitations imposed by nitrogen deficiency on the productivity of subterranean clover-based annual pasture in southern Australia

1980 ◽  
Vol 31 (1) ◽  
pp. 95 ◽  
Author(s):  
PS Cocks
Keyword(s):  
Nitrate Nitrogen ◽  
Nitrogen Deficiency ◽  
Subterranean Clover ◽  
Growing Season ◽  
Mineral Nitrogen ◽  
Botanical Composition ◽  
Mediterranean Environment ◽  
Potential Productivity ◽  
Grazed Pasture ◽  
Rates Of Growth

Potential productivity of pasture in the Mediterranean environment of southern Australia and limitations imposed on productivity by nitrogen deficiency were studied on grazed subterranean clover-based annual pasture at Kybybolite, S.A. Estimates of monthly growth, botanical composition and nitrogen uptake were made on the basis of growth in open and closed quadrats. Ammonium and nitrate nitrogen in the top 10cm of soil were measured frequently, and six estimates of the response of pasture to nitrogen were made during the growing season. Potential herbage productivity was assumed to be 5 % of photosynthetically active radiation. Grazed pasture yielded 12.6 t of dried herbage per hectare compared with a calculated potential of 28.7 t ha-1. It was calculated that nitrogen deficiency probably accounted for about 59 % of the shortfall. Maximum rates of growth in mid spring (October) reached 160 kg ha-1 day-1 in the presence of added nitrogen compared with a calculated potential of 180 kg ha-1 day-1, and measured growth of only 98 kg ha-1 day-1 in the absence of nitrogen. Pasture responded least to added nitrogen in autumn even though, in that season, grasses and herbs dominated subterranean clover. Low responsiveness was associated with high levels of mineral nitrogen in the soil before and for 2 weeks after the first autumn rains. Thereafter mineral nitrogen remained very low, and pasture increasingly responded to nitrogen until it matured in late spring. During this time the proportion of legume steadily increased until, by the end of spring, it reached 50 %. In all, it was calculated that soil released 184 kg nitrogen, and clover fixed 146 kg nitrogen, per hectare over the growing season. In order to reach its potential productivity the pasture needed a further 406 kg nitrogen per hectare. In the absence of fertilizer nitrogen, economically unacceptable on the annual pastures of southern Australia, subterranean clover will need lo fix this extra nitrogen if annual pastures are to reach their potential productivity.

Effects of management on soil fertility under pasture. 1. Influence of experimental grazing and fertilizer systems on growth, composition and nutrient status of the pasture

1974 ◽  
Vol 14 (69) ◽  
pp. 470 ◽  
Author(s):  
JR Simpson ◽  
SM Bromfield ◽  
GT McKinney
Keyword(s):  
Nitrogen Availability ◽  
Subterranean Clover ◽  
Nutrient Status ◽  
Grazing Pressure ◽  
Grass Species ◽  
Botanical Composition ◽  
Annual Grass ◽  
Growth And Nutrition ◽  
Animal Excreta ◽  
Annual Grasses

Pasture plots containing phalaris, subterranean clover and annual grass species were fertilized annually at suboptimal (P1), adequate (P2) or a 'luxury' rate (P3) of superphosphate. A fourth treatment combined rate P3 with fertilizer nitrogen (P3N). Each pasture was grazed during five years at a high (H) or a low (L) grazing pressure in such a way that there was little feed left on the H plots and a large amount on the L plots at the end of summer. In this way eight pasture situations were created which differed in botanical composition, nutrient availability, herbage production and the amount of nutrients returned as animal excreta. The plots were used to investigate the effects of fertilizer input and grazing pressure on the growth and nutrition of the different pasture components. Protected microplots during the fourth and fifth years showed that the P1 plots remained responsive to phosphate. The yields of annual grasses on the microplots were increased by H treatment but the proportion of phalaris to annual grasses was reduced, particularly at P1. Clover yields and total pasture yields were affected by previous grazing pressure only in the drier fourth year. At high levels of superphosphate and grazing (P3H), the greater grass-clover ratio and higher grass nitrogen uptake indicated greater nitrogen availability in this treatment.

