Influence of rotation and time of germinating rains on the productivity and composition of annual pastures in Western Australia

1998 ◽  
Vol 49 (2) ◽  
pp. 225 ◽  
Author(s):  
C. J. Thomson ◽  
C. K. Revell ◽  
N. C. Turner ◽  
M. A. Ewing ◽  
I. F. Le Coultre

A long-term rotation experiment located in south-western Australia was used to measure the effect of rotation and time of germinating rains on the productivity and botanical composition of grazed annual pastures in 2 contrasting seasons in an environment with an average annual rainfall of 325 mm. The density of self-regenerating seedlings of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula), and grasses (Lolium rigidum, Hordeum leporinum, Bromus diandrus) was greatly increased (approx. 3 times the density) when there was a second year of pasture after crop compared with the first year after crop. The lower plant density resulted in first-year pastures having only about 33% of the autumn biomass accumulation of second-year pastures. This difference in early pasture growth had no effect on total pasture production in 1992, but in 1993 total pasture production was 30% greater in second-year pastures compared with first-year pastures. Botanical composition varied between and within seasons with the percentage of subterranean clover increasing throughout the season and the percentage of capeweed decreasing throughout the season. Grasses comprised <20% of the biomass in all seasons and treatments. Production of subterranean clover seed in 1993 was higher in a 1 : 2 crop-pasture rotation than in a 1 : 1 crop-pasture rotation and direct drilling in the cropping phase increased seed set compared with conventional tillage in both 1 : 1 and 1 : 2 crop-pasture rotations. Capeweed seedlings emerged in large numbers after rainfall between February and May and subsequently showed a relative growth rate twice that of subterranean clover and the grasses, but exclusion of rainfall until June resulted in a significant reduction in the emergence of capeweed seedlings. Additionally, capeweed had a lower rate of seedling survival compared with other pasture species, and this is contrary to observations by other researchers that capeweed is highly resistant to moisture stress during early growth.

1955 ◽  
Vol 6 (4) ◽  
pp. 553 ◽  
Author(s):  
RC Rossiter ◽  
PG Ozanne

A 2-year field experiment is described, in which an annual-type pasture was grown on a soil of lateritic origin with various initial rates of rock phosphate and superphosphate. The soil was acutely deficient in plant-available phosphorus at the outset. Application of superphosphate led to the expected increases in total pasture production, but rock phosphate also gave substantial yield increases, even during the first season. Differential species effects were noted; subterranean clover (Trifolium subterraneum L.) and cape-weed (Cryptostemma calendula Druce) responded about equally to superphosphate, but the clover responded to rock phosphate to a greater extent than did cape-weed. Both relative efficiency for total plant growth and percentage utilization of applied phosphorus were much higher with the soluble phosphatic fertilizer than with rock phosphate, especially in the first year. However, phosphorus recovery from rock phosphate was as high in the second year as in the first, whereas there was a marked decrease in the second year from superphosphate.


Author(s):  
D.C. Edmeades ◽  
D.M. Wheeler ◽  
G. Rys ◽  
N. Smith

A field trial was conducted on a yellow-grey earth in the Hawke's Bay (mean annual rainfall 875 mm) over a period of 5 years to measure the effects of lime applications (0, 5, 10 t/ha) on soils high (50 kg P/ha applied annually) or low (5 kg P/ha applied annually) in phosphorus (P). The average annual pasture production on this dryland soil in the absence of applied lime or P was 5060 kg DM/ha (range 3861-6024). The botanical composition of the pasture was variable, average annual legume composition (4/o on DM basis) ranging from 3 to 42%. The predominant. legume was subterranean clover (Trifolium subterranean) with white clover (Trifolium repens) making a small contribution in some years. In the first two years after application responses to lime were large (lo-20%), due entirely to liming stimulating the grass component of the pasture, and consistent with liming enhancing the rate of net mineralisation of soil organic nitrogen (N). In years three and-four-the-dominant treatment effect was to P applications (130% increase in total pasture production), which stimulated legume growth initially, but subsequently increased grass growth. In the fifth year no significant responses to lime or P were observed. The seasonal pattern of pasture responses to either lime or P was related to pasture botanical composition. The size of the annual total DM pasture responses to P was positively related to the legume content of the pasture. Conversely the lime responses were negatively related to pasture legume content. These results suggest that pasture botanical composition could be used to improve the ability to predict lime and P responses based on soil nutrient levels. This may be important where pasture botanical composition is extremely variable over time. Keywords fertiliser, lime, pasture, pasture composition, phosphorus, soil acidity


