Swiss forests are increasingly threatened by excessive nitrogen deposits, with nearly 90% of the forests affected. Excess nitrogen, primarily from human activities like agriculture and traffic emissions, disrupts the natural balance, leading to weakened forests and reduced growth of trees and mycorrhizal fungi. This imbalance also affects soil health, causing acidification and depletion of essential minerals.
The average nitrogen deposit in Swiss forests is 19.4 kg per hectare annually, exceeding critical limits set by the United Nations Economic Commission for Europe. The primary sources of nitrogen pollution are road traffic, industries, and agricultural activities, with ammonia emissions from agriculture being a significant contributor.
Despite regulations to reduce nitrogen oxide emissions, leading to improved air quality in high-traffic areas, ammonia emissions from agriculture have not seen a similar decline. To address this, Switzerland plans to update regulations by 2024, focusing on more efficient manure-spreading techniques to reduce ammonia volatilization.
Moreover, the nitrogen cycle continues to impact water systems, contributing to increased nitrogen levels in Swiss waters. Approximately 70,000 tonnes of nitrogen entered Swiss waters in 2020, with agriculture being a major contributor.
Efforts to mitigate this issue include covering manure storage and quickly incorporating manure into the soil after spreading. By 2030, manure reservoirs are expected to be sealed to further reduce ammonia leakage. Additionally, societal engagement is crucial in addressing these environmental challenges.