Laggan grazing demonstration

Local Land Services is working with a landholder to research fertiliser use on pasture productivity.

Last updated: 01 May 2025

A herd of laggan sheep in fenced area on lush green grass on a sunny blue sky day

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Project overview

Status: In progress

Local Land Services is supporting 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 is investigating 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.

Aerial view of a field divided into sections labeled 'Super,' 'Control,' 'Lime + Super,' and 'Nutrient subtractive trial. — The three native pastures are outlined in the paddock, with the Single superphosphate on the left, control in the middle and Lime + Single superphosphate on the right. Another nutrient subtractive trial box pasture is above at a seperate location.

Work underway

Project updates

2023-2024

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%)

Bar chart comparing monthly rainfall data for 2023-24 with the median rainfall from 1883 to 2023. — Figure 1: Monthly rainfall totals (mm) recorded at the Crookwell Post Office (BOM station 70025). Total rainfall for 2023-24 was 981 mm. The annual long-term median rainfall for this site is 869 mm

2015-2021

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).

Bar chart comparing gross margin ($/ha) between treatments (L+S, Cont, SS) from 2015 to 2020, with a line representing the 18u wool price (c/kg clean). — Figure 1: Gross margin comparison between treatments ($/ha).

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.

Bar chart showing gross margin per hectare for L+S, Cont, and SS treatments from 2015 to 2023–24, alongside a line graph tracking the 18-micron wool price. L+S consistently shows higher margins, with a peak in 2021. Wool price peaks in 2018 and 2021 before declining — Figure 2: Gross margin comparison between treatments ($/ha). This economic analysis is based on (wool income + annual change in mutton value during the 12 month period.

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.

Line graph showing Colwell soil test results from 2014 to 2023 for three fertiliser treatments with associated application rates. — Figure 3: Fertiliser application history and results of annual soil testing on Colwell P (* indicates the years in which superphosphate was applied with molybdenum).

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.