It is imperative that sheep production systems in southern Australia continue to be refined so producers remain financially viable but at the same time the environment is not degraded. As part of a national thrust for development and promotion of better production systems, one research site has been established in Victoria where pastures and animal production are measured together with water and nutrient movement. Results for pasture growth rates over two years are presented here and will be used to develop best industry practice at completion of the project

Chapman, D.

Kearney, G.

Lamb, J.

Quigley, P.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XIX International Grassland Congress Changes in Pasture Growth Rate Due to Fertiliser and Grazing Management P. Quigley Agriculture Victoria, Australia D. Chapman University of Melbourne, Australia J. Lamb Agriculture Victoria, Australia G. Kearney Agriculture Victoria, Australia Follow this and additional works at: https://uknowledge.uky.edu/igc Digital Commons Network Logo  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/19/8/11 This collection is currently under construction. The XIX International Grassland Congress took place in São Pedro, São Paulo, Brazil from February 11 through February 21, 2001. Proceedings published by Fundacao de Estudos Agrarios Luiz de Queiroz This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. ID# 08-16CHANGES IN PASTURE GROWTH RATE DUE TO FERTILISERAND GRAZING MANAGEMENT1P. Quigley, 2D. Chapman, 1J. Lamb and 1G. Kearney1 Agriculture Victoria, Pastoral and Veterinary Institute, Private Bag 105, Hamilton, Victoria,3300, Australia2 Institute of Land and Food Resources, The University of Melbourne, Victoria, 3010,AustraliaAbstractIt is imperative that sheep production systems in southern Australia continue to berefined so producers remain financially viable but at the same time the environment is notdegraded.  As part of a national thrust for development and promotion of better productionsystems, one research site has been established in Victoria where pastures and animalproduction are measured together with water and nutrient movement. Results for pasturegrowth rates over two years are presented here and will be used to develop best industrypractice at completion of the project.Keywords: Phalaris, subterranean clover, phosphorus, stocking rate, sheepIntroductionThere is an urgent need for many livestock producers in southern Australia toincrease the efficiency of production in order to remain financial viable.  A contributing factorto this pressure has been the decline in the quality of pasture over large tracts of this regionduring the last three decades (Quigley et al. 1992, Kemp and Dowling 1991).  Causes haveincluded reduced fertiliser inputs, reduction in resowing, over-grazing in summer and autumn,and under-grazing in spring (Mason and Andrew 1998).  Perennial ryegrass (Lolium perenneL.) pasture and animal production can be substantially increased by optimising rates ofapplied phosphorus fertilisers in this climatic region (Cayley et al. 1998, Cayley and Kearney2000). The additional benefits from using improved pasture species together with appropriaterates of phosphorus fertiliser have now been demonstrated for pastures based on perennialryegrass and phalaris (Phalaris aquatica L.) mixtures (Saul et al. 1993) or for ryegrass alone(Waller et al. 1999). Other research has shown that phalaris-based pastures have potential forhigher productivity when some form of controlled grazing is implemented (Lodge 1997).  InAustralia, however, farm pastures are normally continuously grazed (Cook et al. 1978).  Thispaper reports preliminary data for growth rates of pastures subjected to different grazingmanagement treatments. The project was designed to develop best industry practice for sheepproduction from pasture in the temperate zone of  southern Australia.Material and MethodsThe site for this experiment (370 24’ S, 1410 55’ E) formed part of a national networkof sites, each examining different tactical strategies for improving animal production, and atthe same time maintaining environmental sustainability.  The 20 ha site was sown to phalariscv. Australian and subterranean clover (Trifolium subterraneum L.) cv. Trikkala in 1994. InJuly 1997, five grazing management treatments were replicated three times in plots 1.5 to 2.25ha each (Table 1). These were stocked with Merino ewes.  Those in the 4-paddock rotationwere moved to fresh pasture every 2 weeks, except in spring when they were moved weekly.Ewes on the variable rotations were moved every 2 to 12 days, depending on pasture growth,except from lambing (August) to weaning (November) when they were set-stocked. Eweswere weighed every 4 to 6 weeks, and stocking rates were adjusted several times per year toachieve similar liveweights across all treatments.The low and high P treatments received 8 and 30 kg of phosphorus respectively,applied as superphosphate in autumn each year.  The nitrogen treatment had 50 kg N/haapplied in March and 50 kg N/ha applied in late July.Pasture growth was measured monthly during the 1998 and 1999 growing seasonsusing 20 or 24 exclosure cages per plot (Cayley and Bird 1996). Herbage mass wasdetermined using a falling-plate pasture meter (manufactured by Arborline Pty Ltd, Hamilton,Victoria). The meter was calibrated using 12 herbage cuts, each time measurements weremade.A linear mixed model was fitted using ASREML (Gilmour et al. 1997) to test for theeffects of treatment on pasture growth rate interacted with a cubic smoothing spline of time.Results and DiscussionThe level of P on the set-stocked treatments (A and B) did not affect pasture growthrates. It is likely that, after 2 years from starting this experiment, there has been insufficientdifference in soil available phosphorus to lead to differences in pasture growth rates.Measurement for an additional two growing seasons, with continuing differential fertiliserapplication, will assist in clarifying this conclusion.There were no significant differences among any of the rotational-grazed treatments(C, D, and E), therefore only treatment E is shown in Fig. 1.A combination of nitrogen fertiliser and rotational grazing (E) significantly (P<0.05)increased growth rates above set-stocked treatments (A and B) (Fig 1).  