Effect of rate of nitrapyrin and source of N on soil pH and response of burley tobacco

Abstract

A field experiment was conducted on Maury silt loam soil (Typic Paleudalf) during 2 years to determine the effects of rate of nitrapyrin and source of N fertilizer on soil pH and response of burley tobacco (Nicotiana tabacum L.cv.^xKy‐14'). All sources of N were applied at the rate of 280 kg N ha^‐1. The information was needed to increase the efficiency of N fertilizer use and improve the growth and safety of tobacco.

Results indicated that application of a NO₃ ^‐source of N fertilizer or low rates of nitrapyrin (0.56 to 2.24 kg ha^‐1) decreased surface soil acidification and the concentration of plant Mn, while plant dry weight early in the growing season was increased. The early growth benefits noted for .nitrapyrin did not lead to increased cured leaf yields or value. Cured leaf yield and value were highest in plots receiving Ca(NO₃)₂, followed by KH₄NO₃, then urea.

Concentration of protein N, total alkaloids, and total volatile nitrogenous bases of cured leaves increased and NO₃ ^‐‐N decreased as rate of nitrapyrin increased. Total N concentration of cured leaf, however, was not significantly affected by nitrapyrin application, indicating that the proportion of absorbed N as NH₄ ⁺increased as nitrapyrin rate increased.