Results of fertilizer trials on potatoes in the San Luis Valley

Summary and Conclusions

Fertilizer studies, using the components N, P₂O₅ and K₂O singly and in various combinations on potatoes were completed on 17 farms over a twoyear period and on the San Luis Valley Branch Station where a permanent plot design was used over a four-year period. The experiment was so designed that when one nutrient was varied the other two were held constant.

In general, potato yields were markedly increased by the use of commercial fertilizers. In 1948 the average increase in yield per acre caused by fertilization was 85 sacks; in 1949, 84 sacks.

The major increases in yield resulted from the use of N and P₂O₅ at the rates of 40 and 160 pounds per acre (40-160-0), respectively.

The increase in yield attributable to potash is questionable. On certain farms, when used at comparatively low rates (20 pounds K₂O per acre) beneficial results may occur.

The color, grade and specific gravity of the tubers were influenced less by the fertilizer used than by the differences in environmental factors between growing seasons.