The set-stocked, lowP treatment (A) had significantly (P<0.05) lower growth rates than all the rotation treatments(C, D and E) which also had high P. There was a significant curvature trend between years(P<0.05) but no significant interaction between year and management treatment. Thesedifferences in growth have been attributed to differences in phalaris tiller size but notdifferences in tiller density (Cullen et al. 2000).In 1998, pasture growth commenced following rainfall in April (77 mm monthlytotal) but conditions after this were generally dry until further heavy rain in June (93 mmmonthly total), by which time mean daily temperature was 7.60C and limiting pasture growthrates. In 1999, growth commenced in March (54 mm monthly total) with additional goodrainfall in May (99 mm monthly total). Although combined winter and spring rainfall washigher in 1998 (439 mm) than 1999 (299 mm), maximum growth rates were approximately 57kg DM/ha/day and 67 kg DM/ha/day in 1998 and 1999, respectively. Thompson et al. (2001)have shown that sheep production from this site was substantially improved in response tothese changes in pasture production.Considerable progress is being made in development of better management systemsthat increase financial viability of meat and wool production in temperate rainfall regions ofAustralia.  As a consequence of the national program, progressive landholders are nowbeginning to implement these management systems, with suitable adaptations to fit theirneeds.AcknowledgmentsOur thanks go to Meat and Livestock Australia, Land and Water Resources Researchand Development Corporation and  the Department of Natural Resources and Environmentfor funding; Robert and Marilyn Lyons for access to land and in-kind support.ReferencesCayley J.W.D. and Bird P.R. (1996). Techniques for Measuring Pastures (Pastoral andVeterinary Institute, Hamilton, Victoria).Cayley J.W.D., Hannah M.C., Kearney G.A. and Clark S.G. (1998). Effects ofphosphorus fertiliser and rate of stocking on the seasonal pasture production of perennialryegrass-subterranean clover pasture. Aust. J. Agric. Res.  49: 233-248.Cayley J.W.D. and Kearney G.A. (2000). Profitable use of phosphorus fertiliser fortemperate pastoral Australia. Asian-Aust. J. Anim. Sci. 13: 191-194.Cook S.J., Lazenby A. and Blair G. (1978). Pasture degeneration. II The importance ofsuperphosphate, nitrogen and grazing management. Aust. J. Agric. Res.  29: 19-29.Cullen B., Quigley P. and Chapman D. (2000). Sustainable grazing systems for westernVictoria. 3. How does rotational; grazing increase phalaris production? Proc. 41st Ann. Conf.Vic. Grassland Soc. (In press).Gilmour A.R., Thompson R., Cullis B.R. and Welham S.J. (1997). ASREML. NSWAgriculture.Kemp D.R. and Dowling P.M. (1991). Species distribution within improved pastures overcentral N.S.W. in relation to rainfall and altitude. Aust. J. Agric. Res. 42: 647-659.Lodge G.M. (1997). Phalaris. Pages 8-9 in R.D. FitzGerald and G.M. Lodge, eds. Grazingmanagement of temperate pasture: literature reviews and grazing guidelines for major species.NSW Agric. Tech. Bull. 47.Mason W. and Andrew M. (1998). Sustainable Grazing Systems (SGS) – developing anational experiment. Proc. 9th Aust. Agron. Conf., Wagga Wagga pp. 314-317.Quigley P.E., Ward G.N. and Morgan, T.  (1992). Botanical composition of pasture insouth-western Victoria. Proc. 6th Aust. Agron. Conf., Armidale p. 533.Saul G.R., Jowett D., Morgan T., Noble P.  and Borg D. (1993). Improved pasture species,fertiliser and pasture use to increase the productivity of wool sheep in south-western Victoria.Proc. XVII Int. Grassld Cong., New Zealand pp. 1289-1292.Thompson A.N., Borg D, Graham J.F., Lamb J. and Saul G.R. (2001). Rotational grazingincreases wool and lamb production from phalaris-subterranean clover pastures in southeastern Australia. Proc. XIX Int. Grassld Cong., Brazil (In press).Waller R.A., Sale P.W.G., Saul G.R., Quigley P.E. and Kearney G.A. (1999). Tacticalversus continuous stocking for persistence of perennial ryegrass (Lolium perenne L.) inpastures grazed by sheep in south-western Victoria. Aust. J. Exp. Agric. 39: 265-274.Table 1 - Treatments and details for the experiment.Description Potentialstocking rate(DSE/ha)(a)Target Olsen P(mg/kg)Paddockarea(ha)A Set stock, low P (b) 12 4 – 6 2.25B Set stock, high P (c) 16 12 – 14 1.5C Simple rotation, high P 20 12 - 14 1.5D Intensive rotation, high P 21 12 - 14 1.5E Intensive rotation, high P + N(d) 24 12 - 14 1.5(a) dry sheep equivalent based on a 45 kg wether   (b) Approximately 8 kg P/ha/year;  (c)Approximately 30 kg P/ha/year; (d) 100 kg N/ha/yearFigure 1 - The effects of three management treatments on pasture growth rates in 1998 and1999.199810203040506070M J J A S O N D J F M A M J J A S O N DDateNet pasture growth rate (kg DM/ha/day) Treatment ATreatment BTreatment E1999

Changes in Pasture Growth Rate Due to Fertiliser and Grazing Management

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Changes in Pasture Growth Rate Due to Fertiliser and Grazing Management

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