Root depth of native and sown perennial grass-based pastures, North-West Slopes, New South Wales. 1. Estimates from cores and effects of grazing treatments
G. M. Lodge A B and S. R. Murphy AA NSW Department of Primary Industries, Tamworth Agricultural Institute, 4 Marsden Park Road, Calala, NSW 2340, Australia.
B Corresponding author. Email: greg.lodge@.ndpisw.gov.au
Australian Journal of Experimental Agriculture 46(3) 337-345 https://doi.org/10.1071/EA04276
Submitted: 23 December 2004 Accepted: 12 September 2005 Published: 28 March 2006
Abstract
Studies were undertaken on native and sown perennial grass-based pastures as part of the Sustainable Grazing Systems National Experiment to estimate root depth and describe root distribution in these pastures. Samples from soil cores (0–210 cm maximum sampling depth) taken in 1997 (before grazing treatments were imposed) and 4 years later in spring 2001 were used to examine the effects of different grazing regimes on root length density (cm/cm3), root mass density (mg/cm3), root volume density (cm3/cm3), and diameter (mm) at each of 3 sites. In spring 1997, mean maximum root depth was 107 cm for a native perennial grass pasture near Barraba and 74 cm for a pasture sown with phalaris (Phalaris aquatica) and subterranean clover (Trifolium subterraneum) near Nundle, with values being lower for a native pasture near Manilla (65 cm for a Brown Vertosol and 97 cm for a Red Chromosol). For all pasture types, >20% of root mass density, root length density or root volume density was in the 0–5 cm soil layer and >60% was at a depth of 0–30 cm. At all sites, mean total root mass was around 1000 kg DM/ha. After 4 years of grazing (spring 2001) there were relatively few significant effects of grazing treatment on root length density, root mass density, root volume density, or root diameter. Effects that were significant mostly occurred at 0–5 cm for the native pastures and 0–50 cm for the sown pasture. For the Barraba native pasture, root length, volume and mass densities (0–5 cm) were higher (P<0.05) in the continuously grazed, low stocking rate treatment compared with all other treatments. Similarly, for the Manilla native pasture, root length density was higher (P<0.05) in this treatment at soil depths of 0–5 and >5–10 cm compared with all other treatments. In contrast, for the Nundle sown pasture, root length density (0–5 cm) was lowest (P<0.05) in 2 continuously grazed treatments compared with those that were strategically grazed in autumn and spring.
Additional keywords: root diameter, root distribution, root length density, root mass density, root volume density.
Acknowledgments
We gratefully acknowledge the assistance of Brian Roworth and Michael Honess in collecting and processing the soil and root samples and Bill Austin (1997) and Brian Willoughby (2001) for their assistance in collecting the soil cores. We also thank Kerry Greenwood and Gunnar Kirchhof for their helpful advice in using the scanner and imaging software. These studies were conducted as part of the Sustainable Grazing Systems (SGS) Key Program, which was a joint collaboration between the NSW Department of Primary Industries (formerly NSW Agriculture), Meat & Livestock Australia, Land & Water Australia and other agencies.
Amato M, Pardo A
(1994) Root length and biomass losses during sample preparation with different screen mesh sizes. Plant and Soil 161, 299–303.
| Crossref | GoogleScholarGoogle Scholar |
(verified 1 February 2006).
Murphy SR, Lodge GM
(2002) Ground cover in temperate native perennial grass pastures. I. A comparison of four estimation methods. The Rangeland Journal 24, 288–300.
| Crossref | GoogleScholarGoogle Scholar |
Murphy SR, Lodge GM
(2006) Root depth of native and sown perennial grass-based pastures, North-West Slopes, New South Wales. 2. Estimates from changes in soil water content. Australian Journal of Experimental Agriculture 46, 347–359.
Ridley AM, Simpson RJ
(1994) Seasonal development of roots under perennial and annual grass pastures. Australian Journal of Experimental Agriculture 45, 1077–1087.
| Crossref | GoogleScholarGoogle Scholar |
White RE,
Christy BP,
Ridley AM,
Okom AE, Murphy SR , et al.
(2003) SGS Water Theme: influence of soil, pasture type and management on water use in grazing systems across the high rainfall zone of southern Australia. Australian Journal of Experimental Agriculture 43, 907–926.
| Crossref | GoogleScholarGoogle Scholar |
