Table 13. Nitrogen, phosphate (P2O5) and potash (K2O) recommendations for potatoes grown on mineral soils.

Soil
Test

Yield Goal, cwt/acre

300

350

400

450

500

lb N/acre1

-

150

170

180

200

210

lb P/acre

lb P2O5 /acre1

50
100
150
200
250
300
350
400
450
500
550
600

100
90
70
60
50
30
20
20
20
0
0
0

100
90
80
60
50
40
20
20
20
20
0
0

110
90
80
70
50
40
30
20
20
20
0
0

110
100
80
70
60
40
30
20
20
20
20
0

110
100
80
70
60
40
30
20
20
20
20
20

lb K/acre

Potash recommendations for loamy sands and sandy loams
lb K2O/acre1

50
75
100
125
150
175
200
225
250
275
300
325
350
375
400

280
250
230
200
180
150
130
100
80
50
30
20
0
0
0

300
280
250
230
200
180
150
130
100
80
50
30
0
0
0

330
300
280
250
230
200
180
150
130
100
80
50
30
0
0

350
330
300
280
250
230
200
180
150
130
100
80
50
30
0

380
350
330
300
280
250
230
200
180
150
130
100
80
50
30

lb K/acre

Potash recommendations for loams, clay loams, and clays
lb K2O/acre1

50
75
100
125
150
175
200
225
250
275
300
325
350

280
250
220
190
160
130
100
60
30
0
0
0
0

310
280
250
220
190
160
130
100
60
30
0
0
0

350
310
280
250
220
190
160
130
100
60
30
0
0

380
350
310
280
250
220
190
160
130
100
60
30
0

410
380
350
310
280
250
220
190
160
130
100
60
30

1Recommendations are calculated from the following equations and rounded to the nearest 10 pounds. Credit for nitrogen supplied from manure and legumes should be given. See sections titled "Manures and Other Organic Materials" and "Nitrogen."

XN = 60 + 0.30 * YG. For Russett Burbank add 40 lb nitrogen/acre.

XP = 100 + 0.05 * YG - 0.27 * ST for soil testing less than 400
XP = 23 + 0.02 * YG - 0.03 * ST for soil testing 400 and above

XKs = 175 + 0.50 * YG -1.00 * ST
XKc = 156 + 0.63 * YG - 1.25 * ST

where:

XN = lb N/acre
XP = lb P2O5/acre
XKs = lb K2Ofor sandy loams and loamy sands
XKc = lb K2Ofor loams, clay loams and clays
YG = Yield goal, cwt/acre
ST = Soil test, lb/acre