In parts of this island, cultivation and tillage imply the same thing. However, in this article, tillage is the enterprise and cultivation is the act of preparing land for seed growth.

Most see this as a job associated with the use of machinery, but it should be seen as something much bigger if we are to halt the ever-increasing costs of crop establishment.

The main purpose of cultivation is to enable and encourage seed germination, either of a crop or of other seeds present in or on the soil, such as crop volunteers or shed weed seeds.

Cultivation is also used to help cover seeds that would be vulnerable to pest attack, such as oats or beans, or which might be damaged by herbicides applied post-sowing.

So far, I have not mentioned ploughing as part of cultivation and it can be, or not.

The plough has served us well over the years as a relatively weather-proof method of establishing crops.

However, as our soils become lower in organic matter and especially where soil structure is damaged, we must question the benefit of annual ploughing.

Many farmers have moved to min-till systems on some or all of their land. Two main reasons apply:

Ongoing research has established that there is not a big carbon-loss penalty associated with ploughing, but there is a big cost-saving in time and diesel if it can be done without.

It must also be noted that plough-based systems are experiencing significant problems in recent years. More and more, we see patches of established crop die off in our wetter winters.

Continuing to evolve

Fifty or so years ago, the majority of crops were drilled as a separate job to cultivation.

The majority of cultivation was done in advance of drilling, using tools like ‘S’ or ‘C’ tine harrows, disc harrows or vertical-tine machines.

Such machines would only work properly when soil conditions were dry enough but the combination of operations meant lots of passes over the ground.

The big difference was that the machinery was much lighter back then.

It must also be noted that most land was in relatively good condition in terms of soil health, and especially soil structure, during this era.

Then came the one-pass in the 1980s and this revolutionised crop planting. The bulk or all of the work could generally be done in a single pass – cultivation and drilling. And, in general, if land was dry enough to plough it was regarded as being good enough to cultivate and drill.

The majority of one-pass units had a drill mounted on a power harrow, which could pulverise ground to depth in a single pass.

While the power harrow could be accused of over tilling ground, its major failing (besides cost and speed) was that it could work on a day when it should not be asked to work.

This annual pulverisation, coupled with land that was not receiving any form of organic matter, resulted in a continuous deterioration in soil structure and this made land more difficult to cultivate over time. This added to the time and power required, and bigger and heavier machines were employed to compensate for the tougher ground, as well as increasing scale.

This continuously escalating expense was a catalyst for many to move to non-inversion systems in the pretext of enabling soil improvement.

However, many quickly learned that min-till is not a cure for poor soil conditions and the simple basic advice remains – fix your soil before moving to min-till rather than moving to min-till with the hope of fixing your soil.

The great irony is that if the soil is ‘fixed’ first then the job of min-till gets easier and the window to get work done widens. But, then, the same is true of the benefits of improving soil quality for plough-based systems.

The big problem is that actions to improve soil quality take time – five to seven years at a minimum.

This means that it is not an instant fix, like those from a bag or a bottle, and the problem always is that one should have begun to take measures five years ago.

Organic matter and soil improvement

We pay lip service to the need for soil improvement, but it really took the straw incorporation measure and the incentives to plant catch crops to get people to engage with improvement.

While both incentives require time and effort, most who engaged will admit to seeing real benefits and in a relatively short time window.

It remains important to point out the importance of organic matter in soils. And yes, depending on the source, it can bring nutrients and long-term fertility.

While this can be very useful, the addition of low-nutrient products such as straw or compost can still contribute to long- and short-term fertility just by helping create humus and making the nutrients in the soil more available to plant rooting systems.

All forms of organic materials are potentially beneficial in the soil and having more than one source provides a step-up compared to a single source. This is not always easy, but it can be very worthwhile if you can make it happen.

The biggest benefit from organic matter is its importance in improving soil structure

So what does organic matter do in soil? The simple answer is ‘many different things’, but I want to concentrate here on just three of these; mineralisation, moisture and nutrient storage and soil structure improvement.

Benefits

These different benefits are not mutually exclusive in that they can all happen simultaneously.

The biggest benefit from organic matter is its importance in improving soil structure and this can only be done with the help of soil biology. The thing about biology is that ‘if you feed them, they will come’.

We are all very aware of the impact of organic matter incorporation on earthworm numbers and activity.

Earthworms multiply in the presence of significant organic matter, which is their food. If they are not actively fed then the rate of structure improvement will be limited.

Soils are degraded by rain, temperature, weight and work and degraded soils lose organic matter with the loss of carbon. A little crumb of soil is a mix of clay, silt and sand bound together by organic materials and biological glues and binders.

When a ‘crumb’ of soil is broken down, the sand, silt and clay separate out and the finer particles of silt and clay tend to move down the profile with water and eventually clog up the pores beneath, making water percolation more difficult and the soil more difficult to cultivate.

Active earthworms tend to consume these soil components, along with organic matter (food), as they clean out their burrows and the resultant worm cast or excrement then becomes the food for smaller organisms, which bind bits of the cast together to repair soil structure.

The better the structure you have in your soil, the easier and cheaper it will be to cultivate.

Growth of roots is less impeded than in tight soil that lacks air space and, ultimately, that leads to higher yield potential and more sustainable annual performance.

Because soil structure is so important for sustainability, it should be a priority for all tillage farmers.

