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RESEARCH ARTICLE
Contents Vol 46(3)

Root depth of native and sown perennial grass-based pastures, North-West Slopes, New South Wales. 2. Estimates from changes in soil water content

S. R. Murphy A B and G. M. Lodge A
+ Author Affiliations
- Author Affiliations

A NSW Department of Primary Industries, Tamworth Agricultural Institute, 4 Marsden Park Road, Calala, NSW 2340, Australia.

B Corresponding author. Email: sean.murphy@dpi.nsw.gov.au

Australian Journal of Experimental Agriculture 46(3) 347-359 https://doi.org/10.1071/EA04277
Submitted: 24 December 2004  Accepted: 12 September 2005   Published: 28 March 2006

Abstract

Root depth of pasture is an important hydrological parameter that has substantial implications for the use of rainfall by plants and in estimating deep drainage using biophysical modelling. Studies were undertaken for native and sown perennial grass-based pastures on the North-West Slopes of New South Wales to investigate 4 approaches that may identify the depth of plant roots based on objective assessments of change in soil water content (SWC). The 4 approaches were to examine traces of SWC measured with a neutron moisture meter (NMM) at about 4-week intervals (0–210 cm profile at 20-cm increments) for defined periods with root depth interpreted as, (i) the maximum depth at which there was a distinct decrease in SWC, (ii) the maximum depth at which there was a >0.01 m3/m3 decrease in SWC, (iii) the uppermost depth at which the change in SWC was significant using t0.05, and (iv) the uppermost depth at which the daily rate of change in SWC was significant using t0.05. For each of these approaches, 4 preliminary criteria were applied as filters to the SWC data before they were used in these analyses, (i) the depth of NMM tubes and maximum depth of measurement of SWC was greater than the anticipated pasture root depth, (ii) the depth of initial profile wetting was greater than the anticipated pasture root depth, (iii) there was a drying period of >3 months duration in the major pasture growth phase to allow pastures to extract soil water to the maximum extent, and (iv) the SWC was measured at a sufficient frequency to determine extraction of soil water by roots. SWC data were available from spring 1997 to spring 2001 for Barraba (45 access tubes, native pasture), Manilla (45 tubes, native pasture) and Nundle (36 tubes, sown pasture). Analyses of monthly rainfall compared with mean values identified 3 times where substantial rainfall was followed by an extended drying period. These periods occurred in 1998, 1999 and 2000. SWC data for the 1998 drying period best met all the preliminary filters, particularly criteria (ii) and (iii). Root depth values estimated from these data using the 4 approaches were not significantly different for Barraba (188 ± 4 to 190 ± 3 cm, n = 45), Nundle (142 ± 5 to 143 ± 7 cm, n = 13) and Manilla Red Chromosol (164 ± 7 to 176 ± 7 cm, n = 14), but were significantly different for Manilla Brown Vertosol (98 ± 7 to 121 ± 7 cm, n = 23). It was concluded that reliable estimates of root depth may be readily obtained for a range of soils and environments by firstly applying the 4 simple criteria used in these studies to the SWC data and by determining the depth of significant drying using t0.05. The depth of significant drying approach was the most objective, providing consistent results among sites and accounting for variance among NMM counts and tubes in these studies.

Additional keywords: neutron moisture meter, plant water use, water balance.


Acknowledgments

We gratefully acknowledge the assistance of Brian Roworth and Michael Honesss in collecting and processing the soil and root samples and Bill Austin and Brian Willoughby for their assistance in collecting the soil cores. We also thank Malem McLeod and Brendan George for constructive comments on an earlier draft of this paper. These studies were conducted as part of the Sustainable Grazing Systems (SGS) Key Program, which was a joint collaboration between NSW Agriculture, Meat & Livestock Australia, Land & Water Australia and other agencies.


References


Clewett JF , Clarkson NM , George DA , Ooi SH , Owens DT , Partridge IJ , Simpson GB (2003) ‘Rainman StreamFlow version 4.3: a comprehensive climate and stream flow analysis package on CD to assess seasonal forecasts and manage climate risk.’ (Department of Primary Industries: Brisbane)

Cornish P (1987) Root growth and function in temperate pastures. In ‘Temperate pastures: their production, use and management’. (Eds JL Wheeler, CJ Pearson, GE Roberts) pp. 79–98. (Australian Wool Corporation/CSIRO: Melbourne)

