Effect of nitrogen fertilizer on a kangaroo grass (Themeda australis) grassland

1974 ◽  
Vol 14 (69) ◽  
pp. 526 ◽  
Author(s):  
HJ Fisher

Three rates of nitrogen fertilizer and a standard superphosphate dressing were applied to a Themeda australis grassland with and without broadcast seed of Dactylis glomerata. Two cutting frequencies were imposed and dry matter yields and botanical composition were measured. T. australis responded to nitrogen, but the response was not sufficient for it to predominate over other species, particularly Poa labillardieri, as it had done under low fertility conditions. P. labillardieri yields increased markedly with increasing nitrogen rate. D. glomerata, which established only where nitrogen fertilizer was applied, substantially reduced the increase in P. labillardieri at the high level of nitrogen. Cutting frequency affected botanical composition in degree but not in kind. Both P. labillardieri and D. glomerata yielded less, but T. australis yielded more under more frequent cutting. For pasture improvement in wetter parts of the southern tablelands of New South Wales, it is important to establish a perennial grass at the beginning of the programme to reduce the growth of the undesirable tussock. P. labillardieri.

1975 ◽  
Vol 15 (77) ◽  
pp. 795 ◽  
Author(s):  
JA Thompson

A range of temperate annual and perennial legumes, naturalized or commonly sown in the area, was examined at three field sites in low fertility soils derived from granite on the south western slopes of the New England Region, New South Wales. They were compared over a four year period in terms of their persistence, dry matter and nitrogen production and their compatibility with associated temperate perennial grasses, The response of sown grass to nitrogen fertilizer application was also examined in the absence of legume. Ten legumes were examined at one site and six of these at the other two sites. In general, nitrogen yields were ranked similarly to total dry matter yields of all treatments, including grasses in the absence of legume. However, the legumes were ranked differently in terms of productivity of the legume component and productivity of associated grass. At all sites lucerne gave the highest yields of total dry matter and of legume and the lowest yield and persistence of associated grass-comparable to grass growing in the absence of legume or applied nitrogen. Subterranean clover was ranked second or third in total dry matter yield, depending on site, but provided the highest yield of associated grasscomparable to grass receiving high levels of applied nitrogen. Under this legume soil nitrogen levels tended to be highest. Rose clover, sown at one site only, yielded more legume dry matter than subterranean clover but grass yield was comparable to that with lucerne. The results suggest that subterranean clover is the superior legume for successful mixed sowings although inclusion of white clover could be justified. Lucerne appears to be best sown as a pure sward.


2004 ◽  
Vol 44 (12) ◽  
pp. 1165 ◽  
Author(s):  
A. M. Bowman ◽  
W. Smith ◽  
M. B. Peoples ◽  
J. Brockwell

Total productivity and legume nitrogen fixation (N2 fixation) in dryland pastures were examined in a 2 year study (1999–2001) on 118 farms in central-western New South Wales. Pasture exclosure cages, placed at 217 on-farm sites, were harvested on 7 occasions and the foliage hand-sorted according to species in order to measure shoot dry matter (DM). The separated legume shoot material collected in spring 1999 (52 different legume samples) and 2000 (76 different legume samples) from a subset of representative pastures (41 cages on 28 different farms in 1999, 32 cages on 25 different farms in 2000) was also analysed for concentration of nitrogen (%N) and 15N natural abundance. These data were subsequently used to calculate the proportion of the legume shoot N derived from atmospheric N (%Ndfa), comparative measures of the relative efficiency of N2 fixation (kg N fixed/t DM accumulated) and the amounts of shoot N fixed (kg N/ha). The survey encompassed 8 common pasture types, and 5 others that were less common, ranging from native perennial grass pastures with little legume content to lucerne (Medicago sativa L.) pastures with and without companion clovers. Fifteen legume species were found in the pastures, some only occasionally. Lucerne and white clover (Trifolium repens L.) were the only perennials. Mean spring estimates of %Ndfa were similar in 1999 and 2000 for lucerne (72 and 81%, respectively), rose clover (T. hirtum All., 82 and 77%) and annual medics (Medicago spp., 89 and 86%). For the remaining 12 legume species, measures of %Ndfa ranged from 64 to 95% and averaged 83%. Shoot %N contents were greater for lucerne than for the other 14 legumes and this was reflected in the comparative measures of N2 fixation which ranged from 14.5 kg N/t DM for rose clover to 25.7 kg N/t DM for lucerne in 2000. The most productive pasture type comprised lucerne plus balansa clover [T. michelianum Savi var. balansae (Boiss.) Azn.], white clover or arrowleaf clover (T. vesiculosum Savi), but all pasture types that contained lucerne were highly productive. Spring was the most productive season and summer the least. Lucerne was overwhelmingly the most productive legume and was responsible for >83% of the fixed N in those pastures that contained both lucerne and other legumes. Lucerne productivity was approximately uniform throughout the year whereas, for other pastures, especially those based on rose clover or subterranean clover (T. subterraneum L.), there were sharp peaks in spring and little or no dry matter production over summer. The presence of lucerne in pastures significantly (P<0.05) reduced broadleaf weeds. It was concluded that, where there are requirements in central-western New South Wales agriculture for uniform forage production throughout the year and a high input of fixed N, lucerne is substantially superior to other species.


