Ontario Field Crop Report – week of September 9, 2019

Strategies for reducing compaction from wheel traffic

Figure 1. Tractor modified for CTF. (Photo credit: Steve Laroque, Beyond Agronomy)

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Strategies for reducing compaction from wheel traffic Farm show season is upon us! As we admire the many types and sizes of farm equipment, most of us would rather ignore the elephant in the room; a lot of new farm machinery is simply too heavy to drive across the field without risking deep, potentially permanent, subsoil compaction. Deep compaction is almost entirely the result of axle loads greater than 10 tonnes.

As you’ve likely heard at a recent compaction event near you, 60-80% of compaction damage happens from the first pass. Controlled-traffic farming (CTF) can reduce compaction damage to as little as 15 percent of a field (compared to 40-97 percent – depending on tillage system). (for more information, see “Soil Compaction: Stay off the Field Until the Soil is Ready” at fieldcropnews.com).

Controlled-traffic farming (CTF) uses field traffic lanes for repeated equipment passes, resulting in the least possible soil area impacted by compaction. CTF may require significant investment and modification of equipment (Figure 1) to fit everything on the same traffic lanes. That’s a tough sell, but the following benefits have been found where it’s practiced.


5 Top Benefits of controlled traffic

1. Reduced fuel use and 25 to 50 percent improved fuel efficiency due to reduced draft needs driving on firm wheel tracks with less rolling resistance and less wheel slip compared to soft soil. (1)

2. Yield Increases of 5 to 20 percent for corn and soybeans have been reported, in part due to improved timeliness of operations, and to improved soil health. (1, 2)

3. Improved soil structure without traffic, water infiltration rates and plant available water increase by 50 percent, seed placement and emergence and root development improve, and there is less crop variability. (3; 4)

4. Greater fertilizer use efficiency as applied fertilizer is more accessible to plant roots, and losses from soil erosion, surface runoff, and denitrification are reduced

5. Enhanced soil biology seen as 3-fold greater earthworm numbers in uncompacted soils and improved nutrient cycling from greater biological activity. (1; 5)


Start simple and make a plan

You don’t need to modify or replace all your equipment to see results from controlling traffic. Benefits can be had from any reduction in the proportion of the field compacted. The key is to match equipment operating widths and stay on the same wheel tracks as much as possible. Precise guidance systems are necessary to set and maintain AB lines year to year.

The most common CTF system is a 3:1 ratio (Figure 2a), but other ratios or compromises will also work with some overlaps to get started (Figure 2b). There are many possible configurations – the specifics will have to be worked out based on your available equipment.

Figure 2a. 3:1 CTF system with 30’ seeder (top brown) and header (bottom yellow) and 90’ sprayer (middle green)

Figure 2b. Semi-CTF system (40ft header, 60ft seeder, 120ft sprayer)(Source: Controlled Traffic Farming Technical Manual -https://tinyurl.com/y5oc34ps)

A combine is usually the most expensive piece of equipment on the farm, so it makes sense to build around it. For example, a 12-row/30’ header has an operating width of 30’, which would work well in a 3:1 system with a 90’ sprayer (Figure 3). When combined with a 12-row planter or 30’ drill and 30’ tillage implements, the number of unique wheel tracks is minimized. Assuming for the sake of the exercise that wheel tread spacing on the tractor is equal front to back, the proportion of the field trafficked decreases to around 30 percent (6).

Harvest season demands of grain cart traffic can make keeping tramlines difficult. Auger extension kits might be necessary to keep grain carts on established traffic lanes as much as possible.

Figure 3. Footprint of a 3:1 semi-CTF system with partial wheel size and spacing matching. (Source: Walczykova and Zagorda, 2017)


In summary

  • Controlling traffic means running machinery over the same parts of the field every year so that compaction damage is limited to the smallest proportion of the field
  • Start simple by making an inventory of your equipment and its working width and deciding what will fit in a reduced-traffic system
  • Make a plan for replacing equipment to fit your new system over time
  • Don’t let perfect get in the way of better!

References

1. Isbister, B., Blackwell, P., Riethmuller, G., Davies, S., Whitlock, A. & Neale, T. 2013. Controlled Traffic Farming Technical Manual. Northern Agricultural Catchments Council. Retrieved: https://www.nacc.com.au/wp-content/uploads/2015/05/NACC_Controlled_Traffic_Farming_Technical_Manual.pdf. Date: 9 Sept 2019

2. Chamen, W. C. T. 2011. The effects of low and controlled traffic systems on soil physical properties, yields and the profitability of cereal crops on a range of soil types. PhD thesis. Cranfield University, Cranfield, Bedfordshire, UK.

3. Li, Y.X., Tullberg, J.N., Freebairn, D.M. & Li, H.W. 2009. Functional relationships between soil water infiltration and wheeling and rainfall energy. Soil and Tillage Research 104(1), 156-163. DOI:10.1016/j.still.2008.10.023McHugh, A.D., Tullberg, J.M., Freebairn, D.M. 2009. Controlled traffic farming restores soil structure. Soil & Tillage Research 104 (1) 164-172. DOI:10.1016/j.still.2008.10.010.

4. Pangnakorn, U., George, D.L., Tullberg, J.N. & Gupta, M.L. 2003. Effect of tillage and traffic on earthworm populations in a Vertosol in South-East Queensland. In: Proceedings of the 16th International Soil and Tillage Research Organisation Conference, pp. 881-885. Brisbane, QLD, Australia: ISTRO.

5. Walczykova M., Zagorda M. 2017. The Possibilities of reducing the compacted field area in selected crop rotation. EJPAU 20(4), #13. DOI:10.30825/40.2017.20.4.

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