Guideline Index

Chapter 10: Keeping Nutrients on Farm

10.3 Plan to retain nutrients

The keys to nutrient planning are:

These steps align with the annual nutrient planning cycle as follows:

Nutrient Planning
Figure 10.5  Annual nutrient planning cycle.
Figure 10.5 Annual nutrient planning cycle.

10.3.1 Analyse farm nutrient status

Important tools to understand a farm’s nutrient status are: Soil test and nutrient maps

Farm management zones (areas with similar physical features and management) should be soil tested regularly (see Chapter 15.3.1 for more detail). The results should be considered as part of a time series to note any trends.

It is useful if soil nutrient status can be mapped to identify paddocks with high nutrient levels and those with low levels. Maps make it easy to see the paddocks that are potential ‘critical source areas’ for nutrient loss and where less fertiliser could be applied. Nutrient maps also visually assist in readily identifying where ameliorants such as lime are needed; or where there are opportunities to redistribute excess nutrients, for example in low nutrient status paddocks in which effluent could be recycled. Nutrient budgets

Nutrient budgets (see Chapter 15.5 for more information) provide additional perspectives on nutrient status. They provide insight into the efficiency with which nutrients are converted to produce and highlight potential risks and opportunities for improvement, such as striving to better match inputs against losses. As indicated in the following table, as farm productivity rises due to additional inputs (such as imported feeds) so too may the nutrient surplus.


Table 10.2  Potassium and phosphorus budgets. (Gourley et al, 2007).
Table 10.2 Potassium and phosphorus budgets. (Gourley et al, 2007).

For more information on nutrient budgets, see Gourley et al, 2007.

10.3.2 Determine production potentials

Unlocking the productive potential of a farm involves: Nutrient targets

Nutrient budgets combined with feed budgets are a first step to ensuring adequate nutrition for pastures and livestock. Setting nutrient targets for soils – to optimise production yet minimise risks of environmental loss – is another important step. Areas where nutrient targets have already been achieved for phosphorus may be prioritised as locations in which P applications may be reduced or halted. Soil limitations

In some situations, plants are not able to make use of the nutrients that are present due to other limiting factors. As examples, soil pH may not be suitable and the nutrients may be bound to other elements or the soil may be saturated and plant roots unable to function due to a lack of oxygen, curtailing nutrient uptake. In such situations, simply adding more nutrients will do little to improve productivity but much to increase the risk of nutrient loss, whereas rebalancing the pH or improving soil structure will unlock existing potential. Redistribution options

Options for redistributing nutrients should also be assessed from a cost:benefit perspective. Nutrient budgets for farm management zones and farm nutrient maps may identify some options (e.g. cutting hay in high nutrient (especially potassium) paddocks for feeding out in low nutrient paddocks, applying effluent to low nutrient areas, or changing grazing pressures between paddocks), but management factors and costs must be considered to determine which options are realistic.

10.3.3 Assess risks and critical source areas

Assessing risks involves identifying hazards then considering the likelihood of them occurring and the potential consequences or effects, should the hazard eventuate.

 Risk = Likelihood X Consequence.

For dairy farms, water-borne nutrients often pose the major risk to the local off-farm environment. As such, water movement either above or below the surface, is a key driver and a big influence on risk. Identifying critical source areas is an important step in assessing the risk of nutrients being lost from a farm.

Dairy farmers are used to managing nutrients as a fundamental input to controlling economic and productivity risks. For efficiency and sustainability reasons, farmers will increasingly have to also assess the environmental risks of nutrient inputs. Hazards

‘Cracking the Nutrient Code’ (FIFA, 2001) was developed by Fertilizer Australia and presents a framework for assessing hazards, likelihoods and consequences at a farm scale, including practices checklists. It includes questions to help assess the likelihood and consequences of risks concerning nutrient stores or imbalances and losses, grouped as:

  • Load – excess nutrients, e.g. exceeding optimal soil concentrations.
  • Mine – depleting nutrient stores, e.g. downward trending soil nutrient concentrations that are below optimal levels.
  • Run – losing nutrients in surface run-off, e.g. steep, high rainfall country which is high in nutrients.
  • Leach – losing nutrients in sub-surface water movement; e.g. shallow water tables in permeable soils.
  • Blow – losing nutrients to the atmosphere, e.g. wind erosion of dry, exposed soils.

