See fact sheet 0.500, Soil Sampling , for information on how to take a soil sample. Some Gardeners find that applying half of the fertilizer at planting and the other half in late June works best. If plants appear to be yellowing at midseason, apply nitrogen to the sides of the hills or add it with the irrigation water. Be careful not to apply too much nitrogen. This may delay tuber development and decrease yield.
Some Gardeners prefer to use manure.
If manure is applied, do it the year before planting potatoes. Make sure it is well aged to prevent burning and the possible introduction of diseases and weeds. Manure also promotes common scab on new tubers. Plant potatoes in rows 30 to 36 inches apart. Space seed pieces within the row at 10 to 12 inches at a depth of about 4 inches.