Crawford MC, MacFarlane MR (1995) Lucerne reduces soil moisture and increases livestock production in an area of high groundwater recharge potential. Australian Journal of Experimental Agriculture 35, 171–180.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Dunin FX, Williams J, Verburg K, Keating BA (1999) Can agricultural management emulate natural ecosystems in recharge control in south eastern Australia? Agroforestry Systems 45, 343–364.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Dunin FX, Smith CJ, Zegelin SJ, Leuning R, Denmead OT, Poss R (2001) Water balance changes in a crop sequence with lucerne. Australian Journal of Agricultural Research 52, 247–262.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Evans PS (1978) Plant root distribution and water use patterns of some pasture and crop species. New Zealand Journal of Agricultural Science 21, 261–265. open url image1

Greenwood KL, Hutchinson KJ (1998) Root characteristics of temperate pasture in New South Wales after grazing at three stocking rates for 30 years. Grass and Forage Science 53, 120–128.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Hamblin A, Tennant D (1987) Root length density and water uptake in cereals and grain legumes: how well are they correlated? Australian Journal of Agricultural Research 38, 513–527.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Heng LK, White RE, Chen D, Helyar KR, Fisher R (2001) Seasonal differences in the soil water balance under perennial and annual pastures on an acid Sodosol in southeastern Australia. European Journal of Soil Science 52, 227–236.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Isbell RF (1996) ‘The Australian Soil Classification.’ (CSIRO Publishing: Melbourne)

Lodge GM, Murphy SR, Harden S (2003a) Effects of continuous and seasonal grazing strategies on the herbage mass, persistence, animal productivity and soil water content of a Sirosa phalaris — subterranean clover pasture, North-West Slopes, New South Wales. Australian Journal of Experimental Agriculture 43, 539–552.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Lodge GM, Murphy SR, Harden S (2003b) Effects of grazing and management on herbage mass, persistence, animal production and soil water content of native pastures. 1. A redgrass–wallaby grass pasture, Barraba, North-West Slopes, New South Wales. Australian Journal of Experimental Agriculture 43, 875–890.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Lodge GM, Murphy SR, Harden S (2003c) Effects of grazing and management on herbage mass, persistence, animal production and soil water content of native pastures. 2. A mixed native pasture, Manilla, North-West Slopes, New South Wales. Australian Journal of Experimental Agriculture 43, 891–905.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Lodge GM, Murphy SR (2006) 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. Australian Journal of Experimental Agriculture 46, 337–345. open url image1

Lolicato SJ (2000) Soil water dynamics and growth of perennial pasture species for dryland salinity control. Australian Journal of Experimental Agriculture 40, 37–45.
| Crossref | GoogleScholarGoogle Scholar | open url image1

McGowan M (1974) Depths of water extraction by roots: Application to soil-water balance studies. In ‘Isotope and radiation techniques in soil physics and irrigation studies 1973’. Food and Agriculture Organisation of the United Nations: International Atomic Energy Agency. pp 435–445. (International Atomic Energy Agency: Vienna)

McGowan M, Williams JB (1980) The water balance of an agricultural catchment I. Estimation of evaporation from soil water records. Journal of Soil Science 31, 217–230. open url image1

Murphy SR, Lodge GM (2004) Surface soil water dynamics in pastures in northern New South Wales. 1. Use of electrical resistance sensors. Australian Journal of Experimental Agriculture 44, 273–281.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Salve R, Tokunaga TK (2000) Flow processes in a rangeland catchment in California. Journal of Range Management 53, 489–498. open url image1

Simpson RJ , Bond WJ , Cresswell HP , Paydar Z , Clark SG , et al. (1998) A strategic assessment of sustainability of grazed pasture systems in terms of their water balance. In ‘Proceedings of the 9th Australian agronomy conference, Wagga Wagga’. (Eds DL Michalk, JE Pratley) pp. 239–242. (The Australian Agronomy Society Inc.: Melbourne)

Sinclair DF, Williams J (1979) Components of variance involved in estimating soil water content and water content change using a neutron moisture meter. Australian Journal of Soil Research 17, 237–247.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Tennant D, Hall D (2001) Improving water use of annual crops and pastures — limitations and opportunities in Western Australia. Australian Journal of Agricultural Research 52, 171–182.
| Crossref | GoogleScholarGoogle Scholar | open url image1

White RE, Helyar KR, Ridley AM, Chen D, Heng LK , et al. (2000) Soil factors affecting the sustainability and productivity of perennial and annual pastures in the high rainfall zone of southeastern Australia. Australian Journal of Experimental Agriculture 40, 267–283.
| Crossref | GoogleScholarGoogle Scholar | open url image1

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 | open url image1