Effect of nitrogen,phosphorus, and potassium fertilizers on yield components and specific gravity of potatoes

Netted Gem potatoes were grown at four levels of N, three of P, and two of K fertilizer in metal lysimeters protected from rain by an automatic shelter. The first two increments of N fertilizer, 200 and 400lb/acre (224 and 448 kg/ha), successively increased yields by increasing the number of tubers produced. The first increment also increased the average tuber weight. With 800 lb N/acre (896 kg N/ha), tuber yield and grade of potatoes were reduced from those of the 400-lb/acre (448-kg/ha) treatment becuase the average weight per tuber was reduced. P fertilizer increased yield by increasing the average tuber weight. The increased yield due to N and P fertilizers was almost entirely in the form of Canada No. 1 potatoes. K fertilizer did not affect number or weight of tubers in this high-K soil.     

Effect of chemicals on vine kill,yield and quality of potatoes in the Red River Valley

Sodium arsenite at 9 lb, DNBP at 2.5 lb, diquat at 1 lb, paraquat at 0.5 and 1 lb and prep at 2 and 4 lb/acre were tested as vine killers for potatoes during 1963, 1964 and 1965. Based on ratings 1 or 2 days after spraying, 1 lb diquat, 1 lb paraquat and 2.5 lb/acre DNBP resulted in the quickest kill. Paraquat at 0.5 lb and sodium arsenite at 9 lb/acre were slightly slower. Prep at 2 and 4 lb/acre was consistently slowest. Some of the slower acting chemical gave equally good kill after 7 days. Chemical vine killing usually reduced yields and specific gravity by shortening the growing period. There was no effect from any of the chemicals on the color of potato chips. A slight amount of vascular discoloration did occur in tubers from all treatments. Vascular discoloration of tubers from vines treated with prep at 2 lb/acre was greater than that of tubers from vines which were cut and not sprayed. None of the vascular discoloration was severe enough to be economically important. In a second test sodium arsenite at 9 lb and diquat at 0.5, 1 and 2 lb/acre were applied as single and split applications in 1963. The major effect from the split applications was a slower rate of vine kill.