Growth and Foliar Nitrogen Status of Four Plant Species Exposed to Atmospheric Ammonia

A chamber study was conducted to evaluate the growth response and leaf nitrogen (N) status of four plant species exposed to continuous ammonia (NH₃) for 12 weeks (wk). This was intended to evaluate appropriate plant species that could be used to trap discharged NH₃ from the exhaust fans in poultry feeding operations before moving off-site. Two hundred and forty bare-root plants of four species (Juniperus virginiana (red cedar), Gleditsia triacanthos var. inermis (thornless honey locust), Populus sp. (hybrid poplar), and Phalaris arundinacea (reed canary grass) were transplanted into 4- or 8-L polyethylene pots and grown in four environmentally controlled chambers. Plants placed in two of the four chambers received continuous exposure to anhydrous NH₃ at 4 to 5 ppm while plants in another two chambers received no NH₃. In each of the four chambers, 2 to 4 plants per species received no fertilizer while the rest of the plants were fertilized with a 100 ppm solution containing 21% N, 7% phosphorus, and 7% potassium. The results showed that honey locust was the fastest-growing species. The superior growth of honey locust among all species was also supported by its total biomass, root, and root dry matter (DM) weights. For all species there was a trend for plants exposed to NH₃ to have greater leaf DM than their non-exposed counterparts at 6 (43.0 vs. 30.8%; P = 0.09) and 12 wk (47.9 vs. 36.6%; P = 0.07), and significantly greater (P ≤ 0.05) leaf N content at 6 (6.44 vs. 3.67%) and 12 wk (7.05 vs. 3.51%) when exposed to NH₃. Numerically greater leaf DM due to NH₃ exposure was also consistently measured in poplar at both sampling periods. Hybrid poplar, as well as honey locust and reed canary grass, deposited 1.5 to 2-fold greater N in their leaves than red cedar tissues as a result of NH₃ exposure compared to non-exposed plants. Regardless of the effect of NH₃ on foliar color and damage score of the plants, the increase of foliar N content (g 100 g⁻¹ of fresh foliage weight) after NH₃ exposure at 6 and 12 wk was 0.45 and 0.87 for grass,1.25 and 1.34 for locust, and 2.67 and 6.09 for poplar. However, only honey locust likely benefited from ambient NH₃ as indicated by its consistent leaf color quality and lower damage score, compared with other species that were adversely affected by atmospheric NH₃.

Key Words:

• Juniperus virginiana
• Gleditsia triacanthos
• Populus sp
• Phalaris arundinacea
• Growth
• Leaf nitrogen
• Leaf color and damage score
• Atmospheric ammonia

The assistance of farm technicians, staff, and students from the Department of Poultry Science during data collection is appreciated. David Despot, a plant research technician from the Department of Horticulture contributed significantly to the project from the initial preparation of the pots and plants up to tree management. We are also thankful to Patrick Topper, a research technologist and Dr. Eileen Wheeler from the Department of Agriculture and Bio Engineering, who helped us monitor NH₃ concentration with the photoacoustic unit.

Notes

¹Species used in this study were red cedar (Juniperus virginiana) (R), honey locust (Gleditsia triacanthos) (L), hybrid poplar (Populus sp.) (P), and reed canary grass (Phalaris arundinacea) (G).

²Mean values are not shown because they did not have significant probabilities (P ≥ 0.05).

³Measurement were taken only on red cedar, honey locust, and hybrid poplar.

¹Data in this table were derived from two fertilized plants per species per chamber.

²Species used in this study were red cedar (Juniperus virginiana) (R), honey locust (Gleditsia triacanthos) (L), hybrid poplar (Populus sp.) (P), and reed canary grass (Phalaris arundinacea) (G).

¹Data in this table were derived from two fertilized plants per species per chamber.

²Species used in this study were red cedar (Juniperus virginiana) (R), honey locust (Gleditsia triacanthos) (L), hybrid poplar (Populus sp.) (P), and reed canary grass (Phalaris arundinacea) (G).

¹Leaf color were scored from 1 (deep green), 2 (green), 3 (light green), 4 (light yellow) to 5 (yellow), while leaf damage were scored from 1 (0% damage), 2 (1 to 10% damage), 3 (11 to 20% damage), 4 (21 to 30% damage), 5 (31 to 40% damage), 6 (41 to 50% damage), and 7 (≥ 50% damage).

²Data at week 0 were not subjected to ANOVA because there were no differences within each species.

³Species used in this study were red cedar (Juniperus virginiana) (R), honey locust (Gleditsia triacanthos) (L), hybrid poplar (Populus sp.) (P), and reed canary grass (Phalaris arundinacea) (G).

⁴Mean values are not shown because they did not have significant probabilities (P ≥ 0.05).