Project overview
Local Land Services supported producer Shannon Arnall in the Crookwell region on a grazing demonstration to determine fertiliser use on pastures and productivity.
- Location: ‘Carinya’, Laggan
- Property size: 606ha
- Soils: Quartz based, pH 4.0 (unlimed) with increasing Al to depth
- Pastures: mainly native perennial grasses (weeping grass and wallaby grass) with annual grasses and subterranean clover
- Enterprises: Merino breeding, mostly to Merino sires
Project background
This on-farm demonstration began in January 2015. Shannon Arnall had purchased a new block of ‘native’ country that hadn’t received fertiliser for over 13 years and was keen to increase profitability from the existing pasture in the most cost-effective way.
A simple nutrient trial showed that phosphorus (P) was the major nutrient limiting pasture growth. This was not surprising given the history of the paddock, however the question then became: does it still pay to put fertiliser out in a wool operation?
Project objectives
To investigate the level of pasture and animal production that can be sustainably achieved on a native-based pasture in the Crookwell region.
Specifically, the project investigated the effect of applying fertiliser (single superphosphate) and lime on:
- stocking rates and overall farm profitability (using a fully-costed economic analysis)
- soil fertility and pH
- pasture composition
- soil carbon levels.
Project delivery
Treatments
Paddock 1
Lime + Single superphosphate (L+S): fertiliser applied annually to increase soil P over time to a targeted level. Lime applied as a one-off application (2.5 t/ha) to reduce aluminium levels (by raising soil pH).
Paddock 2
Control: a native pasture of low fertility (that is, the “do nothing” approach).
Paddock 3
Single superphosphate (SS): fertiliser applied annually to increase soil P over time to a targeted level.

Project updates
The livestock production and financials have been crunched for another year and the results for 2023-24 are in.
While wool and sheep meat prices struggled during the 2023-24 period, above average rainfall through the 2023-24 summer/autumn period (Figure 1) resulted in above average wool production and profitability in the fertilised paddocks (Table 1).
In contrast, the control paddock (nil fertiliser) couldn’t capitalise on the good growing conditions and once again carried a relatively low stocking rate (Table 1).
Table 1: Livestock and economic data - average annual results from January 2015 – June 2024
| L+S | Cont | SS | |
| Wethers/ha | 8.2 | 4.1 | 7.1 |
| Wool cut (kg wool/ha, clean) | 34 | 23 | 33 |
| Wool income ($/ha/yr) | 607 | 294 | 511 |
| Meat income ($/ha/yr) | 183 | 59 | 122 |
| Total income ($/ha/yr) | 790 | 353 | 633 |
| Total costs ($/ha/yr) | 245 | 82 | 195 |
| Profit ($/ha/yr) | 545 | 270 | 434 |
| Difference to control | +275 (102%) | +188 (128%) | +168 (62%) |

As expected, adding P into the system led to a rapid and large increase in the amount of sub clover in the fertilised paddocks, especially the L+S. The increase in stocking rate has been a function of both increased pasture quantity and quality. Stocking rates for the first 6 years of the demonstration have averaged:
- Paddock 1: Lime + Single superphosphate (L+S): 7.5 wethers/ha
- Paddock 2: Control: 4.6 wethers/ha
- Paddock 3: Single superphosphate (SS): 6.6 wethers/ha
When all the costs are taken into account (the costs of fertiliser as well as additional variable costs of running more stock), SS has on average increased net profit by $78 - $99/ha/yr above the control (depending on what method of analysis used). The L+S treatment has increased net profit to a far greater extent, boosting returns by $181 - $185/ha/yr above the control (Table 1).
Table 1: Comparison of average annual profit toa far greater extent, boosting returns by $181-$185/ha/yr above the control.
| Method | Lime + Super | Control | Super |
|---|---|---|---|
| Method 1 | |||
| Profit (2015-2020) ($/ha) | 487 | 306 | 405 |
| Difference to control ($/ha) | +181 | - | +99 |
| Method 2 | |||
| Profit (2015-2020) ($/ha) | 467 | 282 | 360 |
| Difference to control ($/ha) | +185 | - | +78 |
While the difference in stocking rate between the SS and L+S paddock is relatively small (average of 0.6 wethers/ha), the 2015-20 period has coincided with exceptionally strong wool and mutton markets. When markets are favourable, small increases in carrying capacity can make a big difference (Figure 1).