It hinges on adding organic matter to the soil as either chopped straw, catch crops or organic manures and preferably some combination of these rather than just one.

It is important to remember that well-structured soils have better resistance to damage, especially when heavy machines must travel the land.

As well as helping to improve the structure in the soil, one must also continue to act to minimise damage.

In terms of cultivation, that should always mean minimising soil disturbance to get the job done. This could involve min-till or direct drill but not necessarily so.

However, it is useful to remember that a multi-annual interval between ploughing will help to lower the soil weed burden, while annual ploughing acts more like a sand-based egg timer – ploughing seeds down and back up again in the following year.

While the plough was traditionally seen as being relatively weather-proof in terms of getting crops planted and established, more and more problems have become evident over the past decade or so.

But is the plough to blame for this or is it more a failing of the one-pass system?

Decades

Very many fields have now had one-pass planting systems for decades.

Many such systems see the tractor go directly on to the ploughed ground and most show considerable wheel sinkage ahead of the power harrow.

So, the cultivation must be quite deep to get a seedbed in these wheel tracks.

This deep cultivation is more likely to be the main cause of subsequent crop loss, especially if the soil is damp during cultivation.

As we must strive to avoid this crop loss, one-pass systems must be set up differently to get on top of this problem.

This means reducing wheel sinkage and reducing cultivation intensity at depth, as it is the only reason why the cultivation must be so deep.

There will still be a need to tighten the loose ploughed ground a little but the various crumbler-roller systems can generally do what’s needed here.

Damaged structure

This issue is not just depth. It is also damaged structure and that must always be tackled, as it can be an obstacle to yield potential.

If roots cannot grow freely through the soil, that will always be an impediment to yield potential. And if roots cannot grow, neither can water move and plant loss is inevitable when land gets saturated.

Natural drainage

A key thing to remember and address here is the natural drainage capacity of the soil.

All farmers should know what that is for all fields and even different parts of fields.

If your drainage is not as good as it used to be 20 or 30 years ago, then you have an issue to address.

This could be partly due to heavier equipment, partly due to having to drive or work the land in sub-optimal conditions, but they are all ultimately due to damaged soil structure.

And metal does not fix structure – it is far more likely to damage it in time.

For improved soil structure, there is really only one cure – organic matter and earthworms.

The majority of modern machinery has a significant amount of in-built adjustment capability.

However, these adjustments are seldom utilised but they are there for a purpose, which could help you do a better job.

Depth adjusters are just one example as well as a range of settings that can increase or decrease the intensity of tillage.

When you buy a cultivator, what items are fixed and which ones are optional? Put some thought into the optional elements and ask yourself what can ‘item one’ do for you versus ‘item two’?

For stubble cultivation, it is important to have a depth control device that will leave the land in little ridges if you hope to reduce juvenile slug numbers by desiccation.

The less intensively you cultivate the quicker you can enable nature to repair your soil

Leaving the surface ridged helps the soil to dry out completely in dry conditions, while firming the soil and leaving it flat and compressed will help conserve moisture to aid their survival, but it might also help seed germination.

Know what every element of a modern cultivation tool is doing for you and ask yourself is that element useful for my objectives? Is a machine capable of working at depth if needed? Cultivator drills are a good modern phenomenon with the capacity to ‘one-pass’ with less intensive cultivation.

The less intensively you cultivate the quicker you can enable nature to repair your soil. So cultivate as little as possible but as much as is necessary.

Stubble cultivation – purposes

Up to now, most of my comments related to crop establishment, whether that be a cash crop or a catch crop.

We also now have an obligation to cultivate stubbles post-harvest, supposedly as a nitrate loss control measure. That is quite a different process and for practical and cost reasons, it is important to keep this operation as shallow as possible.

The practical reasons are that it should take less diesel to cultivate but the biggest reason for this is to avoid generating too much loose soil in case it gets wet before it is handled again. If that happened, you could end up with a field of ‘porridge’.

The first question that every grower should ask is ‘what do I want to achieve from stubble cultivation?’ The answer should not be ‘because I am bound to do so by law’. It is a cost and therefore you must ask where you can get benefit.

As a strong advocate of stubble cultivation, I always had four reasons to do it:

One additional reason to cultivate is the establishment of catch crops post-harvest

When you are achieving two or three of these objectives, it makes stubble cultivation appear less expensive and more worthwhile, even if some of these advantages only mature in the longer term.

One additional reason to cultivate is the establishment of catch crops post-harvest.

So, while you must cultivate, what do you want stubble cultivation to achieve? The need to stay shallow gives discs a potential advantage and machines with steeper disc angles can cut all the ground more easily at shallow depths. However, in many stubbles, shallow cultivation is difficult where the surface has been tightened, either by machines or by rain.

‘Break the crust’

In such fields it will be important to ‘break the crust’ and this problem is best solved over time by improving soil structure through the addition of organic matter. As the ground mellows, it will become easier to operate at shallow depths.

There is a bit of a conflict between slug control and weed germination. For slug control, you need the tilled ground to dry out immediately, while for weed germination you need a firm seedbed and moisture retention through compression.

One will leave a ridged surface while the other will be flat and probably rolled or tightened. That said, there has seldom been a season that did not rain and inevitably all stubbles green up to do that second phase of work following slug control.

The last point to make about cultivation is that it should not be done in damp conditions and we have seen seasons where it cannot be done (like last year) and you would get zero pest control even if you did cultivate.