1963 ◽  
Vol 3 (11) ◽  
pp. 284 ◽  
Author(s):  
MR Gardiner ◽  
RC Gorman

A survey of plant selenium was carried out in the agricultural district of Western Australia in the spring of 1962. Pasture samples were collected from mid-August to mid-November during, or shortly after, the spring flush of growth in the different districts. Pastures were collected from both 'light' and 'heavy' country in each of the districts, and whenever possible, fertilizer history was recorded and botanical composition determined. Pasture samples from the 10-15 inch rainfall belt averaged 0.26 p.p.m. selenium ; from the 15-20 inch rainfall belt, 0.08 p.p.m., from the 21-30 inch rainfall belt, 0.056 3.p.m ; and from the higher than 30 inch belt, 0.036 p.p.m. If the critical level for selenium deficiency syndromes is placed at 0.05 p.p.m., then deficiency levels mg appear in all rainfall belts, the lower limit of which is the 15 inch isobyet. Regression analyses showed that there was a significant difference between the selenium contents of pastures from heavy and light soils in each rainfall area. The indicator condition of selenium levels of 0.05 p.p.m or less (white muscle disease) has not been seen in the northern range of the higher rainfall districts, although here, as elsewhere, plant selenium levels appear to be predicated on mean annual rainfall figures and on type of county. Grasses and cereals tended to dominate the pastures in the areas with less than 15 inches of rainfall a-year, while subterranean clover with admixtures of capeweed and grasses were chiefly found in the higher rainfall districts.


Author(s):  
J.D. Morton ◽  
A.H.C. Roberts

Mowing trials were carried out to determine the rates of fertiliser nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) and frequency of application of K for maximum pasture production on extremely infertile humped and hollowed pakihi soils in the Grey Valley (Souters and Sommervilles dairy units), and flipped soils at Cape Foulwind (Bassetts dairy unit) under high annual rainfall (2000 - 3000 mm) on the West Coast. In the first measurement year, there was no significant increase in pasture production above 480 kg N/ha, 56 kg P/ha, 360 kg K/ha and 136 kg S/ha at Souters and Bassetts and a significant increase in pasture production up to 600 kg N/ha, 56 kg P/ha, 360 kg K/ha and 140 kg S/ha at Sommervilles. In the second year, there was no significant pasture production increase above 480 kg N/ ha, 56 kg P/ha, 360 kg K/ha and 136 kg S/ha at all sites. The high N, K and S rates were required because nutrients were not being recycled through returned clippings. This situation would be similar to the early stages of dairy management on these units where only a small proportion of pasture would receive recycled nutrients through return of excreta. Over time, a larger proportion of the pasture would be affected by excreta and fertiliser nutrient requirements would be expected to decrease. There was no increase in pasture production from applying potassium chloride in more than four applications per year at Souters and Bassetts in the first year, but a significant increase in pasture production from eight compared with four applications per year at Sommervilles, where soil QT (quick test) K levels were lower than at the other two sites. Keywords: flipped, hump and hollowed, nitrogen, phosphorus, potassium, sulphur


