Teddahlia , I agree that multi-dose applications I think are needed depending on the soil type.
This morning I felt like doing some research, so I took to Google with "research articles on growing healthy potatoes". I found what I think is a very thought provoking article on growing potatoes, but most more importantly, most of it I think will apply to Dahlias.
Potato nutrient management research: 5 things we’ve learned
October 25, 2023
In case anyone doesn't want to read the entire article, below are my notes( Excerpts from the article). But I highly recommend reading the entire article as it covers not just basics, but details some of the chemistry of how fertilizers move through the soil.
In Minnesota, potatoes are typically grown under irrigated conditions on sandy, low organic matter soils. Because of a high nutrient requirement and a relatively shallow root system (most roots are within the top foot), the crop is often responsive to applied nutrients, particularly the three primary macronutrients (nitrogen, phosphorus, and potassium).
1. Of all the essential nutrients, nitrogen (N) is the one most often limiting for potato production.
The fastest rate of N uptake occurs between tuber initiation and initial tuber bulking. Depending on cultivar, this can occur between 20-30 days after emergence.
2. Soil-borne diseases such as Verticillium wilt and root knot nematodes can limit potato root health and the ability to take up nutrients.
At the recommended N rate of 240 lbs N/acre for Russet Burbank, N uptake in fumigated plots increase by 50 lbs N/acre over non-fumigated plots…
3. Improving soil health in potato cropping systems is difficult and takes time but there are some promising strategies that may help.
Soil health is a challenge with potatoes because of the significant soil disturbance that occurs at planting, hilling, and harvest, as well as the need for fumigation to control soil-borne diseases.
4. Phosphorus (P) is a macronutrient that is essential for all forms of life. A deficiency of P in potatoes is associated with delayed vegetative growth, poor tuber set and bulking, and reduced yields. Excess P seldom affects plant growth…
…For this reason, some P fertilizer is usually recommended for potatoes even when soil test P is high. However, a P response is not always guaranteed, even on lower P testing soils.
5. Not enough (and too much) potassium can impact potato yield and quality.
Potassium (K) is an essential element required in high amounts for profitable potato production. High tuber yields can typically remove over 250 lbs K2O/acre.
The most common K source is potassium chloride (0-0-60). Chloride is also an essential element. It is considered a micronutrient but is taken up by the plant in macronutrient quantities.
