Potatoes

Potatoes are heavy-feeding root crops with nutrient demands that shift dramatically across their relatively short growing season. During the first two months, nitrogen drives the rapid canopy development needed to capture sunlight and fuel photosynthesis. From tuber initiation through bulking — when 60-80% of total yield is determined — the demand pivots sharply toward potassium and phosphorus. Potassium is the single most consumed nutrient by potato crops, critical for carbohydrate transport from leaves to developing tubers, starch accumulation, and skin quality. Phosphorus plays an outsized role in early root development and directly regulates tuber set — the number of tubers each plant initiates. Because potato root systems are shallow (mostly in the top 18-24 inches) with limited root hair development, they are inefficient at scavenging nutrients compared to other crops, making banded fertilizer placement at planting far more effective than broadcasting. Soil pH is a unique consideration for potatoes: while most vegetables prefer near-neutral conditions, potatoes perform best in moderately acidic soil (pH 5.0-6.5) because alkaline conditions above pH 5.5 dramatically increase the risk of common scab, a disfiguring skin disease. This means growers often intentionally maintain lower pH than ideal for other crops. Over-fertilizing with nitrogen late in the season is one of the most damaging mistakes, as it delays tuber maturity, reduces specific gravity and starch content, and produces watery tubers with poor storage quality.