1978 ◽  
Vol 18 (94) ◽  
pp. 718 ◽  
Author(s):  
DL Garden ◽  
DR Brooks ◽  
J Bradley

The effects of superphosphate rate (nil; 250 kg ha-l initial with 125 kg ha-1 maintenance; and 500 kg ha-1 initial with 250 kg ha-1 maintenance) and cutting interval (2, 4, 6 or 8 weeks) on dry matter yield, growth rate, botanical composition and chemical composition of native pastures on a sandstone soil in the Clarence Valley, New South Wales were studied over a period of three years. Mean annual dry matter yield of unfertilized native pasture was 990 kg ha-l and this was increased to 1322 kg ha-1 at the higher rate of superphosphate. Dry matter yield was depressed from 1587 to 647 kg ha-1 by decreasing cutting interval from 8 weeks to 2 weeks. Pasture growth was limited to the September to May period and 87 per cent of the total annual production occurred in summer and autumn. Maximum growth occurred in the February/March period, with 16.2 kg ha-1 day-1 being the maximum recorded for the unfertilized pasture and 19.9 kg ha-1 day-1 for pasture at the higher rate of superphosphate. Changes in botanical composition were neither large nor consistent. Phosphorus content of the native pasture averaged 0.12 per cent. Crude protein content averaged 7.4 per cent, with levels in standing herbage in winter-spring falling to 3 per cent. Phosphorus yield was 1.1 kg ha-1 year-1 and crude protein yield was 65.8 kg ha-1 year-1. Superphosphate increased phosphorus content and yield, and crude protein yield. Increasing cutting interval decreased phosphorus and crude protein contents but increased phosphorus and crude protein yields by its effect on dry matter yield. Maximum yields obtained were 3.3 kg ha-1 year-1 phosphorus and 100 kg ha-1 year-1 crude protein. It was concluded that the increases obtained would be insufficient to produce worthwhile improvements in animal production, and that an increase in the legume content of these pastures is required before this could occur.


1973 ◽  
Vol 13 (64) ◽  
pp. 567 ◽  
Author(s):  
EC Wolfe ◽  
A Lazenby

The effects of superphosphate (0, 42, 125, and 375 kg ha-1 year-1), grass species (tall fescue, perennial ryegrass, and phalaris) and grass seeding rate (0, 1.1, 4.5, and 17.9 kg ha-1) on the productivity and botanical composition of grass-white clover pastures were investigated from 1967 to 1970 on a previously unfertilized site at Armidale, New South Wales. In all years, total pasture yields were increased by each additional increment of superphosphate applied. During the establishment year, the addition of 375 kg ha-1 superphosphate increased clover dry matter yield by more than 3500 kg ha-1, whereas grass production was low (< 1500 kg ha-1) on all treatments. Thereafter, the increases in grass yields at each level of superphosphate were the equal of, or exceeded, the clover responses, which were mainly linear throughout the experiment. Neither grass seeding rate nor grass species had a major effect on total pasture productivity. Their effects on the relative yields of the grass and clover components were most evident at the highest rate of superphosphate. At SP0, grass and clover percentages declined from 1967 to 1970 and at SP125 the proportions of grass, clover and weeds were about equal in all years. At SP375, the strong overall trend from clover-dominance in 1967 to grass-dominance in 1970 was most rapid in treatments sown with 4.5 or 17.9 kg ha-1 grass and least rapid in phalaris-white clover pastures. In 1969 and 1970, when most pastures at SP375, had reached the grass-dominant stage of their development, within-year fluctuations in grass and clover content were least in the fescue-white clover pastures.


