Statistical methodologies for drawing causal inference from an unreplicated farmlet experiment conducted by the Cicerone Project

Murison, R. D.; Scott, J. M.

doi:10.1071/an11331

Cited by 17 publications

(17 citation statements)

References 32 publications

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“…Issues relating to assigning causal inference to the farmlet treatments have been discussed in detail in a related paper by Murison and Scott (2013).…”

Section: Statistical Analysesmentioning

confidence: 99%

The effects of pasture inputs and intensive rotational grazing on superfine wool production, quality and income

Cottle

Gaden²,

Hoad

et al. 2013

Anim. Prod. Sci.

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Abstract.A farmlet experiment was conducted between July 2000 and December 2006 as part of the Cicerone Project, which sought to enhance the profitability and sustainability of grazing enterprises on the Northern Tablelands of New South Wales, Australia. A self-replacing Merino enterprise was grazed as the dominant livestock enterprise, together with 20% of the carrying capacity as cattle, on each of three farmlet treatments: higher levels of soil fertility and pasture renovation with flexible rotational grazing over eight paddocks (farmlet A), moderate soil fertility and pasture renovation with flexible rotational grazing over eight paddocks (farmlet B) and moderate soil fertility and pasture renovation with intensive rotational grazing over 37 paddocks (farmlet C). Prior to commencement of the trial, the three 53-ha farmlets were allocated equivalent areas of land based on soil type, slope and recent fertiliser history.This paper describes the effects of the three pasture and grazing management strategies on the production, quality and value of the wool produced per head, per ha and per farmlet. Up until 2001 there were no differences in wool production between farmlets. Thereafter, significant differences between farmlets emerged in greasy fleece weight per head and price received per kg of fleece wool. For example, the clean fleece value averaged over the 2003-05 shearings for all hoggets, ewes and wethers was 1531, 1584 and 1713 cents/kg for farmlets A, B and C, respectively.There were small but significant differences, which varied between sheep class and year, between the farmlets in average fibre diameter and staple length but less so with staple strength. In general, while the differences between farmlets in staple strength varied over time, farmlets A and B tended to have wool with longer staple length and broader fibre diameter than farmlet C and this affected wool value per kg.Differences in wool income per ha between farmlets grew in later years as the farmlet treatments took effect. In spite of farmlet A having a slightly lower wool value per kg, after taking into account its greater fleece weight per head and its higher stocking rate, the total wool income per ha was higher than on either farmlets B or C. The average gross wool income per ha from 2003 to 2005 was $303, $215 and $180 for farmlets A, B and C, respectively. The highest amount of greasy wool produced was in 2004 when 38.2, 26.5 and 21.5 kg/ha was harvested from farmlets A, B and C, respectively.The fibre diameter profiles of 2-year-old ewes showed similar profiles for farmlets A and B but a significantly finer fibre diameter profile for farmlet C ewes due to intensive rotational grazing. However, sheep on all three farmlets produced wool with high staple strength.Multivariate analyses revealed that greasy fleece weight, staple length and staple strength were significantly positively correlated with the proportion of the farm grazed at any one time, and with soil phosphorus, legume herbage and green digestible herbage thus highlighting...

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“…Issues relating to assigning causal inference to the farmlet treatments have been discussed in detail in a related paper by Murison and Scott (2013).…”

Section: Statistical Analysesmentioning

confidence: 99%

The effects of pasture inputs and intensive rotational grazing on superfine wool production, quality and income

Cottle

Gaden²,

Hoad

et al. 2013

Anim. Prod. Sci.

Self Cite

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“…The data from before or early in the trial showed little difference between the initial farmlet conditions and so the observed differences in trends over time among the farmlets could be inferred to have arisen due to the different management systems imposed (Murison and Scott 2013).…”

Section: Reflections From the Researchers And Extension Specialistsmentioning

confidence: 99%

Section: Reflections From the Researchers And Extension Specialistsmentioning

confidence: 99%

“…This presented significant challenges to researchers and their paradigms as discussed by Murison and Scott (2013). Given that there was credible evidence of similar starting conditions from the farmlet planning process (Scott et al 2013e), the lack of replication was not considered to be a fatal flaw, especially as appropriate methods are available for inferring causal inference (Murison and Scott 2013). And yet convincing scientists of the validity of producer-led trials like Cicerone is just one requirement; arguably, a more important requirement is that producers have sufficient confidence in the findings to use them and have an impact within the wider industry.…”

Section: Reflections From the Researchers And Extension Specialistsmentioning

confidence: 99%

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Reflections on the concept, conduct and findings of the producer-led Cicerone Project

Coventry¹,

Sutherland²,

Waters

et al. 2013

Anim. Prod. Sci.

