What is Conservational Tillage

With all types of tillage, the primary goal remains consistent: breaking up compaction and creating a more favorable environment for planting. Whether it’s conventional plowing, reduced tillage, or no-till practices, farmers strive to improve soil structure, enhance nutrient availability, and promote optimal root growth. Where they differ, however, is that conservational tillage is a system that retains at least 30% of the soil surface covered with crop residue. We’ll be looking into some methods of conservational tillage as well as some regenerative solutions to problems typically solved by tilling.

Conservational Tillage

As tillage comes under increased scrutiny more farmers are adopting tillage techniques that minimize soil disturbance. With conservational tillage we often find a hybrid of traditional tillage and no-till. Often these methods will disturb a small area for planting while maintaining some underlying undisturbed soil. This preserves the microbial life in the undisturbed parts of the soil, allowing them to recolonize disturbed land more quickly. As illustrated in the image below once disturbed microbial communities decline severely and take years to reach their former levels of microbial biomass.

Strip Till

Strip tilling involves tilling narrow strips of soil where crops will be planted, leaving the areas between the rows untilled. This method combines the benefits of no-till and conventional tillage, promoting soil health while providing a suitable seedbed for crop establishment. The preservation of soil between planted rows acts as a microbial bank allowing for plants roots to more quickly develop microbial relationships that will help to boost their growth. This method also helps to protect soil structure, retain moisture that would be lost as evaporation during tilling, improve soil health, and prevent erosion and leaching.

(Xuemei & Zhang, 2019)

Strip tillage works best for soils with good drainage and structure, strip-till in heavy clay soils may need additional management and have a longer transition period to see benefits. Studies have shown strip tillage works well with conventional crops such as corn, soy, cotton and beets, this is an important note as corn, one of the most commonly grown crops in the US, typically struggles to match conventional tillage yields in no-till systems.

Ridge Till

(My Daily APHG - Ms. Silvius's AP Human Geography (weebly.com))

See the picture above for a step-by-step explanation of ridge till. In step 1: the ridges have been formed and a field is shown after winter and prior to planting. Step 2: 2-3 inches of the ridge tops are removed, and seeds are planted into the ridge. Step 3: depending on weed pressure this process may be repeated, a cultivator is run through the valley of the ridge to recreate the ridge and kill weeds growing around the crop. See some of the cultivation implements and how they fit into the ridge system.

Step 4: as the ridges are formed, previously undisturbed soil mulches the tops of the ridges around the crop further killing weeds in the field.

Ridge fields were popular in the Early to Mid -1900s especially in the Midwest. Some farmers believe this planting style fell out of favor as seed drills became more popular.

However, there are a lot of advantages of ridge till over traditional tillage and some studies are now suggesting it could be better than No-till. (Liu, 2018) In a 2018 study ridge till was shown to stimulate inorganic N retention capacity, and have higher average soil organic matter and total nitrogen when compared to conservation tillage or no till. Ridge till dries faster than a regular field, so some wetter spring climates may benefit through an earlier planting. Ridge till works best in poorly draining soils, the increased surface area from the ridges allows for faster evaporation. Additionally, the elevation of the ridges can help to keep roots from drowning while the valleys can help to direct excess water into the soil profile. Cultivation between rows kills weeds, and building new ridges also covers weeds, blocking out light and killing them. As soil is intentionally left undisturbed this still allows for safe places for worms, roots, fungal networks and soil microbes.

Mulch Till

Mulch tillage is a form of conservation tillage that involves leaving a minimum of one-third of the soil surface covered with stubble mulch. In this method, crop residues from the previous harvest are left on the soil surface to act as a natural mulch.

This method conserves much needed organic matter while providing a better surface to plant into than just stubble. The main benefit of mulch tillage is its ability to suppress weed growth. Mulch also acts as a temperature regulator, keeping the soil protected from harsh sunlight and heat while adding additional biomass to preserve warmth in the cold. Additionally, mulch also helps to dampen compaction caused by rainfall and prevents erosion. For farms facing soil borne illnesses mulch can also work as a physical barrier between the plant and the disease. For drier soils, mulch helps to boost water retention while reducing loss through evaporation.

With any system, it is important to consider what your primary crop will be. Some studies have shown grain crops (rice, wheat, sorghum) tend to have a positive increase in yield under mulch (Du, C.; Li, L.; ,2022) while other studies have shown vegetable crops tend to show an initial decline in yield, sometimes meeting the yields of conventional tillage over time. It is important to note, however, that across all studies an improvement in water use efficiency and soil quality was seen over time.

Tools of No-Till

We must admit, tillage solved multiple problems, so now let’s consider how we can solve those problems using no-till instead.

