Till vs No-Till – Which Is Better For Your Garden

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Robert Pavlis

I started gardening a long time ago and at that time tilling was standard practice. Most gardeners did not have a tiller so they did it by hand with a shovel. In some circles the idea of not tilling started to make waves. My first introduction was Ruth Stout’s no-till garden. Just cover everything with straw. Better for the soil and a whole lot less work. No-till became more popular in agriculture in the mid 1990 but few gardeners followed suit. Even today, many gardeners have never heard of the technique and continue the practice of spring tilling.

No-till is claimed to be better for soil and the environment since it releases less carbon dioxide into the air.

I have been promoting this idea in gardening circles for 15 years or more and slowly the idea is catching on with gardeners, but it might be time to take a step back and have a close look at the claimed benefits of no-till because science now has a lot more data on this.

Till vs No-till - Which Is Better For Your Garden
Till vs No-till – Which Is Better For Your Garden

The Claims For No-Till

One of the main claims for no-till is that it prevents the negative effect that tilling has on climate change. The story goes like this. Tilling adds air into the soil. This air increases microbial activity which reduces the organic matter (food source for microbes) in soil. This organic matter is converted to CO2 through respiration and then escapes into the atmosphere.

Compost Science for Gardeners by Robert Pavlis

If that was not bad enough, the loss of organic matter reduces the quality of soil. Tilling is blamed for the degradation of agricultural soil.

Even the United Nations Environment Program restates the claim that changing to no-till practices in agriculture, results in an accumulation of organic carbon in soil, thus mitigating climate change through carbon sequestration. You can read this story all over the place online and especially in fringe gardening groups. Unfortunately, the science does not agree.

In order to understand the difference between tilling and no-till it is important to look at various aspects of soil. You can’t just look at the level of organic matter. It is also important to understand that this is a very complex issue affected by location, climate, soil type, crop type, use of cover crops, type of crop rotation. etc. Any single blanket statement is at best an average and exceptions do exist.

Does Tilling Reduce Organic Matter (OM) In Soil?

There have been many studies that compare the soil organic matter in till and no-till systems and some of these have been done on farms that have been under scientific control for many years. I had no trouble finding studies that showed no-till increases OM, but I also found studies that showed tilling and no-till resulted in the same amount of soil organic matter. One metadata review of the global literature put it this way, “only about half the 100+ studies comparing soil carbon sequestration with no-till and conventional tillage indicated increased sequestration with no till”. Another meta study compared conventional tillage to no-till for 69 paired-experiments, where soil sampling extended deeper than 40 cm and found no increase in total organic matter with no-till.

Changes in organic matter at different soil depths, till vs no-till, Source:
Changes in organic matter at different soil depths, till vs no-till, Source: Pawlson et al

Another meta study that looked at a lot of studies but did not eliminate ones that were not paired experiments found that the OM decreases in the upper level and increased in lower levels, however the overall change still showed a decrease in organic matter. The amount of decrease was related to soil type with some showing no decrease and others showing some decrease.

Moving to no-till may increase the total OM level or it might not depending on soil types and other parameters. Tilling does increase the OM level at lower depths and neither the significance or the cause are clear. It could be that tilling moves more organic matter to lower levels, or it might be due to plants being able to grow deeper roots in tilled soil.

Building Natural Ponds book, by Robert Pavlis

Does tilling add air to soil which then causes a loss of organic matter? This is true for a short period after the tilling event, but over a period of months or years this effect is insignificant compared to other processes.

How Does No-Till Affect Climate Change?

An in-depth review of the science was done in 2014 and found that “The claims made for climate change mitigation through conversion to no-till agriculture are overstated for the global
potential for soil C sequestration”. Moving to no-till can reduce greenhouse gases through things like reduced fuel usage but there is little reduction from sequestering more carbon in soil. Moving to no-till will have limited effects on climate change.

How Does Tilling Affect Soil Aggregation?

Aggregate size decreases as the amount of tillage increases. No-till produces the highest degree of aggregation, reduced till is not as good and conventional till results in the least amount of aggregation. Aggregation improves air flow into the soil, increases water holding capacity, and results in better growth of both roots and microbes.

How Does Tilling Affect Microbes?

Most studies looking at microbe activity look at no-till combined with other techniques like improved cover crops and find an increase in microbe activity which may be due mostly to the increased vegetation. One study looking only at no-till in Mediterranean climates found a 71% increase in microbial biomass.