1971 ◽  
Vol 11 (49) ◽  
pp. 211 ◽  
Author(s):  
NJ Barrow

At Pinjarra and Bakers Hill, Western Australia, the rate of breakdown of elemental sulphur applied in different size gradings was followed over two seasons by periodically measuring the elemental sulphur remaining in the soil. Similar measurements were made on experiments at Kwolyin, Darkan, and Pinjarra in which commercial sulphur fertilizer was applied in the autumn of two successive years. Particles finer than about 200 mesh oxidized quickly and would be a poor source of slowly available sulphur. Particles between 40 and 100 mesh appeared to provide the best compromise between too fast and too slow oxidation. Oxidation appeared to be faster at sites with higher annual rainfall and faster in the second year of application than the first. The commercial sulphur fertilizer was an effective source of slowly available sulphur and produced pasture responses at all three sites in the first year. Responses continued into the second year but the level of effectiveness relative to a current dressing could, not be accurately measured. At the Pinjarra site, two annual applications produced a 2.5-fold increase in yield of clover. A total of 19 soils were tested in incubation experiments for their ability to oxidize sulphur. All soils were able to do this and differences between soils were small when small amounts of sulphur were used. Differences between soils were larger when large amounts of sulphur were used.


2002 ◽  
Vol 42 (2) ◽  
pp. 149 ◽  
Author(s):  
M. D. A. Bolland ◽  
W. J. Cox ◽  
B. J. Codling

Dairy and beef pastures in the high (>800 mm annual average) rainfall areas of south-western Australia, based on subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum), grow on acidic to neutral deep (>40 cm) sands, up to 40 cm sand over loam or clay, or where loam or clay occur at the surface. Potassium deficiency is common, particularly for the sandy soils, requiring regular applications of fertiliser potassium for profitable pasture production. A large study was undertaken to assess 6 soil-test procedures, and tissue testing of dried herbage, as predictors of when fertiliser potassium was required for these pastures. The 100 field experiments, each conducted for 1 year, measured dried-herbage production separately for clover and ryegrass in response to applied fertiliser potassium (potassium chloride). Significant (P<0.05) increases in yield to applied potassium (yield response) were obtained in 42 experiments for clover and 6 experiments for ryegrass, indicating that grass roots were more able to access potassium from the soil than clover roots. When percentage of the maximum (relative) yield was related to soil-test potassium values for the top 10 cm of soil, the best relationships were obtained for the exchangeable (1 mol/L NH4Cl) and Colwell (0.5 mol/L NaHCO3-extracted) soil-test procedures for potassium. Both procedures accounted for about 42% of the variation for clover, 15% for ryegrass, and 32% for clover + grass. The Colwell procedure for the top 10 cm of soil is now the standard soil-test method for potassium used in Western Australia. No increases in clover yields to applied potassium were obtained for Colwell potassium at >100 mg/kg soil. There was always a clover-yield increase to applied potassium for Colwell potassium at <30 mg/kg soil. Corresponding potassium concentrations for ryegrass were >50 and <30 mg/kg soil. At potassium concentrations 30–100 mg/kg soil for clover and 30–50 mg/kg soil for ryegrass, the Colwell procedure did not reliably predict yield response, because from nil to large yield responses to applied potassium occurred. The Colwell procedure appears to extract the most labile potassium in the soil, including soluble potassium in soil solution and potassium balancing negative charge sites on soil constituents. In some soils, Colwell potassium was low indicating deficiency, yet plant roots may have accessed potassum deeper in the soil profile. Where the Colwell procedure does not reliably predict soil potassium status, tissue testing may help. The relationship between relative yield and tissue-test potassium varied markedly for different harvests in each year of the experiments, and for different experiments. For clover, the concentration of potassium in dried herbage that was related to 90% of the maximum, potassium non-limiting yield (critical potassium) was at the concentration of about 15 g/kg dried herbage for plants up to 8 weeks old, and at <10 g/kg dried herbage for plants older than 10–12 weeks. For ryegrass, there were insufficient data to provide reliable estimates of critical potassium.


