When is it time to till a no-till field?

Tillage is a tool for managing many things that can go wrong on a given field. It breaks compaction (if done at the right soil moisture), improves drainage (again if done at the right soil moisture), and manages inoculum loads from residue borne insects and pathogens that impact corn, soybean, and wheat. Just like pesticides and fertilizers – too much tillage also can bring another set of problems, a compacted plow layer, but more importantly, soil erosion. With any agronomic practice, including tillage, there are benefits and drawbacks.

Below is a list of potential problems associated with no-till fields.

The Pathogens

High levels of disease from pathogens that survive on and in crop residue: This year in 2016, we have had outbreaks of a number of pathogens that cause ear molds and leaf blights on corn, leaf spots and seed rots on soybean. The likes of what we have not seen for some time. All of these pathogens will overwinter during the 2017 cycle – so they will be ready to go and infect next season’s crop – the higher the inoculum the more disease that the 2017 season will see.

The Insects

Similar to pathogens, insects can also survive on and in crop residue. Some of the top culprits are true armyworm (which like the grassy weeds and cover like rye), and fall armyworm (which prefer broadleaf weeds). The populations of caterpillars are usually tough to predict since they are migratory and their presence in the spring depends on flight patterns. In addition, higher slug populations are often associated with fields that have a lot of residue. Some of these issues in no-till fields could be controlled by appropriate weed management and good spring scouting.

The Weeds

Most weeds are controlled adequately in no-tillage systems with the currently available herbicide systems. Tillage can be an effective option for management of biennial and perennial weeds – primarily those that have simple root systems (e.g. deep taproots). Tillage can also help with control of perennials with creeping roots or rhizomes, but primarily when integrated with an herbicide application. A combination of fall and spring tillage operations, or even thorough spring tillage alone, can control marestail for at least the current growing season. Tillage must completely uproot emerged marestail plants and uniformly mix the upper few inches of soil. The spring tillage should ideally occur as close to planting as possible. Be aware also that in fields where the soil seedbank is heavily infested with marestail seed, tillage can turn up seeds to the soil surface where germination and emergence is more likely.

Agronomy

Consider soil drainage. In poorly drained fields, tillage can help reduce yield losses from late planting. Tilled fields will warm up and dry out quicker in the spring. In well-drained fields, no-till is often a better option with many benefits including conservation of soil moisture, reduction in erosion and soil crusting, and reduction in fuel and labor. Corn response to tillage is strongly influenced by soil type and crop rotation. No-till cropping systems are more likely to succeed on poorly drained soils (like those in Northwest Ohio) if corn follows soybean or forage legumes rather than corn or a small grain, such as wheat. On the poorly drained silty clay loam soils, where corn follows soybean or meadow, yield differences between no-till and plowed soils are reduced. Crop rotation with soybeans generally has much less effect on corn response to tillage on the well-drained silt loam. This yield advantage to growing corn following soybean is often much more pronounced when drought occurs during the growing season.

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5 comments

  1. How about soil loss and nutrient movement into our streams, lakes and Rivers and the millions spent to remedy this. Conservation of moisture during hot dry weather, time, labor, equipment investment, loss of organic matter. These are all advantages farmers gain from eliminating tillage where they can.
    Yes it takes a little more management but the rewards are priceless. Bill

  2. Nutrient loss can come from no till just as easily. In a 50 km trip this fall I counted 136 violations more than 1/2 were from no till fields that were planted and sprayed over the edge of the ditch. We need to stop thinking in terms of till and no till and just focus on doing things right. We need to stop thinking conservation and think regenerative. Never leave soil bare – cover crop or double crop everything

  3. Yes, no-till does provide habitat for insects but it also provides habitat for predators that will attack these insects. Thar is what Paul Harvey would call the rest of the story.

  4. Where to begin? The authors have glossed over, ignored, and even incorrectly analyzed the characteristics and consequences of tillage and zero till resulting in misleading readers to incorrect conclusions. Bill, Jim, and Don have all made accurate points in helping to correct or include facts the authors omitted. Here are a few more:
    1. Drainage. The authors conclude tillage can improve drainage. Reality is that any improvement is short lived. Rainfall impact, erosion, and field traffic will not only quickly remove any drainage benefit from tillage, but will result in overall reduced drainage through destroyed soil structure. This necessitates another round of tillage, creating a death spiral.
    2. Pathogens and Insects. As one of the respondents noted, the authors gathered only half of the story. I’d say they have only half of half. As the respondents noted, there are also good insects than can control pests. Tillage kills them. The other missed half: crop rotation. Let’s stop trying to make tillage do what it can’t: control pathogen and insect build-up from years of short crop rotations. It doesn’t matter if you till or not, if you do years of continuous corn you will have issues. Pests have even figured out the corn-bean rotation. We need to get more complex by adding more crops.
    3. Long term consequences. Eventually, every loan comes due, with interest. The authors pointed out short term benefits of tillage (with some benefits such as drainage the benefits could be as short as a few weeks), but glossed over the production impacts of soil erosion and declining soil health. When solving any farm cash flow issues, a short term loan can always help. But looking from the perspective of long term farm profitability, paying back loans and interest from the past can destroy the viability of a farm, especially if you don’t figure out a way to make the farm profitable on its own. I should know, as a son of an auctioneer I watched farm after farm succumb to built up debt burdens from the past that eventually caught up. It is much better, albeit more challenging mentally, to solve problems without causing bigger problems in the future. Don’t mortgage the future to simply “get through” a current struggle.

  5. As you can read from previous comments, no-till folks do not agree with the points of the article. Here are specific comments by a person who no-tills and helps other farmers adopt no-till and cover crops. I have left out his name…
    “That is amazing, I had no idea that plowing resulted in no pathogens, no weeds, no insects and no agronomic issues. So let me get this straight, if I plow there is no need for seed applied insecticides, no need for herbicide applications no need for fungicide application, no agronomic issues (crusting, compaction, ponding) and no need to install subsurface drainage. Someone should tell “the tillage farmer” and their agronomist about this revelation, because “the tillage farmer” appears to apply more insecticide, herbicide, fungicide and tile than any no-tiller (zero-till).
    Where are the bullet points listing all the potential problems to tillage? By excluding “a list of potential problems associated with tillage” these “experts” appear ignorant or biased. Every farmer and every agronomic system has potential problems, as well as benefits. It’s the mindset that we approach a seemingly insurmountable challenge with that usually determines success.
    The National Center for Water Quality (Heidelberg) can substantiate the reduction of sediment loads and particulate P as a result of conservation tillage (i.e.: no-till) systems dating back to their introduction in the Lake Erie Watershed.”

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