Seed-Placed Nitrogen Fertilizer: A Second Opinion Please
Soil Texture |
1 in. spread† |
2 in. spread† |
3 in. spread† |
(disc or knife)‡ |
(spoon or hoe) |
(sweep) | |
Row spacing |
|||
6" 9" 12" |
6" 9" 12" |
6" 9" 12" | |
SBU* |
|||
17% 11% 8% |
33% 22% 17% |
50% 33% 25% | |
CEREAL SEED |
|||
Light (sandy loam) |
10 0 0 |
20 15 10 |
30 20 15 |
Medium (loam to clay loam) |
20 15 10 |
30 25 20 |
40 30 25 |
Heavy (clay to heavy clay) |
25 20 10 |
40 30 25 |
50 40 30 |
CANOLA SEED |
|||
Light (sandy loam) |
0 0 0 |
10 0 0 |
20 10 0 |
Medium (loam to clay loam) |
0 0 0 |
20 10 0 |
30 20 10 |
Heavy (clay to heavy clay) |
10 0 0 |
30 20 10 |
40 30 20 |
- Reduced yield in severe cases.
- Delayed maturity. Cereals may compensate for fewer plants by producing more tillers, which may mature at slower rates.
- Reduced weed competitiveness. Herbicide use may need to be intensified.
Another place producers and agronomists can get a second opinion on safe fertilizer rate guidelines is from a spreadsheet calculator developed by South Dakota State University (SDSU) soil specialists4. It is Excel operated and called the Seed-Placed Fertilizer Decision Aid.
This spreadsheet uses data from a number of research sources. It lets the grower or adviser set the level of stand thinning they are willing to accept. In Table 2, I have used the SDSU calculator to assess the stand risk from our rather conservative Manitoba guidelines in Table 1. I have used the same examples of furrow opening, row spacing, and the light (coarse) and heavy (fine-medium) soil textures and a moist soil condition.
Soil Texture |
1 in. spread† |
2 in. spread† |
3 in. spread† |
(disc or knife)‡ |
(spoon or hoe) |
(sweep) | |
Row spacing |
|||
6" 9" 12" |
6" 9" 12" |
6" 9" 12" | |
SBU* |
|||
17% 11% 8% |
33% 22% 17% |
50% 33% 25% | |
Estimated stand reduction % | |||
CEREAL SEED |
|||
Light (sandy loam) |
10 - - |
9 11 10 |
9 9 9 |
Heavy (clay to heavy clay) |
16 18 13 |
12 14 16 |
10 12 12 |
CANOLA SEED |
|||
Light (sandy loam) |
- - - |
15 - - |
30 15 - |
Heavy (clay to heavy clay) |
20 - - |
30 30 20 |
26 29 25 |
- Replace a portion or all of the urea as ESN polymer coated urea. The manufacturer at ESN (44-0-0) indicates the safe rate for seed placement can be three times thata of urea.
Of course there are numerous other placement and timing options for nitrogen that do not compromise crop stand and these could all be considered.