1986 ◽  
Vol 26 (2) ◽  
pp. 165 ◽  
Author(s):  
GM Lodge

Three irrigated lucerne cultivars, Pioneer Brand 545 (winter dormant), Condura 73 Brand (semiwinter dormant), and CUF 101 (highly winter active), were harvested at fixed cutting intervals of either 25, 28 ,35, 42 or 48 days from September to April in each of four years. This paper reports the effects of these cutting frequencies on the dry matter yield, leaf to stem ratio and persistence of these cultivars. The effect of cutting frequency on mean total yield (the sum of the mean yields for each harvest) was significant (P<0.05) in each year of the experiment, except year 3. Yields were highest in the 35-day cutting frequency in years 1 and 2. In the fourth year of the experiment the mean total yield of Pioneer Brand 545 and Condura 73 Brand was 29% higher (P<0.05) than CUF 101. By the fourth year substantial amounts of grass were present in the 25- and 28-day cutting interval plots. The contrasts between dormant and active cultivars for the dry matter yield of each of the individual harvests were not consistent in the first two years. In the third and fourth years the active initially outyielded the dormant cultivars at all cutting intervals, but yields of both were generally similar at the end of the season. Increasing the interval between successive harvests generally decreased the mean leaf to stem ratio. The ratio of leaf to stem for CUF 101 was significantly lower (P<0.05) than that for Pioneer Brand 545, with Condura 73 Brand tending to be intermediate. Within cutting intervals, mean declines in plant persistence were similar for cultivars from the different dormancy groups. Largest changes in plant frequency occurred in the fourth year when the mean frequency for the 25- and 28-day plots decreased from 69 to 12% compared with a mean decline from 74 to 65% for the 42- and 48-day cutting intervals. Productive stand life in this experiment was 3 years, even though disease was negligible. Under these conditions grass invasion was mainly related to harvest interval and much less to cultivar dormancy.


1979 ◽  
Vol 19 (101) ◽  
pp. 698 ◽  
Author(s):  
GM Lodge ◽  
EA Roberts

The effects of phosphorus (P), sulphur (S) and stocking rate on the dry matter yield, and chemical and botanical composition of natural pasture were examined from November, 1971 to May, 1976 in a 20 point central composite design. P and S were applied annually at five levels (0, 6, 15, 23, 29 kg P ha-1; 0, 14, 34, 54, 67 kg S ha-1) and the plots were grazed continuously at five stocking rates (2.2, 3.2, 4.8, 6.3, 7.3 dry ewes ha-1). Each of the factors, P, S, and stocking rate affected total dry matter. At 4.8 and 6.3 sheep ha-1 the optimum rate of P was 15 kg ha-1, but at 3.2 sheep ha-1 it increased from 15 kg ha-1 to 23 kg ha-1 over the period. S had little effect on yield at the start and end of the experiment, but in between its effect depending on stocking rate; at 3.2 sheep ha-1 low levels (<I4 kg ha-1) were optimal, but at 4.8 and 6.3 sheep ha-1 very high levels (>54 kg ha-1) were needed. The quantity of green grass and legume was low in winter and was not consistently affected by any of the factors. The level of N in the green grass remained at less than 2%. Over the period of the experiment the basal cover of perennial grass and the frequency of annual legume declined, while the percentage of bare ground and annual grass increased. These changes over time could not be related to any of the factors, except that the percentage of A. ramosa declined at the higher stocking rates. In some years high stocking rate decreased the percentage of A. ramosa and S. variabilis, and increased that of C. truncata, D. linkii, K. phleoides and T. glomeratum. In terms of pasture yield, fertilized perennial grass pastures on the North-West Slopes have potential carrying capacities of at least 4.8 dry sheep ha-1. However, to support this high stocking rate without significantly affecting pasture yield high levels of S, around 54 kg ha-1, and moderate levels of P, around 15 kg ha-1, are required. At this higher stocking rate no major changes in botanical composition occurred.