Changes in pH and organic carbon were minimal in a long-term field study in the Western District of Victoria

2002 ◽  
Vol 53 (2) ◽  
pp. 115 ◽  
Author(s):  
J. W. D. Cayley ◽  
M. R. McCaskill ◽  
G. A. Kearney
Keyword(s):  
Organic Carbon ◽  
Average Rate ◽  
Perennial Grass ◽  
Subterranean Clover ◽  
Grazing Pressure ◽  
Rate Of Change ◽  
Stocking Rate ◽  
Mean Values ◽  
Stocking Rates

Changes in soil pH from a long-term experiment at Hamilton, Vic., associated with time, fertiliser application, and stocking rate were assessed. The pH was measured in a 1 :5 suspension of soil in water (pHW) from 1980 onwards and in a 1:5 suspension of soil in 0.01 M CaCl2 (pHCa) from 1984 onwards. Topsoils (0–10 cm) were sampled regularly from 1980 to 1999, and the soil profile to a depth of 80 cm in 1994. The site was sown to perennial ryegrass, phalaris, and subterranean clover in 1977. Treatments fertilised with different amounts of superphosphate were grazed by sheep at stocking rates of 7–19 dry sheep equivalents (DSE)/ha. Average applications of phosphorus (P) ranged from 0.5 to 38.7 kg P/ha.year. The pHCa of the topsoil in 1984 was 4.9. It decreased at an average rate of 0.005 pHCa or 0.008 pHW units/year, with little variation due to fertiliser or stocking rate. Measurements in 1994 revealed subtle but statistically significant (P < 0.01) trends in soil pHCa that were associated with grazing pressure, inputs of fertiliser, and whether or not areas sampled were used by the sheep for camping. The top 0–5 cm of soil was slightly less acidic (+0.07 pHCa units) in the camp areas compared with non-camp areas. Below 5 cm to a depth of 80 cm, camp areas were more acidic (–0.19 pHCa units). At the highest stocking rates, heavier applications of superphosphate were associated with greater subsoil acidity: –0.06 pHCa units per 100 kg phosphorus (P) applied. There was no relationship at medium stocking rates. At low stocking rates, higher P applications were associated with more alkaline subsoils. Net removal of product from 1979 to 1994 (wool and meat removed from plots and excreta transferred to camps) was estimated to be equivalent to 140–380 kg/ha of lime over this 15-year period. The organic carbon (OC) content of the topsoil did not change over 20 years of records from 1979, and was unaffected by inputs of P. In 1994, the OC content of the 0–5 cm layer of topsoil was greater than the 5–10 cm layer (mean values 5.5% and 3.8% respectively; P < 0.001). The OC content of camp areas was higher than that of non-camp areas, this difference being more pronounced in the 0–5 cm layer (P < 0.01). It was concluded that the rate of change of pH was slow because of the high pH buffering capacity of the soil, the small amount of alkalinity removed in product, and the generally high perennial grass content of the pastures. Soils shown to be at greatest risk of acidification from this study were those under camp areas, and where high fertiliser rates were applied to pastures with a low perennial grass content. Rotational grazing should diminish these problems by reducing the concentration of excreta in camp areas, and favouring perennials over annuals in both camp and non-camp areas. Inputs of lime may eventually be needed to compensate for the acidifying effect of product removal.

The effects of sheep treading and grazing on pasture and soil characteristics of irrigated annual pastures

1979 ◽  
Vol 30 (4) ◽  
pp. 741 ◽  
Author(s):  
PA Witschi ◽  
DL Michalk
Keyword(s):  
Bulk Density ◽  
Subterranean Clover ◽  
Soil Characteristics ◽  
Combined Effect ◽  
Late Winter ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Grazing Experiment ◽  
Wimmera Ryegrass ◽  
Stocking Rates

The two experiments reported examined the effects of sheep treading on pasture growth and soil characteristics on autumn-irrigated subterranean clover-Wimmera ryegrass pastures and their subsequent influence on winter production. Treading only (experiment 1) increased the bulk density of soil by 40% as the stocking rate increased from 0 to 39.2 sheep ha-1. This caused a 33% reduction in late winter production (July), the decline (675 kg ha-1) being due mainly to a reduction in the proportion of ryegrass in the pasture. The combined impacts of treading and grazing (experiment 2) proved more detrimental to subsequent pasture recovery. At the July measurement, treading reduced production by 20% when the stocking rate was increased from 0 to 19.6 sheep ha-1, while the combined effect produced a 58% loss in yield. In addition to stocking rate, the length of the pre-grazing establishment period proved critical, with greater compaction evident in plots stocked 24 h after irrigation. This compaction affected the botanical composition, significantly more ryegrass being present in compacted plots, although increased tillering was encouraged by intense defoliation at high stocking rates which intensified this effect.

