To till or not to till?

When it comes to tillage, having a goal in mind and matching it with the right piece of equipment at the right soil moisture is not always easy. Join us Aug. 1-2 to discuss considerations regarding tillage, surface drainage and manure applications.

Tillage decisions often relate to managing residue and, at the same time, reducing erosion. When manure and subsurface drainage are part of the cropping system, there are additional factors to consider.

Poorly drained fields that may pond during excessive rain events may actually create more runoff and erosion of soil and nutrients. Subsurface drainage increases water infiltration and, therefore, reduces surface runoff events. In fields such as these, any surface applied manures and fertilizers can also be vulnerable to moving off site. Injection or incorporation of manure and fertilizers are important not only for water quality, but for producers as well, so they are not literately flushing money down the creek.

Once the subsurface drainage is in place, a new concern surfaces – how to keep the nutrients from moving to the tile. Tillage will break up the macro pores, roughen the soil and allow the soil to absorb the water and nutrients before it reaches the subsurface drainage. But, how much tillage is enough to achieve the goal and how much tillage is too much? When tillage leaves only 1 percent residue on the surface, you can lose nearly 27 tons of soil per acre. Injecting manure and planting into corn stubble leaves over 65 percent of the residue in place and decreases the soil loss to just 2.4 tons per acre.

No-till situations bring another set of goals and objectives. The purist no-till person who has manure will not want to inject or incorporate manure. Incorporation for solid manure is often aggressive and decreases the surface residue – not a good fit for no-till goals. Liquid manure, on the other hand, can be easily injected with minimal soil disturbance. Some studies of solid manures actually show a reduction in runoff when surface applied obviously due to high bedding sources in these types. Again, we are looking at a balance between one goal, incorporating manure or fertilizer, and another, leaving the optimal residue on the surface to decrease erosion.

No-till systems also create better water infiltration that is often credited to macro pores from worms and decaying roots. Although wonderful soil quality factors, when liquid manures are applied without any tillage, these same positive macro pours can create conduits to the subsurface drain systems. An Iowa study has documented greater nitrogen losses in tile drains from no-tillage systems compared to conventional systems. Light to moderate tillage, enough to disrupt the macro pour channels, can reduce this risk. Now the goal becomes using enough tillage to disrupt macro pours while still maintaining as much surface residue or surface roughness as possible to reduce runoff events.

A farmers approach to tillage, surface drainage and manure application is influenced by field layout and soil type. Understanding each field, watching water move in heavy rain events and adjusting management practices to address any concerns needs to be on-going.

Attending events such as the Farm Drainage and Nutrient Management field day, August 1-2, will give producers many tools to address water, soil and nutrient movement on their farm. During the field day we will discuss these systems and how to gain the greatest nutrient value from manure with the least risk of runoff and movement to subsurface drain systems. There will be equipment vendors with displays and field demonstrations to compare how the amount of tillage that is achieved by each system, the resulting reside that is left and considerations for when and how they may fit into your goals on your farm, be it for manure, fertilizer or stand establishment. As of press time (May 29), the tillage demonstrations will include Salford, John Deere,Sunflower, Landoll vertical and Kuhn-Krausa. Check the Land Improvement Contractors of America Michigan Chapter website for more details closer to the event.

The event is located at 5211 W. Chicago Road, Jonesville, Mich., (view map) at the Bruce and Jennifer Lewis Pleasant View Farm. The field day is free and will repeat sessions over the course of the two-day event. More detailed times and events can be found at the Land Improvement Contractors of America Michigan Chapter website.

For more details on tillage, manure management and water quality, check out the Iowa State Bulletin Tillage, Manure Management, and Water Quality.

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