Gary has some kind of knack. A lot of things seem to work for him that would not work for the rest of us.
Here's part of what cornell university says about potatoes:
"Unlike most vegetables, potatoes perform best in acid soil with pH 4.8 - 5.5. Use scab-resistant varieties with pH above 6.0. ...[ to prevent scab disease if you have had it in your garden] Lower soil pH to 5.2 with sulfur." https://www.gardening.cornell.edu/homega ... ec6be.html
Wood ash is very alkaline and consistently adding it to your soil will raise your soil pH considerably.
Gary is right that potatoes are high potassium users. But whether adding potassium actually makes any difference depends on the potassium levels in your soil already (you would have to send a soil sample to be tested, or just try adding it and see what happens). One agronomist found a significant increase in potato yield in fields that had added potassium. " However, research done in Washington State in the late 1990s showed little yield or quality response to potassium fertilization.The difference may lie in soil potassium test levels." In other words if your soil has adequate potassium levels already, adding more doesn't make much difference. https://westernfarmpress.com/vegetables/ ... d-potatoes
Sources of potassium that won't increase pH include kelp meal and other seaweed, greensand, sulfate of potash (helps lower pH). You can also bury lemon and orange rinds and banana peels in the soil in your potato patch. These are potassium sources that break down pretty quickly.
You didn't tell us where you are located. There are hardly any garden questions that can be discussed without regard to location/ climate. It makes a difference re what might have happened to your potatoes. If you are in a very hot area as I am, heat may have finished them off. Potatoes grow best when the nights stay cool. The ideal potato growing temperature is 45Â° to 80Â°F (with soil temperature not more than 70). Potatoes should be planted a month prior to your average last frost date as long as the soil is not too soggy.