Problem 1: Soil compaction and Erosion

The best natural solution to avoiding compaction is by maintaining soil quality. Two of the biggest challenges when maintaining soil quality are erosion and compaction. Our best means to avoid these problems are minimizing soil disturbance and avoiding bare soil at all costs. There’s a variety of ways we can do this:

Mulching: covering the soil surface with organic or inorganic materials like straw, wood chips, or plastic. These materials act as a protective layer, reducing the impact of raindrops and preventing soil compaction. Mulch also helps retain moisture, regulate soil temperature, and suppresses weed growth.

Cover Cropping: involves planting specific crops (cover crops) during fallow periods or between cash crops. Cover crops protect the soil from erosion by wind and water. Their extensive root systems hold the soil together, improve soil structure, and enhance nutrient cycling. When these cover crops are eventually incorporated into the soil, they add organic matter, and their roots leave tunnels behind as they decay, preventing compaction and erosion.

Living Mulch: Living mulch refers to using low-growing plants (often groundcovers) to cover the soil surface between rows of cash crops. Living mulch serves similar purposes as traditional mulch: reducing soil compaction, preventing erosion, and retaining moisture. Additionally, they provide habitat for beneficial insects and contribute to overall ecosystem health.

Interplanting/Companion Planting: Interplanting or companion planting involves strategically placing different plant species together in the same garden bed. The most famous historical example of this is “The Three sisters” a practice used by indigenous peoples across the Americas where corn, beans, and squash are planted together. The corn’s stalk acts as a pole for the beans, while the beans fix additional nitrogen into the soil, and the squash’s large leaves block out light preventing weed growth around the crops. There are less complex companion planting methods that has been shown to be beneficial. Studies have shown marigolds interplant compatibly with a variety of crops and have shown use in controlling whitefly populations. (Conboy, 2019)

Problem 2: Weed control & Cover Crop Termination

All the methods above can greatly suppress weeds when implemented, but sometimes a field’s weed pressure is too great, or a cover crop needs to be terminated. What is the regenerative way to do this?

Roller Crimper: Designed to crimp the stem, killing the cover crop, this method lays down your cover crop without incorporating it into the soil. This method preserves root structure and turns your cover crop into a thick mulch layer.

Flail Mower: When you’re not looking for a thick mulch layer or looking to plant into a soil with less surface plant residue, the flail mower could be your answer. A flail mower can shred your weeds or crops into much smaller pieces, which, in a biologically active soil, will degrade relatively quickly.

Problem 3: Seed Bed/Planting

For no-tillers, the planter is the most crucial piece of equipment on their farm. It does the job of opening a slit in the soil, dropping in seed, and closing the seed trench, all while managing residue efficiently in the field. (Dobberstein & Gerlach,2023)

No Till Planter

(Wambugu,2021)

Fortunately, most plants will work for no-till, but there are some factors you may want to consider. In the diagram above are the ground preparation components of a typical planter system. Depending on how you low- or no-till you may be able to use your current planter as is, but if that’s not cutting it or you’re planning to plant into heavy mulch, there are no-till optimized versions of every component and even some add-ons. For more info on ways to modify your planter for no-till see: What You Should Know About No-Till Planters (no-tillfarmer.com)

Where Does No-till work best?

No-till farming can be effective in various soil types, but it tends to work best in loamy soils, which have a balanced mixture of sand, silt, and clay, making them ideal for retaining moisture and providing good nutrient availability. Clay soils, although more challenging due to compaction and waterlogging, can benefit from no-till practices over time as they improve soil structure by increasing organic matter and promoting biological activity. Sandy soils also benefit from no-till farming as it helps reduce erosion and improve water retention by maintaining a cover of organic matter. Additionally, no-till farming is particularly beneficial in sloping or highly erosive soils as it helps prevent soil erosion and maintains soil structure, while also conserving moisture, which is crucial in dry regions.

In terms of climate, crops seem to adapt to no-till best in temperate areas, followed by subtropical, and then tropical climates which struggle the most to adapt to no-till. No-till tends to prefer arid, rain fed, or irrigated environments.

When it comes to specific crops like wheat, corn, and soy, no-till farming offers several advantages. For wheat, no-till practices can enhance soil moisture retention and reduce erosion, which is particularly beneficial in regions prone to dry conditions. It also helps in maintaining soil structure and organic matter, leading to healthier crops. Corn benefits from no-till farming through improved soil health and reduced erosion. The practice helps in maintaining soil moisture and reducing the need for irrigation, which can be crucial during dry spells. Soybeans, on the other hand, thrive in no-till systems as they benefit from the increased organic matter and improved soil structure. This leads to better root development and nutrient uptake, ultimately enhancing crop yields.

Does No-till actually get results?

Here’s the rub, in one of the largest meta-analysis of no-till studies most crops (excluding cotton and oilseeds) will suffer a decline in yields during the first 1-2 years of no-till, but, within 3-10 years most no-till crops typically are able to match their conventional tillage counterparts. The benefits of no-till aren’t in the short terms yields, it’s the long term ability to continue growing healthy crops. No-till is about preservation and prevention, it is preserving the land and its organic matter for a long-term healthy farmland to pass on to future generations and preventing the next dust bowl.