When considering hazards associated with water-borne nutrients it is often useful to also consider the hazards associated with water-borne dairy pathogens. Pathogens can travel via similar pathways to nutrients and some management innovations to contain nutrient losses will also reduce the risk of pathogens entering waterways. Likelihood

The dairy industry has developed several tools to help assess risks.

The Farm Nutrient Loss Index (FNLI) considers management practices, climate and the physical characteristics of different farm management zones likely to be at risk of losing nutrients to the environment. The tool can provide detail to help apply the Fertilizer Australia framework and identify potential ‘critical source areas’ on individual farms. It can remove some subjectivity from an assessment. Coupled with the Dairy Self Assessment Tool (Dairy SAT) – a best practices checklist – the FNLI provides some quantitative input to qualitative assessments such as ‘Cracking the Nutrient Code’.

For more information on the FNLI and DairySAT see the ‘tools and guidelines’ at:

For more information on Cracking the Nutrient Code, see:

It is essential that risk assessments consider:

  • those areas of a farm likely to pose most risk (critical source areas),
  • management practices likely to be a hazard, and
  • the location of individual farms in their catchment context (e.g. degrees of connectivity).

Understanding Dairy Catchments’ is a tool to help assess risks for dairying in a catchment context. It helps users understand the critical links between the management of different areas and the likelihood of negative impacts for a catchment. For more information see: Potential consequences

The significance of an impact on the environment can be considered in light of the value of the environmental asset in question and the vulnerability of the asset. In this context, environmental assets are things like lakes, rivers, estuaries and wetlands, and the plants and animals they support.

The Commonwealth Government’s Environment Protection and Biodiversity Conservation Act and associated website ( provide a good place to begin to assess the significance of an asset. It includes lists of threatened flora and fauna including migratory birds, ecological communities and critical habitats . Internationally important wetlands listed under the Ramsar Convention are also recorded along with information on nationally important wetlands. Similar lists and protection measures may also be relevant from a State or regional level.

The vulnerability of the asset to an impact is affected by the asset itself – e.g. whether the asset is able to recover from an impact or if it will suffer permanent, irreversible change – and the impact; e.g. its severity and extent, and whether it is a sudden impact or a cumulative one in response to gradual changes. Characteristics of the local environment (or ‘receiving waters’) will help determine some of those aspects. For example, a high energy coast with strong flushing coastal currents (an ‘open’ system) will usually be more resilient than a shallow, low energy terminal lake into which streams drain (a ‘closed’ system). The social characteristics of local communities may also be relevant, with some communities being highly aware and concerned regarding the environment.

When considering nutrients, concentrations are often important in assessing immediate threats but loads (the amount of nutrient in the water-body over time) and budgets are important in understanding how concentrations may change over time, and if systems are on the verge of being overloaded or saturated. Once saturated, wetland ecosystems may become much more sensitive to small additional loads of nutrients which may trigger major, irreversible changes in the environment.

When assessing potential consequences, it is useful to know whether short term nutrient concentrations or long term loads pose the greatest threat to the environment (Kleinman et al, 2011). Catchment management officers may be able to help work this out and provide directions to programs with support for on-farm change.

10.3.4 Document a plan

The nutrient management plan, (including the recycling of effluent, redistribution of nutrients between paddocks and rebalancing soil chemistry) should fit within a whole farm management plan. In regard to fertilisers, its focus will be on determining which fertilisers to use, where, when and in what amount (see the ‘4Rs’ Framework – the right sources of nutrients, in the right place, at the right rate and right time)

Considerations in a whole-farm context include:

  • Nutrient balance. Inputs need to replace outputs in produce plus unavoidable losses. For phosphorus, inputs must also provide for the buffering capacity (PBI) of the soil (Weaver & Wong, 2011).
  • Critical levels. Inputs should achieve critical soil concentrations to optimise production but not exceed them or any known critical levels that increase the risk of loss to the environment.

For more information see Chapter 16.

10.3.5 Monitor and evaluate

Keeping an eye on how the nutrient management plan is being implemented and the impact it is having on production, soil nutrient levels and profit will be an on-going exercise. Observations from that monitoring, and any trends, will help fine-tune the plan for the future (See Chapter 1.7).

As part of the evaluation it is also worthwhile estimating the savings being generated from improved nutrient management. The simplest measure may be a reduction in fertiliser costs or a reduction in the application of specific nutrients (e.g. phosphorus applications may not be required). Revisiting whole-farm or management zone nutrient budgets may be another way to consider the reductions in nutrient loss due to improved management.