Table 15. Phosphate (P2O5) and potash (K2O) recommendations for alfalfa, clover, birdsfoot trefoil and grass hay grown on mineral soils.

Yield Goal, tons/acre
Soil
Test		 Alfalfa
Other		 2
31		 3
4		 4
5		 5
6		 6
7		 7
-		 8
-
10
20
30
40
50
60
70
80
90
100		 60
40
30
20
0
0
0
0
0
0		 70
60
40
30
20
0
0
0
0
0		 90
70
60
40
30
20
0
0
0
0		 90
80
70
60
40
30
20
0
0
0		 110
90
80
70
60
40
30
20
0
0		 120
110
90
80
70
60
40
30
20
0		 130
120
110
90
80
70
60
40
30
20
lb K/acre Potash recommendations for loamy sands and sandy loams
lb K2O/acre2
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400		 240
210
190
160
140
110
90
60
40
0
0
0
0
0
0		 260
240
210
190
160
140
110
90
60
40
0
0
0
0
0		 290
260
240
210
190
160
140
110
90
60
40
0
0
0
0		 310
290
260
240
210
190
160
140
110
90
60
40
0
0
0		 340
310
290
260
240
210
190
160
140
110
90
60
40
0
0		 360
340
310
290
260
240
210
190
160
140
110
90
60
40
0		 390
360
340
310
290
260
240
210
190
160
140
110
90
60
40
lb K/acre Potash recommendations for loams, clay loams and clays
lb K2O/acre2
50
75
100
125
150
175
200
225
250
275
300
325
350		 190
150
110
80
40
0
0
0
0
0
0
0
0		 240
200
160
120
90
50
0
0
0
0
0
0
0		 290
250
210
170
140
100
60
30
0
0
0
0
0		 340
300
260
220
190
150
110
70
40
0
0
0
0		 390
350
310
270
240
200
160
120
90
50
0
0
0		 440
400
360
320
290
250
210
170
140
100
60
20
0		 490
450
410
370
340
300
260
220
190
150
110
70
40

1Use appropriate yield goal for grass hay. Use appropriate column from Table 11 for grass pasture.
2 Recommendations are calculated from the equations and rounded to the nearest 10 pounds.

For alfalfa:

where:

XP = 44 + 12.5 * YG - 1.25 * ST
XKs = 238 + 25 * YG - 1.00 * ST
XKc = 162 + 50 * YG - 1.50 * ST

For other forages:

XP = 32 + 12.5 * YG - 1.25 * ST
XKs = 213 + 25 * YG - 1.00 * ST
KKc = 112 + 50 * YG - 1.50 * ST

where:

XP = lb P2O5/acre
XKs = lb K2O/acre for sandy loams and loamy sands
XKc = lb K2O/acre for loams, clay loams and clays
YG = Yield goal, tons/acre
ST = Soil test, lb/acre