Potential of deficit irrigation to increase marginal irrigation response of perennial ryegrass (Lolium perenne L.) on Tasmanian dairy farms
R. P. Rawnsley A C , B. R. Cullen B , L. R. Turner A , D. J. Donaghy A , M. Freeman A and K. M. Christie AA Tasmanian Institute of Agricultural Research, University of Tasmania, PO Box 3523, Burnie, Tasmania 7320, Australia.
B Melbourne School of Land and Environment, University of Melbourne, Melbourne, Vic. 3010, Australia.
C Corresponding author. Email: Richard.Rawnsley@utas.edu.au
Crop and Pasture Science 60(12) 1156-1164 https://doi.org/10.1071/CP08446
Submitted: 15 November 2008 Accepted: 19 August 2009 Published: 23 November 2009
Abstract
In the cool temperate dairy regions of Tasmania, there is heavy reliance on irrigation to maximise pasture performance by ensuring that plants do not suffer water stress. Consequently, irrigation water has often been applied at a greater amount than plant water requirements, resulting in low efficiencies.
An irrigation experiment was undertaken in north-western Tasmania between October 2007 and April 2008, examining the effect of deficit irrigation treatments on pasture growth and water-use efficiency. A rainfall deficit (potential evapotranspiration minus rainfall) of 20 mm was implemented to schedule irrigation, at which point 20, 16, 12, 8, or 0 mm of irrigation water was applied, referred to as treatments I100%, I80%, I60%, I40%, and I0%, respectively. The trial was a randomised complete block design with 4 replications. There were 21 irrigation events between October and April. The experimental area was grazed by 60 Holstein Friesian heifers at a grazing interval coinciding with emergence of 2.5–3.0 new ryegrass leaves/tiller of the I100% treatment.
Cumulative pasture consumption for the irrigated period was 9.2, 8.9, 7.6, 6.9, and 3.7 t dry matter (DM)/ha for the I100%, I80%, I60%, I40%, and I0% treatments, respectively. The resulting marginal irrigation water-use index (MIWUI; marginal production due to irrigation) was 1.29, 1.54, 1.55, and 1.87 t DM/ML, for the I100%, I80%, I60%, and I40% treatments, respectively. The results of this study were modelled using the biophysical model DairyMod, with strong agreement between observed and modelled data. DairyMod was then used to simulate the MIWUI for 5 differing dairy regions of Tasmania using 40 years of climatic data (1968–2007) under 3 differing nitrogen management strategies by the 5 irrigation treatments. The modelling indicated that a MIWUI greater than 2 t DM/ML can be achieved in all regions. The current study has shown that the opportunity exists for irrigated pastoral systems to better manage an increasingly scarce resource and substantially improve responses to irrigation.
Additional keywords: irrigation, dairy, pastures, perennial ryegrass, modelling.
Armstrong D,
Knee J,
Doyle P,
Pritchard K, Gyles O
(2000) Water use efficiency on irrigated dairy farms in northern Victoria and southern New South Wales. Australian Journal of Experimental Agriculture 40, 643–653.
| Crossref | GoogleScholarGoogle Scholar |
Cotching WE,
Cooper J,
Sparrow LA,
McCorkell BE, Rowley W
(2002a) Effects of agricultural management on dermosols in northern Tasmania. Australian Journal of Soil Research 40, 65–79.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Cotching WE,
Cooper J,
Sparrow LA,
McCorkell BE,
Rowley W, Hawkins K
(2002b) Effects of agricultural management on vertosols in Tasmania. Australian Journal of Soil Research 40, 1267–1286.
| Crossref | GoogleScholarGoogle Scholar |
Cotching WE,
Hawkins K,
Sparrow LA,
McCorkell BE, Rowley W
(2002c) Crop yields and soil properties on eroded slopes of red ferrosols in north-west Tasmania. Australian Journal of Soil Research 40, 625–642.
| Crossref | GoogleScholarGoogle Scholar |
Crush JR,
Waller JE, Care DA
(2005) Root distribution and nitrate interception in eleven temperate forage grasses. Grass and Forage Science 60, 385–392.
| Crossref | GoogleScholarGoogle Scholar |
Cullen BR,
Eckard RJ,
Callow MN,
Johnson IR,
Chapman DF,
Rawnsley RP,
Garcia SC,
White T, Snow VO
(2008) Simulating pasture growth rates in Australian and New Zealand grazing systems. Australian Journal of Agricultural Research 59, 761–768.
| Crossref | GoogleScholarGoogle Scholar |
Earle DF, McGowan AA
(1979) Evaluation and calibration of an automated rising plate meter for estimating dry matter yield of pasture. Australian Journal of Experimental Agriculture and Animal Husbandry 19, 337–343.
| Crossref | GoogleScholarGoogle Scholar |
Eckard RJ, Franks DR
(1998) Strategic nitrogen fertiliser use on perennial ryegrass and white clover pasture in north-western Tasmania. Australian Journal of Experimental Agriculture 38, 155–160.
| Crossref | GoogleScholarGoogle Scholar |
English M
(1990) Deficit irrgation. 1. Analytical framework. Journal of Irrigation and Drainage Engineering – ASCE 116, 399–412.
| Crossref | GoogleScholarGoogle Scholar |
Fulkerson WJ, Donaghy DJ
(2001) Plant soluble carbohydrate reserves and senescence – key criteria for developing an effective grazing management system for ryegrass-based pastures: a review. Australian Journal of Experimental Agriculture 41, 261–275.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Ganji A,
Ponnambalam K,
Khalili D, Karamouz M
(2006) A new stochastic optimization model for deficit irrigation. Irrigation Science 25, 63–73.
| Crossref | GoogleScholarGoogle Scholar |
Jeffrey SJ,
Carter JO,
Moodie KM, Beswick AR
(2001) Using spatial interpolation to construct a comprehensive archive of Australian climate data. Environmental Modelling & Software 16, 309–330.
| Crossref | GoogleScholarGoogle Scholar |
Johnson IR,
Chapman DF,
Snow VO,
Eckard RJ,
Parsons AJ,
Lambert MG, Cullen BR
(2008) DairyMod and EcoMod: biophysical pastoral simulation models for Australia and New Zealand. Australian Journal of Experimental Agriculture 48, 621–631.
| Crossref | GoogleScholarGoogle Scholar |
Payero JO,
Tarkalson DD,
Irmak S,
Davison D, Petersen JL
(2008) Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate. Agricultural Water Management 95, 895–908.
| Crossref | GoogleScholarGoogle Scholar |
Tedeschi LO
(2006) Assessment of the adequacy of mathematical models. Agricultural Systems 89, 225–247.
| Crossref | GoogleScholarGoogle Scholar |
Zhang H, Oweis T
(1999) Water-yield relations and optimal irrigation scheduling of wheat in the Mediterranean region. Agricultural Water Management 38, 195–211.
| Crossref | GoogleScholarGoogle Scholar |