Recommendations for potash are based upon the yield goal, soil cation exchange capacity (CEC), and the soil-test level (Table 6). Soils with higher CEC values have a greater chance of potassium becoming unavailable to the crop and require more potash than low CEC soils. Table 6 recommendations only account for grain removal of potassium by the crop. Recommendations should be greater in fields where the straw may be baled and removed.
| Table 6. Potash Recommendations for Wheat at Various Yield Potentials, CEC, and Soil-Test Levels. | ||||||||
| Yield Potential (bu/acre) | Soil CEC |
Soil Test K (ppm)
|
||||||
| 25 | 50 | 75 | 100 | 125 | 150 | 175 | ||
|
60
|
lb K2O/acre
|
|||||||
|
10
|
155
|
115
|
80
|
40
|
40
|
0
|
0
|
|
|
15
|
195
|
150
|
110
|
65
|
40
|
25
|
0
|
|
|
20
|
240
|
190
|
140
|
90
|
40
|
40
|
0
|
|
|
80
|
|
lb K2O/acre
|
||||||
|
10
|
160
|
125
|
85
|
50
|
50
|
0
|
0
|
|
|
15
|
205
|
160
|
115
|
70
|
50
|
30
|
0
|
|
|
20
|
250
|
200
|
150
|
100
|
50
|
50
|
0
|
|
|
100
|
|
lb K2O/acre
|
||||||
|
10
|
170
|
130
|
95
|
55
|
55
|
0
|
0
|
|
|
15
|
210
|
165
|
125
|
80
|
55
|
35
|
0
|
|
|
20
|
260
|
205
|
155
|
105
|
55
|
55
|
0
|
|
Wheat is almost as sensitive to manganese deficiencies as soybean, and the problem occurs in the same areas of fields. Deficiency symptoms are usually not severe enough to be seen but will reduce yield. Maintaining soil pH between 6.5 and 7.0 will usually eliminate the problem. Manganese sulfate can be applied in a band or in contact with seeds when it is recommended by a soil test. A more practical application method is to mix some manganese sulfate (4 pounds per acre) with liquid nitrogen for application at or before green-up in the spring.