A meta analysis of 62 studies found that microbial biomass was greater under no-till compared to tillage, with the exception that chisel tillage (a form of reduced tillage) was the same as no-till. In the short term, tilling increased CO2 production from microbe activity, but over a longer term both systems have similar activity.

The increase in microbial biomass was less pronounced at lower soil levels.

What about the ratio of fungus to bacteria (F:B ratio)? It is believed that tilling is harmful to fungal growth and results in a decreased F:B ratio. A study looking at prairie soil found that although biomass of both fungi and bacteria increase in no-till, the F:B ratio did not change. A global meta-analysis of 60 studies came to the same conclusion.

Does Tilling Harm Fungi?

The traditional belief is that tilling is harmful to fungi because it “chops up the long mycelium filaments”. Tilling does disrupt mycorrhizal networks but the effects are not strong because the networks are able to re-form. Hyphal fragments can colonize roots and regrow. Dr. Maherali explained “a common method of propagation is to culture AM fungi using a host plant in a ‘trap culture’, and then to use the cut-up root fragments to inoculate other plants”. Root fragments containing pieces of fungi are called propagules and they are counted as living fungi on commercial product labels.

A single tilling event such as hoeing in the spring or even rototilling once a year will have limited long-term consequences on fungi. This also agrees with the observation that the F/B ratio does not change.

How Does Tilling Affect Soil Erosion?

“Over the last 80 years, tillage and other forms of erosion may have removed about 15 cm of topsoil from 20 million acres of cropland in the state (North Dakota). “I think that’s conservative,” said Dave Franzen, an NDSU soil fertility specialist, in January 2017.” “That 15 cm of lost topsoil contained a massive amount of nutrients, he added. We would have lost an additional 12.5 million tons of phosphate and 40 million tons of nitrogen. That is the equivalent of 75 years of N and P application at present rates.”

A global analysis found that on average soil losses were 60% lower under no-till than conventional tillage. The difference was greatest in low-clay soil and in temperate regions. There was less erosion in tropical clay soils which tend to be better aggregated and less erodible.

How Does Tilling Affect Yield?

The effect of no-till on crop yields is variable. A global meta-analysis looking at 50 crops and 63 countries and found that no-till matched conventional tillage yields for oilseed, cotton, and legume crop categories. No-till had some negative impact on wheat (−2.6%), rice (−7.5%) and maize (−7.6%). No-till reduced yields, on average, by 5.1% across 50 crops but yields dropped by as much as 20% for miscellaneous crops and root crops.

Yields tended to be lower in the first few years after starting no-till but increased after three years. “Overall, no-till yields were reduced by 12% without N fertilizer addition and 4% with inorganic N addition”. No-till performed best under rainfed conditions in dry climates.

No-till reduced yields the most in tropical latitudes (−15.1%) and the least in temperate latitudes (−3.4%). One downside of no-till in colder climates is that the soil stays colder in spring which delays planting. Tilling opens up the soil allowing it to dry and warm up.

Yields for no-till agriculture improve over time and are best in drier conditions, but even in ideal conditions, no-till has not been shown to provide higher yields than conventional tilling.

Factors Other Than Tilling May Be More Important

Agriculture is a much larger system than just tilling and it is important to look at it more holistically. Dr. Louis Schipper, University of Waikato, explained it well. All organisms produce CO2 through respiration but that is only one-half of the equation. The other half is plants. They take CO2 from the air through photosynthesis and add it to soil through their roots and as dead organic matter. When these two systems are in equilibrium, the soil organic matter level does not change.

Organic levels go down when the organisms in soil continue to live and plants stop adding organic matter. This is the case in bare soil. Keeping soil covered all year long with either crops or cover crops is more import to the OM in soil than the method of tilling. The type of crop rotation used also plays an important role.

Reasons For Tilling

There are some good reasons for tilling. In cold climates it opens the soil allowing it to warm up and dry out. This allows earlier planting.

If you have to change pH, either with lime or sulfur, it is important to incorporate this into the soil, or it can take a long time to change pH.

Phosphate moves very slowly through soil. Farmers tend to apply it very closely to the seeds as they plant them. Adding phosphate on top of the soil, won’t affect plants at the root level for years.

Best Practices For Gardeners

“Minimizing tillage is good for soils but eliminating tillage is not necessary for healthy soil“. There was a significant increase of no-till agriculture in Ontario a number of years ago, but over the last seven years there has been a reduction because it was not producing the expected higher yields. Adding winter wheat to their soybean-corn rotation had a more positive impact on soil health than the type of tillage.

