Influence of Site and Fertiliser Addition on Nutrient Cycling in Eucalyptus globulus Plantations in Gippsland, South-eastern Australia. I. Foliage and Litter Quality

1999 ◽  
Vol 47 (2) ◽  
pp. 189 ◽  
Author(s):  
Neeta Hooda ◽  
Christopher J. Weston
Keyword(s):  
Litter Quality ◽  
Nitrogen And Phosphorus ◽  
Nutrient Return ◽  
Total N ◽  
South Eastern ◽  
Sampling Position ◽  
Eastern Australia ◽  
Labile N ◽  
Old Trees ◽  
South Eastern Australia

The productivity of Eucalyptus plantations on many sites in south-eastern Australia is limited by nitrogen and phosphorus supply. Therefore, after canopy closure, nutrient return and decomposition are key processes maintaining productivity. To gain a better understanding of the effects of site and fertilisers on these processes, foliage and litter quality in E. globulus (Labill.) plantations in Gippsland, south-eastern Australia were characterised on three sites covering a range of soil types, inherent soil fertility and fertiliser treatments. Foliage and litter quality were estimated by sequential extraction of labile forms of N, P and C with cold, then hot, trichloroacetic acid (TCA). Selected treatments were sampled in N × P factorial fertiliser trials of 6-year-old trees where nutrients were added up to 2 years of age. Foliage and litter were categorised as recent or old depending on sampling position. Site significantly influenced concentrations of total and labile N and P (P < 0.0001) in foliage and litter. Phosphorus fertiliser increased total P concentrations in old foliage at two sites, with the greatest absolute and relative increases at the least fertile site (Glencoe). Inorganic P extracted by cold (4°C) TCA accounted for 30-55% of total leaf and litter P and was the fraction most responsive to P fertiliser addition. Total N concentration and N fractions in foliage and litter were not influenced by N fertiliser addition. Inorganic N extracted by cold and hot (90°C) TCA accounted for less than 2% of total N and was not significantly different among fertiliser treatments. Both sugar and phenol concentrations in foliage and litter varied significantly between sites, with the least fertile site showing significantly higher concentrations of phenols in recent litter. Sugars and phenols extracted in cold TCA decreased from old foliage to litter at all sites and were not influenced by N and P fertiliser addition. The results show that additions of 200 kg ha-1 of P cause perturbations in P cycle that are bigger in magnitude and are sustained for longer periods of time compared to changes in N cycle with 400 kg ha-1 of N additions.

Nitrogen balances in temperate perennial grass and clover dairy pastures in south-eastern Australia

2007 ◽  
Vol 58 (12) ◽  
pp. 1167 ◽  
Author(s):  
R. J. Eckard ◽  
D. F. Chapman ◽  
R. E. White
Keyword(s):  
Ammonium Nitrate ◽  
Management Practices ◽  
Perennial Grass ◽  
Dairy Farms ◽  
Nutrient Inputs ◽  
N Losses ◽  
Total N ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

Nitrogen (N) fertiliser use on dairy pastures in south-eastern Australia has increased exponentially over the past 15 years. Concurrently, imports of supplementary feed onto dairy farms have increased, adding further nutrients to the system. These trends raise questions about the environmental effects of higher nutrient inputs to dairy farms. To gauge possible effects, annual N balances were calculated from an experiment where N inputs and losses were measured for 3 years from non-irrigated grass/clover pastures receiving either no N fertiliser (Control) or 200 kg N/ha applied annually as ammonium nitrate or urea. Estimated total N inputs, averaged over the 3 years, were 154, 314, and 321 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively, while N outputs in meat and milk were 75, 99, and 103 kg N/ha.year, respectively. The corresponding calculated N surplus was 79, 215, and 218 kg N/ha.year for the 3 treatments, respectively, and the ratio of product N/total-N inputs for the 3 treatments ranged from 50% in the control to 32% for both N treatments. Total N losses averaged 56, 102, and 119 kg N/ha.year, leaving a positive N balance of 23, 112, and 99 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively. The ratio of product N/total-N inputs or the N surplus may be useful in monitoring the efficiency of conversion of N into animal products and the potential environmental effect at a whole-farm scale. However, additional decision support or modelling tools are required to provide information on specific N losses for a given set of conditions and management inputs. Given the large range in N losses there is opportunity for improving N-use efficiency in dairy pastures through a range of management practices and more tactical use of grain and N fertiliser.

Persistence and productivity of perennial ryegrass in sheep pastures in south-western Victoria: a review

2001 ◽  
Vol 41 (1) ◽  
pp. 117 ◽  
Author(s):  
R. A. Waller ◽  
P. W. G. Sale
Keyword(s):  
Perennial Ryegrass ◽  
Seedling Recruitment ◽  
Climatic Conditions ◽  
Grazing Management ◽  
Annual Rainfall ◽  
Nitrogen And Phosphorus ◽  
Dormant State ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

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.

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