Brennan, M. A.

Lodge, G. M.

Murphy, Sean R.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Plant Root Depth of Tropical Perennial Grasses in a Temperate Environment Sean R. Murphy Department of Primary Industries, Australia G. M. Lodge Department of Primary Industries, Australia M. A. Brennan Department of Primary Industries, Australia Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/3-1/31 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House 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. 瞯 ]464　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　Grasslands/Rangelands Resources and Ecology ——— Soil‐Plant‐Animal InterrelationshipsPlant root depth of tropical perennial grasses in a temperate environmentS .R . Murphy 1 ,2 , G .M . Lodge , and M .A . Brennan1 NSW Department o f Primary Industries , 4 Marsden Park Road Calala , NSW AUSTRA L IA 2340 .2 Future FarmIndustries CRC .1 E‐mail : sean .murphy＠ dp i .nsw .gov .auKey words : tropical grass , soil water , rootsIntroduction The influence of perennial grasses on the soil water balance has been determined by measuring the pattern anddepth of soil drying achieved by plant roots ( Murphy and Lodge ２００６) . Pasture species having a greater plant root depth and anincreased ability to use available soil water may produce more herbage mass , and so increase livestock production . The North‐West Slopes region of New South Wales ( NSW) is classed as a temperate environment , but it has warm to hot summers and asummer dominant rainfall distribution . Summer active species , such as tropical perennial grasses , may be suited to thisenvironment to utilise available soil water during the summer season .Materials and methods An experimental site was established on a red chromosol on the North‐West Slopes of NSW ( ３１°１６′S ,１５０°５２′E , ４９０ m alt . , ６７１ mm AAR) to compare soil drying and plant root depth of some introduced and endemic perennialgrasses . Four treatments including three tropical species ( Digitaria eriantha cv .�Premier�; Chloris gayana cv .�Katambora�;Bothriochloa bladii cv . �Swann�) and a mix of native species ( A ustrodanthonia bipartita cv . Bunderra ; B . macra ;Dicanthium sericeum ; C . truncata) were randomly allocated to plots ( ６ x ９ m ) across three replicates . T reatments wereestablished in December ２００５ by seeding at a rate of ２ kg / ha of germinable seed into a prepared bed at a depth of １０ mm . Asingle aluminium access tube was installed in the centre of each plot to a maximum depth of １ .７ m and a calibrated neutronmoisture meter was used to measure volumetric soil water content ( m３ /m３ ) at ０ .２ m depth intervals . Soil water content wasmeasured through the growing season at ３‐week intervals from １ September ２００６ to ３１ May ２００７ . Maximum depth of dryingand subsequently plant root depth was interpreted as the depth where drying of ＞ ０ .０２ m３ /m３ was achieved ( Murphy andLodge ２００６ ) .Results and discussion Soil water content at the start of the growing season was near to field capacity , with a mean value of ５５１mm ensuring a high amount of plant available water for each treatment . By May ２００７ , Katambora dried the soil to a depth of１ .６ m ( Figure １) . Swann and Premier showed drying to lesser depths of １ .４ and １ .２ m , respectively ( Figure １ ) . Depth ofdrying under native grasses was considerably shallower at １ .０ m . These data indicated that plant root depth was at least １ .６ mfor Katambora , １ .４ m for Swann , １ .２ m for Premier and １ .０ m for native grasses .Figure 1 Volumetric soil w ater content ( SWC ) at the start (１ Sep tember ２００６ , ● ） and end (３１ May２００７ ,○ ） o f the g row ing season f or ( a) Katambora , ( b) P remier , ( c) Sw ann and ( d) native g rasses .Conclusions In the temperate environment of the North‐West Slopes of NSW , three introduced tropical grasses extracted soilwater through the growing season to a greater depth than a mix of native perennial grasses . These preliminary results indicatethat the tropical species are potentially well suited to make use of available water in summer in this environment .ReferenceMurphy , S .R . , Lodge , G .M . ( ２００６ ) . Root depth of sown and native perennial grass‐based pastures , North‐West SlopesNew South Wales . ２ . Estimates from changes in soil water content . A ust . J . Ex p . A gric . ４６ , ３４７‐３５９ .(a) Volumetric SWC 0.0 0.1 0.2 0.3 0.4 0.5 0 r---.--..----.--.--, 0.2 0.4 0.6 I o.8 .c C. "' C 1.2 1.4 1.6 1.8 .._ ______ _ (b) Volumetric SWC 0 .0 0 .1 0.2 0.3 0.4 0.5 0 ,---.--r--,--...,.--, 0.2 0.4 0.6 I o.8 £ C. "' C 1.2 1.4 1.6 1.8 ._ ______ _ (c) Volumetric SWC 0.0 0.1 0.2 0.3 0.4 0.5 0 ,---,-..... --r--T""--, 0.2 0.4 0.6 I 08 £ C. "' C 1.2 1.4 1.6 1.8 (d) Volumetric SWC OD Q1 0.2 03 0.4 0~ 0 .-..... -T""--.-...... --, 0.2 0.4 0.6 I o.8 £ C. "' C 1.2 1.4 1.6 1.8 

Plant Root Depth of Tropical Perennial Grasses in a Temperate Environment

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Plant Root Depth of Tropical Perennial Grasses in a Temperate Environment

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