By John Pirrung, Field Technician, SWNYDLFC

One of the more common conversations I see happening between growers lately is figuring out if a no-till system is actually worth switching to. There's quite a number of moving parts to consider, and what might be a helpful change for one person could worsen an existing problem for another. This article series aims to clear up some of the confusion about the ways that tillage (or a lack thereof) impacts our fields, and how the challenges you face could determine whether it's the right move for you. 

What's all the fuss about till vs no-till? 

Though tilling may seem harmless, research shows that intensive tilling can severely damage soil over the years, reducing its productivity and workability. No-till systems are ones that prepare the seedbed differently, aiming to disturb the soil as little as possible, in order to minimize the long-term damage that tilling can cause.  

What do we get from tilling? 

We've been tilling our fields for many good reasons, based on real concerns. Whether it's to prepare the seedbed, incorporate amendments into the soil (like manure or lime), manage surface residue, or control weeds, tilling has a number of benefits. All of these issues can be tackled at the same time by frequent tilling. 

What do we lose from tilling? 

Repeated tillage can damage the structure of the soil, reducing its ability to store and cycle water and nutrients. It also makes it more difficult for beneficial fungi, bacteria, and earthworms to survive and thrive. Most notably, tilling can cause the topsoil to erode over time, especially on fields with a slope over 18%. 

What do we get from *not* tilling? 

Choosing to opt for no-till means that you can preserve your topsoil, prevent it from eroding and build it back up over time. It will also help maintain a healthier soil structure, providing better habitat for microorganisms and improving water retention. You're also saving time and fuel when you choose not to till. 

What do we lose when we don't till? 

Leaving a field untilled for many years does wonders for the soil, but also for weeds. Perennial weeds can become a problem over time if not kept in check by herbicides, and slugs enjoy fields with heavy residue. Also, the increased water retention can be an issue during wet springs, leaving the soil too wet or too cold to plant on time.  

How exactly do tilling decisions impact nutrient cycling? 

The main effect that tilling has on nutrients is that it changes how quickly and easily they can move around, both into plants and out of the soil. Let's see how it affects three different elements: 

Carbon 

Tilling the soil exposes more of the organic matter to oxygen, making it decompose faster into CO2. Rapid decomposition creates lots of available carbon in the short term, but reduces the amount of carbon left in the ground in the long term, depleting the stores faster than they can rebuild. In no-till, a slower carbon turnover allows that carbon layer to build up, and it creates a much more stable and diverse environment for beneficial microbes. In particular, the nitrogen-fixing bacteria that are associated with soybeans rely on healthy, stable soils to perform well. 

Nitrogen 

Similarly, tilling rapidly increases nitrogen mineralization, which is the process that makes it available to plants. While this is helpful in the short term, the plants can only use so much nitrogen at once, and the rest can leach out of the soil. Comparatively, in a no-till system, the nitrogen mineralizes more slowly, especially organic nitrogen from crop residues. This means less of it is immediately available to the plants, but more can be stored in the soil for long periods of time without leaching away. Nitrates in particular, which may originate from manures or fertilizers, are especially susceptible to leaching, while ammonium and organic nitrogen are less susceptible and can be stored in the soil to be used in future seasons. 

Phosphorus 

Tilling mixes phosphorus deep into the soil, making it more available to the roots. Normally, this nutrient will only permeate the first two inches of soil in a no-till system. However, mixed-in phosphorus can be eroded away alongside the rest of the tilled soil. No-till can reduce erosion, but also leaves it vulnerable to runoff as it remains more concentrated near the surface.  

How do we decide which tilling method is best for our farm? 

Consider tilling if you are: 

• Concerned that your seedbed will be too wet and/or too cold for planting 

• Dealing with heavy residue or struggling with proper seedto-soil contact 

• Battling recurring weed infestations or persistent diseases 

• Trying to minimize your use of herbicides 

• Working to break up extremely compacted soils 

• Trying to quickly incorporate bulk organic amendments into the soil 

Consider no-till if you are: 

• Trying to reduce fertilizer use and improve nutrient cycling 

• Worried about soil moisture retention and drought risk 

• Wanting to build up more organic matter and improve your soil structure 

• Farming on sloped or erosion-prone land 

• Concerned about long term soil microbial health 

• Using or considering using cover crops or other integrated pest management strategies 

What other options do I have? 

While till or no-till is often seen as a yes-or-no question, there are other hybrid options that can possibly give you the best of both worlds. Strategic tillage, which is occasionally tilling in specific areas of a field that is otherwise not tilled, can help to remedy issues that no-till brings. Similarly, there are systems for strip tillage and ridge tillage, which can offer a middleground approach that still benefits the soil. There are many more approaches to tillage between just till and no-till that could work for you. We will cover these alternatives in more detail in future articles. 

Unsurprisingly, there's no one-size-fits-all answer. Everyone will have different concerns and priorities. Consider your own main concerns: are you dealing with some particularly nasty weeds? Are you trying to cut back spending on labor, fuel, or fertilizer? Are your fields simply too wet or too dry? Think about the challenges that are costing you the most time and money, and see if any of these tilling strategies can help reduce that cost. 

Sources 

• https://crops.extension.iastat... consider-permanent-vegetation-steeply-sloping-soils 

• https://crops.extension.iastat... frequent-tillage-and-its-impact-soil-quality  

• https://extension.missouri.edu... 

• https://extension.umn.edu/soil... reducing-tillage-intensity  

• https://www.canr.msu.edu/resou...  

• https://www.sustainable-soil-m... sustainable_soil_management/ soil_management_field_crops/ conservation_tillage_effects_soil_properties.htm