|
Here's an example of how you can estimate the amount of residue cover you'll end up with
after planting. |
|
Example
Let's say a producer harvested 45 bu/a of soybeans (fragile residue) last year and wants
to no-till corn this spring. He will spring-apply anhydrous ammonia with closing discs,
followed by no-till planting using 1-inch, wavy (fluted) coulters. He measured 85% residue
cover after harvest, the winter was cold with little snowfall so decomposition was minimal.
Using table 6* as needed, the producer listed the estimated residue amounts following each
operation he was planning:
| Field Operation | Residue remaining (fragile)
after each operation |
|---|
After harvest (estimated or measured)
Overwinter (cold winter)
Apply anhydrous ammonia
No-till plant with one fluted coulter |
85%
80%
50%
80% |
By multiplying each of the "residue remaining" percentages, the producer can get an idea
about how much cover may be left after planting.
.85 x .80 x .50 x .80 = 27 percent cover (after planting)
Twenty-seven percent residue cover after planting may not (and often is not) enough to
provide the benefits the producer seeks. Remember, soybean residue is very fragile and even
some no-till systems will leave lower levels of cover. Note that a major reduction in cover
is likely to occur as a result of anhydrous applicator action (and possibly, the associated
closing discs). Other more conserving systems of banding liquid nitrogen might be considered
as a way to ensure more residue cover will be left after an actual field operation.
Table 6. Percentage of crop residue remaining for a sample of conservation tillage and
planting operations.
| Implement | Non-fragile** | Fragile** |
|---|
| (% Crop Residue Remaining) |
|---|
| Full-Width Tillage Equipment |
|---|
Chisel plow with straight chisel points
Chisel plow with twisted points
Springtooth harrow
Tandem disc, 5" or deeper |
50-70
40-60
60-80
40-70 |
30-40
20-30
50-70
25-40 |
| Unclassified Machines |
|---|
Anhydrous applicator w/closing discs
Paratill / Paraplow |
60-75
80-90 |
30-50
75-85 |
| Drills |
|---|
Hoe opener drills
Single disc opener drills
Double disc opener drills |
50-80
85-100
80-100 |
40-60
75-85
60-80 |
| Row Planters (equipped with) |
|---|
Ripple coulters
Fluted coulters
2 or 3 Fluted coulters
Row cleaning devices
Ridge-till planter |
75-90
65-85
60-80
60-80
40-60 |
70-85
55-80
50-75
50-60
20-40 |
| Climatic Effects (over-winter weathering) |
|---|
Following fall harvest | 80-95 | 70-80 |
*The complete version of the table is available from your local USDA
Natural Resources Conservation Service office (see NRCS National Agronomy Manual, CRM
Section, Part 503).
**See page 10 for a list of
fragile and non-fragile crops.
| 
