USDA FOREST SE 



ESEARCH NOTE NE-158 



>^rthea8tern 

 Txperiment Statioii 



FOREST SERVICE, U.S. DEPT. OF AGRICULTURE, 6816 MARKET STREET, UPPER DARBY, PA. 19082 



THE EFFECTS OF VARIOUS COMBINATIONS 

 OF NITROGEN, PHOSPHORUS, AND POTASSIUM 

 ON PAPER BIRCH SEEDLING GROWTH 



U. S. DEPT. OF AGRfCUlTURP 

 NATIONAL AGRICULTURAL l]3R\n 



RECEIVED 



CURRENT SERIAL RECcks 



Abstract. — The combined effects of various concentrations of N, P, 

 and K on the growth of paper birch seedlings were tested in sand 

 culture tests. All other elements were held constant. The best seed- 

 ling growth and dry weight of foliage generally occurred at con- 

 centrations of 400 p.p.m. N, 50 p.p.m. P or 600 p.p.m. N, 75 p.p.m. 

 P. The concentration of K had relatively little effect. The optimum 

 combination was not found but the results suggested that the 

 amount of K should be increased 



The response of paper birch seedlings to 

 varied supplies of a single element while hold- 

 ing constant the supply of all other elements 

 was reported earlier (1). However, these re- 

 sults may differ when the supply of two or 

 more elements is varied at the same time. 



To gain some insight into these interac- 

 tions, I tested the combined effect of different 

 levels of nitrogen (N), phosphorus (P), and 

 potassium (K) on the growth of paper birch 

 (Betula papyrifera Marsh) seedlings. Also, I 

 wanted to identify the combination of these 

 elements that resulted in optimum response. 



The results of this study showed that the 

 greater average heights and the greater aver- 

 age dry weights followed treatments high in 

 N and intermediate in P, with K making little 

 if any contribution at the levels tested. How- 



ever, the element concentrations for optimum 

 growth were not found. 



Methods 



The study was conducted in a growth 

 room. Seedlings were grown in 4 -inch plastic 

 pots filled with quartz sand and perlite. 

 Fluorescent and incandescent lamps provided 

 about 3,000 foot-candles of light at the top 

 of the seedlings. Day length was 16 hours. 

 Day and night temperatures were kept as 

 close as possible to 85 and 65 degrees F, 

 respectively. 



Trials of combined N, P, and K were run, 

 using a response surface design {3, 4) to 

 determine treatment effects. After a number 

 of trials, a promising treatment of 400 p.p.m. 



1 