Unlike P, pasture response to lime is highly variable and difficult to predict. At this site lime has had a positive effect on pasture growth, sub clover performance and overall economic returns.
However, it is important to note the L+S paddock has a slight eastern facing aspect which could be providing a slight advantage (the Control and SS paddocks have a western aspect).
Further work is required to verify the production advantage observed as a result of topdressing lime at this site.
Annual monitoring of pasture composition shows that all three paddocks have maintained a very strong native perennial grass base. This is despite three drought years occurring during the first 5 years (2017, 18 and 19).
Pasture stability is just as important as any production increase. Native pasture species have adapted to shallow acidic soils and maintaining their presence across the landscape is important.
Sowing introduced pasture species into these soils is expensive and successful establishment comes with considerable risk. Persistence of these introduced species can also be variable.
Pasture production and economics
These results show that when Phosphorus (P) and Sulphur (S) is applied at this site, stocking rates on average have increased by 3 wethers/ha above the Control (72% increase). The surface application of lime at 2.5 t/ha has increased stocking rate by a further 1.1 wethers/ha above the SS treatment (Table 1). The biggest increase in livestock production has come from addressing both P and S deficiencies, with lime lifting production to a lesser degree.
An economic comparison shows that SS has on average increased net profit by $154 - $168/ha/yr above the control (depending on what method of analysis used). The L+S treatment has increased net profit to a far greater extent, boosting returns by $272 - $275/ha/yr above the control (Table 1).
While the effect of lime on soil pH was limited to the top 2.5 cm of soil, lime appears to have had a positive effect on legume production at this site. The increase in legume production in the L+S paddock has increased stocking rate by 1.1 wethers/ha and overall profit by $111/ha above the SS paddock (Figure 2). However, applying lime is still a considerable up-front cost to the producer and any potential benefit will only be realised if major nutrient deficiencies are addressed.

Soil nutrients
Regular applications of single superphosphate between 2015 and 2024 have increased P and S levels in the two fertilised paddocks (Figure 3). This has led to a significant increase in the amount of sub clover in the fertilised paddocks, especially in the L+S treatment. The increase in stocking rate has been a function of both increased pasture quantity and quality. Note: fertiliser was not applied in 2022 and 2023 due to wet conditions.

Soil PH
Soil testing to 20 cm shows that the lime has only had an impact on the top 2.5 cm of soil, lifting pH (CaCl2) from 4.2 to 5.0 and reducing aluminium from 16 % to 0 %. This was achieved within the first 16 months of application.
Despite the lime only having an impact to a depth of 2.5cm, the application of lime has had a positive effect on pasture growth, sub clover performance and overall economics.
Soil carbon
Baseline 0-10 cm soil testing at the end of 2014 showed that soil carbon levels were already high at this site, ranging between 4.0 and 5.0 %. Annual soil testing shows a declining trend in the first two years, before a notable increase in soil carbon levels in 2017. However, this increase was short-lived due to drought conditions in 2018 and 2019 (Figure 4).
Soil carbon levels in all paddocks increased in 2020 on the back of an extremely strong season, however the last three years there has been a declining trend across all treatments.
At this stage there is no clear effect on soil carbon levels due to the different paddock treatments. The measured changes appear more related to seasonal conditions.

Project outcomes
After 10 years of investigating the impact of fertiliser and lime on pasture and livestock production.
Results showed carrying capacity and profitability more than doubled through regular, targeted fertiliser inputs and a one-off application of lime.
Trial findings
Native perennial pastures can respond to fertiliser
The results from the Laggan grazing demonstration showed a similar response in fertiliser application to native pastures, to a previous a long-term grazing demonstration in the Bookham NSW district, despite being almost twice the elevation (1000 m vs 520 m).
Over the 10 years of the Laggan grazing demonstration, stocking rates for the 3 paddocks have averaged:
- Control: 4.0 wethers/ha
- Single Superphosphate: 7.2 wethers/ha
- Lime+Single superphosphate: 8.2 wethers/ha
These stocking rates shows a clear link between fertiliser application and pasture response allowing for a higher stocking rate.
Native pastures are often made up of a range of native grass species, and some species are more responsive to nutrients than others. Weeping Grass (Microlaena stipoides) is one native pasture species which the trials have shown responds well to increasing soil fertility and is found both at Laggan and Bookham trial sites.
Pasture research has shown that some Wallaby Grass species (but not all) are also very responsive to fertiliser while Red Grass (Bothriochloa) and Kangaroo Grass (Themeda) are less responsive to soil fertility.
Therefore, many factors will affect fertiliser response in a native pasture, including pasture species, environment and soil type/depth. Read more about fertilising native pastures.
Nutrients drive production; lime is the ‘cream on the cake’
The grazing demonstration has shown that when P and S is applied at this site, stocking rates on average have had an 81% increase from 4.0 wethers/ha to 7.2 wethers/ha.
- A one-off surface application of lime in early 2015 increased stocking rate by a further 1.0 wether/ha on top of the SS treatment.
- The biggest increase in livestock production and profitability has come from addressing P and S deficiencies. Lime was the ‘cream on the cake’, further increasing legume production, stocking rate and overall profitability.
- When averaged over the 10 years, an economic comparison shows that SS increased net profit by $218/ha/yr above the control. The application of lime with fertiliser increased returns by a further $105/ha above the SS treatment (Table 1).
- While the difference in stocking rate between the SS and L+S paddock is relatively small (average of 1.0 wethers/ha), there have been periods over the last 10 years where wool and mutton markets have been very strong. When markets are favourable, small increases in carrying capacity and livestock production per head (wool cut and liveweight gain) can make a big difference to the bottom line (Figure 1).
| Control | Single superphosphate | Lime + Single superphosphate | |
|---|---|---|---|
| Wethers/ha | 4.0 | 7.2 | 8.2 |
Wool cut (kg wool/ha, clean) | 15.0 | 29.3 | 35.5 |
| Wool income ($/ha/yr) | 283.9 | 523.5 | 612.9 |
| Meat income ($/ha/yr) | 76.6 | 176.2 | 238.8 |
| Total income ($/ha/yr) | 360.4 | 699.7 | 851.7 |
| Total costs ($/ha/yr) | 79.3 | 200.4 | 247.5 |
| Profit ($/ha/yr) | 281.2 | 499.3 | 604.2 |
| Difference to control | +218 (78% increase) | +323 (115% increase) |