2003 ◽  
Vol 43 (10) ◽  
pp. 1221 ◽  
Author(s):  
M. D. A. Bolland ◽  
J. S. Yeates ◽  
M. F. Clarke

The dry herbage yield increase (response) of subterranean clover (Trifolium subterraneum L.)-based pasture (>85% clover) to applications of different sources of sulfur (S) was compared in 7 field experiments on very sandy soils in the > 650 mm annual average rainfall areas of south-western Australia where S deficiency of clover is common when pastures grow rapidly during spring (August–November). The sources compared were single superphosphate, finely grained and coarsely grained gypsum from deposits in south-western Australia, and elemental S. All sources were broadcast (topdressed) once only onto each plot, 3 weeks after pasture emerged at the start of the first growing season. In each subsequent year, fresh fertiliser-S as single superphosphate was applied 3 weeks after pasture emerged to nil-S plots previously not treated with S since the start of the experiment. This was to determine the residual value of sources applied at the start of the experiment in each subsequent year relative to superphosphate freshly-applied in each subsequent year. In addition, superphosphate was also applied 6, 12 and 16 weeks after emergence of pasture in each year, using nil-S plots not previously treated with S since the start of the experiment. Pasture responses to applied S are usually larger after mid-August, so applying S later may match plant demand increasing the effectiveness of S for pasture production and may also reduce leaching losses of the applied S.At the same site, yield increases to applied S varied greatly, from 0 to 300%, at different harvests in the same or different years. These variations in yield responses to applied S are attributed to the net effect of mineralisation of different amounts of S from soil organic matter, dissolution of S from fertilisers, and different amounts of leaching losses of S from soil by rainfall. Within each year at each site, yield increases were mostly larger in spring (September–November) than in autumn (June–August). In the year of application, single superphosphate was equally or more effective than the other sources. In years when large responses to S occurred, applying single superphosphate later in the year was more effective than applying single superphosphate 3 weeks after pasture emerged (standard practice), so within each year the most recently applied single superphosphate treatment was the most effective S source. All sources generally had negligible residual value, so S needed to be applied each year to ensure S deficiency did not reduce pasture production.


2006 ◽  
Vol 46 (8) ◽  
pp. 993 ◽  
Author(s):  
S. M. Robertson

The impact of different management strategies on production and profit can be evaluated with knowledge of how sheep production responds to changes in the available feed base and sheep or pasture management. This study aimed to quantify on-farm pasture and sheep production in mixed sheep and cropping systems in the Victorian Mallee of south-eastern Australia (325 ± 50 mm annual rainfall) as a prelude to computer simulation modelling. During 2001 (average rainfall) and 2002 (extreme drought) pasture production, the feed base and sheep production were monitored in 15 paddocks on 5 properties located across the region. Crop stubbles were the major source of feed for 6 months of the year, enabling ewes to maintain liveweight. There was more variation in pasture parameters between paddocks at the 1 location than between locations. The botanical composition, plant density, soil fertility and management were key variables associated with between-paddock variation in pasture production. Variation in pasture production between years was larger than within-year differences. In contrast, stocking rates were not much lower in the drought year of 2002 than in 2001. This study suggests there is potential for management to improve pasture production, and demonstrates the importance of feed sources other than annual pasture for sheep production in environments where the annual pasture growing season is short.


2010 ◽  
Vol 50 (2) ◽  
pp. 138 ◽  
Author(s):  
B. A. McGregor

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.


Author(s):  
A.D. Mackay

A grazing trial evaluated the agronomic effectiveness of 3 different types of phosphate (P) fertilisers. The same fertilisers were also evaluated in a small-plot mowing trial located within the grazing trial. In the grazing trial, which covered 35 ha of summer moist hill country, the partially acidulated phosphate rock (PAPR) and reactive phosphate rock (RPR) were as effective as superphosphate in stimulating legume and pasture production in the first year. In the second year the two slow-release materials continued to perform as well as SSP. In contrast in the mowing trial, superphosphate was more effective than RPR in the first year. This trial technique clearly underestimates the initial effectiveness of PAPR and RPR in grazed hill country. The traditional small-plot mowing trial technique, and the role of PAPR and RPR fertilisers in hill country, both need re-evaluation. Keywords hill country, superphosphate, slow release fertilisers, mowing trials, grazed pasture


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