Fertilisers for pastures guide

For many graziers, 2023 will be the first opportunity in a while to get fertiliser out on paddocks.

The well above average rainfall received in 2021 and 2022 has thrown many fertiliser plans into disarray. With paddocks waterlogged and too wet to traverse for most farm vehicles, spreading fertiliser has been out of the question for most land managers.

With paddocks now drying out over summer, trafficability has become less of a concern but high fertiliser prices may still cause some to balk at applying fertiliser. Many are questioning the need and value of applying fertiliser under current conditions, especially given the amount of residual pasture in paddocks.

In this article:

  1. Download the fertilisers for pastures guide
  2. 2023 cost / benefit analysis of fertiliser and paddock productivity
  3. What impact is fertiliser price having on my bottom line?
  4. Do I need to apply fertiliser?

Fertilisers for pastures guide front coverThis booklet is a guide to help landholders make better fertiliser decisions for their pastures. Much of the information comes from a major grazing project on the Camden district dairy farm at Elizabeth Macarthur Agricultural Institute. The findings have been combined with results from other fertiliser trials.

The information targets the higher rainfall (over 750mm) districts of eastern NSW, grazing mostly dairy, beef cattle or horses under relatively high stocking rates. It is also suitable for farmers grazing goats, sheep, alpaca and donkeys. The pastures in this region are generally rainfed with some properties using supplementary irrigation.

In this zone, many of the soils are weathered and low in nutrients and organic matter. The soils may have other features that also limit pasture growth eg shallow depth, acidity and salinity. An assessment of these factors is a necessary part of making better fertiliser decisions.

The need for fertilisers is closely related to the intensity of production. Dairy farms require high inputs due to high grazing intensity and continuous product removal. On the other hand, pastures grazed at lower stocking rates such as a beef breeding enterprise or horses, have a much lower need for fertilisers.

A very wide range of products is available, from conventional, factory-made fertilisers to the raw, organic alternatives derived from animal manure or food processing wastes. Some products contain a mixture of both materials.

This book covers the basics of soil testing and outlines the effect of acidity, salinity and sodicity on soil fertility. There is information on individual nutrients, cation exchange capacity, trace minerals and nutrient budgets. There are sections on using organic materials as fertilisers, on how to use plant and animal symptoms to detect nutrient deficiencies and on animal health issues involving fertiliser.

Download the guide. PDF, 16018.2 KB

Cost / benefit analysis of fertiliser and paddock productivity

Some of the factors to consider before applying fertiliser in 2023.

  • Despite fertiliser prices easing over the last 12 months, many are questioning the need and value of applying fertiliser under current conditions
  • Gross margin analysis shows that it still pays to put out fertiliser. A two-fold increase in fertiliser price ($350/t vs $700/t) only reduces returns by around 8% or $4.30/ha.
  • It is important to remember that you don’t need to apply fertiliser to your whole farm. Being strategic about application rates and what paddocks you target can go a long way to reducing your fertiliser bill, especially when prices are high.

What impact is fertiliser price having on my bottom line?

While global fertiliser prices have eased from the all-time highs seen last April/May (figure 1), fertiliser prices remain very high and an ongoing cause of concern in agricultural production systems. In addition to high fertiliser prices, livestock prices have also continued to soften over the last 12 months. This begs the question - is there still value in applying fertiliser?

One way to assess the impact of fertiliser price is to construct a gross margin and adjust the fertiliser price to see what impact it has on the bottom line. Tables 1 and 2 are an example of a 2023 gross margin for a typical self-replacing merino flock and a feeder steer breeding operation. In both gross margins we’ve used single superphosphate (SSP) as it is the most common and cost-effective way to apply phosphorus (P) and sulphur (S) – two key nutrients that are often most limiting in grazing systems.

Until recent years, SSP was quite stable and for a long period of time hovered around the $340 - $360/t mark (delivered on-farm excluding GST). So, for comparisons sake the first column in Tables 1 and 2 looks at the economics if SSP was sitting back at $350/t. At $350/t gross margins for the example sheep and cattle enterprise are $52.80 and $53.66/ha respectively.

In the next two columns everything stays the same, but SSP price is increased to $600/t and $700/t. The good news here is that even though fertiliser price has doubled between the first and last columns, the overall gross margin has only reduced by around 8% or $4.30/ha and both enterprises are still generating good returns at almost $50/ha. One of the big advantages of strong commodity prices in recent years is they really do help to absorb increasing input costs.