All of the above studies are based on agriculture and it can be difficult to apply the findings to gardens. For example, many gardeners don’t till, but use a shovel. That may be less destructive? Gardeners also tend to amend soil more with organic matter and use mulch.

Organic faming has few tools for weed control and therefore rely heavily on tilling. Gardeners can easily reduce the weed problem with mulching, which is much less practicable on larger farms.

No-till may not increase sequestered carbon and may even reduce yields slightly in the short term, but it is still a good choice for improving the quality of soil. It increases soil aggregation, reduces erosion and increases its microbiology.

Gardeners should look at cover crops to increase the organic matter in soil and keep the soil covered at all times. The downside is that perennial cover crops may need to be tilled in before planting, but that is probably better than leaving the soil bare. Cover crops are also of less value in cold climates that have shorter growing periods.

The bottom line is that both tilling and no-till can produce good crops. Tilling may produce higher yields, but no-till may be better for long term soil health. If you have a normal small garden, skip the tilling and use mulch. If you have a larger market garden there are pros and cons for both options.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

17 thoughts on “Till vs No-Till – Which Is Better For Your Garden”

  1. I like the saying of Jeff Poppen the Barefoot Farmer. He said “You till until you can no-till, then you no-till until you need to till.” I started out my garden with heavy clay soils by double digging like John Jeavons of “Intensive Gardening” proposed so I could heavily lime my acid soils. After a full soil assessment of course. The following years I no-till because there’s just no reason to. I just weed and mulch giving the worms, insects, spiders, and all the fauna a break. By not tilling I also give time for the fungi to grow and do their part.

    Reply
    • That is such a great quote and so true in my opinion. I garden in the mountains of southwest Colorado and the clay is unbearably hard. I till in organic matter into all of my new beds so the worms and microbes can work their magic and I subsequently practice no-till by just adding a couple of inches of compost each year.

      Reply
  2. One reason to till is not mentioned here, and often left out of the conversation: tunnelling rodents. We have a terrible problem with voles, in our old garden and the new one (both in the Northern French countryside). I find tilling to destroy their galleries and drive them out is the only way to save our veggies. I’ve lost every single shallot planted and nearly all the beets. Nothing else worked. So I will combine mulching and other permaculture methods with an occasional pass with the rototiller. Wish I didn’t have to!

    Reply
  3. Charles Dowding got me onto the no-dig bandwagon years ago. Surprised and interesting to see that no-till had such decreased yields in agriculture. Charles does a no-dig and dug? bed comparison every season. Some crops don’t have a noticeable difference but I don’t recall any of the No-dig crops having less of a yield.

    Reply
  4. Thank you for an interesting discussion on no-till gardening. With so much attention given to no-till agriculture in the commercial farming world, it is little wonder that a lot of us gardeners are also interested in the application of this technique.

    My personal experience with no-till and cover crops has been mixed. I help manage a school garden with approximately 30 raised beds that average about 100 square feet per bed. For the past three years we hav dedicated 6 raised beds to no-till and added fall seeding of various cover crops. While I am a big fan of cover crops, the accompaniment of no-till brings challenges. For one, we have not had consistent winter kill with our cover crops including annual rye, spelt, and buckwheat. This leaves us with the conundrum of unwanted cover crop growth beginning in early spring. Not wanting to use chemicals (general school garden policy), we are left with few alternatives to tilling. If we do get winter kill to the cover crop, the roots present challenges to seeding fine seeds. Transplants often work better within this environment. However, as you have pointed out, we have yet to detect significant differences in vegetable production between the two methods.

    Soil compaction seems to worsen with no-till in my heavy clay soil. In theory you would think the root structures would keep the soil aerated and help with aggregation. But between the rain and regular watering with inadvertent little footprints, compaction is an ever present concern. We usually end up tilling in organic matter.

    I totally agree with your assessment that a lot of factors are involved with the growing of pants. It is difficult to isolate the effect of one or two variables. I believe there may be a sweet spot between till and no-till, but have yet to find it. I look forward to more research.

    Reply
  5. I use some tillage in my home vegetable garden, and also often do a one-time till for new landscape beds.

    A couple thoughts/questions:

    1. Somebody pointed out, the harvesting process for root crops is every bit as disturbing and invasive as tilling the soil would be, so if you’re growing something like potatoes, does it really make much of a difference at the end of the day?

