Effects of nitrogen and phosphorus fertilizers and gypsum on a Danthonia caespitosa-Stipa variabilis grassland. 1. Response to fertilizer application over four successive years

1978 ◽  
Vol 18 (91) ◽  
pp. 253 ◽  
Author(s):  
GJ Tupper

The effect of nitrogen and phosphorus fertilizers and gypsum was assessed over four years on a Danthonia caespitosa-Stipa variabilis grassland, growing on the semi-arid Riverine Plain in south-eastern Australia. Fertilizers were applied annually and gypsum once only. The treatments were combined factorially. Seasonal production of total dry matter and individual species, and nitrogen and phosphorus contents of the plant tops, were measured. Forage production increased in response to the additives in years in which the annual rainfall varied from well below to near average. They accentuated the normal pattern of a spring peak, but also gave lesser increases in production in winter and autumn. Summer production was not measured because of the absence of effective summer rainfall. Nitrogen and phosphorus fertilizers and gypsum all contributed to the increased production, and the combination of the three additives produced the greatest yield. Over all seasons the yield of grassland treated with nitrogen plus phosphorus plus gypsum averaged 250 per cent of the control, or approximately 1500 kg ha-1. The main contributors to increases in yield were D. caespitosa, S. variabilis, annual herbs, and legumes. The perennial grasses were particularly favoured by nitrogen fertilizer whereas the yield of legumes was suppressed. The yield of legumes increased greatly in response to phosphorus fertilizer. With the exception of two species, all plants which increased in yield are acceptable to sheep. Nitrogen and phosphorus contents were above the minimum requirements for domestic herbivores.

2003 ◽  
Vol 43 (8) ◽  
pp. 817 ◽  
Author(s):  
W. H. Johnston ◽  
D. L. Garden ◽  
A. Rančić ◽  
T. B. Koen ◽  
K. B. Dassanayake ◽  
...  

Experiments conducted from November 1996 to June 2002 in adjacent small catchments near Wagga Wagga, New South Wales, compared the productivity and hydrology of a heavily fertilised (about 30 kg phosphorus/ha.year) Phalaris aquatica (phalaris) pasture with that of a lightly fertilised (about 14 kg phosphorus/ha every second year) native grassland that contained a mixture of C3 and C4 perennial grasses, dominantly C4 Bothriochloa macra (redgrass).In summer, the native catchment was dominated by C4 perennial grasses while the phalaris catchment was dominated by annual C4 weedy species. During the cooler months, the phalaris pasture contained higher proportions of Vulpia spp., and other less-desirable annual grasses. Throughout the experiment, the native catchment was dominated by redgrass, whereas in the phalaris catchment the persistence of phalaris declined. Redgrass became prominent on the more arid aspects of the phalaris catchment as the experiment progressed.Pasture production in the phalaris catchment was higher in most seasons than the native catchment, which resulted in an overall stocking rate advantage of about 80%. The productivity gain per unit of P input was 0.4 for the phalaris catchment compared with 1 for the native catchment, implying that phosphorus was applied to the phalaris catchment at an excessive rate.During wet periods the native catchment produced substantially more runoff than the phalaris catchment, while in dry times it developed substantially larger soil water deficits. Runoff from the phalaris catchment was higher in suspended and dissolved nitrogen and phosphorus than for the native catchment. Higher runoff from the native catchment combined with its drier soil profile in summer indicated that its deep drainage potential was less than in the phalaris catchment.


1968 ◽  
Vol 48 (5) ◽  
pp. 467-472 ◽  
Author(s):  
A. Johnston ◽  
A. D. Smith ◽  
L. E. Lutwick ◽  
S. Smoliak

In 1962 and 1963, nitrogen and phosphorus fertilizers were applied at various rates to native fescue range and to range seeded to bromegrass and creeping red fescue. Effect of fertilizers was studied 1, 2, and 3 years after application. Seeded range vegetation responded better than native range vegetation to all levels of fertilizer application. Unfertilized seeded range yielded only one-third as much as unfertilized native range but, at medium to high rates of N or N + P, seeded range yielded from 2 to [Formula: see text] times as much as native range.


