Soil Pollution

Soil salinization occurs when water-soluble salts accumulate in the soil to a level that impacts on agricultural production, environmental health, and economics. - Salt at higher level causes soil aggregates to break down, collapsing soil pores and reducing the movement of water and air. This makes soil impermeable. - In the early stages, salinity affects the metabolism of soil organisms and reduces soil productivity, but in advanced stages it destroys all vegetation and other organisms living in the soil, consequently transforming fertile and productive land into barren and desertified lands.

**Statement 1 is incorrect:** Excessive use of nitrogen fertilizers actually reduces the need for nitrogen-fixing microorganisms in the soil. Plants can readily utilize the added nitrogen, so these microbes wouldn't need to fix atmospheric nitrogen for the plants' benefit. **Statement 2 is correct:** Nitrogenous fertilizers can release acidic compounds as they break down in the soil, leading to increased soil acidity. **Statement 3 is correct:** When applied in excess, nitrogen fertilizers (especially nitrates) can be easily washed away by rain or irrigation water. This can contaminate groundwater sources.