Applying lime

Page last updated: Monday, 7 October 2019 - 4:03pm

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Efficacy and cost of incorporating lime

Composite photo of different tillage implements
There are a range of options available to incorporate lime to depth. It's important to carefully consider the applicability of different options in different circumstances

The efficacy with which various implements can incorporate surface applied lime depends on numerous factors including:

  • Soil type, in particular clay content, which can affect the cohesion, fracturing and flow of the soil.
  • Soil moisture conditions - in sandplain soils moisture can help the sand maintain its form (greater cohesion) allowing slots to remain open for longer but may reduce fracturing and soil flow. Wetter soils are softer so this can improve the penetration of soil by implements and reduce draft. Dry surface sand flows easier when worked (less cohesion) which can be an advantage for moving limed topsoil behind soil openers. Optimal movement probably occurs when there is some subsoil moisture but the limed topsoil is dry and can readily flow into the fractured subsoil.
  • Implement type - variations between machinery brands such as width of tines, curved or laid-back tines which may promote a lifting (delving) action; curvature (dish depth) of discs are just some examples.
  • Implement set up and use - for disc ploughs and mouldboard ploughs setup greatly influences the incorporation result. Having ploughs more open will increase the work rate and the space between ploughshares available for soil to move but may limit the working depth.
  • Speed of operation - higher speeds can result in more soil throw and mixing but may require a shallower working depth.

The table below gives a brief description of various tillage implements, the mixing action of each implement, typical working depth and some supplementary information on the efficacy of lime incorporation. Note that every situation is different and this information is designed to be used simply as a guide when considering options for incorporating lime.

Table 1 Details of tillage implements and a summary of their efficacy when assessed for lime incorporation
Incorporation implement (approx. cost range $/ha) Overview of tillage action by implement Typical working depth (cm) Depth of lime incorporation achieved (cm) Lateral spread of lime and incorporation efficacy *Images with purple soil are from application of universal pH indicator to identify placement of lime within the soil profile

Deep ripping ($45-55/ha)


Set up of a typical farm deep ripper with parrelel ripping tynes attached to a rectangular structured steel chassis
A standard deep ripper used to break out compacted subsoil
Narrow strong deep working tines used to break out subsoil compaction 30-40 10-15, variable

Limed topsoil tends to be mixed in the surface layer where the tine passes through but generally the slot behind the tine closes rapidly so there is little opportunity for limed topsoil to fall deeper into the subsoil


Root proliferation in a rip line
Root proliferation in a rip line. Although limed topsoil is often mixed in the surface layer, there is variable movement of lime down the profile

Shallow leading tine ripping ($40-50/ha)


Image of a shallow leading tine ripper showing placement and working depth of different sets of ripping tines
This shallow leading tine ripper has four sets of tines and is typically used for research purposes. Commerical shallow leading tine rippers have two sets of tines which rip at 20-30cm and then again at 30-50/60cm in the same pass
Ripping with shallow leading tines allowing deeper break out by deeper working, trailing tines 40-50 10-15

Limed topsoil can be incorporated better due to multiple tines disturbing the soil in the one pass, although incorporation is still limited as tines are narrow and slots close rapidly behind the tines


Soil profile showing less compacted soil after deep ripping with a shallow leading tine ripper
A yellow sand deep ripped to 500 mm with a shallow leading tyne ripper

Shallow leading tine ripper with topsoil inclusion plates ($40-55/ha)


Image of a ripping tine with topsoil inclusion plates fitted to the rear of the tine
Topsoil inclusion plate fitted to the rear tine of a shallow leading tine ripper
The addition of topsoil inclusion plates to the rear tines allows for the movement of topsoil rich in organic matter to depth 40-50 30-40

The topsoil inclusion plates keep the slot behind the rear ripping tines open for limed topsoil to fall into the subsoil. The result is vertical seems of organic matter rich/limed topsoil behind placed to depth behind the rear ripping tines


Vertical seems of topsoil rich in organic matter streaming down the soil profile of a yellow sandy earth in Dandaragan
Seems of topsoil with good pH placed to depth through the use of topsoil inclusion plates

Ripper with wings ($45-55/ha)


Image of winged plates fitted to a ripping tyne to allow for greater soil disturbance when ripping
A ripping tine with wings allows for greater soil disturbance as it operates below the soil surface and tends to lift subsurface soil
Wings mounted on ripper tines that operate below the soil surface when ripping which creates greater soil disturbance as they tend to lift subsurface soil 30-40 20-25 Limed topsoil can flow into the space opened up via the lifting (delving) action of the wings. Lateral incorporation is improved with 'tongues' of topsoil up to 8cm wide on either side of the ripping tine where the wings had passed

Ripper with 'Horwood' opener ($45-55/ha)


Deep ripping tine with a Horwood attachment
Ripping tine with a 'Horwood attachment' to hold open the soil slot longer and allow limed topsoil to drop into the subsoi
Plates extend behind the ripping tine to hold open the soil slot longer operating just below the topsoil 30-40 20-26 Holding the slot open for longer below the soil surface allows limed topsoil to drop into the subsoil. A continuous stream of limed topsoil was achieved but the slot narrowed with depth being only 1-2cm wide at depth

Ripper with 'Railway Fishplate' opener ($50-60/ha)


A rectangular plate fitted to the back of the ripping tine
A 'railway fishplate' opener is essentially a plate bolted onto the side of the ripping tine to increase the level of soil disturbance
Plates bolted onto the side of the ripping tines effectively increasing the tine width and the degree of soil disturbance 30-40 19-23 More disturbance resulted in more mixing. Width of mixing was increased up to 14 cm in some instances but this was variable

Deep digger® ($60-70/ha?)


