Big crops mean big residue left behind! One the positives of big residues means lots of organic matter to return to the soil, which supports soil health and return or cycling of various nutrients like P, K and micros. All of this supports microbial life, reduces the potential for soil erosion by helping to keep ground covered through the vulnerable non-growing season and supports resilient soils.
Residue Management Begins at Harvest
How do you manage those residues? Residue management has traditionally been tillage, but the first step in residue management should begin with the combine. As combines get bigger and headers get wider, its crucial to employ the right straw chopper/spreader to manage the residue coming through the combine. It is imperative that the chopper be able to spread the residue evenly over the full width of the header. It’s also very important that the chaff is spread separately than the straw when windrowing so that matting doesn’t occur in a concentrated band right behind the combine. This matting, regardless of crop, impacts seeding effectiveness, germination uniformity and early growth of the next crop. It also increases the potential for slug damage. Figure 1 shows residue being spread evenly behind the combine and to the width of the header in both wheat (chaff) and soybeans.
The real concerns for crop residues lying on the soil surface are twofold:
- Covering the soil prevents spring sunlight from drying out and warming up the soil, which may delay planting dates.
- Crop residues can interfere directly with seeding if the tillage and planting equipment is unable to cut the residue. Where the disks cannot cut the residue it gets pushed down into the seed trench and creates a barrier for good seed-soil contact that is critical to ensuring rapid and uniform germination of new seeds. This is called “hair-pinning”.
Traditional Crop Residue Management
The way most people deal with residue is to use medium to aggressive fall tillage to cut and bury residue. However, this usually results in more aggressive tillage to bury the residue because it is wet and not brittle so doesn’t cut easily with less aggressive tillage. Aggressive fall tillage often leaves the soil bare over the harsh winter period resulting in susceptibility to erosion via rainfall and wind.
Rapid Shallow Spring Tillage to Cut Overwintered Crop Residues
It is possible to use fast shallow spring tillage to cut residue ahead of planting. In spring the surface residue is brittle and the warm, drier, long days compared to fall, make the residue easier to cut. This topic is covered by Horst Bohner in a recent episode of the 2021 Ontario Virtual Diagnostic Days (time 55.00).
Residue Management by Moving Residue
But what if you didn’t have to cut the residue at all?! What if you just pushed it out of the way?
This option has been explored by Lawrence Hogan and Steve Howard of the Lucknow area in Huron County. Their goal in farming is to prevent soil erosion, promote soil health, lower production costs (equipment, time, fuel) and get superior crop yields.
They want to plant no-till directly into undisturbed soil but they still have the same problem as everyone else, how to deal with the corn stubble? One thing that started their journey was putting Calmers chopping rolls onto their corn head to precondition the residue. The second part of the equation is a tool from an outfit in Quebec. This tool shown in Figure 2 does not do any tillage. It is essentially two sets of row cleaners on 30″ spacing that will push the corn residue away from the interrow area of last year’s corn rows. The residue is pushed against the corn rows on both sides leaving an essentially bare soil area into which they plant either 10″ twin row soybeans with the corn planter, or 7″ twin rows with the drill.
The row cleaner operates at a reasonable speed with very little power and does not till the soil. They usually clear 1-2 days ahead of the planter/drill to give the bare soil time to absorb sunlight to heat and dry it into optimal seeding conditions. In this way they don’t have to deal with the corn root balls and get all the positives of no-till without the often-cited negatives. This year they were averaging around 70 bu/ac of soybeans in these fields. This system was also covered in Episode 7 of the 2020 Ontario Diagnostic Days (time 58.38).
With the residue out of the way the planter and drill can effectively plant soybeans without any tillage other than the seed openers on the planting implements (Figure 3).
This system results in excellent stands of soybeans as shown in Figure 4 where you can see the residue concentration between each set of twin rows but the area between the two rows is essentially bare and does not interfere with twin row no-till soybean planting/drilling.
This system is worth thinking about if your goal is lower costs, improved soil management and continuing to achieve top yields!
Source: Field Crop News