2001 ◽  
Vol 41 (1) ◽  
pp. 117 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale

Loss of perennial ryegrass (Lolium perenne L.) from the pasture within several years of sowing is a common problem in the higher rainfall (550–750 mm annual rainfall), summer-dry regions of south-eastern Australia. This pasture grass came to Australia from northern Europe, where it mostly grows from spring to autumn under mild climatic conditions. In contrast, the summers are generally much drier and hotter in this region of south-eastern Australia. This ‘mismatch’ between genotype and environment may be the fundamental reason for the poor persistence. There is hope that the recently released cultivars, Fitzroy and Avalon, selected and developed from naturalised ryegrass pastures in south-eastern Australia for improved winter growth and persistence will improve the performance of perennial ryegrass in the region. Soon-to-be released cultivars, developed from Mediterranean germplasm, may also bridge the climatic gap between where perennial ryegrass originated and where it is grown in south-eastern Australia. Other factors that influence perennial ryegrass persistence and productivity can be managed to some extent by the landholder. Nutrient status of the soil is important since perennial ryegrass performance improves relative to many other pasture species with increasing nitrogen and phosphorus supply. It appears that high soil exchangeable aluminium levels are also reducing ryegrass performance in parts of the region. The use of lime may resolve problems with high aluminium levels. Weeds that compete with perennial ryegrass become prevalent where bare patches occur in the pasture; they have the opportunity to invade pastures at the opening rains each year. Maintaining some herbage cover over summer and autumn should reduce weed establishment. Diseases of ryegrass are best managed by using resistant cultivars. Insect pests may be best managed by understanding and monitoring their biology to ensure timely application of pesticides and by manipulating herbage mass to alter feed sources and habitat. Grazing management has potential to improve perennial ryegrass performance as frequency and intensity of defoliation affect dry matter production and have been linked to ryegrass persistence, particularly under moisture deficit and high temperature stress. There is some disagreement as to the merit of rotational stocking with sheep, since the results of grazing experiments vary markedly depending on the rotational strategy used, climate, timing of the opening rains, stock class and supplementary feeding policy. We conclude that flexibility of grazing management strategies is important. These strategies should be able to be varied during the year depending on climatic conditions, herbage mass, and plant physiology and stock requirements. Two grazing strategies that show potential are a short rest from grazing the pasture at the opening rains until the pasture has gained some leaf area, in years when the opening rains are late. The second strategy is to allow ryegrass to flower late in the season, preventing new vegetative growth, and perhaps allowing for tiller buds to be preserved in a dormant state over the summer. An extension of this strategy would be to delay grazing until after the ryegrass seed heads have matured and seed has shed from the inflorescences. This has the potential to increase ryegrass density in the following growing season from seedling recruitment. A number of research opportunities have been identified from this review for improving ryegrass persistence. One area would be to investigate the potential for using grazing management to allow late development of ryegrass seed heads to preserve tiller buds in a dormant state over the summer. Another option is to investigate the potential, and subsequently develop grazing procedures, to allow seed maturation and recruitment of ryegrass seedlings after the autumn rains.


1978 ◽  
Vol 18 (91) ◽  
pp. 262 ◽  
Author(s):  
GJ Tupper

The residual effects of nitrogen and phosphorus fertilizers applied over four consecutive years and gypsum applied once only, were assessed over five years on a Danthonia caespitosa-Stipa variabilis grassland, growing on the semi-arid Riverine Plain of south-eastern Australia. Totals of 155 and 31 0 kg ha-1 of N, 100 and 200 kg ha-1 of P, and 3.34 and 6.68 t ha-1 of CaS0,. 2H2O had been added. The increase in dry matter production in response to nitrogen ceased one year after the last application of nitrogen fertilizer. After five years, grassland which had received 200 kg ha-1 of phosphorus and 6.68 t ha-1 of gypsum yielded 6500 kg ha-1 of dry matter, compared with 1300 kg ha-1 in the absence of fertilizers and gypsum. Legume growth was still suppressed five years after nitrogen fertilizer had been applied, but legumes increased production greatly in response to the previous phosphorus and phosphorus-gypsum treatments. Nitrogen content of the herbage averaged 2.1 per cent four years after the previous high level phosphorus treatment, compared with 1.6 per cent with the control after four years. It was unaffected by previous nitrogen fertilizer. Phosphorus content was reduced for the first three years after nitrogen fertilizer was last added, but was increased by phosphorus fertilizer to 0.28 per cent, compared with 0.1 8 per cent on the control, four years after phosphorus fertilizer was last added. Soil moisture characteristics, and total soil nitrogen and carbon showed no differences between treatments. The Truog phosphorus in the soil under the high phosphorus level decreased from 103 p.p.m. to 53 p.p.m., compared with the unaltered control level of 7 p.p.m, over the five year period.