Conclusion

While there is a short-term benefit to tilling, the medium-to-long term leads inevitably to scant levels of organic matter, poor soil structure, heavy erosion, increased compaction, limited water retention capacity, bacterial dominated soil, weed pressure, and aggressive pests and pathogens. Effectively, tilling builds an ecosystem that is reliant on external inputs to extinguish self-perpetuated problems.

While it takes some extra work, alterations to strategy, and a learning curve to reach comfortable implementation, integrating practices like cover plants, no-till, crop rotations, and intercropping can begin to build soil health over time. It is important to consider your soil type and primary crops when selecting what conservation tillage method is right for you. When done properly, conservation tillage results in improved drought resilience, increases in organic matter that provide higher latent nutrient levels for planted cash crops, increased biodiversity that helps to control pests and diseases, and more to money can flow back to the farmer for their hard work instead of being squeezed between inconsistent yields and increasing input costs.

As an illustration of the long term effects of Till vs No-till here’s a 75+ year study from the University of Illinois Soil Health Services. As we can see from the picture below soil carbon has declined drastically (over 50%!) in just 50 years of convetional agriculture. This soil carbon being measure took thousands of years to build up through natural processes that healthy bank of organic matter, traditional tillage takes as much as it can out of that bank providing good yields at the time with no concerns of the future. Conservational tillage provides the savings you need for a continued healthy soil. You aren’t exhausting soil resources but maintaining a natural system.

For a great video showcasing the differences between no-till and tilled after 50 years please see: Differences in Tilled and No-till Soils | No-till on the Plains | Agriculture Production Systems Modeling Nature (notill.org)

Soil Basics | University of Maryland Extension. (n.d.). Extension.umd.edu. https://extension.umd.edu/resource/soil-basics/

Conboy, N. J. A., McDaniel, T., Ormerod, A., George, D., Gatehouse, A. M. R., Wharton, E., Donohoe, P., Curtis, R., & Tosh, C. R. (2019). Companion planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne limonene. PLOS ONE, 14(3), e0213071. https://doi.org/10.1371/journal.pone.0213071 ‌ ‌ Lv, Xuemei & Zhang, Yunxiu & Li, Huawei & Fan, Shoujin & Feng, Bo & Kong, Lingan. (2019). Wheat belt-planting in China: an innovative strategy to improve production. Plant Production Science. 23. 1-7. 10.1080/1343943X.2019.1698972.

Differences in Tilled and No-till Soils | No-till on the Plains | Agriculture Production Systems Modeling Nature. (n.d.). Www.notill.org. Retrieved May 31, 2024, from https://www.notill.org/resources/basics-of-no-till/differences-in-tilled-and-no-till-soils

Thompson, H. (2015, May 20). The Oldest Stone Tools Yet Discovered Are Unearthed in Kenya. Smithsonian Magazine. https://www.smithsonianmag.com/science-nature/oldest-known-stone-tools-unearthed-kenya-180955341/

Siyi Liu, Xiaoping Zhang, Aizhen Liang, Jinbo Zhang, Christoph Müller, Zucong Cai,Ridge tillage is likely better than no tillage for 14-year field experiment in black soils: Insights from a 15N-tracing study, Soil and Tillage Research, Volume 179, 2018, Pages 38-46, ISSN 0167-1987, https://doi.org/10.1016/j.still.2018.01.011.

What You Should Know About No-Till Planters. Dobberstein & Gerlach. Www.no-Tillfarmer.com. https://www.no-tillfarmer.com/articles/10520-what-you-should-know-about-no-till-planters#:~:text=It%20does%20the%20job%20of%20opening%20a%20slit

The Soil Health Exchange: Natural Solutions to Soil Compaction — Beyond Mechanical Means and Cover Crops. (2023, October 5). CropWatch. https://cropwatch.unl.edu/2023/soil-health-exchange-natural-solutions-soil-compaction-beyond-mechanical-cover-crops Alagbo, O.; Spaeth, M.; Saile, M.; Schumacher, M.; Gerhards, R. Weed Management in Ridge Tillage Systems—A Review. Agronomy 2022, 12, 910. https://doi.org/10.3390/agronomy1204091

Randall, G.W.; Vetsch, J.A.; Murrel, T.S. (2001). "Soybean Response to Residual Phosphorus for Various Placements and Tillage Practices" (PDF). Better Crops with Plant Food. Vol. 85, no. 4. p. 12.

Du, C.; Li, L.; Effah, Z. Effects of Straw Mulching and Reduced Tillage on Crop Production and Environment: A Review. Water 2022, 14, 2471. https://doi.org/10.3390/w14162471