The increase in production between the paddocks has gone hand-in-hand with legume production – the stronger the legume component, the higher carrying capacity and overall profitability.
Interestingly, despite lime only having an impact on soil pH and aluminium down to a depth of 2.5 cm, the L+S paddock has consistently had a stronger legume component, carried more livestock and generated higher returns than the SS paddock.
As expected, legumes performed poorly in the Control paddock due to low soil fertility (Table 2).
| Species | Control | Single superphosphate | Lime + Single superphosphate |
|---|---|---|---|
| Microlaena | 47 | 37 | 28 |
| Wallaby grass | 21 | 15 | 13 |
| Annual grasses | 3 | 5 | 7 |
| Legumes | 7 | 23 | 37 |
| Weeds | 3 | 2 | 4 |
| Bare ground | 7 | 7 | 3 |
| Litter | 13 | 13 | 9 |
The Laggan grazing demonstration shows what can be achieved by simply addressing P & S deficiencies to stimulate the legume component.
Legumes in a pasture increase production in two ways:
- directly through providing grazing animals with highly digestible forage; and
- by fixing atmospheric nitrogen and releasing into the soil, which in turn increases pasture growth and quality.
Regular soil testing enables you to ‘fine tune’ your fertiliser program
The aim of any fertiliser program should be to apply the minimum amount of fertiliser required to grow the grass you need. This process involves:
- identifying your starting point (through a soil test)
- setting appropriate nutrient targets
- gradually working towards your target using modest applications of fertiliser and increase in livestock numbers to match feed supply.
The Laggan Grazing Demonstration is an example of how to apply this approach (Figure 2).

- Initial soil testing showed major deficiencies in P and S.
- Initially it was decided to apply 125kg/ha/yr of single superphosphate, however after the first three years of the demonstration it became apparent that this rate was sufficient to address maintenance P, but not enough to build soil P levels.
- Based on this information it was decided to increase the application rate to 160kg/ha. This higher rate resulted in the soil test results slowly heading towards the identified Colwell P target range.
- Stocking rate increased over time with increasing soil P levels.
Soil test results can vary significantly from year-to-year depending on the amount of fertiliser applied, seasonal conditions and when samples are taken.
Regular (annual) soil testing is the key to identifying trends and checking the appropriateness of fertiliser application rates.
Find out what's happening in the South East

Get the latest news, seasonal advice, and project updates or be the first to hear about upcoming events.
- Subscribe to the Circular.
- Follow Local Land Services South East on Facebook.
- View our events page to see what's happening near you.
Funding and partnerships
Thank you to Shannon Arnall for providing the land to run the demonstration and for the on-going support.
Local Land Services’ Laggan Grazing Demonstration received financial support from the Australian Government through the National Landcare Program.
For more information contact Senior Agriculture Advisor Matthew Lieschke on 0428 271 127 or matthew.lieschke@lls.nsw.gov.au
Contact Local Land Services NSW
Our team welcome your enquiries, feedback and comments. Contact our team
Our website is in the final stages of migrating to nsw.gov.au.
Use the search function to find the information or resources you need.