2011 ◽  
Vol 33 (1) ◽  
pp. 87 ◽  
Author(s):  
R. B. Hacker ◽  
I. D. Toole ◽  
G. J. Melville

The roles of nitrogen (N) and phosphorus (P) in controlling vegetation transitions in a degraded semi-arid grassland were investigated in a factorial experiment that combined two initial levels of perennial plant density (low and high), three levels of N (N+, N0 and N–) and two levels of P (P+ and P0). Increased levels of both N and P were achieved by fertiliser addition while sucrose was used to reduce the level of N. Vegetation dynamics were driven primarily by soil N rather than P. Addition of sucrose, which was inferred to result in the immobilisation of mineral N, reduced the growth of annual species and facilitated the establishment and growth of native perennial grasses. Addition of P generally had no significant effect on dry matter production, either in total or for species grouped as forbs, annual grasses and perennial grasses, or on recruitment and mortality of perennial grasses. However, at some times of observation addition of P increased ground cover and/or the basal circumference of some perennial grass species. Basal circumference for Enteropogon acicularis was also increased by addition of N. Soil biological activity, measured by decomposition of cotton strips, was increased by addition of N, which maintained vegetation in an annual-dominated condition, and was not affected by addition of P. Carbon addition has the potential to assist restoration of this grassland. However, the capacity of some native grass species to respond to increased fertility suggests that once restoration is achieved some increase in fertility may be beneficial for pastoral production.


1999 ◽  
Vol 50 (1) ◽  
pp. 29 ◽  
Author(s):  
W. H. Johnston ◽  
C. A. Clifton ◽  
I. A. Cole ◽  
T. B. Koen ◽  
M. L. Mitchell ◽  
...  

This paper presents a case for the selection and development of a wider range of perennial grasses for pastoral use in the higher rainfall (annual rainfall >500 mm) zone of southern Australia, especially the southern sector of the Murray–Darling Basin. There is also a need to reconsider the use of ‘high-input’ pastures on hill lands by developing more appropriate recommendations for managing existing native grass pastures productively. Past experiments which compared native grass based pastures with sown pastures promoted the view that indigenous grasses were inferior in most respects to exotic improved species. Even though many of the findings were confounded with fertiliser, stocking rate, and other treatment effects, they reinforced the general direction of cultivar development programs which in the temperate zone have been based mainly on the 4 exotic C3 species Phalaris aquatica L., Dactylis glomerata L., Lolium L. spp., and Festuca elatior var. arundinacea (Schreb.) Hackel (syn. Festuca arundinacea Schreb). This has led to an imbalance in the adaptability and range of species available to be sown in pastures, particularly for sowing on less productive landscapes where stony, shallow, infertile, acid soils limit the persistence of current cultivars. The pre-European vegetation of temperate Australia comprised species with a capacity for active growth and transpiration during summer. The water use pattern resulted in soil moisture being near capacity in late winter and spring, and exhausted by summer’s end. Replacement of this vegetation with annual-growing and summer-dormant C3 species has changed the water use pattern so that soils are drier in spring and wetter in autumn. This has reduced the pre-winter soil moisture deficit, which in turn has increased rates of deep drainage in winter. Land degradation in southern Australia is a consequence of this changed water use pattern. Deep drainage of water beyond the reach of plant roots has mobilised salts stored in the landscape and caused watertables to rise, which has led to large areas becoming saline. Lack of growth in summer in pastures consisting of senescent annual-growing species and dormant C3 perennial grasses limits utilisation of the products of nitrogen mineralisation, which allows nitrate nitrogen to accumulate in summer and be readily leached by rainfall in autumn. This increases rates of soil acidification. Although there may be scope to reduce deep drainage by increasing pasture growth in spring in areas where there is little likelihood of summer rainfall, this is not the case in south-eastern Australia where significant falls of rain occur during summer and autumn.


