The Influence of Certain Fertilizing Materials on the Soil Reaction and Nutrient Level in the Potato Row during the Growing Season

This is a continuation of an experiment conducted at the Virginia Truck Experiment Station in 1948³ to determine the influence of acid and neutral fertilizers on the soil reaction in the potato row during the growing season. Results from the 1948 study indicate that fertilizers applied in bands in the potato row had a marked influence on lowering the soil reaction, and that the degree of this influence was dependent upon where the sample was taken with respect to the fertilizer bands. The purpose of this study was to determine whether fertilizer materials might differ in their influence on the soil reaction, with some possibly being more effective than others in reducing the pH of soils where there was danger of scab. A commercial 5-10-5 fertilizer was used for treatment 1, and hand mixed materials were used for the other five treatments. In treatment 2, all the nitrogen was derived from NH₄NO₃, while in treatment 3, it was derived from (NH₄)₂SO₄. In treatments 4 and 5 the nitrogen was derived from NH₄NO₃, and 50 and 100 pounds of sulfur, respectively, were added per ton of fertilizer. All of the treatments were applied at the rate of 2,000 pounds per acre except treatment 6 where the fertilizer mixture was applied at the rate of 3,000 pounds per acre. Soil samples were taken 2, 4, 8, and 12 weeks after planting at certain locations around the band. Phosphorus, potassium, pH, nitrate and conductivity tests were run on all samples. The six fertilizer mixtures markedly lowered the soil reaction in the potato row during the 1949 and 1950 growing seasons. This influence varied with the sampling location or position of the soil sample with respect to the fertilizer bands, with the greatest influence being exerted above the bands. The lowering of the pH was associated with increases in salt concentration in nitrates and in potassium. There was no important differences in the influence of the six different mixtures on the soil acidity except where the soil samples were taken from the fertilizer bands.³Dunton, E.M., Jr. et. al. Agro. Journ. 42:512 (1950).