Irrigated potatoes

BMPs for irrigated potatoes

Review nitrogen rate, application timing and source BMPs for irrigated potatoes.

Factors affecting N rate:

Know the type of potato you're growing
- Determinate varieties tend to use less nitrogen
- Indeterminate varieties require more N
Market class N requirements
- Fresh market (smaller) tubers require less N
- Processing (large) tubers requires more N
- Seed potatoes require less N
Know your yield goal (depends on market class, cultivar type and soil organic matter)
Projected killing date (primarily for fresh market)
Nitrogen credits (ex. previous legume crop, etc. and irrigation water if nitrate > 10 ppm)

Application timing

N demand is high in tuberization stage (Growth stage III, 50-70 days after planting)
N demand moderate to high during bulking (Growth stage IV)
- Any N applied after mid-tuber bulking will not be used efficiently
No fall N is recommended on sandy soils
Starter: 40 - 60 lb N/acre depending on variety
Hilling: N should be incorporated
Majority of soluble N should be applied 10 - 50 days after emergence

Nitrogen source

Water management

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