Forage Options for Dairy Farms with Reduced Water Availability in the Southern Murray Darling Basin of Australia

Mary-Jane Rogers,Alister Lawson,Kevin Kelly

doi:10.3390/su9122369

Abstract

The dairy industry in the southern Murray Darling Basin region of Australia is a major consumer of irrigation water because rainfall is low relative to evapotranspiration and the industrys relies heavily on irrigated temperate pastures and fodder crops. Water reforms, and potential climate change scenarios for this region suggest that there will be an overall decline in rainfall and water available for irrigation in the future. For the irrigated dairy industry to remain economically viable, there is a need for dairy farmers to improve the water productivity (WP) of their forage systems and to be able to respond to year-to-year, and within year, variation in water availability. Researchers and dairy farmers are evaluating strategies to increase WP. These include: (i) selecting better-adapted species for current and predicted climatic conditions; (ii) using species that can survive and still be productive under reduced irrigation and then recover when full irrigation is restored; (iii) modifying irrigation strategies to reduce water use whilst maintaining WP; and (iv) grazing management strategies that facilitate the survival during, and recovery after, periods of moisture stress. This review will examine these strategies and discusses their potential to optimise forage production from irrigation water inputs so that the dairy industry in the southern Murray Darling Basin remains viable in the future.

Highlights

The Murray Darling Basin of south-eastern Australia covers an area of over 1 million km2
With pressurised irrigation systems such as spray or drip—which are rarely used in the region—there is the ability to reduce the volume of water applied at individual irrigations, thereby increasing the range of deficit irrigation options available, including sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI) [24]
We have reviewed strategies that optimise forage production from limited and variable water inputs in the southern Murray Darling Basin

Summary

Introduction

The Murray Darling Basin of south-eastern Australia covers an area of over 1 million km. Total Water Productivity (TWP) (see Table 1) is a useful way of comparing the efficiency of different irrigation management and forage systems in the region [23]. These changes are the collective result of; reduced water availability—due to changes in Government water policy, the transfer of water between industries and a series of drought years—and on-farm changes such as larger herd sizes, higher per cow production and increased supplement use, which reduce the proportion of grazed pasture in the cows’ diet These changes are likely to continue into the future as dairy farming systems adapt to ongoing water availability issues, and technology and management changes. This review outlines strategies that may be required to optimise forage production from all water inputs so that the dairy industry in the southern Murray Darling Basin remains viable into the future. Issues related to sustainability of irrigation systems in the region such as drainage, water tables and salinity are not addressed in this review

Species Performance under Full Irrigation

Perennial Forages

Annual Pastures

Winter Fodder Crops

Summer Fodder Crops

Irrigation Strategies to Improve Water Productivity

Grazing Management of Water-Stressed Pastures

Findings

Summary and Conclusions