The correct option is 2 and 3 only because excessive use of nitrogenous fertilizers can lead to increased soil acidity due to the accumulation of ammonium ions, which can displace calcium and magnesium ions, resulting in a lower pH. Additionally, high levels of nitrogen can contribute to nitrate leaching into groundwater, posing environmental risks such as water pollution and eutrophication in aquatic ecosystems. Thus, while nitrogen-fixing microorganisms may thrive in nitrogen-rich environments, their proliferation is not a direct negative consequence of fertilizer overuse, making options 2 and 3 the accurate concerns related to agricultural practices.