Influence of direct and residual effect of soil pH, lifting date, magnesium fertilization on potato varieties yield

Potato growing on field with soil pH 3,7 - 4,4 caused decrease of potato tubers and stalks yield, and Mg fertilization increase yield only on soils with this acidity. Among tested varieties. Bryza had the strongest reaction on soil acidity. The highest residual effect, expressed in potato tubers yield had seed-potatoes from erlier lifting date. However seed-potatoes growing on soil with pH 3.7 - 4.4 and with Mg fertilization had lower yield