Measuring and predicting the consequences of drought for a range of perennial grasses on the Northern Tablelands of New South Wales

Boschma, S. P.; Scott, J. M.

doi:10.1071/ea98014

Cited by 18 publications

(23 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4). This is consistent with the findings of Boschma and Scott (2000), who found that severe grazing during moderate drought conditions in spring led to higher mortality of desirable perennial grasses than under severe drought conditions or severe grazing in summer and autumn. Optimisation results suggest that the expected benefit from high utilisation during spring outweighs the potential costs of pasture resource degradation, provided that sufficient grazing rest is provided to the pasture in the preceding winter and following summer.…”

Section: Optimal Stocking Ratesupporting

confidence: 82%

Optimising pasture and grazing management decisions on the Cicerone Project farmlets over variable time horizons

et al. 2013

View full text Add to dashboard Cite

Abstract. This study addresses the problem of balancing the trade-offs between the need for animal production, profit, and the goal of achieving persistence of desirable species within grazing systems. The bioeconomic framework applied in this study takes into account the impact of climate risk and the management of pastures and grazing rules on the botanical composition of the pasture resource, a factor that impacts on livestock production and economic returns over time. The framework establishes the links between inputs, the state of the pasture resource and outputs, to identify optimal pasture development strategies. The analysis is based on the application of a dynamic pasture resource development simulation model within a seasonal stochastic dynamic programming framework. This enables the derivation of optimum decisions within complex grazing enterprises, over both short-term tactical (such as grazing rest) and long-term strategic (such as pasture renovation) time frames and under climatic uncertainty. The simulation model is parameterised using data and systems from the Cicerone Project farmlet experiment. Results indicate that the strategic decision of pasture renovation should only be considered when pastures are in a severely degraded state, whereas the tactical use of grazing rest or low stocking rates should be considered as the most profitable means of maintaining adequate proportions of desirable species within a pasture sward. The optimal stocking rates identified reflected a pattern which may best be described as a seasonal saving and consumption cycle. The optimal tactical and strategic decisions at different pasture states, based on biomass and species composition, varies both between seasons and in response to the imposed soil fertility regime. Implications of these findings at the whole-farm level are discussed in the context of the Cicerone Project farmlets.

show abstract

Section: Optimal Stocking Ratesupporting

confidence: 82%

Optimising pasture and grazing management decisions on the Cicerone Project farmlets over variable time horizons

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The management of the farmlets in response to climatic uncertainty has been conceptually described as a complex decision problem that is familiar to graziers who commonly have to make decisions in spite of imperfect knowledge of the state of a farm's resources and an uncertain climate (Behrendt et al 2013a). Rational responses to these climatic constraints include employing deep-rooted perennial species that permit some growth over dry periods (Boschma and Scott 2000) and ensuring the retention of sufficient temperate C 3 species, which, especially when adequate soil nitrogen is available, are capable of some modest growth under cold winter temperatures (Newman et al 1962).…”

Section: Discussionmentioning

confidence: 99%

Comparing the climate experienced during the Cicerone farmlet experiment against the climatic record

et al. 2013

Self Cite

View full text Add to dashboard Cite

Abstract. Farming systems research conducted under dryland conditions is subject to the vagaries of the climate during the experimental period. Whether such an experiment experiences a representative series of climatic years must be examined in relation to the longer term climatic record. The Cicerone Project's farmlet experiment was conducted on the Northern Tablelands of New South Wales, Australia, to investigate the profitability and sustainability of three different management systems: one managed under typical, moderate-input conditions (farmlet B); a second which employed a higher level of pasture inputs and soil fertility (farmlet A); and a third which focussed on the use of moderate inputs and intensive rotational grazing (farmlet C).The climate experienced during the 6.5-year experimental period was compared with the 118-year climatic record, using a biophysical simulation model of grazed systems. The model utilised the long-term daily climate data as inputs and provided outputs that allowed comparison of parameters known to affect grazed pastures. Modelled soil-available water, the number of soil moisture stress days (SMSDs) limiting pasture growth, and growth indices over the experimental period (2000-06) were compared with data over the climatic record from 1890 to 2007. SMSDs were defined as when the modelled available soil moisture to a depth of 300 mm was <17% of water-holding capacity. In addition, minimum temperatures and, in particular, the frequency of frosts, were compared with medium-term (1981-2011) temperature records.Wavelet transforms of rainfall and modelled available soil water data were used to separate profile features of these parameters from the noise components of the data. Over the experimental period, both rainfall and available soil water were more commonly significantly below than above the 95% confidence intervals of both parameters. In addition, there was an increased frequency of severe frosting during the dry winters experienced over the 6.5-year period. These dry and cold conditions were likely to have limited the responses to the pasture and grazing management treatments imposed on the three farmlets. In particular, lower than average levels of available soil water were likely to have constrained pasture production, threatened pasture persistence, and reduced the response of the pasture to available soil nutrients and, as a consequence, livestock production and economic outcomes.Ideally, dryland field experimentation should be conducted over a representative range of climatic conditions, including soil moisture conditions both drier and wetter than average. The drier than average conditions, combined with a higher than normal frequency of severe frosts, mean that the results from the Cicerone Project's farmlet experiment need to be viewed in the context of the climate experienced over this 6.5-year period.