    2. What about liming acid soil? Do you feel that at this point, tilling would be advantageous? There are a lot of studies showing that throwing lime on top of soil really only affects the pH a couple of inches down. My soil pH was in the upper 4’s before amending it with lime and of course some compost, and the first year, a lot of things just did not grow well as a result until I raised the pH. Had I not tilled in the line, I assume it would’ve taken much longer for it to have any sort of real affect. Any thoughts on this?

    Reply
    • 1) You normally till in spring, harvest in fall. Doing both disturbs soil more than only doing 1. Other root crops can be harvested with much less soil disturbance.
      2) Liming would be a good reason to till.

      Reply
  6. I have wonderful soil in my home vegetable garden without tilling or cover crops. I cover the bed in fall with leaves and vegetative matter from my ornamental gardens. I pull the mulch back in spring, then re-apply in late June. I’ve read that a mulch of this type can be just as effective as cover crops for improving soil.

    Reply
    • I don’t think that is true. mulch moves slowly into soil and much of the OM will stay in the top part of soil. A cover crop is growing plants, with roots going much deeper. They roots exude organic chemicals and when they die, they rot deep in the soil.

      Mulch is certainly better than bare soil.

      https://youtu.be/4xXJpSV_QjE

      Reply
  7. Thanks Robert. An interesting read as always 🙂

    I (in UK) have a local farmer who has moved to more environmentally friendly methods, relative to his peers. For example direct-drilled Wheat instead of old-school Plough and then Harrow / Roll and only then sow. He has to make a profit of course … but the reduction of multiple tractor passes through the field reduces fossil fuel usage/cost, and perhaps compaction. He is now also getting a “Carbon Credit” based on an audit, so his reduced tractor fuel use is also getting him a healthy subsidy. He would tell you that his soil is in better shape than before and he is saving money – and as a side effect less CO2 and he uses less Nitrogen fertilizer than before.

    We have other farmers who have moved to “regenerative”. They are growing under-storey crops, like Clover, for Nitrogen instead of applying granular fertiliser. Their yields are less, but their input costs are tiny. Fertilizer cost has recently skyrocketed of course, so the regenerative farmer will make a fortune selling their Wheat this year (futures-price has nearly doubled already), as their inputs are not much impacted

    I can’t translate that into what I might choose to do in my home vegetable patch! I already have raised beds, cover them with home made compost, and winter green-manure cover crops. Not sure about “no till” thought as my Potatoes, Parsnips / other roots, Leeks etc. all cause fairly significant soil disturbance to harvest them. If that is disrupting mycorrhizal fungi I can’t see how I could avoid that! every time the crop rotation has one of those crops. Either way, my soil colour is a lot “richer” than it was when I first moved here.

    Reply
  8. This a good summary. I have been using no till for a number of years in my garden. I do a lot of mulching esp in off season. It does seem like a good way to go for all the reasons you state. I agree cover crops are hard to do in northern climates unless you have the space to have fallow plots. Mulching makes more sense.

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  9. I wonder if the presence of Asian Jumping Worms will make no-till less effective. Will they prevent organic matter from entering deep in the soil , which is normally ascribed to the action of common earthworms ?

    Reply
    • Thank you Robert. Yet another great post!

      Thanks to your input, and that of other experts, I switched to no till-gardening a couple years ago. I was less concerned with carbon sequestration, but more concerned with maximizing my soil’s biome. I assumed that improved soil biome equated with better yields. I’m thus surprised that correlation doesn’t exist.

      I live in a Minneapolis suburb with heavy clay soil. Rather than using a cover crop in our very short growing season, I instead layer leaves and vegetative biomass (e.g. food scraps and peelings) onto the soil year-round.

      In the spring, I push that layer aside to plant crops, but leave it between plant rows. By the end of my growing season, that biomass composts into topsoil. Initially that biomass is unsightly, so I sprinkle potting soil onto it. But soon my vegetables grow and cover the “mess”. Since that composting biomass needs nitrogen, I fertilize between plant rows to ensure the process doesn’t rob nutrients from my plants.

      Robert, I think that as a result of these actions that I have healthy soil, full of compost, happy worms, and probably plenty of helpful flora/fauna biome. Does my process seem sound?

      I also prefer no-till gardening as it’s far less work! 🙂

      All the very best,
      -Steve-

      Reply

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