Nitrogen makes up about 80% of the atmosphere. It is a macronutrient found in almost all living things and is key in determining plant growth. However, the Industrial Revolution released of nitrogen into our ecosystem turning nitrogen into nitric acid, a pollutant that acidifies terrestrial and aquatic ecosystems. A wide range of studies show that as the amount of nitric acid increases, the soil’s pH decreases which has been known to hinder some plants from growth
This experiment investigates the negative effects of nitrogen deposition on English pea (Pisum sativum) height, chlorophyll levels, harvest, and dry biomass. We hypothesized there to be no significance between the height and chlorophyll levels in relation to their treatments. We predict that nitrogen deposition will significantly decrease the harvest and dry biomass weight. Pea plants were grown in a garden setting where they received ambient rain and weekly simulated acid rain treatments. The peas were treated with either a pH of 2, 3, 4, 5 or 6. The control plants only received ambient rainfall.
Results/Conclusions
Plants watered with a pH of 2 and 3 developed brown spots and other morphological abnormalities. The plants treated with a pH of 2 were shorter but not enough to be significant. Unfortunately, our harvest data was negatively affected by unplanned herbivory. It is important to note that peas from pH 2 were brittle and shorter. The chlorophyll and height levels were different between pH treatments, but were not significant. We expected this because the previous trial had no significance in relation to pH and height, as well as pH and chlorophyll levels.
The root biomass was the most significant, with a p-value of 0.055. English peas are legumes that rely on nitrogen fixing bacteria in the ground. Other studies have shown that nitrogen deposition causes a decline in biotic community under the soil. Therefore, the peas watered with a pH of 2 and 3 likely had less bacteria to create root nodules causing them to weigh less.
Overall, there were morphological changes when English Peas were treated with a pH of 2 and 3. It was evident in the field, that nitrogen deposition was harming plant growth and development. Our results were shy of significance but suggest a strong influence of nitrogen deposition on English pea growth and biomass.