Potatoes do best in fertile, well-drained soils. However, potatoes will grow in many types of soils. Soils that are poorly drained tend to produce poorly shaped potatoes and tuber rot. Potatoes can be planted earlier on lighter, better-drained soils as these soils dry out and warm up earlier. These soils will produce more uniformly shaped potatoes but have a tendency to dry out if there isn’t a lot of rain. These soils respond well to irrigation.
The measure of soil acidity is the pH. Soils with pH levels at 7.0 are considered “neutral.”Â Soil with a pH level higher than 7.0 is considered alkaline.Â Soil with a pH lower than 7.0 is considered acid. Maine has many acid soils.
Potatoes do well across a wide range of pH, but prefer slightly acidic soils: a soil pH of 5.3 to 6.0 is typical for potato production. If your soil is more acidic than this, mixing in wood ash will help raise the pH and make your soil more alkaline.
However, higher soil pH levels are more conducive to scab, a potato disease caused by a soil-bome pathogen. If your soil has a higher pH, choose a scab-resistant variety, such as “Russet Burbank.” Fertilizers work better at neutral (7.0) pH than a lower pH.
Lime will also raise the pH of soil. A soil test will tell you how much lime to add.
The lime needs to be mixed into the soil. This is best done in the fall, but can also be done in the spring before planting.
GROWING POTATO FACTS:
Adding lime to improve the soil and reduce acidity usually increases the size of the crop, but it also increases the incidence of scab â€” a condition that affects the skin of the potato but not the eating quality.
Products that make improvements to the soil will further enhance and rebuild your soil. When we grow organically we combine basic gardening and farming procedures with an ethical philosophy of environmental preservation.