Non-inversion tillage

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This form of tillage increases the ability of roots to penetrate deeper into the soil to reach nutrients and moisture that were formerly unavailable. It also breaks up hard pans that stunt crops and can bring drought on earlier than it would come normally.

It has minimal negative impact on soil structure and can have many benefits if done at the right time.

This term plus deep tillage and deep ripping used to mean putting a few tines or often just one tine into the soil and dragging them or it through with high power to open up the soil to depth.

These days it is increasingly called non-inversion tillage meaning that the soil is not turned over (not inverted), just left in place with a slot visible on the surface.

And these days it is not done with a great big ripper tine behind a bulldozer or huge tractor.

It is more often an implement with multiple narrow tines, pulled by a regular tractor and not going as deep.

Sometimes it leaves just a vertical thin slot, other times it leaves an inverted T-shaped thin slot deeper in the soil.

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What this means

The aim of non-inversion tillage is to break up hard pans and increase available soil depth by slicing thinly through the pan vertically while lifting and then dropping the soil. This lifting and dropping can cause shattering of the soil on each side of the slot and as a result, lots of cracks. These cracks allow soil moisture, gases and roots to penetrate, opening up deeper layers and eliminating the hard pans.

Note: the effects and the benefits are far less in structureless soils and so in soils with low clay/high sand content.

CAUTION: Non-inversion tillage may be extremely damaging where there is a dispersible clay. A dispersible soil loses all its structure and just dissolves in water. So when moisture goes down the slots left by the implement, it disperses the clay into a liquid form. The soil above this dispersed clay is then prone to collapsing into the hole left by the dispersion.

Non-inversion tillage is most commonly done

as part of opening up new ground
before planting trees into one of the riplines. The trees benefit from
- easier root penetration
- greater water infiltration
- a herbicidal effect on the outer riplines keeps competition down. This is a useful way to use non-inversion tillage as a herbicide.
And it makes planting easier.
to encourage deeper rooting by existing plants, especially in pasture and
particularly to deal with a hard pan. The closer a hard pan is to the surface and the harder the pan is, the more likely that there will be severe problems. The more severe the problems, the more likely that non-inversion tillage will give benefits, particularly in this year's yields.

Potential benefits of non-inversion tillage

Non-inversion tillage done in the right way, at the right time and under the right conditions for that soil can deliver many benefits including

better growth of plants and tap-rooted and other deep rooted plants in particular
better soil aeration
better infiltration of rain and irrigation
improved root penetration and deeper rooting leading to
- greater drought resistance
- longer growing seasons where soil moisture is a limiting factor and
nutrient trapping (when done across a slope or across the prevailing wind direction the slots can trap soil, organic matter and nutrients).

Whether to use non-inversion tillage

Non-inversion tillage will generally only be useful if the soil has a hard pan or is hard below the present root depth. The tillage will need to pass through this layer. If the hard pan is too deep for the implement, any potential benefits may be lost. So the first step is to find out. Get more info on finding and preventing as well as the effects of hard pans.

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Using this

When non-inversion tillage is likely to work

The best time to deep till is before good rains. The lifting and shattering opens up the soil to air and gas exchange. If no rain comes, your soil will lose more moisture more quickly. So for best results (and sometimes to get any result), you will need to time any non-inversion tillage for when rains are highly likely.

If rain comes and there are enough plants already growing, enough seed reserves in the soil or you sow seed, plant roots can penetrate along the resulting cracks, bringing organic matter and widening the cracks. Of course, the rain needs to come in your growing season. If the rain arrives when plants have shut down for the season, the benefits will be less or even zero.

And plants need a fertile soil to make the most of it.

After a fire has killed off a lot of vegetation, non-inversion tillage on the contour can help to reduce erosion and can improve infiltration and so get the ground back to normal by encouraging good pasture regeneration.

Some points about the "How" of it

Working on the contour or at least across the slope will be less erosive and more effective than up and down the slope.

Tools used: It can use a fair bit of power, but it should not be brute force pummeling a soil into shape. All that will do is further damage your soil. So a standard ripper is not suitable unless the pan is very deep and even then, Yeomans plows®, Wallace ploughs®, Agrowplows®, Paraplows® and similar implements are usually best. Talk to other farmers and your advisor.

If you go too deep you will waste fuel, break shanks and take longer. From 1½ to 2 times the present root depth is a good starting point. You can adjust this to suit the tractor, implement and operator as well as the soil, how you are using that spot and how you plan to use it (which plants will be there, whether you will be grazing or cropping it etc) and the likelihood of rain.

Note: You don't always need a lot of power, I have seen a home-made single-tine shallow non-inversion tillage behind a solo draught horse. And I've seen another one behind a four-wheel ag bike - pretty tough on the drive train and suspension.


A very rough guide to power use/tine
Depth	Sandy soils	Heavy, tight soils
Top 10 cm/4 inches	2 kW (3 BHP)	5 kW (7 BHP)
Each extra 10 cm/4"	4 kW (5.5 BHP)	15 kW (20 BHP)
This is based on Australian implements and situations. Check with your adviser, your situation is different

Check with your local adviser on power requirements. Some advisers in Australia give their clients a set of rules of thumb similar to this:

In sandy soils you will probably need around 2 kW (3 BHP)/tine for the first 10 cm/4 inches of depth
then add 4 kW (5.5 BHP)/tine for each extra 10 cm
In heavy, tight clays, it might be 5 kW (7 BHP)/tine for the first 10 cm of depth
with 15 kW (20 BHP)/tine for each extra 10 cm of depth.

Coulters can help cut through litter and pasture mats, but if you don't need them and don't use them, you will probably get more surface disturbance and this can lead to better erosion control and better moisture and nutrient trapping.

Be careful to limit any compaction (from stock or vehicles) after tillage or the cracks can close up again, removing much of the benefit.

When non-inversion tillage is not a good idea

As with any other tillage it is not a good idea to do non-inversion tillage when soil is too dry (it will crumble to powder) nor too wet (it will smear and seal the sides of the slot).

Non-inversion tillage will not work well for you if:

rain is not likely for months (or even just weeks if the weather is very hot and dry)
you can't keep stock and vehicles out of the field to minimize compaction and thus the cracks closing up again
weeds in the field would be better dealt with by grazing, slashing etc, perhaps followed by non-inversion tillage
you will be short of feed soon and may need to graze the field. Non-inversion tillage would be likely to reduce that feed under dry conditions
nutrient levels are too low to take advantage of the greater potential growth
perennial pastures or crops would be too badly damaged by root pruning. Follow-up rains or irrigation will help plants recover. However, be careful of root pruning on avocados, citrus and other tree crops that are sensitive to root disturbance as well as generally in any perennial pasture, orchard, vineyard or plantation.

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Taking this further

Rotationally grazing pastures to cause grazing shock is one way to get similar benefits.

Green manures and pastures that are slashed can extend the benefits (think about how this works). There's more about bringing this into effect in Return a third to the soil

Check out what a hard pan is, some of its causes, its effects and how you can detect a hard pan.

If you are looking at a printed version of this page and you would like to visit it on the internet and get a stack of other info that may assist you, the full web address is
http://www.OrganicExchange.com.au/all/fc910251.htm

Related info:

Non-inversion tillage as a herbicide

Grazing shock

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