1985 ◽  
Vol 25 (2) ◽  
pp. 411 ◽  
Author(s):  
DK Muldoon

Sorghum bicolor x S. sudanense hybrid cv. Sudax ST6 and Echinochloa utilis cv. Shirohie were grown under irrigation at Trangie, New South Wales. Six rates of nitrogen (N) fertilizer were applied at sowing: 0, 25, 50, 120, 300, 450 kg N/ha. Height and dry matter yield were recorded at head emergence, together with the leaf hydrocyanic acid (HCN) potential, and leaf and stem dry matter digestibility, nitrogen, sulfur and sodium contents. Both the sorghum hybrid and the millet reached maximum forage yields (16.1 and 7.6 t/ha, respectively) at 350 kg N/ha. However, the tall-growing forage sorghum produced more dry matter than millet and consequently was more responsive to fertilizer nitrogen. In sorghum the leaf HCN potential increased linearly in response to N (8.5 x 10-4 %/kg N.ha). Since there was no compensating increase in the sulfur content (0.072%), and, assuming a requirement of 1.2 g S/g of HCN detoxified, sorghum lacked sufficient sulfur to detoxify the HCN potentially released in the rumen from sorghum receiving 150-200 kg N/ha. At this rate of nitrogen application, sorghum was producing only two-thirds of its forage yield potential. The sodium content of sorghum (0.013%) was not affected by nitrogen. In millet the nitrogen and sodium contents increased as applied nitrogen promoted growth. Plant sulfur was diluted initially but the nitrogen: sulfur ratio increased steadily (0.0067 units/kg N.ha). In contrast to sorghum, therefore, nitrogen fertilizer can be used to increase the dry matter yield of millet without jeopardizing forage quality and hence animal production.


1973 ◽  
Vol 13 (64) ◽  
pp. 575 ◽  
Author(s):  
EC Wolfe ◽  
A Lazenby

The development of an intermittently grazed phalaris-white clover pasture was studied from 1967 to 1970 following factorial annual applications of nitrogen fertilizer (0, 56, 11 2 kg N ha-1) and superphosphate (0, 188, 375 kg ha-1) onto a previously unfertilized site near Armidale, New South Wales. Each year superphosphate increased annual yields of phalaris, clover and total pasture. The response to superphosphate of phalaris was mainly linear, but in the final year of the experiment the yield of clover was greater at the intermediate rate (SP188) than at SP375. Nitrogen increased annual dry matter yields of phalaris and total pasture only in the presence of superphosphate. Clover growth was not suppressed by nitrogen fertilizer until the final year, when total pasture yields were not increased by nitrogen. In the absence of applied nitrogen, pastures on the SP375 treatment were clover-dominant in 1967 and 1968 but strongly grass-dominant in 1970; at SP188, pastures remained clover-dominant after the establishment year. The application of up to 112 kg N ha-1 year -1 reduced the intensity of the clover-dominant phase at SP, and circumvented clover-dominance at SP188. Grass-white clover relationships during pasture development are discussed in relation to the prevention of cattle bloat.


1976 ◽  
Vol 1 (1) ◽  
pp. 49 ◽  
Author(s):  
GG Robinson

On the Northern Tablelands of New South Wales, Danthonia racemosa sown in both a field study and a pot experiment produced as much dry matter as any sown exotic grass species. Dry matter production of D. racemosa was least affected by dry weather conditions in the field while in pots it proved equally as responsive asphalaris tuberosa to nitrogen fertilizer. However, production of D. racemosa during winter was lower than P. tuberosa.


2003 ◽  
Vol 30 (1) ◽  
pp. 89 ◽  
Author(s):  
Fred Ford ◽  
Andrew Cockburn ◽  
Linda Broome

The smoky mouse, Pseudomys fumeus, is an endangered rodent for which ecological information is lacking across much of its range. This paper provides the first detailed study of the local diet and habitat preference of P. fumeus since 1980, conducted on the recently discovered Nullica population in New South Wales. Diet and trap-revealed movements were examined in conjunction with 18 characteristics of habitat to determine the factors influencing habitat choice. Multiple logistic regression of habitat variables and capture locations revealed a floristically determined preference for heath habitat characterised by Epacris impressa, Monotoca scoparia, Leptospermum trinervium, Xanthorrhoea spp. and a variety of legumes. Hypogeal fungi and seeds were the most common food items in the diet of P. fumeus. Fungi were most abundant in winter diet, while seeds and fruit became dominant in late spring and summer. The spring and summer preference for ridge-top heath habitats observed in this study is probably the result of this dietary preference. Resident females constituted 71% of the population in early spring. However, there was a severe decline in numbers of female mice during early spring, and resident males also disappeared from the population. Causes of the decline were unclear. Five of eleven males captured during this study were transient, while no transient females were caught. The sudden decline in the study population, combined with the patchy distribution of suitable habitat and high level of male transience, suggests that P. fumeus form a metapopulation in the Nullica region.


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