Further studies concerning the influence of irrigation on the nitrogen, phosphorus and potash requirements of six potato varieties

Summary

Permanent fertility plots, involving three levels each of N, P and K, in factorial arrangement with and without irrigation, were used to study the fertilizer requirements of six potato varieties. Four years’ results are reported. The soil is a Sassfras fine sandy loam, which is rich in phosphorus and potash, due to many years of heavy fertilization prior to being set up as a fertilizer experiment.

Large yield increases were associated with nitrogen additions, but little response to phosphorus or potash was noted. High nitrogen was more effective with irrigation than without.

Although certain varieties responded best to different fertilizer ratios, most of the varieties can be efficiently fertilized by regulating the rate of application of a 1–1–1 ratio. This rate should be governed to supply the proper amount of nitrogen, since it is by far the most important element involved.

Green Mountain should receive only 125 pounds each per acre of N, P₂O₅ and K₂O; Cobbler, Katahdin, Pontiac and Kennebec should receive 140 pounds, and Essex should receive 160 to 170 pounds. The fertilizer rate should be adjusted somewhat to meet the particular soil conditions and irrigation practice involved on individual farms.