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Cost effective nutrient use on farms is integral to feedbase production and responsible management of environmental resources. There has been increasing strategic and tactical use of nitrogen fertiliser to increase home grown feed production, particularly in the more intensive dairy farm systems. While there has been considerable investment in research and development in this area, gaps in knowledge remain. In the Natural Resource Management and Climate Change (NRM&CC) strategy, specific priority outcome 5 ‘Improved extension of nutrient management principles and practices to achieve a more rigorous objective approach to nutrient management at farm level’ is focused on capturing

the benefits of these investments through a more coordinated approach to extension and education. Priority outcome 4 in the NRM&CC strategy, ‘Long term sustainable use of nutrients through greater understanding of nutrient pathways’, has four specific priorities, namely:

› D1 Analysis of nutrient transformations, in particular N, › D2 Microbial approaches for manipulating N and P › D3 Quantify the risks to the dairy industry from likely

catchment, state, national and international regulatory requirements targeting off farm nutrient loss over the next 5 to 10 years, and

› D4 A review to determine the knowledge gaps in the

current understanding of where dairy nutrients end up in off farm sinks.

These priorities align closely with the research and development encompassed in the Feedbase and Animal Nutrition priority areas -- B4 (Maximising margins:

minimizing foot prints) and to a lesser extent B2 (Improved strategic, tactical and operational decisions in relation to how particular forages fit in the feed production and feeding systems on farm). Priority B4 encompassed improved whole farm nitrogen use efficiency, through setting targets, identifying areas for improvement and quantifying the economic and social impacts of N use efficiency in a whole farm context. It also related to improved feeding system efficiency through better capture of dietary nitrogen within the animal leading to improved energy utilisation for productive purposes (D1). Priority Outcome 3 in the NRM &CC strategy ‘Increased industry capacity to reduce greenhouse gas emissions’ is also closely aligned with this area.

The research in these priorities could involve modelling to examine potential for improvements, fundamental research to understand soil microbial processes and C and N fluxes (and interactions), component research to examine grazing options to increase legumes in pastures, identification of mitigation options, broad scale on farm research and development and development of an on farm metric (i.e. nutrient accounting tool/model). There is a clear overlap with the use of new germplasm (pasture or fodder crops) that might increase N fixation or improve N utilisation.

Research to improve N utilisation in the grazing cow will involve quite sophisticated nutrition/metabolism experiments and it is possible this aspect is best dealt with in a separate program of work as outlined in priority D1 (More efficient utilisation of N and carbohydrate from feed sources for optimised Feed Conversion Efficiency and milk protein + fat production) of the Feedbase and Animal Nutrition strategy. This comment is based on the practicality and costs of such research.

Comments:

Efficient fertiliser use is critical to Australian dairy farms remaining internationally competitive, but increasing scrutiny of environmental impacts is inevitable. Hence, progressing RD&E in this area is a high priority.

Further development of these priorities from the two strategies should occur in concert.

It will be important to review the outputs from current and recent research and development as part of the development process.

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6.2. Water use efficiency

Changes in the availability, price and policies relating to irrigation water use present challenges for those running irrigated dairy farms, but also those using supplementary irrigation water. The need to achieve efficiencies in irrigation water use is clear.

Priority B3 (Improved use of irrigation water to reduce seasonal feed deficits) in the Feedbase and Animal Nutrition strategy overlaps with priorities proposed in Outcome 6 (Increased profit per unit of water use on irrigated dairy farms) in the NRM&CC strategy. The priorities in the NRM&CC strategy are:

› F1 Identification and research into new dairy farm irrigation delivery and water management systems

› F2 Development of crop modelling tools that can be

used in a predictive sense

› F3 Economics of investment in new on-farm irrigation

infrastructure and irrigation methods, and

› F4 Improved understanding of the economic role of

water in a farm systems context.

There is a considerable body of recent and current research across these areas which should be analyzed in developing an RD&E program in this area.

Comments:

Improved water use is important to the viability of many dairy farms meaning the RD&E proposed is high priority.

Further development of these priorities should be a joint activity.

It will be important to review the outputs from current and recent research and development as part of the development process.

6.3. Pasture plant improvement

The Dairy Futures CRC Program 1 (Designer Forages) is expected to produce cultivars with superior agronomic performance and with improved nutritive characteristics. Examples might be cultivars which exhibit advantages in nutrient uptake, in adaptation to variations in water supply, and in nutritive characteristics (e.g. higher sugar concentration and estimated metabolisable energy (ME) content). It is likely that evaluation of advantages in genetic material from the program will initially be through traditional pot or plot scale comparisons. The benefits at a farm systems level will be evaluated in CRC Program 3 or by commercial partners using modelling approaches. Feedbase and Animal Nutrition Priority A4 (Evaluation of the potential benefits of forage plant cultivar improvements within dairy systems) forecasts there will be a need for research to confirm the agronomy, grazing management and environmental conditions necessary for expression of traits as well as interactions between new plant products and other components of the cow’s diet in the context of different farming systems.

In modelling the benefits of plant improvement at a farm systems level, it will be important that the approach involves appropriate discipline expertise (e.g. agronomy, soil biology, ruminant nutrition) as well as practical know how from consultants and farmers as an expert panel to ensure assumptions made are sensible. The complexity of the modelling will depend on the trait, as it will be easier to examine the advantages of increased yield as compared to changes in the nutritive characteristics of plants.

Some existing models will have limitations in relation to the likely questions. For example, in an agronomic context, a feedbase model such as Dairy Mod is usually calibrated against data from plot and/or well managed field scale studies. While analysis using such models gives a useful insight into what might be possible, there are implicit assumptions that the agronomy, grazing management and environment will allow expression of the ‘new’ trait. It is also usually assumed that farmers can or do apply a high level of management.

Some questions will be more complex than others. For example, modelling the benefits of high sugar ryegrass at a farming systems level will require deep consideration of the assumptions made. While the estimated ME of such material (from laboratory estimates) may be higher, this does not necessarily mean the ME actually available to cows will be improved by the same amount. The interactions between grazed pasture and supplements in the diet modify the ME actually derived by cows

Comments:

Improved water use is important to the viability of many dairy farms