1981 ◽  
Vol 3 (1) ◽  
pp. 83 ◽  
Author(s):  
GM Lodge ◽  
JA Taylor ◽  
RDB Whalley

Techniques for using grid and unmarked transparent perspex overlays to estimate the area of tufted native perennial grasses were investigated in field and laboratory studies. Basal area was overestimated by using an unmarked overlay to trace the periphery of actual or atificial plant bases at ground level; this was caused by the amount of airspace included in the estimate. The compression of hand-held tufts reduced the airspace and improved the estimate of plant basal area. In the laboratory studies, the estimation by eye of filled cells in a transparent grid overlay was accurate over a range of areas from 0.02 to 10.39 cm2, although it required considerable operator training. Changes in herbage mass occur as a result of change in the number of plants per unit area (plant density), the basal area of individual plants or the plant mass per unit of basal area of individual plants. Field studies were undertaken at two sites to collect data on each of these components of herbage mass and to investigate whether or not such information could be used to estimate the herbage mass of individual species in a pasture. The relationship between the mass per unit basal area of certain plant parts would appear to have some potential for use in studies of the seasonal changes in various plant components, such as green leaf and stem. This relationship could be used to examine the response of some species to fertilizer application, grazing and defoliation and hence the process of change in species composition with management. Estimates of the herbage mass per unit area of individual native perennial grasses calculated from plant density, plant basal area and mass per unit of basal area data compared favourably with estimates of total herbage mass of individual species obtained from clipped quadrats. Suggested techniques for collecting data in the field and the time involved in sampling are discussed.


1954 ◽  
Vol 2 (1) ◽  
pp. 69 ◽  
Author(s):  
EF Biddiscombe ◽  
EG Cuthbertson ◽  
RJ Hutchings

Features of the autecology of four native perennial grasses (Stipa, Chloris, and Digitaria spp.) and an important group of winter annual species are reported from a 5-yr study of a naturaI pasture at Trangie, N.S.W. The investigation was mainly concerned with the response of the species to changes in seasonal climatic conditions. The study period (1948–52) was relatively moist (mean annual rainfall 25.6 in.) and the growing season (May–November) longer than average. Available moisture showed considerable variation in autumn and spring, and was the primary factor in the variable success of germination and seedling survival among the perennial grasses. Plant development in the perennial grasses is discussed for three study intervals, March 1948–50 (above average rainfall), March 1950–51 (recurrent flooding over 8 months), and March 1951–52 (including a long, dry summer) ; in all pkriods striking fluctuations were noted in persistency and basal area of established plants, particularly the small plants of each species. Available moisture is advanced as the principal factor controlling seasonal distribution of green forage production by the perennial grasses, temperature becoming limiting only at midwinter (June–July). All species conformed to a similar production pattern, showing a midsummer minimum (except in January 1951), late summer and spring peaks, and a midwinter trough. Flowering and maturation periods are listed for the perennial grasses, and infrequent but heavy seed production recorded for all species. Characteristic features of the root systems are discussed in relation to drought resistance and response to effective rainfall. Germination of Medicago spp. was most frequent in May and June (1-in. soil temperature 51–61°F), but was also successful in March, April, and July. Erodium cygnorum and Hordezcm leporinum favoured late February to early May (65–75°F) for germination. Among high populations percentage seedling survival was low, even in a very favourable season. Given adequate winter moisture (as in 1948 and 1949), Medicago spp. and E. cygnorum showed virtually an exponential increase in green forage production between May and September. The level of September production of these species is shown to be correlated with moisture availability in April. The principal factors ensuring regular recurrence of the winter annuals in pastures of the Trangie environment are outlined and discussed.


2009 ◽  
Vol 31 (1) ◽  
pp. 103 ◽  
Author(s):  
Juliana McCosker ◽  
John Rolfe ◽  
Rod Fensham

A bare ground index derived by remote sensing would provide a rapid methodology for assessing the biodiversity condition of an ecosystem, providing that ground cover is a satisfactory correlate with key biodiversity attributes. The relationship between plant species richness and the abundance of individual species was examined in relation to ground cover within silver-leaved ironbark (Eucalyptus melanophloia F. Muell.) woodlands in the Desert Uplands bioregion of north-eastern Australia. There was significant correlation between the bare ground index and ground cover and biomass measurements. Twenty-four species, including the perennial grasses Sehima nervosum (Rottler) Stapf, Themeda triandra Forssk. and Bothriocloa ewartiana (Domin) C.E. Hubb., were significantly and negatively correlated with bare ground. Scleroleana birchii (F. Muell.) Domin and Sida fibulifera Lindl.displayed significant positive relationships with increasing bare ground, and where abundant indicate heavy grazing in this land type. The study suggests that satellite-derived data does provide a meaningful methodology for assessing vegetation condition although it is strongly associated with seasonal conditions, but is only useful in relation to the regional average for a land type. The findings suggest that plant diversity is maintained at a relatively high level throughout most of these woodlands in the Desert Uplands.


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