Image of a deep digger with large curved tines
The wide curved tines of the Deep Digger® are capable of ripping deeper than standard deep rippers
Large wide curved tines in a V-shaped arrangement capable of ripping deeper than standard deep rippers 40-60 23-25

Wider tines and some delving action allows some topsoil flow around and behind the tines but overall incorporation is fairly minimal for the cost. Tines would need to be modified to achieve better incorporation


Soil pit profile showing the incorporation of lime and organic matter of the deep digger and the compaction of traffic on the loose soil.
Incorporation of lime to a depth of approximately 25cm in West Binnu using the Deep Digger. The loose soil has been subsequently compacted by traffic

Offsets ($40/ha)


A standard set of off set discs being towed behind a tractor but not when ploughing
A standard set of offset discs that cultivate the topsoil
Standard offset (two-way) discs that cultivate the topsoil 10-15 10-15

Very little limed topsoil is incorporated into the subsoil layers due to inadeqaute working depth. Mixing will still improve the reaction of the lime in the topsoil that may then allow for faster lime movement into the subsoil


Soil pit profile showing offset discs have been observed to incorporate lime to a depth of 10-15cm
Incorporation of lime to 10-15cm in a yellow sandplain soil in Carnamah using offset discs

Large offsets ($50-60/ha)


Grower standing alongside a large offset disc plough
Large offset discs can cultivate to a greater working depth than standard offsets
Large offsets (two-way) discs, typically greater than 70cm in diameter, that can cultivate deeper than standard offsets 24-25 24-25 Limed topsoil is effectively incorporated to the working depth. Some layering occurs on an angle from the surface but generally the mixing is good. Visually it appears about two-thirds to three-quarters of the profile is treated to the working depth. The incorporation depth can be less if hardpans or gravel layers prevent disc penetration

One-way plough ($30-40/ha)


A small one-way plough used for research trials
A small one-way plough used for research trials
Discs throw the soil one-way, can achieve partial turning of the soil but mixing occurs as soil tumbles off the disc 15-25 15-25 Limed topsoil is partially mixed and layered on an angle from the surface because of the cultivation process. Despite partial inversion and layering continuous pathways of limed topsoil are still available for root growth. About half to two-thirds of the topsoil is  buried. Can bring acidic subsoil to the surface so more surface lime may be required post-ploughing.

Rotary spader ($120-150/ha)


Image of a spader in the shed showing the spades attached to the main rotating shaft
A rotary spader used to bury some topsoil and lift up some subsoil
Rotating spades bury some topsoil while lifting up some subsoil. About two thirds of the topsoil is buried below 10 cm. Soil tends to take on a marbled apperance 28-35 28-35

Very effective at mixing limed topsoil into the subsoil. Does lift some acidic subsoil to the surface so additional lime may be required in subsequent years. Because spades are offset and overlapping lime is incorporated through the entire profile to the working depth, although pockets of acidic subsoil may remain.


Soil pit profile showing the marbling of the soil after the passing of a spading implement.
A soil profile of a yellow sand in Carnamah after spading. The spader thoroughly mixed the top soil and subsurface soil throughout the profile, bringing acid soil to the surface and burying the top soil and lime
Soil profile in a small soil pit where the soil was rotary spaded. The rotary spader has buried some of the topsoil to depth of 25 cm but also lifted some pockets or seams of subsoil into the top 10cm of soil.
Soil profile at a trial site showing buried topsoil in spaded treatment. The rotary spader has buried some of the topsoil to depth of 25cm but also lifted some pockets or seams of subsoil into the top 10cm of soil

Mouldboard plough ($100-150/ha)


Growers will often topdress lime after mouldboard ploughing and bringing acidic subsoil to the surface
Curved mouldboard shares lift, roll and invert the soil aided by skimmers that scalp the topsoil into the base of the furrow. Square ploughs achieve a similar result 28-35 28-35

Inversion buries limed topsoil in a layer and can bring a thick layer of acidic subsoil to the surface that needs treating with more surface-applied lime. Continuous ameliorated pathways are not always present if inversion has been effective.


Distribution of lime in the subsurface and surface after mouldboard ploughing
A mouldboarded soil profile showing acidic soil brought to the surface and limed topsoil buried at depth after complete inversion. Additional lime has then been topdressed (stained purple from universal pH indicator) but there is no preferntial pathway of good pH to allow for root growth between the two layers  
Soil pit profile showing setup of the mouldboard is critical for full inversion of topsoil
In this example in Carnamah, an incomplete soil iversion after mouldboard ploughing resulted in seams of limed topsoil alongside acidic subsurface soil

TopDown® plough (>$100/ha?)


Image of a topdown plough with one wing folded upward
A Topdown® plough has a combination of leading offset discs then curved ripping tines, levelling discs and packers
A cominbination of leading offset discs then curved ripping tines, levelling discs and packers 20-35 20-25

Off set mixed well through to their working depth. Curved ripping tines then open a slot allowing surface soil to fall into 20-25 cm. This incorporation is a broad 'V' shape beginning at the width of the tine at the surface and finishing to a point at 20-25cm. Thr curved tines also lift acidic sub surface soils to the surface in seams. Not as effective in gravelly soils or soils with hard pans or layers that are difficult to penetrate


Soil profile showing incorporation pattern of lime using a topdown plough
The TopDown plough achieved lime incorporation to 28cm in Carnamah, incorporating lime in large V shaped patterns as subsurface soil is dragged to the surface either side of the tyne

Contact information

+61 (0)8 9368 3493
Gaus Azam
+61 (0)8 9690 2159