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Abstract. The Cicerone Project began as a producer-led partnership that sought, over a period of 8 years, to enhance the profitability and sustainability of livestock enterprises by improving the connection between those producers, research and extension. Following a detailed survey, the research and extension needs of livestock producers were identified and several applied investigations were conducted to meet those needs and delivered through a range of extension activities. This final paper of the Cicerone Special Issue reflects on the entire Project from a wide array of perspectives, including livestock producers, researchers, extension specialists and staff employed by the Project, all of whom are authors of this paper.A notable early successful outcome of the Project was the improved precision of footrot diagnosis, which has been of value to the entire sheep industry, and that flowed from a field investigation of benign and virulent footrot combined with detailed genetic investigations, which led to an improved testing regime. This paper also reflects on the findings of an unreplicated agricultural ecosystem research trial, which measured the impact of pasture renovation, increased soil fertility and grazing management on the profitability and sustainability of three different 53-ha farmlets. Valuable findings from this whole-farmlet trial included the need for a high quality feed supply for increasing stocking rate and animal liveweights; the ability and utility of satellite imagery to detect changes in pasture growth, composition and recent grazing pressure; the value of short grazing and long rest periods for controlling Barber's pole worms of sheep; the impact of increased stocking rates on whole-farm profitability and risk; methods of optimising decisions relating to pasture renovation, fertiliser applications and grazing management; and an integrated analysis of all key measured components of the farmlet management systems. Collectively, these findings were powerful as they were demonstrated at a scale credible to livestock producers using the 'compare -measure -learn -adopt' approach, which was the key philosophy adopted by the Cicerone Project.By comparing and measuring different whole-farm systems, and by ensuring that producers had ownership of the trial process, the Project successfully delivered objective findings that producers trusted and which increased our understanding of important drivers of complex grazing enterprises under variable climatic conditions. Some of these drivers included: the influence of soil phosphorus on botanical composition and subsequent livestock production, the role of pasture renovation and soil fertility on herbage supply, herbage quality and stocking rate, and the improved gastrointestinal nematode control delivered by intensive rotational grazing.The beneficiaries of the Project included the 180 farmer members who participated in some 61 field days and workshops; the research and extension collaborators including four postgraduates who completed their research in...

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“…The statistical approaches to analysing unreplicated field studies such as this farmlet experiment have been discussed in relation to the literature in a related paper by Murison and Scott (2013). Soil P and S levels were examined using a linear fixed effects model fit by REML to account for the randomness of paddock selection for soil sampling within each farmlet.…”

Section: Statistical Analysesmentioning

confidence: 99%

Whole-farm management of soil nutrients drives productive grazing systems: the Cicerone farmlet experiment confirms earlier research

et al. 2013

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Abstract. The Cicerone Project included a study of three 53-ha farmlets, each subjected to a different management system. The systems varied first in their input of fertilisers and sown pastures and second in their grazing management. Farmlet A undertook a high level of pasture renovation and had soil fertility targets of 60 mg/kg Colwell phosphorus (P) and 10 mg/kg KCl-40 sulfur (S), while farmlets B and C both had a low rate of pasture renovation and targets of 20 mg/kg P and 6.5 mg/kg S. In addition, both farmlets A and B adopted a flexible rotational grazing regime over the eight paddocks of each farmlet, whereas farmlet C, which had 37 paddocks, adopted intensive rotational grazing.This paper first reviews the literature relating to soil fertility research in the summer-dominant rainfall region of the Northern Tablelands of New South Wales, Australia. It then examines whether the soil fertility targets set for the farmlets were attained and how the consequences of fertiliser management measured in this trial related to earlier research findings.Fertiliser applications, comprising both capital and maintenance rates, were based on soil test results but at times were constrained by the availability of finance. Soil tests over 5 years indicated that only nitrogen (N), P and S varied with time within the farmlets while the other indices of soil fertility remained similar. Phosphorus and S levels increased in response to fertiliser applications whereas N levels responded to increases in legume composition, which was stimulated by the higher P and S levels. Multivariate statistical analyses demonstrated that farmlet productivity was driven by P and S fertility and thus the two farmlets with lower P and S fertility (farmlets B and C) had similar but lower levels of farmlet productivity compared with farmlet A. Significant increases in several measured pasture productivity parameters were observed in response to the higher P and S fertility on farmlet A, especially when climatic conditions were favourable. The results of the Cicerone farmlet experiment confirm the findings of earlier research on the Northern Tablelands, and elsewhere in the high rainfall zone, that has demonstrated that higher soil fertility levels and pasture renovation enhance the productivity of grazing enterprises more than grazing management, without imposing significant risks to the environment.

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Statistical methodologies for drawing causal inference from an unreplicated farmlet experiment conducted by the Cicerone Project

Cited by 17 publications

References 32 publications

The effects of pasture inputs and intensive rotational grazing on superfine wool production, quality and income

The effects of pasture inputs and intensive rotational grazing on superfine wool production, quality and income

Reflections on the concept, conduct and findings of the producer-led Cicerone Project

Whole-farm management of soil nutrients drives productive grazing systems: the Cicerone farmlet experiment confirms earlier research

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