Effect of Spacing and Fertilization on the Yield of Potatoes

Abstract

Combined fertilizer and spacing experiments with potatoes were conducted at Corozal on Lares clay soil, at Isabela on a Coto clay soil, and at Aibonito on a Juncos clay soil. The experiments were planted in December 1953 and January 1954. The areas were located at different elevations with variation in soils and climate. The potato variety Kennebec, resistant to blight, was planted. The major results were: 1. Nitrogen did not consistently increase the yield of potatoes significantly. 2. Phosphorus increased the yield of potatoes most. 3. Potassium failed to increase the yield of potatoes significantly. 4. The Coto clay soil gave the highest yield increases attributable to the use of phosphorus fertilizers. 5. The 6-inch planting distance gave the highest potato yields in all three experiments. 6. The interaction between fertilizer and planting distance, or number of potato seed pieces planted per acre, was not significant. As the number of seed pieces increased there was no need for higher rates of fertilizer applications. 7. A highly significant correlation was obtained between number of potato seed pieces planted per acre and yield in all three experiments. This relationship indicates that, as the number of seed pieces increases, the yields also increase. 8. For all three experiments the mean reductions in yield caused by the omission of nitrogen, phosphorus, and potassium were 15.2, 28.5, and 6.3 percent, respectively. 9. Taking yield at 6-inch spacings as 100, the reduction in yield at 9 inches was 15.6, at 12 inches 20.5, at 15 inches 30.3, and at 18 inches 38.1 percent.