show abstract

“…Plant losses resulting from the moisture and defoliation treatments imposed are presented in Boschma and Scott (2000) and summarised in Table 1. Correlation matrices and multiple regression were used to determine which of the measured plant traits described in this and previous papers (Boschma and Scott 2000;Boschma et al 2003) were most highly correlated with plant mortality. Only those species that had 40% or more plant losses in a treatment and/or losses from over half of the plots (Boschma and Scott 2000) were used in the analysis.…”

Section: Traits Important For Plant Resiliencementioning

confidence: 99%

“…Correlation matrices and multiple regression were used to determine which of the measured plant traits described in this and previous papers (Boschma and Scott 2000;Boschma et al 2003) were most highly correlated with plant mortality. Only those species that had 40% or more plant losses in a treatment and/or losses from over half of the plots (Boschma and Scott 2000) were used in the analysis. Therefore, for the spring-summer data, only Dactylis and Lolium were analysed, whereas for the summer-autumn data all species, except Festuca and Microlaena, were analysed.…”

Section: Traits Important For Plant Resiliencementioning

confidence: 99%

“…In an earlier paper, we discussed some of the broad factors involved in plant responses to drought and their potential effect on animal production using selected data from a rain-out shelter experiment (Boschma and Scott 2000). In a companion paper to this, we examined the dynamics of water-soluble carbohydrates (WSC) and fructans under drought and defoliation stress (Boschma et al 2003).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The response to moisture and defoliation stresses, and traits for resilience of perennial grasses on the Northern Tablelands of New South Wales, Australia

Boschma¹,

Hill²,

Scott³

et al. 2003

Aust. J. Agric. Res.

Self Cite

View full text Add to dashboard Cite

A field experiment was conducted to study the effects of defoliation and moisture stresses on perennial pasture grasses and to identify traits associated with their resilience. The experiment, conducted near Armidale on the Northern Tablelands of NSW, studied 4 introduced perennial grass species (Phalaris aquatica, Festuca arundinacea, Dactylis glomerata, and Lolium perenne) and 2 native grass species (Microlaena stipoides and Austrodanthonia richardsonii) subjected to 3 moisture regimes (non-stress moisture, moderate drought, and severe drought) and 2 defoliation intensities (severe and moderate). Basal area, herbage mass, phenological growth stage, nitrogen concentration, root mass, and rooting depth were compared over 2 independent 6-month periods: spring-summer (). Multiple regression was used to determine which traits were important for determining plant resilience.The differences between species and their respective responses were evident in the traits measured. In general, basal area tended to increase over summer and show little change during autumn. Severe defoliation stimulated plant growth, resulting in higher harvested herbage mass than from those moderately defoliated. Reproductive development was suppressed by severe drought and reduced by moderate drought. Severe defoliation suppressed flowering of Dactylis and Lolium at both drought intensities, compared with moderate defoliation. Phalaris, Festuca, and Austrodanthonia were the deepest rooting species during spring-summer, and Dactylis the shallowest. All species had similar rooting depths during summer-autumn, with those under severe and moderate drought having the deepest and shallowest rooting, respectively.Carbohydrate reserves and basal area were important traits for determining plant resilience during spring-summer. During summer-autumn, maintaining basal area and plant biomass through moderate grazing was important for resilience. A R 0 2 1 8 5 R e s p o n s e t o d r o u g h t a n d t r a i t s f o r r e s i l i e n c e S . P . B o s c h m a e t a l .

show abstract

Measuring and predicting the consequences of drought for a range of perennial grasses on the Northern Tablelands of New South Wales

Cited by 18 publications

References 4 publications

Optimising pasture and grazing management decisions on the Cicerone Project farmlets over variable time horizons

Optimising pasture and grazing management decisions on the Cicerone Project farmlets over variable time horizons

Comparing the climate experienced during the Cicerone farmlet experiment against the climatic record

The response to moisture and defoliation stresses, and traits for resilience of perennial grasses on the Northern Tablelands of New South Wales, Australia

Contact Info

Product

Resources

About