Major environmental problem associated with fertilizer use is contamination of water with nitrates, phosphates and potassium. Consider the following statements with this reference:
1. Nitrates easily leach into the groundwater making it dangerous to human health
2. Phosphates are most readily lost from soil because of the high solubility in water
3. Potassium causes problem of Eutrophication
Which among the above statements is / are correct?
Nutrients are lost from agricultural fields through runoff, drainage, or attachment to eroded soil particles. The amounts lost depend on the soil type and organic matter content, the climate, slope of the land, and depth to groundwater, as well as on the amount and type of fertilizer and irrigation used. The three major nutrients in fertilizers are nitrogen, phosphorus and potassium. Of these, nitrogen is the most readily lost because of its high solubility in the nitrate form. Leaching of nitrate from agricultural fields can elevate concentrations in underlying groundwater to levels unacceptable for drinking water quality.
The nitrogen from fertilizers and manures are eventually converted by bacteria in the soil to nitrates. These nitrates can be leached into the groundwater or be washed out of the soil surface into streams and rivers. High nitrate levels in drinking water are considered to be dangerous to human health. Phosphorus cannot be readily washed out of the soil, but is bound to soil particles and moves together with them. Phosphonls can therefore be washed into surface waters together with the soil that is being eroded. The phosphorus is not considered to be dangerous, but it stimulates the excessive growth of algae and t his process is called eutrophication. These algae eventually die and decompose, removing the oxygen from the water which in turn kill the fish. Potassium, the third major nutrient in fertilizers, does not cause water quality problems because it is not hazardous in drinking water and is not a limiting nutrient for growth of aquatic plants. It is tightly held by soil particles and so can be removed from fields by erosion, but generally not by leaching.
This question is a part of GKToday's Integrated IAS General Studies Module