Table 1. Sheep Enterprise Gross Margins - Fertiliser Price Variable
MERINO EWES (18 micron) joined to Merino Rams*

1000 Merino ewe self -replacing flock

2023 Budget

SSP@ $350/t

2023 Budget

SSP @ $600/t

2023 Budget

SSP @ $700/t

Gross Income/DSE

$92.65

$92.65

$92.65

Variable Costs/DSE (excluding fertiliser)

$34.48

$34.48

$34.48

SSP ($/t delivered)

$350.00

$600.00

$700.00

Total cost to apply SSP @ 125kg/ha ($/ha)

$53.75

$85.00

$97.50

Total cost to apply SSP @ 125kg/ha ($/DSE)

$5.38

$8.50

$9.75

Gross Margin/DSE

$52.80

$49.67

$48.42


* Assumptions:

  • Stocking Rate – 10 DSE/ha
  • 2022 average sheep and wool prices used
  • Fertiliser spreading cost @ $10/ha

Table 2. Cattle Enterprise Gross Margins - Fertiliser Price Variable
Feeder Steer Enterprise - Steers sold at 16 months ^

100 cow self-replacing breeding herd

2023 Budget

SSP @ $350/t

2023 Budget

SSP @ $600/t

2023 Budget

SSP @ $700/t

Gross Income/DSE

$76.22

$76.22

$76.22

Variable Costs/DSE (excluding fertiliser)

$17.44

$17.44

$17.44

SSP ($/t delivered)

$350.00

$600.00

$700.00

Total cost to apply SSP @ 125kg/ha ($/ha)

$53.75

$85.00

$97.50

Total cost to apply SSP @ 125kg/ha ($/DSE)

$5.12

$8.10

$9.29

Gross Margin/DSE

$53.66

$50.69

$49.50

^ Assumptions:

  • Stocking Rate – 10.5 DSE/ha
  • Steers and surplus heifers sold at 15-16 months of age (steers 440kg lwt; heifers 390kg lwt)
  • July 2022 to December 2022 average beef prices used
  • Fertiliser spreading cost @ $10/ha

Do I need to apply fertiliser?

Even though the straight economics might be indicating that it still pays to apply fertiliser, you still need outlay a significant amount of cash to cover the bill! However, it is important to remember that you don’t need to apply fertiliser to the whole farm. Being strategic about application rates and what paddocks you target can go a long way to reducing your fertiliser bill, especially when prices are high. Before applying fertiliser it’s important to consider several factors including:

  1. Current nutrient status

    This can be easily identified by undertaking a soil test to determine if there are any key nutrient deficiencies and the extent to which these deficiencies may be impacting potential pasture growth. Most graziers have sold fibre or livestock, or for some, made hay or harvested grain in recent years, all resulting in nutrients leaving the farm that may need replacing to maintain nutrient balance and pasture productivity.

    Soil testing can go a long way to help build a fertiliser strategy for a farm and is best done in consultation with your local LLS agricultural advisor or local agronomist. Identification of paddocks where nutrient replacement is more important (lambing / weaning paddocks, pasture improved or hay cutting paddocks) may also help prioritise where nutrients are most essential if funds are limited.

    The Five Easy Steps program is freely available on the MLA website and is an excellent information package on how to implement a robust soil testing program and fine-tune fertiliser inputs.

  2. Past fertiliser history

    One of the major benefits of having a good fertiliser history is it gives you greater capacity to skip applications when encountered with price hikes, supply constraints, wet seasons and so on. However, regular soil testing is crucial to monitor overall nutrient status and to make sure key nutrients (particularly P and S) do not fall too low relative to your stocking rate.

    Producers that have a good fertiliser history also have the option of cutting back fertiliser rates to reduce cost. Long term soil testing data from Bookham NSW shows that around 70kg/ha/yr of SSP is sufficient to maintain soil phosphorus levels in a native pasture running 13-14 DSE/ha.

    Interestingly, an application rate of 70kg/ha @ $600/t works out to be around $52/ha spread, which is very close to the ‘normal’ cost back when single super was worth $350/t à refer to Column 1 in the gross margin tables. In other words, by reducing the application rate to around 70kg/ha we can reduce fertiliser input costs back to a more ‘normal’ level and keep the system ‘ticking over’. However, it is important to note that the maintenance rate will vary between properties and can only be worked out with confidence by doing regular (i.e. annual) soil testing to track nutrient trends over time.

  3. Your current stocking rate

    The key with any fertiliser program is to make sure the nutrient status of your soil is in balance with your soil type, environment and stocking rate. If you have a lot of surplus feed and your stocking rates are below optimal (eg. if still rebuilding from the drought), then it may be prudent not to fertilise. There is no point in spending money to grow more grass if you’re not going to use it.

  1. Are your paddocks in a responsive state?
    If the decision is to pull back on input costs, it would be worth targeting key paddocks that you will be relying on this season. For example, lambing, weaning, finishing paddocks etc. However, to gain the maximum benefit from fertilising these paddocks it is critical that these paddocks are in a ‘responsive’ state for growth – i.e. well grazed/open so light can get down to ground level and stimulate new growth. If you have paddocks that have a large amount of carry-over feed and you are unlikely to get on top of it before winter, you would be better to skip fertilising these paddocks for now and target them further down the track.

    Understanding and managing soil nutrition is an important part of having productive and sustainable pastures be they native or improved. As outlined above, there are several factors to consider to ensure you can get the most out of your pasture productivity, as well as your bottom line.

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