Rab Abdur - International Union of Soil Sciences

The relationships between clay content and FC and PWP found in this study are consistent with those
reported for other soils (e.g. King and Stark 2005; Minasny et al. 1999; Iqbal et al. 2005). For example, Iqbal
et al. (2005) found greater values of volumetric water content at paddock locations where the percentage clay
content was high; an indication of the greater water holding capacity of soil micropores between clay-sized
particles. Minasny et al. (1999) found a positive non-linear relationship between clay content and FC and
PWP. The equations developed in this study can be used to predict FC and PWP for similar soil types. These
samples used in this study (N=72) cover a wide range in soil textural composition but limited range in
organic carbon content. Therefore, further research, covering wide range of landuse systems, soil types and
climatic conditions, is required to improve these predictive equations.
Conclusions
FC, PWP and PAWC were found to be significantly higher for GV followed by HYC and RS. FC was
affected by both clay content and organic carbon (OC) content but PWP was only affected by clay content
but not by OC. The developed equations can be used to predict FC and PWP for similar soils elsewhere.
However, further research is needed to validate/improve the predictive models for a wider range of organic
carbon content, soil types, soil texture and climatic conditions.
Acknowledgement
This research was jointly funded the Grains Research and Development Corporation and the Victorian
Department of Primary Industries. The authors would like to thank A. Weidemann, I. McLelland, M.
McLelland and R. Dunlop for the use of their paddocks.
References
Better Soils (2005) Better Soils. Module 5: Managing soil moisture, 5.1 Soil Water Holding Capacity.
http://www.bettersoils.com.au/module5/5_1.htm
Cock GJ (1985) Moisture characteristics of irrigated Mallee soils in South Australia. Australian Journal of
Experimental Agriculture 25, 209-13
Hochman Z, Dalgliesh NP, Bell KL (2001) Contribution of soil and crop factors to plant available soil water
capacity of annual crops on Black and Grey Vertosols. Australian Journal of Soil Research 52, 955 -
961.
Iqbal J, Read JJ, Thomasson AJ, Jenkins JN (2005) Relationships between Soil–Landscape and Dryland
Cotton Lint Yield. Soil Science Society of American Journal 69, 872-882.
Isbell RF (2002) ‘The Australian Soil Classification.’ (CSRIO Publishing: Collingwood, Vic.)
Jensen ME, Burman RD, Allen RG (1990) Evapotranspiration and Irrigation Water Requirements. ASCE
Manuals and Reports on Engineering Practice No. 70. American Society of Civil Engineers, New
York, NY.
Keating BA, Carberry PS, Hammer GL, Probert ME, Robertson MJ, Holzworth D, Huth NI, Hargreaves
JNG, Meinke H, Hochman Z, McLean G, Verburg K, Snow V, Dimes JP, Silburn M, Wang E, Brown
S, Bristow KL, Asseng S, Chapman S, McCown RL, Freebairn DM, Smith CJ (2003) An overview of
APSIM, a model designed for farming systems simulation. European Journal of Agronomy 18, 267-
288.
King BA, Stark JC (2005) Spatial variability considerations in interpreting soil moisture measurements for
irrigation scheduling. http://info.ag.uidaho.edu/pdf/BUL/BUL0837.pdf
Minasny B, McBratney AB, Bristow KL (1999) Comparison of different approaches to the development of
pedotransfer functions for water-retention curves. Geoderma 93, 225–253.
Murphy SR, Lodge GM (2001) Soil water characteristics of a red chromosol and brown vertosol and pasture
growth. Proceedings of the 10th Australian Agronomy Conference, Hobart, 2001.
http://www.regional.org.au/au/asa/2001/2/b/murphy1.htm?print=1
Payne RW, Harding SA, Murray DA, Soutar DM, Baird DB, Welham SJ, Kane AF, Gilmour AR, Thomson
R, Webster R, Wilson GT (2007) ‘The Guide to GenStat, Release 10. Part 2: Statistics.’ (VSN
International, Hertfordshire, UK).
Rab MA, Fisher PD, Armstrong RD, Abuzar M, Robinson NJ, Chandra S (2009) Advances in precision
agriculture in south-eastern Australia. IV. Spatial variability in plant-available water capacity of soil
and its relationship with yield in site-specific management zones. Crops and Pastures 60, 885-900.
Ratliff LF, Ritchie JT, Cassel DK (1983) A survey of field-measured limits of soil water availability and
related to laboratory-measured properties. Soil Science Society of America Journal 47, 770–775.
© 2010 19 th World Congress of Soil Science, Soil Solutions for a Changing World
1 – 6 August 2010, Brisbane, Australia. Published on DVD.
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