Time of first autumn irrigation and the yield and animal production of a subterranean clover-annual ryegrass pasture

1970 ◽  
Vol 10 (44) ◽  
pp. 279 ◽  
Author(s):  
LF Myers ◽  
VR Squires
Keyword(s):  
New South ◽  
Subterranean Clover ◽  
Growing Season ◽  
Annual Ryegrass ◽  
Stocking Rate ◽  
South Wales ◽  
Seed Yields ◽  
Stocking Rates ◽  
Practical Implications ◽  
Clover Content

In two experiments at Deniliquin, New South Wales, the length of the prewinter growing season of an irrigated pasture was controlled by varying the date of the opening autumn irrigation : Irrigation began in February, March, or April for treatments T1, T2, and T3 respectively. In the first, winter yields of ungrazed pasture (July) fell by approximately 1500 lb DM/acre for each month that the first irrigation was delayed after February. Clover content of the pasture was progressively less as the opening irrigation was delayed. Seed yields were unchanged by length of growing season, but increased markedly with increased phosphate supply. In the second experiment, which was grazed at three stocking rates (5, 7, and 10 sheep/acre), the response to treatments was less than in the first (ungrazed) experiment. Pasture yield (available feed) and liveweight gain were similar on treatments T1 and T2. However, at the 10 sheep/acre rate, T1 plots survived for 14 months longer than T2plots. There was no evidence that a stocking rate of 7 sheep/ acre could not be maintained indefinitely on the treatment T1. Annual production exceeded 68 lb clean wool (90 lb greasy) an acre and the plots were supporting a total liveweight exceeding 1000 lb/acre. The influence of autumn rains on the response to early autumn irrigation and the practical implications of the results are discussed briefly.

scholarly journals Effects of grazing systems on herbage mass and liveweight gain of Tibetan sheep in Eastern Qinghai-Tibetan Plateau, China

2015 ◽  
Vol 37 (2) ◽  
pp. 181 ◽  
Author(s):  
Y. Sun ◽  
J. P. Angerer ◽  
F. J. Hou
Keyword(s):  
Tibetan Plateau ◽  
Growing Season ◽  
Cold Season ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Forage Production ◽  
Tibetan Sheep ◽  
Grazing Systems ◽  
Grazing Period ◽  
Opposite Tendency

Grazing strategies, consisting of grazing systems and stocking rate adjustments, have evolved from the need to sustain efficient use of the forage resources by livestock, increase animal performance and sustain forage production. A 3-year study was conducted with Tibetan sheep on the Eastern Qinghai-Tibetan Plateau, China to compare: (1) two grazing systems [season-long continuous (SLC; July to December) versus short duration with seasonal rotation (SDSR; July to September in growing-season pasture and October to December in cold-season pasture) with a stocking rate of 24 sheep months ha–1(SM ha–1)]; (2) SDSR system with 24, 36 and 48 SM ha–1; and (3) seasonal aspects of stocking rate under the SDSR system by comparing strategies of heavy stocking rate in the growing season and light stocking rate in the cold season (SDSR-HL) versus light stocking rate in the growing season and heavy stocking rate in the cold season (SDSR-LH). No differences were found between grazing systems in liveweight gain per head or per ha and in residual herbage mass. Liveweight gain per head for treatment SDSR24 was greater than for treatments SDSR36 and SDRS48, whereas liveweight gain per ha showed the opposite tendency. No differences were found between the SDSR-HL and SDSR-LH treatments in liveweight gain per head or per ha, whereas the ratio of residual herbage mass at the end of grazing the growing-season pasture to the cold pasture of treatment SDSR-LH was more than twice that of treatment SDSR-HL. Daily liveweight gain of Tibetan sheep decreased linearly with increasing grazing pressure in both growing and cold seasons. It was estimated that, at a grazing pressure index of 310 sheep days t–1 DM peak herbage mass, liveweight gain per head and ha appears to be optimised over the whole grazing period. Liveweight loss by Tibetan sheep during the cold season was apparent regardless of grazing pressure indicating that temperature had a stronger influence on sheep performance in the cold season than herbage availability.

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